;;; irc.el --- Configuration for IRC chat -*- lexical-binding: t -*-

;; Author: William Carroll <wpcarro@gmail.com>
;; Version: 0.0.1
;; Package-Requires: ((emacs "25.1"))

;;; Commentary:
;; Need to decide which client I will use for IRC.

;;; Code:

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;; Dependencies
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(require 'erc)
(require 'cycle)
(require 'string)
(require 'prelude)
(require 'al)
(require 'set)
(require 'maybe)
(require 'macros)
(require '>)
(require 'password-store)
(require 'general)

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;; Configuration
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(defcustom irc-install-kbds? t
  "When t, install the keybindings defined herein.")

(setq erc-rename-buffers t)

;; Setting `erc-join-buffer' to 'bury prevents erc from stealing focus of the
;; current buffer when it connects to IRC servers.
(setq erc-join-buffer 'bury)

;; TODO: Find a way to avoid putting "freenode" and "#freenode" as channels
;; here.  I'm doing it because when erc first connects, it's `(buffer-name)' is
;; "freenode", so when `irc-next-channel' is called, it 404s on the
;; `cycle-contains?' call in `irc-channel->cycle" unless "freenode" is there. To
;; make matters even uglier, when `erc-join-channel' is called with "freenode"
;; as the value, it connects to the "#freenode" channel, so unless "#freenode"
;; exists in this cycle also, `irc-next-channel' breaks again.
(defconst irc-server->channels
  `(("irc.freenode.net"    . ,(cycle-new "freenode" "#freenode" "#nixos" "#emacs" "#pass"))
    ("irc.corp.google.com" . ,(cycle-new "#drive-prod")))
  "Mapping of IRC servers to a cycle of my preferred channels.")

;; TODO: Here is another horrible hack that should be revisted.
(setq erc-autojoin-channels-alist
      (->> irc-server->channels
           (al-map-values #'cycle-to-list)
           (al-map-keys (>-> (s-chop-prefix "irc.")
                             (s-chop-suffix ".net")))))

;; TODO: Assert that no two servers have a channel with the same name. We need
;; this because that's the assumption that underpins the `irc-channel->server'
;; function. This will probably be an O(n^2) operation.
(prelude-assert
 (set-distinct? (set-from-list
                 (cycle-to-list
                  (al-get "irc.freenode.net"
                          irc-server->channels)))
                (set-from-list
                 (cycle-to-list
                  (al-get "irc.corp.google.com"
                          irc-server->channels)))))

(defun irc-channel->server (server->channels channel)
  "Using SERVER->CHANNELS, resolve an IRC server from a given CHANNEL."
  (let ((result (al-find (lambda (k v) (cycle-contains? channel v))
                         server->channels)))
    (prelude-assert (maybe-some? result))
    result))

(defun irc-channel->cycle (server->channels channel)
  "Using SERVER->CHANNELS, resolve an IRC's channels cycle from CHANNEL."
  (al-get (irc-channel->server server->channels channel)
          server->channels))

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;; Library
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(defun irc-message (x)
  "Print message X in a structured way."
  (message (string-format "[irc.el] %s" x)))

;; TODO: Integrate Google setup with Freenode setup.

;; TODO: Support function or KBD for switching to an ERC buffer.

(defun irc-kill-all-erc-processes ()
  "Kill all ERC buffers and processes."
  (interactive)
  (->> (erc-buffer-list)
       (-map #'kill-buffer)))

(defun irc-switch-to-erc-buffer ()
  "Switch to an ERC buffer."
  (interactive)
  (let ((buffers (erc-buffer-list)))
    (if (list-empty? buffers)
        (error "[irc.el] No ERC buffers available")
      (switch-to-buffer (list-head (erc-buffer-list))))))

(defun irc-connect-to-freenode ()
  "Connect to Freenode IRC."
  (interactive)
  (erc-ssl :server "irc.freenode.net"
           :port 6697
           :nick "wpcarro"
           :password (password-store-get "programming/irc/freenode")
           :full-name "William Carroll"))

;; TODO: Handle failed connections.
(defun irc-connect-to-google ()
  "Connect to Google's Corp IRC using ERC."
  (interactive)
  (erc-ssl :server "irc.corp.google.com"
           :port 6697
           :nick "wpcarro"
           :full-name "William Carroll"))

;; TODO: Prefer defining these with a less homespun solution. There is a
;; function call `erc-buffer-filter' that would be more appropriate for the
;; implementation of `irc-next-channel' and `irc-prev-channel'.
(defun irc-next-channel ()
  "Join the next channel for the active server."
  (interactive)
  (with-current-buffer (current-buffer)
    (let ((cycle (irc-channel->cycle irc-server->channels (buffer-name))))
      (erc-join-channel
       (cycle-next! cycle))
      (irc-message
       (string-format "Current IRC channel: %s" (cycle-current cycle))))))

(defun irc-prev-channel ()
  "Join the previous channel for the active server."
  (interactive)
  (with-current-buffer (current-buffer)
    (let ((cycle (irc-channel->cycle irc-server->channels (buffer-name))))
      (erc-join-channel
       (cycle-prev! cycle))
      (irc-message
       (string-format "Current IRC channel: %s" (cycle-current cycle))))))

(add-hook 'erc-mode-hook (macros-disable auto-fill-mode))
(add-hook 'erc-mode-hook (macros-disable company-mode))

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;; Keybindings
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(when irc-install-kbds?
  (general-define-key
   :keymaps 'erc-mode-map
   "<C-tab>" #'irc-next-channel
   "<C-S-iso-lefttab>" #'irc-prev-channel))

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;; Tests
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(provide 'irc)
;;; irc.el ends here