# This file builds an Emacs pre-configured with the packages I need
# and my personal Emacs configuration.
{ lib, pkgs, ... }:

pkgs.makeOverridable
  ({ emacs ? pkgs.emacsGcc }:
  let
    emacsWithPackages = (pkgs.emacsPackagesGen emacs).emacsWithPackages;

    # If switching telega versions, use this variable because it will
    # keep the version check, binary path and so on in sync.
    currentTelega = epkgs: epkgs.melpaPackages.telega;

    # $PATH for binaries that need to be available to Emacs
    emacsBinPath = lib.makeBinPath [
      (currentTelega pkgs.emacsPackages)
      pkgs.libwebp # for dwebp, required by telega
    ];

    identity = x: x;

    tazjinsEmacs = pkgfun: (emacsWithPackages (epkgs: pkgfun (with epkgs; [
      ace-link
      ace-window
      avy
      bazel
      browse-kill-ring
      cargo
      clojure-mode
      cmake-mode
      company
      counsel
      counsel-notmuch
      d-mode
      direnv
      dockerfile-mode
      eglot
      elfeed
      elixir-mode
      elm-mode
      erlang
      exwm
      flymake
      go-mode
      google-c-style
      gruber-darker-theme
      haskell-mode
      ht
      hydra
      idle-highlight-mode
      ivy
      ivy-prescient
      jq-mode
      kotlin-mode
      lsp-mode
      magit
      markdown-toc
      meson-mode
      multi-term
      multiple-cursors
      nginx-mode
      nix-mode
      notmuch
      paredit
      password-store
      pinentry
      polymode
      prescient
      protobuf-mode
      rainbow-delimiters
      rainbow-mode
      refine
      request
      restclient
      rust-mode
      sly
      string-edit
      swiper
      telephone-line
      terraform-mode
      toml-mode
      transient
      undo-tree
      use-package
      uuidgen
      vterm
      web-mode
      websocket
      which-key
      xelb
      yaml-mode
      yasnippet
      zoxide

      # Wonky stuff
      (currentTelega epkgs)

      # Custom depot packages (either ours, or overridden ones)
      tvlPackages.dottime
      tvlPackages.nix-util
      tvlPackages.passively
      tvlPackages.rcirc
      tvlPackages.term-switcher
      tvlPackages.tvl
    ])));

    # Tired of telega.el runtime breakages through tdlib
    # incompatibility. Target to make that a build failure instead.
    tdlibCheck =
      let
        tgEmacs = emacsWithPackages (epkgs: [ (currentTelega epkgs) ]);
        verifyTdlibVersion = builtins.toFile "verify-tdlib-version.el" ''
          (require 'telega)
          (defvar tdlib-version "${pkgs.tdlib.version}")
          (when (or (version< tdlib-version
                              telega-tdlib-min-version)
                    (and telega-tdlib-max-version
                          (version< telega-tdlib-max-version
                                    tdlib-version)))
             (message "Found TDLib version %s, but require %s to %s"
                     tdlib-version telega-tdlib-min-version telega-tdlib-max-version)
            (kill-emacs 1))
        '';
      in
      pkgs.runCommandNoCC "tdlibCheck" { } ''
        export PATH="${emacsBinPath}:$PATH"
        ${tgEmacs}/bin/emacs --script ${verifyTdlibVersion} && touch $out
      '';
  in
  lib.fix
    (self: l: f: pkgs.writeShellScriptBin "tazjins-emacs" ''
      export PATH="${emacsBinPath}:$PATH"
      exec ${tazjinsEmacs f}/bin/emacs \
        --debug-init \
        --no-site-file \
        --no-site-lisp \
        --no-init-file \
        --directory ${./config} ${if l != null then "--directory ${l}" else ""} \
        --eval "(require 'init)" $@
    '' // {
      # Call overrideEmacs with a function (pkgs -> pkgs) to modify the
      # packages that should be included in this Emacs distribution.
      overrideEmacs = f': self l f';

      # Call withLocalConfig with the path to a *folder* containing a
      # `local.el` which provides local system configuration.
      withLocalConfig = confDir: self confDir f;

      # Build a derivation that uses the specified local Emacs (i.e.
      # built outside of Nix) instead
      withLocalEmacs = emacsBin: pkgs.writeShellScriptBin "tazjins-emacs" ''
        export PATH="${emacsBinPath}:$PATH"
        export EMACSLOADPATH="${(tazjinsEmacs f).deps}/share/emacs/site-lisp:"
        exec ${emacsBin} \
          --debug-init \
          --no-site-file \
          --no-site-lisp \
          --no-init-file \
          --directory ${./config} \
          ${if l != null then "--directory ${l}" else ""} \
          --eval "(require 'init)" $@
      '';

      # Expose telega/tdlib version check as a target that is built in
      # CI.
      #
      # TODO(tazjin): uncomment when telega works again
      inherit tdlibCheck;
      # meta.targets = [ "tdlibCheck" ];
    })
    null
    identity
  )
{ }