{ config, lib, ... }: 
let
  cfg = config.default-applications;
  mkCommand = name: default: lib.mkOption {
    type = lib.types.str;
    default = default;
    description = "The default ${name}'s command'";
  };
  mkDesktopFile = name: default: lib.mkOption {
    type = lib.types.str;
    default = default;
    description = "The default ${name}'s .desktop file";
  };
  # Empty entries mess things up when a mimetype has more than one app.
  removeEmpty = desktop-files: builtins.filter (name: name != "") desktop-files;
in {
  options.default-applications = {
    web-browser = {
      command = mkCommand "web browser" "librewolf";
      desktop-file = mkDesktopFile "web browser" "librewolf.desktop";
    };
    text-editor = {
      command = mkCommand "text editor" "neovide";
      desktop-file = mkDesktopFile "text editor" "neovide.desktop";
    };
    image-viewer = {
      command = mkCommand "image viewer" "imv";
      desktop-file = mkDesktopFile "image viewer" "imv.desktop";
    };
    video-viewer = {
      command = mkCommand "video viewer" "mpv";
      desktop-file = mkDesktopFile "video viewer" "mpv.desktop";
    };
    audio-player = {
      command = mkCommand "audio player" "";
      desktop-file = mkDesktopFile "audio player" "";
    };
    terminal-emulator = {
      command = mkCommand "terminal emulator" "foot";
      runTuiCommand = mkCommand "(when running a tui program) terminal emulator" "foot";
      runCliCommand = mkCommand "(when running a cli command) terminal emulator" "foot -H";
      openDirCommand = mkCommand "(when opening a dir) terminal emulator" "foot -D";
      desktop-file = mkDesktopFile "terminal emulator" "foot.desktop";
    };
    file-manager = {
      command = mkCommand "file manager" "";
      desktop-file = mkDesktopFile "file manager" "";
    };
  };
  config = {
    xdg.mimeApps = {
      enable = true;
      defaultApplications = {
        # Web Browser
        "text/html" = (removeEmpty [ cfg.web-browser.desktop-file cfg.text-editor.desktop-file ]);
        "text/xml" = [ cfg.web-browser.desktop-file ];
        "application/xhtml+xml" = [ cfg.web-browser.desktop-file ];
        "application/javascript" = [ cfg.web-browser.desktop-file ];
        "application/rss+xml" = [ cfg.web-browser.desktop-file ];
        "application/atom+xml" = [ cfg.web-browser.desktop-file ];
        "application/pdf" = [ cfg.web-browser.desktop-file ];
        "application/x-www-form-urlencoded" = [ cfg.web-browser.desktop-file ];
        "multipart/form-data" = [ cfg.web-browser.desktop-file ];

        # Text Editor
        "text/nix" = [ cfg.text-editor.desktop-file ];
        "text/plain" = [ cfg.text-editor.desktop-file ];
        "text/x-python" = [ cfg.text-editor.desktop-file ];
        "text/x-c" = [ cfg.text-editor.desktop-file ];
        "text/x-java-source" = [ cfg.text-editor.desktop-file ];
        "text/x-shellscript" = [ cfg.text-editor.desktop-file ];
        "text/x-markdown" = [ cfg.text-editor.desktop-file ];
        "text/css" = [ cfg.text-editor.desktop-file ];
        "application/json" = [ cfg.text-editor.desktop-file ];
        "application/xml" = [ cfg.text-editor.desktop-file ];
        "application/x-yaml" = [ cfg.text-editor.desktop-file ];
        "application/x-perl" = [ cfg.text-editor.desktop-file ];
        "application/x-php" = [ cfg.text-editor.desktop-file ];
        "application/x-sql" = [ cfg.text-editor.desktop-file ];
        "application/x-sh" = [ cfg.text-editor.desktop-file ];
        "application/x-cmake" = [ cfg.text-editor.desktop-file ];
        "application/x-latex" = [ cfg.text-editor.desktop-file ];
        "application/x-tex" = [ cfg.text-editor.desktop-file ];
        "text/x-log" = [ cfg.text-editor.desktop-file ];
        "text/csv" = [ cfg.text-editor.desktop-file ];

        # Image Viewer
        "image/jpeg" = [ cfg.image-viewer.desktop-file ];
        "image/jpg" = [ cfg.image-viewer.desktop-file ];
        "image/png" = [ cfg.image-viewer.desktop-file ];
        "image/gif" = [ cfg.image-viewer.desktop-file ];
        "image/bmp" = [ cfg.image-viewer.desktop-file ];
        "image/webp" = [ cfg.image-viewer.desktop-file ];
        "image/tiff" = [ cfg.image-viewer.desktop-file ];
        "image/x-xbitmap" = [ cfg.image-viewer.desktop-file ];
        "image/x-xpixmap" = [ cfg.image-viewer.desktop-file ];
        "image/x-portable-pixmap" = [ cfg.image-viewer.desktop-file ];
        "image/x-portable-graymap" = [ cfg.image-viewer.desktop-file ];
        "image/svg+xml" = (removeEmpty [ cfg.image-viewer.desktop-file cfg.web-browser.desktop-file ]);
        "image/heif" = [ cfg.image-viewer.desktop-file ];
        "image/heic" = [ cfg.image-viewer.desktop-file ];

        # Video Viewer
        "video/mp4" = [ cfg.video-viewer.desktop-file ];
        "video/x-msvideo" = [ cfg.video-viewer.desktop-file ];
        "video/x-matroska" = [ cfg.video-viewer.desktop-file ];
        "video/webm" = [ cfg.video-viewer.desktop-file ];
        "video/ogg" = [ cfg.video-viewer.desktop-file ];
        "video/mpeg" = [ cfg.video-viewer.desktop-file ];
        "video/quicktime" = [ cfg.video-viewer.desktop-file ];
        "video/x-flv" = [ cfg.video-viewer.desktop-file ];
        "application/vnd.rn-realmedia" = [ cfg.video-viewer.desktop-file ];
        "application/x-mplayer2" = [ cfg.video-viewer.desktop-file ];
      
        # Audio Player
        "audio/mpeg" = [ cfg.audio-player.desktop-file ];
        "audio/og" = [ cfg.audio-player.desktop-file ];
        "audio/wa" = [ cfg.audio-player.desktop-file ];
        "audio/fla" = [ cfg.audio-player.desktop-file ];
        "audio/aa" = [ cfg.audio-player.desktop-file ];
        "audio/x-ms-wm" = [ cfg.audio-player.desktop-file ];
        "audio/x-matrosk" = [ cfg.audio-player.desktop-file ];

        # Terminal Emulator and File Manager
        "inode/directory" = (removeEmpty [ cfg.file-manager.desktop-file "open-terminal-here.desktop" ]);
      };
    };
    # Allows terminals to work instead of file managers
    home.file."open-terminal-here" = {
      target = ".local/share/applications/open-terminal-here.desktop";
      text = ''
        [Desktop Entry]
        Name=Open Terminal Here
        Comment=Open terminal in this directory
        Exec=${cfg.terminal-emulator.openDirCommand} %f
        Icon=utilities-terminal
        Type=Application
        Terminal=false
        MimeType=inode/directory;
        NoDisplay=true
      '';
    };
  };
}