{ config, lib, pkgs, ... }:

with lib;

let

  cfg = config.xsession.windowManager.i3;

  commonOptions = import ./lib/options.nix {
    inherit config lib cfg pkgs;
    moduleName = "i3";
  };

  configModule = types.submodule {
    options = {
      inherit (commonOptions)
        fonts window floating focus assigns modifier workspaceLayout
        workspaceAutoBackAndForth keycodebindings colors bars startup gaps menu
        terminal defaultWorkspace workspaceOutputAssign;

      keybindings = mkOption {
        type = types.attrsOf (types.nullOr types.str);
        default = mapAttrs (n: mkOptionDefault) {
          "${cfg.config.modifier}+Return" = "exec ${cfg.config.terminal}";
          "${cfg.config.modifier}+Shift+q" = "kill";
          "${cfg.config.modifier}+d" = "exec ${cfg.config.menu}";

          "${cfg.config.modifier}+Left" = "focus left";
          "${cfg.config.modifier}+Down" = "focus down";
          "${cfg.config.modifier}+Up" = "focus up";
          "${cfg.config.modifier}+Right" = "focus right";

          "${cfg.config.modifier}+Shift+Left" = "move left";
          "${cfg.config.modifier}+Shift+Down" = "move down";
          "${cfg.config.modifier}+Shift+Up" = "move up";
          "${cfg.config.modifier}+Shift+Right" = "move right";

          "${cfg.config.modifier}+h" = "split h";
          "${cfg.config.modifier}+v" = "split v";
          "${cfg.config.modifier}+f" = "fullscreen toggle";

          "${cfg.config.modifier}+s" = "layout stacking";
          "${cfg.config.modifier}+w" = "layout tabbed";
          "${cfg.config.modifier}+e" = "layout toggle split";

          "${cfg.config.modifier}+Shift+space" = "floating toggle";
          "${cfg.config.modifier}+space" = "focus mode_toggle";

          "${cfg.config.modifier}+a" = "focus parent";

          "${cfg.config.modifier}+Shift+minus" = "move scratchpad";
          "${cfg.config.modifier}+minus" = "scratchpad show";

          "${cfg.config.modifier}+1" = "workspace number 1";
          "${cfg.config.modifier}+2" = "workspace number 2";
          "${cfg.config.modifier}+3" = "workspace number 3";
          "${cfg.config.modifier}+4" = "workspace number 4";
          "${cfg.config.modifier}+5" = "workspace number 5";
          "${cfg.config.modifier}+6" = "workspace number 6";
          "${cfg.config.modifier}+7" = "workspace number 7";
          "${cfg.config.modifier}+8" = "workspace number 8";
          "${cfg.config.modifier}+9" = "workspace number 9";
          "${cfg.config.modifier}+0" = "workspace number 10";

          "${cfg.config.modifier}+Shift+1" =
            "move container to workspace number 1";
          "${cfg.config.modifier}+Shift+2" =
            "move container to workspace number 2";
          "${cfg.config.modifier}+Shift+3" =
            "move container to workspace number 3";
          "${cfg.config.modifier}+Shift+4" =
            "move container to workspace number 4";
          "${cfg.config.modifier}+Shift+5" =
            "move container to workspace number 5";
          "${cfg.config.modifier}+Shift+6" =
            "move container to workspace number 6";
          "${cfg.config.modifier}+Shift+7" =
            "move container to workspace number 7";
          "${cfg.config.modifier}+Shift+8" =
            "move container to workspace number 8";
          "${cfg.config.modifier}+Shift+9" =
            "move container to workspace number 9";
          "${cfg.config.modifier}+Shift+0" =
            "move container to workspace number 10";

          "${cfg.config.modifier}+Shift+c" = "reload";
          "${cfg.config.modifier}+Shift+r" = "restart";
          "${cfg.config.modifier}+Shift+e" =
            "exec i3-nagbar -t warning -m 'Do you want to exit i3?' -b 'Yes' 'i3-msg exit'";

          "${cfg.config.modifier}+r" = "mode resize";
        };
        defaultText = "Default i3 keybindings.";
        description = ''
          An attribute set that assigns a key press to an action using a key symbol.
          See <link xlink:href="https://i3wm.org/docs/userguide.html#keybindings"/>.
          </para><para>
          Consider to use <code>lib.mkOptionDefault</code> function to extend or override
          default keybindings instead of specifying all of them from scratch.
        '';
        example = literalExpression ''
          let
            modifier = config.xsession.windowManager.i3.config.modifier;
          in lib.mkOptionDefault {
            "''${modifier}+Return" = "exec i3-sensible-terminal";
            "''${modifier}+Shift+q" = "kill";
            "''${modifier}+d" = "exec ''${pkgs.dmenu}/bin/dmenu_run";
          }
        '';
      };

      modes = mkOption {
        type = types.attrsOf (types.attrsOf types.str);
        default = {
          resize = {
            "Left" = "resize shrink width 10 px or 10 ppt";
            "Down" = "resize grow height 10 px or 10 ppt";
            "Up" = "resize shrink height 10 px or 10 ppt";
            "Right" = "resize grow width 10 px or 10 ppt";
            "Escape" = "mode default";
            "Return" = "mode default";
          };
        };
        description = ''
          An attribute set that defines binding modes and keybindings
          inside them

          Only basic keybinding is supported (bindsym keycomb action),
          for more advanced setup use 'i3.extraConfig'.
        '';
      };
    };
  };

  commonFunctions = import ./lib/functions.nix {
    inherit config cfg lib;
    moduleName = "i3";
  };

  inherit (commonFunctions)
    keybindingsStr keycodebindingsStr modeStr assignStr barStr gapsStr
    floatingCriteriaStr windowCommandsStr colorSetStr windowBorderString
    fontConfigStr keybindingDefaultWorkspace keybindingsRest workspaceOutputStr;

  startupEntryStr = { command, always, notification, workspace, ... }:
    concatStringsSep " " [
      (if always then "exec_always" else "exec")
      (if (notification && workspace == null) then "" else "--no-startup-id")
      (if (workspace == null) then
        command
      else
        "i3-msg 'workspace ${workspace}; exec ${command}'")
    ];

  configFile = pkgs.writeText "i3.conf" (concatStringsSep "\n"
    ((if cfg.config != null then
      with cfg.config;
      ([
        (fontConfigStr fonts)
        "floating_modifier ${floating.modifier}"
        (windowBorderString window floating)
        "hide_edge_borders ${window.hideEdgeBorders}"
        "focus_wrapping ${focus.wrapping}"
        "focus_follows_mouse ${lib.hm.booleans.yesNo focus.followMouse}"
        "focus_on_window_activation ${focus.newWindow}"
        "mouse_warping ${if focus.mouseWarping then "output" else "none"}"
        "workspace_layout ${workspaceLayout}"
        "workspace_auto_back_and_forth ${
          lib.hm.booleans.yesNo workspaceAutoBackAndForth
        }"
        "client.focused ${colorSetStr colors.focused}"
        "client.focused_inactive ${colorSetStr colors.focusedInactive}"
        "client.unfocused ${colorSetStr colors.unfocused}"
        "client.urgent ${colorSetStr colors.urgent}"
        "client.placeholder ${colorSetStr colors.placeholder}"
        "client.background ${colors.background}"
        (keybindingsStr { keybindings = keybindingDefaultWorkspace; })
        (keybindingsStr { keybindings = keybindingsRest; })
        (keycodebindingsStr keycodebindings)
      ] ++ mapAttrsToList (modeStr false) modes
        ++ mapAttrsToList assignStr assigns ++ map barStr bars
        ++ optional (gaps != null) gapsStr
        ++ map floatingCriteriaStr floating.criteria
        ++ map windowCommandsStr window.commands ++ map startupEntryStr startup
        ++ map workspaceOutputStr workspaceOutputAssign)
    else
      [ ]) ++ [ cfg.extraConfig ]));

  # Validates the i3 configuration
  checkI3Config =
    pkgs.runCommandLocal "i3-config" { buildInputs = [ cfg.package ]; } ''
      # We have to make sure the wrapper does not start a dbus session
      export DBUS_SESSION_BUS_ADDRESS=1

      # A zero exit code means i3 successfully validated the configuration
      i3 -c ${configFile} -C -d all || {
        echo "i3 configuration validation failed"
        echo "For a verbose log of the failure, run 'i3 -c ${configFile} -C -d all'"
        exit 1
      };
      cp ${configFile} $out
    '';

in {
  meta.maintainers = with maintainers; [ sumnerevans sebtm ];

  options = {
    xsession.windowManager.i3 = {
      enable = mkEnableOption "i3 window manager";

      package = mkPackageOption pkgs "i3" { };

      config = mkOption {
        type = types.nullOr configModule;
        default = { };
        description = "i3 configuration options.";
      };

      extraConfig = mkOption {
        type = types.lines;
        default = "";
        description =
          "Extra configuration lines to add to ~/.config/i3/config.";
      };
    };
  };

  config = mkIf cfg.enable (mkMerge [
    {
      assertions = [
        (hm.assertions.assertPlatform "xsession.windowManager.i3" pkgs
          platforms.linux)
      ];

      home.packages = [ cfg.package ];

      xsession.windowManager.command = "${cfg.package}/bin/i3";

      xdg.configFile."i3/config" = {
        source = checkI3Config;
        onChange = ''
          # There may be several sockets after log out/log in, but the old ones
          # will fail with "Connection refused".
          for i3Socket in ''${XDG_RUNTIME_DIR:-/run/user/$UID}/i3/ipc-socket.*; do
            if [[ -S $i3Socket ]]; then
              ${cfg.package}/bin/i3-msg -s $i3Socket reload >/dev/null |& grep -v "Connection refused" || true
            fi
          done
        '';
      };
    }

    (mkIf (cfg.config != null) {
      warnings = (optional (isList cfg.config.fonts)
        "Specifying i3.config.fonts as a list is deprecated. Use the attrset version instead.")
        ++ flatten (map (b:
          optional (isList b.fonts)
          "Specifying i3.config.bars[].fonts as a list is deprecated. Use the attrset version instead.")
          cfg.config.bars) ++ [
            (mkIf (any (s: s.workspace != null) cfg.config.startup)
              ("'xsession.windowManager.i3.config.startup.*.workspace' is deprecated, "
                + "use 'xsession.windowManager.i3.config.assigns' instead."
                + "See https://github.com/nix-community/home-manager/issues/265."))
            (mkIf cfg.config.focus.forceWrapping
              ("'xsession.windowManager.i3.config.focus.forceWrapping' is deprecated, "
                + "use 'xsession.windowManager.i3.config.focus.wrapping' instead."))
          ];
    })
  ]);
}
