subtree(users/wpcarro): docking briefcase at '24f5a642' r/3226

git-subtree-dir: users/wpcarro
git-subtree-mainline: 464bbcb15c09813172c79820bcf526bb10cf4208
git-subtree-split: 24f5a642af3aa1627bbff977f0a101907a02c69f
Change-Id: I6105b3762b79126b3488359c95978cadb3efa789

19 files changed, 2536 insertions, 0 deletions

diff --git a/users/wpcarro/assessments/tt/client/.gitignore b/users/wpcarro/assessments/tt/client/.gitignore
new file mode 100644
index 000000000000..1cb4f3034cc3
--- /dev/null
+++ b/users/wpcarro/assessments/tt/client/.gitignore
@@ -0,0 +1,3 @@
+/elm-stuff
+/Main.min.js
+/output.css
diff --git a/users/wpcarro/assessments/tt/client/README.md b/users/wpcarro/assessments/tt/client/README.md
new file mode 100644
index 000000000000..04804ad94fac
--- /dev/null
+++ b/users/wpcarro/assessments/tt/client/README.md
@@ -0,0 +1,18 @@
+# Elm
+
+Elm has one of the best developer experiences that I'm aware of. The error
+messages are helpful and the entire experience is optimized to improve the ease
+of writing web applications.
+
+## Developing
+
+If you're interested in contributing, the following will create an environment
+in which you can develop:
+
+```shell
+$ nix-shell
+$ npx tailwindcss build index.css -o output.css
+$ elm-live -- src/Main.elm --output=Main.min.js
+```
+
+You can now view your web client at `http://localhost:8000`!
diff --git a/users/wpcarro/assessments/tt/client/dir-locals.nix b/users/wpcarro/assessments/tt/client/dir-locals.nix
new file mode 100644
index 000000000000..5c3ae08870b0
--- /dev/null
+++ b/users/wpcarro/assessments/tt/client/dir-locals.nix
@@ -0,0 +1,3 @@
+let
+  briefcase = import /home/wpcarro/briefcase {};
+in briefcase.utils.nixBufferFromShell ./shell.nix
diff --git a/users/wpcarro/assessments/tt/client/elm.json b/users/wpcarro/assessments/tt/client/elm.json
new file mode 100644
index 000000000000..c4095e118e24
--- /dev/null
+++ b/users/wpcarro/assessments/tt/client/elm.json
@@ -0,0 +1,40 @@
+{
+    "type": "application",
+    "source-directories": [
+        "src"
+    ],
+    "elm-version": "0.19.1",
+    "dependencies": {
+        "direct": {
+            "CurrySoftware/elm-datepicker": "4.0.0",
+            "elm/browser": "1.0.2",
+            "elm/core": "1.0.5",
+            "elm/html": "1.0.0",
+            "elm/http": "2.0.0",
+            "elm/json": "1.1.3",
+            "elm/random": "1.0.0",
+            "elm/svg": "1.0.1",
+            "elm/time": "1.0.0",
+            "elm/url": "1.0.0",
+            "elm-community/json-extra": "4.2.0",
+            "elm-community/list-extra": "8.2.3",
+            "elm-community/maybe-extra": "5.2.0",
+            "elm-community/random-extra": "3.1.0",
+            "justinmimbs/date": "3.2.1",
+            "krisajenkins/remotedata": "6.0.1",
+            "ryannhg/date-format": "2.3.0"
+        },
+        "indirect": {
+            "elm/bytes": "1.0.8",
+            "elm/file": "1.0.5",
+            "elm/parser": "1.1.0",
+            "elm/virtual-dom": "1.0.2",
+            "owanturist/elm-union-find": "1.0.0",
+            "rtfeldman/elm-iso8601-date-strings": "1.1.3"
+        }
+    },
+    "test-dependencies": {
+        "direct": {},
+        "indirect": {}
+    }
+}
diff --git a/users/wpcarro/assessments/tt/client/index.css b/users/wpcarro/assessments/tt/client/index.css
new file mode 100644
index 000000000000..52114e0e9fb0
--- /dev/null
+++ b/users/wpcarro/assessments/tt/client/index.css
@@ -0,0 +1,142 @@
+@tailwind base;
+@tailwind components;
+@tailwind utilities;
+
+.elm-datepicker--container {
+  position: relative;
+}
+
+.elm-datepicker--input:focus {
+  outline: 0;
+}
+
+.elm-datepicker--picker {
+  position: absolute;
+  border: 1px solid #CCC;
+  z-index: 10;
+  background-color: white;
+}
+
+.elm-datepicker--picker-header,
+.elm-datepicker--weekdays {
+  background: #F2F2F2;
+}
+
+.elm-datepicker--picker-header {
+  display: flex;
+  align-items: center;
+}
+
+.elm-datepicker--prev-container,
+.elm-datepicker--next-container {
+  flex: 0 1 auto;
+  cursor: pointer;
+}
+
+.elm-datepicker--month-container {
+  flex: 1 1 auto;
+  padding: 0.5em;
+  display: flex;
+  flex-direction: column;
+}
+
+.elm-datepicker--month,
+.elm-datepicker--year {
+  flex: 1 1 auto;
+  cursor: default;
+  text-align: center;
+}
+
+.elm-datepicker--year {
+  font-size: 0.6em;
+  font-weight: 700;
+}
+
+.elm-datepicker--prev,
+.elm-datepicker--next {
+  border: 6px solid transparent;
+  background-color: inherit;
+  display: block;
+  width: 0;
+  height: 0;
+  padding: 0 0.2em;
+}
+
+.elm-datepicker--prev {
+  border-right-color: #AAA;
+}
+
+.elm-datepicker--prev:hover {
+  border-right-color: #BBB;
+}
+
+.elm-datepicker--next {
+  border-left-color: #AAA;
+}
+
+.elm-datepicker--next:hover {
+  border-left-color: #BBB;
+}
+
+.elm-datepicker--table {
+  border-spacing: 0;
+  border-collapse: collapse;
+  font-size: 0.8em;
+}
+
+.elm-datepicker--table td {
+  width: 2em;
+  height: 2em;
+  text-align: center;
+}
+
+.elm-datepicker--row {
+  border-top: 1px solid #F2F2F2;
+}
+
+.elm-datepicker--dow {
+  border-bottom: 1px solid #CCC;
+  cursor: default;
+}
+
+.elm-datepicker--day {
+  cursor: pointer;
+}
+
+.elm-datepicker--day:hover {
+  background: #F2F2F2;
+}
+
+.elm-datepicker--disabled {
+  cursor: default;
+  color: #DDD;
+}
+
+.elm-datepicker--disabled:hover {
+  background: inherit;
+}
+
+.elm-datepicker--picked {
+  color: white;
+  background: darkblue;
+}
+
+.elm-datepicker--picked:hover {
+  background: darkblue;
+}
+
+.elm-datepicker--today {
+  font-weight: bold;
+}
+
+.elm-datepicker--other-month {
+  color: #AAA;
+}
+
+.elm-datepicker--other-month.elm-datepicker--disabled {
+  color: #EEE;
+}
+
+.elm-datepicker--other-month.elm-datepicker--picked {
+  color: white;
+}
diff --git a/users/wpcarro/assessments/tt/client/index.html b/users/wpcarro/assessments/tt/client/index.html
new file mode 100644
index 000000000000..9e6cef70dbb4
--- /dev/null
+++ b/users/wpcarro/assessments/tt/client/index.html
@@ -0,0 +1,38 @@
+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="google-signin-client_id" content="580018768696-4beppspj6cu7rhjnfgok8lbmh9a4n3ok.apps.googleusercontent.com">
+    <title>Elm SPA</title>
+    <link rel="stylesheet" type="text/css" href="./output.css" />
+    <link rel="stylesheet" type="text/css" href="./print.css" media="print" />
+    <script src="https://apis.google.com/js/platform.js" async defer></script>
+    <script src="./Main.min.js"></script>
+  </head>
+  <body class="font-serif">
+    <div id="mount"></div>
+    <script>
+     function onSignIn(googleUser) {
+       console.log(googleUser);
+     }
+
+     var app = Elm.Main.init({node: document.getElementById("mount")});
+
+     app.ports.printPage.subscribe(function() {
+       window.print();
+     });
+
+     app.ports.googleSignIn.subscribe(function() {
+       var auth2 = gapi.auth2.getAuthInstance();
+       var googleUser = auth2.signIn();
+     });
+
+     app.ports.googleSignOut.subscribe(function() {
+       var auth2 = gapi.auth2.getAuthInstance();
+       auth2.signOut().then(function() {
+         console.log('Google user successfully signed out.');
+       });
+     });
+    </script>
+  </body>
+</html>
diff --git a/users/wpcarro/assessments/tt/client/print.css b/users/wpcarro/assessments/tt/client/print.css
new file mode 100644
index 000000000000..3cfb279230cb
--- /dev/null
+++ b/users/wpcarro/assessments/tt/client/print.css
@@ -0,0 +1,3 @@
+.no-print {
+  display: none;
+}
diff --git a/users/wpcarro/assessments/tt/client/shell.nix b/users/wpcarro/assessments/tt/client/shell.nix
new file mode 100644
index 000000000000..15ac040b9462
--- /dev/null
+++ b/users/wpcarro/assessments/tt/client/shell.nix
@@ -0,0 +1,10 @@
+let
+  pkgs = import <nixpkgs> {};
+in pkgs.mkShell {
+  buildInputs = with pkgs; [
+    nodejs
+    elmPackages.elm
+    elmPackages.elm-format
+    elmPackages.elm-live
+  ];
+}
diff --git a/users/wpcarro/assessments/tt/client/src/Admin.elm b/users/wpcarro/assessments/tt/client/src/Admin.elm
new file mode 100644
index 000000000000..d95609ee15e4
--- /dev/null
+++ b/users/wpcarro/assessments/tt/client/src/Admin.elm
@@ -0,0 +1,189 @@
+module Admin exposing (render)
+
+import Common
+import Date
+import Html exposing (..)
+import Html.Attributes exposing (..)
+import Html.Events exposing (..)
+import Maybe.Extra as ME
+import RemoteData
+import State
+import Tailwind
+import UI
+import Utils
+
+
+roleToggle : State.Model -> State.Role -> Html State.Msg
+roleToggle model role =
+    div [ [ "px-1", "inline" ] |> Tailwind.use |> class ]
+        [ UI.toggleButton
+            { toggled = model.inviteRole == Just role
+            , label = State.roleToString role
+            , handleEnable = State.UpdateInviteRole (Just role)
+            , handleDisable = State.UpdateInviteRole Nothing
+            }
+        ]
+
+
+inviteUser : State.Model -> Html State.Msg
+inviteUser model =
+    div [ [ "pb-6" ] |> Tailwind.use |> class ]
+        [ UI.header 3 "Invite a user"
+        , UI.textField
+            { handleInput = State.UpdateInviteEmail
+            , inputId = "invite-email"
+            , inputValue = model.inviteEmail
+            , pholder = "Email..."
+            }
+        , div [ [ "pt-4" ] |> Tailwind.use |> class ]
+            [ roleToggle model State.User
+            , roleToggle model State.Manager
+            , roleToggle model State.Admin
+            ]
+        , UI.baseButton
+            { enabled =
+                List.all
+                    identity
+                    [ String.length model.inviteEmail > 0
+                    , ME.isJust model.inviteRole
+                    ]
+            , extraClasses = [ "my-4" ]
+            , label =
+                case model.inviteResponseStatus of
+                    RemoteData.Loading ->
+                        "Sending..."
+
+                    _ ->
+                        "Send invitation"
+            , handleClick =
+                case model.inviteRole of
+                    Nothing ->
+                        State.DoNothing
+
+                    Just role ->
+                        State.AttemptInviteUser role
+            }
+        ]
+
+
+allTrips : State.Model -> Html State.Msg
+allTrips model =
+    case model.trips of
+        RemoteData.NotAsked ->
+            UI.absentData { handleFetch = State.AttemptGetTrips }
+
+        RemoteData.Loading ->
+            UI.paragraph "Loading..."
+
+        RemoteData.Failure e ->
+            UI.paragraph ("Error: " ++ Utils.explainHttpError e)
+
+        RemoteData.Success xs ->
+            ul []
+                (xs
+                    |> List.map
+                        (\trip ->
+                            li []
+                                [ UI.paragraph (Date.toIsoString trip.startDate ++ " - " ++ Date.toIsoString trip.endDate ++ ", " ++ trip.username ++ " is going " ++ trip.destination)
+                                , UI.textButton
+                                    { label = "delete"
+                                    , handleClick = State.AttemptDeleteTrip trip
+                                    }
+                                ]
+                        )
+                )
+
+
+allUsers : State.Model -> Html State.Msg
+allUsers model =
+    case model.accounts of
+        RemoteData.NotAsked ->
+            UI.absentData { handleFetch = State.AttemptGetAccounts }
+
+        RemoteData.Loading ->
+            UI.paragraph "Loading..."
+
+        RemoteData.Failure e ->
+            UI.paragraph ("Error: " ++ Utils.explainHttpError e)
+
+        RemoteData.Success xs ->
+            ul []
+                (xs
+                    |> List.map
+                        (\account ->
+                            li []
+                                [ UI.paragraph
+                                    (account.username
+                                        ++ " - "
+                                        ++ State.roleToString account.role
+                                    )
+                                , UI.textButton
+                                    { label = "delete"
+                                    , handleClick = State.AttemptDeleteAccount account.username
+                                    }
+                                ]
+                        )
+                )
+
+
+users : List String -> Html State.Msg
+users xs =
+    ul []
+        (xs
+            |> List.map
+                (\x ->
+                    li [ [ "py-4", "flex" ] |> Tailwind.use |> class ]
+                        [ p [ [ "flex-1" ] |> Tailwind.use |> class ] [ text x ]
+                        , div [ [ "flex-1" ] |> Tailwind.use |> class ]
+                            [ UI.simpleButton
+                                { label = "Delete"
+                                , handleClick = State.AttemptDeleteAccount x
+                                }
+                            ]
+                        ]
+                )
+        )
+
+
+render : State.Model -> Html State.Msg
+render model =
+    div
+        [ [ "container"
+          , "mx-auto"
+          , "text-center"
+          ]
+            |> Tailwind.use
+            |> class
+        ]
+        [ UI.header 2 "Welcome!"
+        , div []
+            [ UI.textButton
+                { label = "Logout"
+                , handleClick = State.AttemptLogout
+                }
+            ]
+        , div [ [ "py-3" ] |> Tailwind.use |> class ]
+            [ case model.adminTab of
+                State.Accounts ->
+                    UI.textButton
+                        { label = "Switch to trips"
+                        , handleClick = State.UpdateAdminTab State.Trips
+                        }
+
+                State.Trips ->
+                    UI.textButton
+                        { label = "Switch to accounts"
+                        , handleClick = State.UpdateAdminTab State.Accounts
+                        }
+            ]
+        , case model.adminTab of
+            State.Accounts ->
+                div []
+                    [ inviteUser model
+                    , allUsers model
+                    ]
+
+            State.Trips ->
+                allTrips model
+        , Common.allErrors model
+        ]
diff --git a/users/wpcarro/assessments/tt/client/src/Common.elm b/users/wpcarro/assessments/tt/client/src/Common.elm
new file mode 100644
index 000000000000..63ba97b794ac
--- /dev/null
+++ b/users/wpcarro/assessments/tt/client/src/Common.elm
@@ -0,0 +1,37 @@
+module Common exposing (..)
+
+import Html exposing (..)
+import Maybe.Extra as ME
+import State
+import UI
+import Utils
+
+
+allErrors : State.Model -> Html State.Msg
+allErrors model =
+    div []
+        (State.allErrors
+            model
+            |> List.map
+                (\( mError, title ) ->
+                    case mError of
+                        Nothing ->
+                            text ""
+
+                        Just err ->
+                            UI.errorBanner
+                                { title = title
+                                , body = Utils.explainHttpError err
+                                }
+                )
+        )
+
+
+withSession : State.Model -> (State.Session -> Html State.Msg) -> Html State.Msg
+withSession model renderWithSession =
+    case model.session of
+        Nothing ->
+            div [] [ UI.paragraph "You need a valid session to view this page. Please attempt to log in." ]
+
+        Just session ->
+            renderWithSession session
diff --git a/users/wpcarro/assessments/tt/client/src/Login.elm b/users/wpcarro/assessments/tt/client/src/Login.elm
new file mode 100644
index 000000000000..b1a436098afd
--- /dev/null
+++ b/users/wpcarro/assessments/tt/client/src/Login.elm
@@ -0,0 +1,199 @@
+module Login exposing (render)
+
+import Common
+import Html exposing (..)
+import Html.Attributes exposing (..)
+import Html.Events exposing (..)
+import State
+import Tailwind
+import UI
+import Utils
+
+
+googleSignIn : Html State.Msg
+googleSignIn =
+    div
+        [ class "g-signin2"
+        , attribute "onsuccess" "onSignIn"
+        , onClick State.GoogleSignIn
+        ]
+        []
+
+
+loginForm : State.Model -> Html State.Msg
+loginForm model =
+    div
+        [ [ "w-full"
+          , "max-w-xs"
+          , "mx-auto"
+          ]
+            |> Tailwind.use
+            |> class
+        ]
+        [ div
+            [ [ "bg-white"
+              , "shadow-md"
+              , "rounded"
+              , "px-8"
+              , "pt-6"
+              , "pb-8"
+              , "mb-4"
+              , "text-left"
+              ]
+                |> Tailwind.use
+                |> class
+            ]
+            [ div [ [ "text-center", "pb-6" ] |> Tailwind.use |> class ]
+                [ UI.textButton
+                    { handleClick = State.ToggleLoginForm
+                    , label =
+                        case model.loginTab of
+                            State.LoginForm ->
+                                "Switch to sign up"
+
+                            State.SignUpForm ->
+                                "Switch to login"
+                    }
+                ]
+            , div
+                [ [ "mb-4" ] |> Tailwind.use |> class ]
+                [ UI.label_ { for_ = "username", text_ = "Username" }
+                , UI.textField
+                    { inputId = "Username"
+                    , pholder = "Username"
+                    , handleInput = State.UpdateUsername
+                    , inputValue = model.username
+                    }
+                ]
+            , case model.loginTab of
+                State.LoginForm ->
+                    text ""
+
+                State.SignUpForm ->
+                    div
+                        [ [ "mb-4" ] |> Tailwind.use |> class ]
+                        [ UI.label_ { for_ = "email", text_ = "Email" }
+                        , input
+                            [ [ "shadow"
+                              , "appearance-none"
+                              , "border"
+                              , "rounded"
+                              , "w-full"
+                              , "py-2"
+                              , "px-3"
+                              , "text-gray-700"
+                              , "leading-tight"
+                              , "focus:outline-none"
+                              , "focus:shadow-outline"
+                              ]
+                                |> Tailwind.use
+                                |> class
+                            , id "email"
+                            , placeholder "who@domain.tld"
+                            , onInput State.UpdateEmail
+                            ]
+                            []
+                        ]
+            , div
+                [ [ "mb-4" ] |> Tailwind.use |> class ]
+                [ UI.label_ { for_ = "password", text_ = "Password" }
+                , input
+                    [ [ "shadow"
+                      , "appearance-none"
+                      , "border"
+                      , "rounded"
+                      , "w-full"
+                      , "py-2"
+                      , "px-3"
+                      , "text-gray-700"
+                      , "leading-tight"
+                      , "focus:outline-none"
+                      , "focus:shadow-outline"
+                      ]
+                        |> Tailwind.use
+                        |> class
+                    , id "password"
+                    , type_ "password"
+                    , placeholder "******************"
+                    , onInput State.UpdatePassword
+                    ]
+                    []
+                ]
+            , case model.loginTab of
+                State.LoginForm ->
+                    div [ [ "flex", "space-around" ] |> Tailwind.use |> class ]
+                        [ UI.simpleButton
+                            { handleClick = State.AttemptLogin
+                            , label = "Login"
+                            }
+                        , div [ [ "pl-4" ] |> Tailwind.use |> class ] [ googleSignIn ]
+                        ]
+
+                State.SignUpForm ->
+                    if
+                        List.all identity
+                            [ String.length model.username > 0
+                            , String.length model.email > 0
+                            , String.length model.password > 0
+                            ]
+                    then
+                        div []
+                            [ UI.simpleButton
+                                { handleClick = State.AttemptSignUp
+                                , label = "Sign up"
+                                }
+                            ]
+
+                    else
+                        UI.disabledButton { label = "Sign up" }
+            ]
+        ]
+
+
+login :
+    State.Model
+    -> Html State.Msg
+login model =
+    div
+        [ [ "text-center"
+          , "py-20"
+          , "bg-gray-200"
+          , "h-screen"
+          ]
+            |> Tailwind.use
+            |> class
+        ]
+        [ UI.header 3 "Welcome to Trip Planner"
+        , loginForm model
+        , Common.allErrors model
+        ]
+
+
+logout : State.Model -> Html State.Msg
+logout model =
+    div
+        [ [ "text-center"
+          , "py-20"
+          , "bg-gray-200"
+          , "h-screen"
+          ]
+            |> Tailwind.use
+            |> class
+        ]
+        [ UI.header 3 "Looks like you're already signed in..."
+        , UI.simpleButton
+            { label = "Logout"
+            , handleClick = State.AttemptLogout
+            }
+        , Common.allErrors model
+        ]
+
+
+render : State.Model -> Html State.Msg
+render model =
+    case model.session of
+        Nothing ->
+            login model
+
+        Just x ->
+            logout model
diff --git a/users/wpcarro/assessments/tt/client/src/Main.elm b/users/wpcarro/assessments/tt/client/src/Main.elm
new file mode 100644
index 000000000000..de71a72db0df
--- /dev/null
+++ b/users/wpcarro/assessments/tt/client/src/Main.elm
@@ -0,0 +1,62 @@
+module Main exposing (main)
+
+import Admin
+import Browser
+import Html exposing (..)
+import Login
+import Manager
+import State
+import Url
+import User
+
+
+viewForRoute : State.Route -> (State.Model -> Html State.Msg)
+viewForRoute route =
+    case route of
+        State.Login ->
+            Login.render
+
+        State.UserHome ->
+            User.render
+
+        State.ManagerHome ->
+            Manager.render
+
+        State.AdminHome ->
+            Admin.render
+
+
+view : State.Model -> Browser.Document State.Msg
+view model =
+    { title = "TripPlanner"
+    , body =
+        [ case ( model.session, model.route ) of
+            -- Redirect to /login when someone is not authenticated.
+            -- TODO(wpcarro): We should ensure that /login shows in the URL
+            -- bar.
+            ( Nothing, _ ) ->
+                Login.render model
+
+            ( Just session, Nothing ) ->
+                Login.render model
+
+            -- Authenticated
+            ( Just session, Just route ) ->
+                if State.isAuthorized session.role route then
+                    viewForRoute route model
+
+                else
+                    text "Access denied. You are not authorized to be here. Evacuate the area immediately"
+        ]
+    }
+
+
+main =
+    Browser.application
+        { init = State.init
+        , onUrlChange = State.UrlChanged
+        , onUrlRequest = State.LinkClicked
+        , subscriptions = \_ -> Sub.none
+        , update = State.update
+        , view = view
+        }
diff --git a/users/wpcarro/assessments/tt/client/src/Manager.elm b/users/wpcarro/assessments/tt/client/src/Manager.elm
new file mode 100644
index 000000000000..cd15c99a34a8
--- /dev/null
+++ b/users/wpcarro/assessments/tt/client/src/Manager.elm
@@ -0,0 +1,70 @@
+module Manager exposing (render)
+
+import Array
+import Common
+import Html exposing (..)
+import Html.Attributes exposing (..)
+import Html.Events exposing (..)
+import RemoteData
+import State
+import Tailwind
+import UI
+import Utils
+
+
+allUsers : State.Model -> Html State.Msg
+allUsers model =
+    case model.accounts of
+        RemoteData.NotAsked ->
+            UI.absentData { handleFetch = State.AttemptGetAccounts }
+
+        RemoteData.Loading ->
+            UI.paragraph "Loading..."
+
+        RemoteData.Failure e ->
+            UI.paragraph ("Error: " ++ Utils.explainHttpError e)
+
+        RemoteData.Success xs ->
+            ul []
+                (xs
+                    |> List.map
+                        (\account ->
+                            li []
+                                [ UI.paragraph
+                                    (account.username
+                                        ++ " - "
+                                        ++ State.roleToString account.role
+                                    )
+                                , UI.textButton
+                                    { label = "delete"
+                                    , handleClick = State.AttemptDeleteAccount account.username
+                                    }
+                                ]
+                        )
+                )
+
+
+render : State.Model -> Html State.Msg
+render model =
+    Common.withSession model
+        (\session ->
+            div
+                [ class
+                    ([ "container"
+                     , "mx-auto"
+                     , "text-center"
+                     ]
+                        |> Tailwind.use
+                    )
+                ]
+                [ h1 []
+                    [ UI.header 2 ("Welcome back, " ++ session.username ++ "!")
+                    , UI.textButton
+                        { label = "Logout"
+                        , handleClick = State.AttemptLogout
+                        }
+                    , allUsers model
+                    , Common.allErrors model
+                    ]
+                ]
+        )
diff --git a/users/wpcarro/assessments/tt/client/src/Shared.elm b/users/wpcarro/assessments/tt/client/src/Shared.elm
new file mode 100644
index 000000000000..addb0a4ffd12
--- /dev/null
+++ b/users/wpcarro/assessments/tt/client/src/Shared.elm
@@ -0,0 +1,7 @@
+module Shared exposing (..)
+
+clientOrigin =
+    "http://localhost:8000"
+
+serverOrigin =
+    "http://localhost:3000"
diff --git a/users/wpcarro/assessments/tt/client/src/State.elm b/users/wpcarro/assessments/tt/client/src/State.elm
new file mode 100644
index 000000000000..b3f78bb16980
--- /dev/null
+++ b/users/wpcarro/assessments/tt/client/src/State.elm
@@ -0,0 +1,1014 @@
+port module State exposing (..)
+
+import Array exposing (Array)
+import Browser
+import Browser.Navigation as Nav
+import Date
+import DatePicker
+import Http
+import Json.Decode as JD
+import Json.Decode.Extra as JDE
+import Json.Encode as JE
+import Json.Encode.Extra as JEE
+import Process
+import RemoteData exposing (WebData)
+import Shared
+import Task
+import Time
+import Url
+import Url.Builder as UrlBuilder
+import Url.Parser exposing ((</>), Parser, int, map, oneOf, s, string)
+import Utils
+
+
+
+--------------------------------------------------------------------------------
+-- Types
+--------------------------------------------------------------------------------
+
+
+type Msg
+    = DoNothing
+    | UpdateUsername String
+    | UpdateEmail String
+    | UpdatePassword String
+    | UpdateRole String
+    | UpdateAdminTab AdminTab
+    | UpdateTripDestination String
+    | UpdateTripStartDate DatePicker.Msg
+    | UpdateTripEndDate DatePicker.Msg
+    | UpdateTripComment String
+    | UpdateEditTripDestination String
+    | UpdateEditTripComment String
+    | ClearErrors
+    | ToggleLoginForm
+    | PrintPage
+    | GoogleSignIn
+    | GoogleSignOut
+    | UpdateInviteEmail String
+    | UpdateInviteRole (Maybe Role)
+    | ReceiveTodaysDate Date.Date
+    | EditTrip Trip
+    | CancelEditTrip
+      -- SPA
+    | LinkClicked Browser.UrlRequest
+    | UrlChanged Url.Url
+      -- Outbound network
+    | AttemptGetAccounts
+    | AttemptGetTrips
+    | AttemptSignUp
+    | AttemptLogin
+    | AttemptLogout
+    | AttemptDeleteAccount String
+    | AttemptCreateTrip Date.Date Date.Date
+    | AttemptDeleteTrip Trip
+    | AttemptInviteUser Role
+    | AttemptUpdateTrip TripPK Trip
+      -- Inbound network
+    | GotAccounts (WebData (List Account))
+    | GotTrips (WebData (List Trip))
+    | GotSignUp (Result Http.Error Session)
+    | GotLogin (Result Http.Error Session)
+    | GotLogout (Result Http.Error String)
+    | GotDeleteAccount (Result Http.Error String)
+    | GotCreateTrip (Result Http.Error ())
+    | GotDeleteTrip (Result Http.Error ())
+    | GotInviteUser (Result Http.Error ())
+    | GotUpdateTrip (Result Http.Error ())
+
+
+type Route
+    = Login
+    | UserHome
+    | ManagerHome
+    | AdminHome
+
+
+type Role
+    = User
+    | Manager
+    | Admin
+
+
+type alias Account =
+    { username : String
+    , role : Role
+    }
+
+
+type alias Session =
+    { role : Role
+    , username : String
+    }
+
+
+type alias Review =
+    { rowid : Int
+    , content : String
+    , rating : Int
+    , user : String
+    , dateOfVisit : String
+    }
+
+
+type AdminTab
+    = Accounts
+    | Trips
+
+
+type LoginTab
+    = LoginForm
+    | SignUpForm
+
+
+type alias Trip =
+    { username : String
+    , destination : String
+    , startDate : Date.Date
+    , endDate : Date.Date
+    , comment : String
+    }
+
+
+type alias TripPK =
+    { username : String
+    , destination : String
+    , startDate : Date.Date
+    }
+
+
+type alias Model =
+    { route : Maybe Route
+    , url : Url.Url
+    , key : Nav.Key
+    , session : Maybe Session
+    , todaysDate : Maybe Date.Date
+    , username : String
+    , email : String
+    , password : String
+    , role : Maybe Role
+    , accounts : WebData (List Account)
+    , startDatePicker : DatePicker.DatePicker
+    , endDatePicker : DatePicker.DatePicker
+    , tripDestination : String
+    , tripStartDate : Maybe Date.Date
+    , tripEndDate : Maybe Date.Date
+    , tripComment : String
+    , trips : WebData (List Trip)
+    , editingTrip : Maybe Trip
+    , editTripDestination : String
+    , editTripComment : String
+    , adminTab : AdminTab
+    , loginTab : LoginTab
+    , inviteEmail : String
+    , inviteRole : Maybe Role
+    , inviteResponseStatus : WebData ()
+    , updateTripStatus : WebData ()
+    , loginError : Maybe Http.Error
+    , logoutError : Maybe Http.Error
+    , signUpError : Maybe Http.Error
+    , deleteUserError : Maybe Http.Error
+    , createTripError : Maybe Http.Error
+    , deleteTripError : Maybe Http.Error
+    , inviteUserError : Maybe Http.Error
+    }
+
+
+allErrors : Model -> List ( Maybe Http.Error, String )
+allErrors model =
+    [ ( model.loginError, "Error attempting to authenticate" )
+    , ( model.logoutError, "Error attempting to log out" )
+    , ( model.signUpError, "Error attempting to create your account" )
+    , ( model.deleteUserError, "Error attempting to delete a user" )
+    , ( model.createTripError, "Error attempting to create a trip" )
+    , ( model.inviteUserError, "Error attempting to invite a user" )
+    ]
+
+
+
+--------------------------------------------------------------------------------
+-- Functions
+--------------------------------------------------------------------------------
+
+
+roleToString : Role -> String
+roleToString role =
+    case role of
+        User ->
+            "user"
+
+        Manager ->
+            "manager"
+
+        Admin ->
+            "admin"
+
+
+endpoint : List String -> List UrlBuilder.QueryParameter -> String
+endpoint =
+    UrlBuilder.crossOrigin Shared.serverOrigin
+
+
+encodeRole : Role -> JE.Value
+encodeRole x =
+    case x of
+        User ->
+            JE.string "user"
+
+        Manager ->
+            JE.string "manager"
+
+        Admin ->
+            JE.string "admin"
+
+
+decodeRole : JD.Decoder Role
+decodeRole =
+    let
+        toRole : String -> JD.Decoder Role
+        toRole s =
+            case s of
+                "user" ->
+                    JD.succeed User
+
+                "manager" ->
+                    JD.succeed Manager
+
+                "admin" ->
+                    JD.succeed Admin
+
+                x ->
+                    JD.fail ("Invalid input: " ++ x)
+    in
+    JD.string |> JD.andThen toRole
+
+
+decodeSession : JD.Decoder Session
+decodeSession =
+    JD.map2
+        Session
+        (JD.field "role" decodeRole)
+        (JD.field "username" JD.string)
+
+
+encodeLoginRequest : String -> String -> JE.Value
+encodeLoginRequest username password =
+    JE.object
+        [ ( "username", JE.string username )
+        , ( "password", JE.string password )
+        ]
+
+
+login : String -> String -> Cmd Msg
+login username password =
+    Utils.postWithCredentials
+        { url = endpoint [ "login" ] []
+        , body = Http.jsonBody (encodeLoginRequest username password)
+        , expect = Http.expectJson GotLogin decodeSession
+        }
+
+
+logout : Cmd Msg
+logout =
+    Utils.getWithCredentials
+        { url = endpoint [ "logout" ] []
+        , expect = Http.expectString GotLogout
+        }
+
+
+signUp :
+    { username : String
+    , email : String
+    , password : String
+    }
+    -> Cmd Msg
+signUp { username, email, password } =
+    Utils.postWithCredentials
+        { url = endpoint [ "accounts" ] []
+        , body =
+            Http.jsonBody
+                (JE.object
+                    [ ( "username", JE.string username )
+                    , ( "email", JE.string username )
+                    , ( "password", JE.string password )
+                    , ( "role", JE.string "user" )
+                    ]
+                )
+        , expect = Http.expectJson GotSignUp decodeSession
+        }
+
+
+updateTrip : TripPK -> Trip -> Cmd Msg
+updateTrip tripKey trip =
+    Utils.putWithCredentials
+        { url = endpoint [ "trips" ] []
+        , body =
+            Http.jsonBody
+                (JE.object
+                    [ ( "tripKey", encodeTripKey tripKey )
+                    , ( "destination", JE.string trip.destination )
+                    , ( "startDate", encodeDate trip.startDate )
+                    , ( "endDate", encodeDate trip.endDate )
+                    , ( "comment", JE.string trip.comment )
+                    ]
+                )
+        , expect = Http.expectWhatever GotUpdateTrip
+        }
+
+
+inviteUser : { email : String, role : Role } -> Cmd Msg
+inviteUser { email, role } =
+    Utils.postWithCredentials
+        { url = endpoint [ "invite" ] []
+        , body =
+            Http.jsonBody
+                (JE.object
+                    [ ( "email", JE.string email )
+                    , ( "role", encodeRole role )
+                    ]
+                )
+        , expect = Http.expectWhatever GotInviteUser
+        }
+
+
+createTrip :
+    { username : String
+    , destination : String
+    , startDate : Date.Date
+    , endDate : Date.Date
+    , comment : String
+    }
+    -> Cmd Msg
+createTrip { username, destination, startDate, endDate, comment } =
+    Utils.postWithCredentials
+        { url = endpoint [ "trips" ] []
+        , body =
+            Http.jsonBody
+                (JE.object
+                    [ ( "username", JE.string username )
+                    , ( "destination", JE.string destination )
+                    , ( "startDate", encodeDate startDate )
+                    , ( "endDate", encodeDate endDate )
+                    , ( "comment", JE.string comment )
+                    ]
+                )
+        , expect = Http.expectWhatever GotCreateTrip
+        }
+
+
+deleteTrip :
+    { username : String
+    , destination : String
+    , startDate : Date.Date
+    }
+    -> Cmd Msg
+deleteTrip { username, destination, startDate } =
+    Utils.deleteWithCredentials
+        { url = endpoint [ "trips" ] []
+        , body =
+            Http.jsonBody
+                (JE.object
+                    [ ( "username", JE.string username )
+                    , ( "destination", JE.string destination )
+                    , ( "startDate", encodeDate startDate )
+                    ]
+                )
+        , expect = Http.expectWhatever GotDeleteTrip
+        }
+
+
+deleteAccount : String -> Cmd Msg
+deleteAccount username =
+    Utils.deleteWithCredentials
+        { url = endpoint [ "accounts" ] [ UrlBuilder.string "username" username ]
+        , body = Http.emptyBody
+        , expect = Http.expectString GotDeleteAccount
+        }
+
+
+decodeReview : JD.Decoder Review
+decodeReview =
+    JD.map5
+        Review
+        (JD.field "rowid" JD.int)
+        (JD.field "content" JD.string)
+        (JD.field "rating" JD.int)
+        (JD.field "user" JD.string)
+        (JD.field "timestamp" JD.string)
+
+
+encodeTripKey : TripPK -> JE.Value
+encodeTripKey tripKey =
+    JE.object
+        [ ( "username", JE.string tripKey.username )
+        , ( "destination", JE.string tripKey.destination )
+        , ( "startDate", encodeDate tripKey.startDate )
+        ]
+
+
+encodeDate : Date.Date -> JE.Value
+encodeDate date =
+    date |> Date.toIsoString |> JE.string
+
+
+decodeDate : JD.Decoder Date.Date
+decodeDate =
+    JD.string |> JD.andThen (Date.fromIsoString >> JDE.fromResult)
+
+
+fetchTrips : Cmd Msg
+fetchTrips =
+    Utils.getWithCredentials
+        { url = endpoint [ "trips" ] []
+        , expect =
+            Http.expectJson
+                (RemoteData.fromResult >> GotTrips)
+                (JD.list
+                    (JD.map5
+                        Trip
+                        (JD.field "username" JD.string)
+                        (JD.field "destination" JD.string)
+                        (JD.field "startDate" decodeDate)
+                        (JD.field "endDate" decodeDate)
+                        (JD.field "comment" JD.string)
+                    )
+                )
+        }
+
+
+fetchAccounts : Cmd Msg
+fetchAccounts =
+    Utils.getWithCredentials
+        { url = endpoint [ "accounts" ] []
+        , expect =
+            Http.expectJson
+                (RemoteData.fromResult >> GotAccounts)
+                (JD.list
+                    (JD.map2
+                        Account
+                        (JD.field "username" JD.string)
+                        (JD.field "role" decodeRole)
+                    )
+                )
+        }
+
+
+sleepAndClearErrors : Cmd Msg
+sleepAndClearErrors =
+    Process.sleep 4000
+        |> Task.perform (\_ -> ClearErrors)
+
+
+isAuthorized : Role -> Route -> Bool
+isAuthorized role route =
+    case ( role, route ) of
+        ( User, _ ) ->
+            True
+
+        ( Manager, _ ) ->
+            True
+
+        ( Admin, _ ) ->
+            True
+
+
+homeRouteForRole : Role -> String
+homeRouteForRole role =
+    case role of
+        User ->
+            "/user"
+
+        Manager ->
+            "/manager"
+
+        Admin ->
+            "/admin"
+
+
+routeParser : Parser (Route -> a) a
+routeParser =
+    oneOf
+        [ map Login (s "topic")
+        , map UserHome (s "user")
+        , map ManagerHome (s "manager")
+        , map AdminHome (s "admin")
+        ]
+
+
+{-| Set init to `prod` when going live.
+-}
+prod : () -> Url.Url -> Nav.Key -> ( Model, Cmd Msg )
+prod _ url key =
+    let
+        ( startDatePicker, startDatePickerCmd ) =
+            DatePicker.init
+
+        ( endDatePicker, endDatePickerCmd ) =
+            DatePicker.init
+    in
+    ( { route = Nothing
+      , url = url
+      , key = key
+      , session = Nothing
+      , todaysDate = Nothing
+      , username = ""
+      , email = ""
+      , password = ""
+      , role = Nothing
+      , accounts = RemoteData.NotAsked
+      , tripDestination = ""
+      , tripStartDate = Nothing
+      , tripEndDate = Nothing
+      , tripComment = ""
+      , trips = RemoteData.NotAsked
+      , editingTrip = Nothing
+      , editTripDestination = ""
+      , editTripComment = ""
+      , startDatePicker = startDatePicker
+      , endDatePicker = endDatePicker
+      , adminTab = Accounts
+      , loginTab = LoginForm
+      , inviteEmail = ""
+      , inviteRole = Nothing
+      , inviteResponseStatus = RemoteData.NotAsked
+      , updateTripStatus = RemoteData.NotAsked
+      , loginError = Nothing
+      , logoutError = Nothing
+      , signUpError = Nothing
+      , deleteUserError = Nothing
+      , createTripError = Nothing
+      , deleteTripError = Nothing
+      , inviteUserError = Nothing
+      }
+    , Cmd.batch
+        [ Cmd.map UpdateTripStartDate startDatePickerCmd
+        , Cmd.map UpdateTripEndDate endDatePickerCmd
+        , Date.today |> Task.perform ReceiveTodaysDate
+        ]
+    )
+
+
+{-| When working on a feature for the UserHome, use this.
+-}
+userHome : () -> Url.Url -> Nav.Key -> ( Model, Cmd Msg )
+userHome flags url key =
+    let
+        ( model, cmd ) =
+            prod flags url key
+    in
+    ( { model
+        | route = Just UserHome
+        , session = Just { username = "mimi", role = User }
+        , trips =
+            RemoteData.Success
+                [ { username = "mimi"
+                  , destination = "Barcelona"
+                  , startDate = Date.fromCalendarDate 2020 Time.Sep 25
+                  , endDate = Date.fromCalendarDate 2020 Time.Oct 5
+                  , comment = "Blah"
+                  }
+                , { username = "mimi"
+                  , destination = "Paris"
+                  , startDate = Date.fromCalendarDate 2021 Time.Jan 1
+                  , endDate = Date.fromCalendarDate 2021 Time.Feb 1
+                  , comment = "Bon voyage!"
+                  }
+                ]
+      }
+    , cmd
+    )
+
+
+managerHome : () -> Url.Url -> Nav.Key -> ( Model, Cmd Msg )
+managerHome flags url key =
+    let
+        ( model, cmd ) =
+            prod flags url key
+    in
+    ( { model
+        | route = Just ManagerHome
+        , session = Just { username = "bill", role = Manager }
+      }
+    , cmd
+    )
+
+
+adminHome : () -> Url.Url -> Nav.Key -> ( Model, Cmd Msg )
+adminHome flags url key =
+    let
+        ( model, cmd ) =
+            prod flags url key
+    in
+    ( { model
+        | route = Just AdminHome
+        , session = Just { username = "wpcarro", role = Admin }
+      }
+    , cmd
+    )
+
+
+port printPage : () -> Cmd msg
+
+
+port googleSignIn : () -> Cmd msg
+
+
+port googleSignOut : () -> Cmd msg
+
+
+{-| The initial state for the application.
+-}
+init : () -> Url.Url -> Nav.Key -> ( Model, Cmd Msg )
+init flags url key =
+    prod flags url key
+
+
+{-| Now that we have state, we need a function to change the state.
+-}
+update : Msg -> Model -> ( Model, Cmd Msg )
+update msg model =
+    case msg of
+        DoNothing ->
+            ( model, Cmd.none )
+
+        UpdateUsername x ->
+            ( { model | username = x }, Cmd.none )
+
+        UpdatePassword x ->
+            ( { model | password = x }, Cmd.none )
+
+        UpdateEmail x ->
+            ( { model | email = x }, Cmd.none )
+
+        UpdateAdminTab x ->
+            ( { model | adminTab = x }, Cmd.none )
+
+        UpdateRole x ->
+            let
+                maybeRole =
+                    case x of
+                        "user" ->
+                            Just User
+
+                        "manager" ->
+                            Just Manager
+
+                        "admin" ->
+                            Just Admin
+
+                        _ ->
+                            Nothing
+            in
+            ( { model | role = maybeRole }, Cmd.none )
+
+        UpdateTripDestination x ->
+            ( { model | tripDestination = x }, Cmd.none )
+
+        UpdateTripStartDate dpMsg ->
+            let
+                ( newDatePicker, dateEvent ) =
+                    DatePicker.update DatePicker.defaultSettings dpMsg model.startDatePicker
+
+                newDate =
+                    case dateEvent of
+                        DatePicker.Picked changedDate ->
+                            Just changedDate
+
+                        _ ->
+                            model.tripStartDate
+            in
+            ( { model
+                | tripStartDate = newDate
+                , startDatePicker = newDatePicker
+              }
+            , Cmd.none
+            )
+
+        UpdateTripEndDate dpMsg ->
+            let
+                ( newDatePicker, dateEvent ) =
+                    DatePicker.update DatePicker.defaultSettings dpMsg model.endDatePicker
+
+                newDate =
+                    case dateEvent of
+                        DatePicker.Picked changedDate ->
+                            Just changedDate
+
+                        _ ->
+                            model.tripEndDate
+            in
+            ( { model
+                | tripEndDate = newDate
+                , endDatePicker = newDatePicker
+              }
+            , Cmd.none
+            )
+
+        UpdateTripComment x ->
+            ( { model | tripComment = x }, Cmd.none )
+
+        UpdateEditTripDestination x ->
+            ( { model | editTripDestination = x }, Cmd.none )
+
+        UpdateEditTripComment x ->
+            ( { model | editTripComment = x }, Cmd.none )
+
+        ClearErrors ->
+            ( { model
+                | loginError = Nothing
+                , logoutError = Nothing
+                , signUpError = Nothing
+                , deleteUserError = Nothing
+                , createTripError = Nothing
+              }
+            , Cmd.none
+            )
+
+        ToggleLoginForm ->
+            ( { model
+                | loginTab =
+                    case model.loginTab of
+                        LoginForm ->
+                            SignUpForm
+
+                        SignUpForm ->
+                            LoginForm
+              }
+            , Cmd.none
+            )
+
+        PrintPage ->
+            ( model, printPage () )
+
+        GoogleSignIn ->
+            ( model, googleSignIn () )
+
+        GoogleSignOut ->
+            ( model, googleSignOut () )
+
+        UpdateInviteEmail x ->
+            ( { model | inviteEmail = x }, Cmd.none )
+
+        UpdateInviteRole mRole ->
+            ( { model | inviteRole = mRole }, Cmd.none )
+
+        ReceiveTodaysDate date ->
+            ( { model | todaysDate = Just date }, Cmd.none )
+
+        EditTrip trip ->
+            ( { model
+                | editingTrip = Just trip
+                , editTripDestination = trip.destination
+                , editTripComment = trip.comment
+              }
+            , Cmd.none
+            )
+
+        CancelEditTrip ->
+            ( { model
+                | editingTrip = Nothing
+                , editTripDestination = ""
+                , editTripComment = ""
+              }
+            , Cmd.none
+            )
+
+        LinkClicked urlRequest ->
+            case urlRequest of
+                Browser.Internal url ->
+                    ( model, Nav.pushUrl model.key (Url.toString url) )
+
+                Browser.External href ->
+                    ( model, Nav.load href )
+
+        UrlChanged url ->
+            let
+                route =
+                    Url.Parser.parse routeParser url
+            in
+            case route of
+                Just UserHome ->
+                    ( { model
+                        | url = url
+                        , route = route
+                        , trips = RemoteData.Loading
+                      }
+                    , fetchTrips
+                    )
+
+                Just ManagerHome ->
+                    ( { model
+                        | url = url
+                        , route = route
+                        , accounts = RemoteData.Loading
+                      }
+                    , fetchAccounts
+                    )
+
+                Just AdminHome ->
+                    ( { model
+                        | url = url
+                        , route = route
+                        , accounts = RemoteData.Loading
+                        , trips = RemoteData.Loading
+                      }
+                    , Cmd.batch
+                        [ fetchAccounts
+                        , fetchTrips
+                        ]
+                    )
+
+                _ ->
+                    ( { model
+                        | url = url
+                        , route = route
+                      }
+                    , Cmd.none
+                    )
+
+        -- GET /accounts
+        AttemptGetAccounts ->
+            ( { model | accounts = RemoteData.Loading }, fetchAccounts )
+
+        GotAccounts xs ->
+            ( { model | accounts = xs }, Cmd.none )
+
+        -- DELETE /accounts
+        AttemptDeleteAccount username ->
+            ( model, deleteAccount username )
+
+        GotDeleteAccount result ->
+            case result of
+                Ok _ ->
+                    ( model, fetchAccounts )
+
+                Err e ->
+                    ( { model | deleteUserError = Just e }
+                    , sleepAndClearErrors
+                    )
+
+        -- POST /trips
+        AttemptCreateTrip startDate endDate ->
+            ( model
+            , case model.session of
+                Nothing ->
+                    Cmd.none
+
+                Just session ->
+                    createTrip
+                        { username = session.username
+                        , destination = model.tripDestination
+                        , startDate = startDate
+                        , endDate = endDate
+                        , comment = model.tripComment
+                        }
+            )
+
+        GotCreateTrip result ->
+            case result of
+                Ok _ ->
+                    ( { model
+                        | tripDestination = ""
+                        , tripStartDate = Nothing
+                        , tripEndDate = Nothing
+                        , tripComment = ""
+                      }
+                    , fetchTrips
+                    )
+
+                Err e ->
+                    ( { model
+                        | createTripError = Just e
+                        , tripDestination = ""
+                        , tripStartDate = Nothing
+                        , tripEndDate = Nothing
+                        , tripComment = ""
+                      }
+                    , sleepAndClearErrors
+                    )
+
+        -- DELETE /trips
+        AttemptDeleteTrip trip ->
+            ( model
+            , deleteTrip
+                { username = trip.username
+                , destination = trip.destination
+                , startDate = trip.startDate
+                }
+            )
+
+        GotDeleteTrip result ->
+            case result of
+                Ok _ ->
+                    ( model, fetchTrips )
+
+                Err e ->
+                    ( { model | deleteTripError = Just e }
+                    , sleepAndClearErrors
+                    )
+
+        AttemptInviteUser role ->
+            ( { model | inviteResponseStatus = RemoteData.Loading }
+            , inviteUser
+                { email = model.inviteEmail
+                , role = role
+                }
+            )
+
+        GotInviteUser result ->
+            case result of
+                Ok _ ->
+                    ( { model
+                        | inviteEmail = ""
+                        , inviteRole = Nothing
+                        , inviteResponseStatus = RemoteData.Success ()
+                      }
+                    , Cmd.none
+                    )
+
+                Err e ->
+                    ( { model
+                        | inviteUserError = Just e
+                        , inviteResponseStatus = RemoteData.Failure e
+                      }
+                    , sleepAndClearErrors
+                    )
+
+        -- PATCH /trips
+        AttemptUpdateTrip tripKey trip ->
+            ( { model | updateTripStatus = RemoteData.Loading }
+            , updateTrip tripKey trip
+            )
+
+        GotUpdateTrip result ->
+            case result of
+                Ok _ ->
+                    ( { model | updateTripStatus = RemoteData.Success () }
+                    , fetchTrips
+                    )
+
+                Err e ->
+                    ( { model | updateTripStatus = RemoteData.Failure e }
+                    , Cmd.none
+                    )
+
+        -- POST /accounts
+        AttemptSignUp ->
+            ( model
+            , signUp
+                { username = model.username
+                , email = model.email
+                , password = model.password
+                }
+            )
+
+        GotSignUp result ->
+            case result of
+                Ok session ->
+                    ( { model | session = Just session }
+                    , Nav.pushUrl model.key (homeRouteForRole session.role)
+                    )
+
+                Err x ->
+                    ( { model | signUpError = Just x }
+                    , sleepAndClearErrors
+                    )
+
+        -- GET /trips
+        AttemptGetTrips ->
+            ( { model | trips = RemoteData.Loading }, fetchTrips )
+
+        GotTrips xs ->
+            ( { model | trips = xs }, Cmd.none )
+
+        -- POST /login
+        AttemptLogin ->
+            ( model, login model.username model.password )
+
+        GotLogin result ->
+            case result of
+                Ok session ->
+                    ( { model | session = Just session }
+                    , Nav.pushUrl model.key (homeRouteForRole session.role)
+                    )
+
+                Err x ->
+                    ( { model | loginError = Just x }
+                    , sleepAndClearErrors
+                    )
+
+        -- GET /logout
+        AttemptLogout ->
+            ( model, logout )
+
+        GotLogout result ->
+            case result of
+                Ok _ ->
+                    ( { model | session = Nothing }
+                    , Nav.pushUrl model.key "/login"
+                    )
+
+                Err e ->
+                    ( { model | logoutError = Just e }
+                    , sleepAndClearErrors
+                    )
diff --git a/users/wpcarro/assessments/tt/client/src/Tailwind.elm b/users/wpcarro/assessments/tt/client/src/Tailwind.elm
new file mode 100644
index 000000000000..57d419db5a82
--- /dev/null
+++ b/users/wpcarro/assessments/tt/client/src/Tailwind.elm
@@ -0,0 +1,29 @@
+module Tailwind exposing (..)
+
+{-| Functions to make Tailwind development in Elm even more pleasant.
+-}
+
+
+{-| Conditionally use `class` selection when `condition` is true.
+-}
+when : Bool -> String -> String
+when condition class =
+    if condition then
+        class
+
+    else
+        ""
+
+
+if_ : Bool -> String -> String -> String
+if_ condition whenTrue whenFalse =
+    if condition then
+        whenTrue
+
+    else
+        whenFalse
+
+
+use : List String -> String
+use styles =
+    String.join " " styles
diff --git a/users/wpcarro/assessments/tt/client/src/UI.elm b/users/wpcarro/assessments/tt/client/src/UI.elm
new file mode 100644
index 000000000000..7f8f379795f7
--- /dev/null
+++ b/users/wpcarro/assessments/tt/client/src/UI.elm
@@ -0,0 +1,318 @@
+module UI exposing (..)
+
+import Date
+import DatePicker exposing (defaultSettings)
+import Html exposing (..)
+import Html.Attributes exposing (..)
+import Html.Events exposing (..)
+import State
+import Tailwind
+
+
+label_ : { for_ : String, text_ : String } -> Html msg
+label_ { for_, text_ } =
+    label
+        [ [ "block"
+          , "text-gray-700"
+          , "text-sm"
+          , "font-bold"
+          , "mb-2"
+          ]
+            |> Tailwind.use
+            |> class
+        , for for_
+        ]
+        [ text text_ ]
+
+
+errorBanner : { title : String, body : String } -> Html msg
+errorBanner { title, body } =
+    div
+        [ [ "text-left"
+          , "fixed"
+          , "container"
+          , "top-0"
+          , "mt-6"
+          ]
+            |> Tailwind.use
+            |> class
+        , style "left" "50%"
+
+        -- TODO(wpcarro): Consider supporting breakpoints, but for now
+        -- don't.
+        , style "width" "800px"
+        , style "margin-left" "-400px"
+        ]
+        [ div
+            [ [ "bg-red-500"
+              , "text-white"
+              , "font-bold"
+              , "rounded-t"
+              , "px-4"
+              , "py-2"
+              ]
+                |> Tailwind.use
+                |> class
+            ]
+            [ text title ]
+        , div
+            [ [ "border"
+              , "border-t-0"
+              , "border-red-400"
+              , "rounded-b"
+              , "bg-red-100"
+              , "px-4"
+              , "py-3"
+              , "text-red-700"
+              ]
+                |> Tailwind.use
+                |> class
+            ]
+            [ p [] [ text body ] ]
+        ]
+
+
+baseButton :
+    { label : String
+    , enabled : Bool
+    , handleClick : msg
+    , extraClasses : List String
+    }
+    -> Html msg
+baseButton { label, enabled, handleClick, extraClasses } =
+    button
+        [ [ if enabled then
+                "bg-blue-500"
+
+            else
+                "bg-gray-500"
+          , if enabled then
+                "hover:bg-blue-700"
+
+            else
+                ""
+          , if enabled then
+                ""
+
+            else
+                "cursor-not-allowed"
+          , "text-white"
+          , "font-bold"
+          , "py-1"
+          , "shadow-lg"
+          , "px-4"
+          , "rounded"
+          , "focus:outline-none"
+          , "focus:shadow-outline"
+          ]
+            ++ extraClasses
+            |> Tailwind.use
+            |> class
+        , onClick handleClick
+        , disabled (not enabled)
+        ]
+        [ text label ]
+
+
+simpleButton :
+    { label : String
+    , handleClick : msg
+    }
+    -> Html msg
+simpleButton { label, handleClick } =
+    baseButton
+        { label = label
+        , enabled = True
+        , handleClick = handleClick
+        , extraClasses = []
+        }
+
+
+disabledButton :
+    { label : String }
+    -> Html State.Msg
+disabledButton { label } =
+    baseButton
+        { label = label
+        , enabled = False
+        , handleClick = State.DoNothing
+        , extraClasses = []
+        }
+
+
+textButton :
+    { label : String
+    , handleClick : msg
+    }
+    -> Html msg
+textButton { label, handleClick } =
+    button
+        [ [ "text-blue-600"
+          , "hover:text-blue-500"
+          , "font-bold"
+          , "hover:underline"
+          , "focus:outline-none"
+          ]
+            |> Tailwind.use
+            |> class
+        , onClick handleClick
+        ]
+        [ text label ]
+
+
+textField :
+    { pholder : String
+    , inputId : String
+    , handleInput : String -> msg
+    , inputValue : String
+    }
+    -> Html msg
+textField { pholder, inputId, handleInput, inputValue } =
+    input
+        [ [ "shadow"
+          , "appearance-none"
+          , "border"
+          , "rounded"
+          , "w-full"
+          , "py-2"
+          , "px-3"
+          , "text-gray-700"
+          , "leading-tight"
+          , "focus:outline-none"
+          , "focus:shadow-outline"
+          ]
+            |> Tailwind.use
+            |> class
+        , id inputId
+        , value inputValue
+        , placeholder pholder
+        , onInput handleInput
+        ]
+        []
+
+
+toggleButton :
+    { toggled : Bool
+    , label : String
+    , handleEnable : msg
+    , handleDisable : msg
+    }
+    -> Html msg
+toggleButton { toggled, label, handleEnable, handleDisable } =
+    button
+        [ [ if toggled then
+                "bg-blue-700"
+
+            else
+                "bg-blue-500"
+          , "hover:bg-blue-700"
+          , "text-white"
+          , "font-bold"
+          , "py-2"
+          , "px-4"
+          , "rounded"
+          , "focus:outline-none"
+          , "focus:shadow-outline"
+          ]
+            |> Tailwind.use
+            |> class
+        , onClick
+            (if toggled then
+                handleDisable
+
+             else
+                handleEnable
+            )
+        ]
+        [ text label ]
+
+
+paragraph : String -> Html msg
+paragraph x =
+    p [ [ "text-xl" ] |> Tailwind.use |> class ] [ text x ]
+
+
+header : Int -> String -> Html msg
+header which x =
+    let
+        hStyles =
+            case which of
+                1 ->
+                    [ "text-6xl"
+                    , "py-12"
+                    ]
+
+                2 ->
+                    [ "text-3xl"
+                    , "py-6"
+                    ]
+
+                _ ->
+                    [ "text-2xl"
+                    , "py-2"
+                    ]
+    in
+    h1
+        [ hStyles
+            ++ [ "font-bold"
+               , "text-gray-700"
+               ]
+            |> Tailwind.use
+            |> class
+        ]
+        [ text x ]
+
+
+link : String -> String -> Html msg
+link path label =
+    a
+        [ href path
+        , [ "underline"
+          , "text-blue-600"
+          , "text-xl"
+          ]
+            |> Tailwind.use
+            |> class
+        ]
+        [ text label ]
+
+
+absentData : { handleFetch : msg } -> Html msg
+absentData { handleFetch } =
+    div []
+        [ paragraph "Welp... it looks like you've caught us in a state that we considered impossible: we did not fetch the data upon which this page depends. Maybe you can help us out by clicking the super secret, highly privileged \"Fetch data\" button below (we don't normally show people this)."
+        , div [ [ "py-4" ] |> Tailwind.use |> class ]
+            [ simpleButton
+                { label = "Fetch data"
+                , handleClick = handleFetch
+                }
+            ]
+        ]
+
+
+datePicker :
+    { mDate : Maybe Date.Date
+    , prompt : String
+    , prefix : String
+    , picker : DatePicker.DatePicker
+    , onUpdate : DatePicker.Msg -> State.Msg
+    }
+    -> Html State.Msg
+datePicker { mDate, prompt, prefix, picker, onUpdate } =
+    let
+        settings =
+            { defaultSettings
+                | placeholder = prompt
+                , inputClassList =
+                    [ ( "text-center", True )
+                    , ( "py-2", True )
+                    ]
+            }
+    in
+    div [ [ "w-1/2", "py-4", "mx-auto" ] |> Tailwind.use |> class ]
+        [ DatePicker.view mDate settings picker |> Html.map onUpdate ]
+
+
+wrapNoPrint : Html State.Msg -> Html State.Msg
+wrapNoPrint component =
+    div [ [ "no-print" ] |> Tailwind.use |> class ] [ component ]
diff --git a/users/wpcarro/assessments/tt/client/src/User.elm b/users/wpcarro/assessments/tt/client/src/User.elm
new file mode 100644
index 000000000000..87871b78dbc4
--- /dev/null
+++ b/users/wpcarro/assessments/tt/client/src/User.elm
@@ -0,0 +1,245 @@
+module User exposing (render)
+
+import Common
+import Date
+import DatePicker
+import Html exposing (..)
+import Html.Attributes exposing (..)
+import Html.Events exposing (..)
+import Maybe.Extra as ME
+import RemoteData
+import State
+import Tailwind
+import UI
+import Utils
+
+
+createTrip : State.Model -> Html State.Msg
+createTrip model =
+    div []
+        [ UI.header 3 "Plan Upcoming Trip"
+        , UI.textField
+            { pholder = "Where are you going?"
+            , inputId = "destination"
+            , handleInput = State.UpdateTripDestination
+            , inputValue = model.tripDestination
+            }
+        , div [ [ "flex" ] |> Tailwind.use |> class ]
+            [ UI.datePicker
+                { mDate = model.tripStartDate
+                , prompt = "Set departure date"
+                , prefix = "Departure: "
+                , picker = model.startDatePicker
+                , onUpdate = State.UpdateTripStartDate
+                }
+            , UI.datePicker
+                { mDate = model.tripEndDate
+                , prompt = "Set return date"
+                , prefix = "Return: "
+                , picker = model.endDatePicker
+                , onUpdate = State.UpdateTripEndDate
+                }
+            ]
+        , UI.textField
+            { pholder = "Comments?"
+            , inputId = "comment"
+            , handleInput = State.UpdateTripComment
+            , inputValue = model.tripComment
+            }
+        , UI.baseButton
+            { enabled =
+                List.all
+                    identity
+                    [ String.length model.tripDestination > 0
+                    , String.length model.tripComment > 0
+                    , ME.isJust model.tripStartDate
+                    , ME.isJust model.tripEndDate
+                    ]
+            , extraClasses = [ "my-4" ]
+            , handleClick =
+                case ( model.tripStartDate, model.tripEndDate ) of
+                    ( Nothing, _ ) ->
+                        State.DoNothing
+
+                    ( _, Nothing ) ->
+                        State.DoNothing
+
+                    ( Just startDate, Just endDate ) ->
+                        State.AttemptCreateTrip startDate endDate
+            , label = "Schedule trip"
+            }
+        ]
+
+
+renderEditTrip : State.Model -> State.Trip -> Html State.Msg
+renderEditTrip model trip =
+    li []
+        [ div []
+            [ UI.textField
+                { handleInput = State.UpdateEditTripDestination
+                , inputId = "edit-trip-destination"
+                , inputValue = model.editTripDestination
+                , pholder = "Destination"
+                }
+            , UI.textField
+                { handleInput = State.UpdateEditTripComment
+                , inputId = "edit-trip-comment"
+                , inputValue = model.editTripComment
+                , pholder = "Comment"
+                }
+            ]
+        , div []
+            [ UI.baseButton
+                { enabled =
+                    case model.updateTripStatus of
+                        RemoteData.Loading ->
+                            False
+
+                        _ ->
+                            True
+                , extraClasses = []
+                , label =
+                    case model.updateTripStatus of
+                        RemoteData.Loading ->
+                            "Saving..."
+
+                        _ ->
+                            "Save"
+                , handleClick =
+                    State.AttemptUpdateTrip
+                        { username = trip.username
+                        , destination = trip.destination
+                        , startDate = trip.startDate
+                        }
+                        { username = trip.username
+                        , destination = model.editTripDestination
+                        , startDate = trip.startDate
+                        , endDate = trip.endDate
+                        , comment = model.editTripComment
+                        }
+                }
+            , UI.simpleButton
+                { label = "Cancel"
+                , handleClick = State.CancelEditTrip
+                }
+            ]
+        ]
+
+
+renderTrip : Date.Date -> State.Trip -> Html State.Msg
+renderTrip today trip =
+    li
+        [ [ "py-2" ]
+            |> Tailwind.use
+            |> class
+        ]
+        [ if Date.compare today trip.startDate == GT then
+            UI.paragraph
+                (String.fromInt (Date.diff Date.Days trip.startDate today)
+                    ++ " days until you're travelling to "
+                    ++ trip.destination
+                    ++ " for "
+                    ++ String.fromInt
+                        (Date.diff
+                            Date.Days
+                            trip.startDate
+                            trip.endDate
+                        )
+                    ++ " days."
+                )
+
+          else
+            UI.paragraph
+                (String.fromInt (Date.diff Date.Days today trip.endDate)
+                    ++ " days ago you returned from your trip to "
+                    ++ trip.destination
+                )
+        , UI.paragraph ("\"" ++ trip.comment ++ "\"")
+        , UI.wrapNoPrint
+            (UI.textButton
+                { label = "Edit"
+                , handleClick = State.EditTrip trip
+                }
+            )
+        , UI.wrapNoPrint
+            (UI.textButton
+                { label = "Delete"
+                , handleClick = State.AttemptDeleteTrip trip
+                }
+            )
+        ]
+
+
+trips : State.Model -> Html State.Msg
+trips model =
+    div []
+        [ UI.header 3 "Your Trips"
+        , case model.trips of
+            RemoteData.NotAsked ->
+                UI.paragraph "Somehow we've reached the user home page without requesting your trips data. Please report this to our engineering team at bugs@tripplaner.tld"
+
+            RemoteData.Loading ->
+                UI.paragraph "Loading your trips..."
+
+            RemoteData.Failure e ->
+                UI.paragraph ("Error: " ++ Utils.explainHttpError e)
+
+            RemoteData.Success xs ->
+                case model.todaysDate of
+                    Nothing ->
+                        text ""
+
+                    Just today ->
+                        div [ [ "mb-10" ] |> Tailwind.use |> class ]
+                            [ ul [ [ "my-4" ] |> Tailwind.use |> class ]
+                                (xs
+                                    |> List.sortWith (\x y -> Date.compare y.startDate x.startDate)
+                                    |> List.map
+                                        (\trip ->
+                                            case model.editingTrip of
+                                                Nothing ->
+                                                    renderTrip today trip
+
+                                                Just x ->
+                                                    if x == trip then
+                                                        renderEditTrip model trip
+
+                                                    else
+                                                        renderTrip today trip
+                                        )
+                                )
+                            , UI.wrapNoPrint
+                                (UI.simpleButton
+                                    { label = "Print iternary"
+                                    , handleClick = State.PrintPage
+                                    }
+                                )
+                            ]
+        ]
+
+
+render : State.Model -> Html State.Msg
+render model =
+    Common.withSession model
+        (\session ->
+            div
+                [ class
+                    ([ "container"
+                     , "mx-auto"
+                     , "text-center"
+                     ]
+                        |> Tailwind.use
+                    )
+                ]
+                [ UI.wrapNoPrint (UI.header 2 ("Welcome, " ++ session.username ++ "!"))
+                , UI.wrapNoPrint (createTrip model)
+                , trips model
+                , UI.wrapNoPrint
+                    (UI.textButton
+                        { label = "Logout"
+                        , handleClick = State.AttemptLogout
+                        }
+                    )
+                , Common.allErrors model
+                ]
+        )
diff --git a/users/wpcarro/assessments/tt/client/src/Utils.elm b/users/wpcarro/assessments/tt/client/src/Utils.elm
new file mode 100644
index 000000000000..60343cd87018
--- /dev/null
+++ b/users/wpcarro/assessments/tt/client/src/Utils.elm
@@ -0,0 +1,109 @@
+module Utils exposing (..)
+
+import DateFormat
+import Http
+import Time
+import Shared
+
+
+explainHttpError : Http.Error -> String
+explainHttpError e =
+    case e of
+        Http.BadUrl _ ->
+            "Bad URL: you may have supplied an improperly formatted URL"
+
+        Http.Timeout ->
+            "Timeout: the resource you requested did not arrive within the interval of time that you claimed it should"
+
+        Http.BadStatus s ->
+            "Bad Status: the server returned a bad status code: " ++ String.fromInt s
+
+        Http.BadBody b ->
+            "Bad Body: our application had trouble decoding the body of the response from the server: " ++ b
+
+        Http.NetworkError ->
+            "Network Error: something went awry in the network stack. I recommend checking the server logs if you can."
+
+
+getWithCredentials :
+    { url : String
+    , expect : Http.Expect msg
+    }
+    -> Cmd msg
+getWithCredentials { url, expect } =
+    Http.riskyRequest
+        { url = url
+        , headers = [ Http.header "Origin" Shared.clientOrigin ]
+        , method = "GET"
+        , timeout = Nothing
+        , tracker = Nothing
+        , body = Http.emptyBody
+        , expect = expect
+        }
+
+
+postWithCredentials :
+    { url : String
+    , body : Http.Body
+    , expect : Http.Expect msg
+    }
+    -> Cmd msg
+postWithCredentials { url, body, expect } =
+    Http.riskyRequest
+        { url = url
+        , headers = [ Http.header "Origin" Shared.clientOrigin ]
+        , method = "POST"
+        , timeout = Nothing
+        , tracker = Nothing
+        , body = body
+        , expect = expect
+        }
+
+
+deleteWithCredentials :
+    { url : String
+    , body : Http.Body
+    , expect : Http.Expect msg
+    }
+    -> Cmd msg
+deleteWithCredentials { url, body, expect } =
+    Http.riskyRequest
+        { url = url
+        , headers = [ Http.header "Origin" Shared.clientOrigin ]
+        , method = "DELETE"
+        , timeout = Nothing
+        , tracker = Nothing
+        , body = body
+        , expect = expect
+        }
+
+putWithCredentials :
+    { url : String
+    , body : Http.Body
+    , expect : Http.Expect msg
+    }
+    -> Cmd msg
+putWithCredentials { url, body, expect } =
+    Http.riskyRequest
+        { url = url
+        , headers = [ Http.header "Origin" Shared.clientOrigin ]
+        , method = "PUT"
+        , timeout = Nothing
+        , tracker = Nothing
+        , body = body
+        , expect = expect
+        }
+
+
+
+formatTime : Time.Posix -> String
+formatTime ts =
+    DateFormat.format
+        [ DateFormat.monthNameFull
+        , DateFormat.text " "
+        , DateFormat.dayOfMonthSuffix
+        , DateFormat.text ", "
+        , DateFormat.yearNumber
+        ]
+        Time.utc
+        ts