{ lib
, callPackage
, config
}:
let
  buildShellExtension = callPackage ./buildGnomeExtension.nix { };

  # Index of all scraped extensions (with supported versions)
  extensionsIndex = lib.importJSON ./extensions.json;

  # A list of UUIDs that have the same pname and we need to rename them
  extensionRenames = import ./extensionRenames.nix;

  # Take all extensions from the index that match the gnome version, build them and put them into a list of derivations
  produceExtensionsList = shell-version:
    lib.trivial.pipe extensionsIndex [
      # Does a given extension match our current shell version?
      (builtins.filter
        (extension: (builtins.hasAttr shell-version extension."shell_version_map"))
      )
      # Take in an `extension` object from the JSON and transform it into the correct args to call `buildShellExtension`
      (map
        (extension: {
          inherit (extension) uuid name description link pname;
          inherit (extension.shell_version_map.${shell-version}) version sha256 metadata;
        })
      )
      # Build them
      (map buildShellExtension)
    ];

  # Map the list of extensions to an attrset based on the UUID as key
  mapUuidNames = extensions:
    lib.trivial.pipe extensions [
      (map (extension: lib.nameValuePair extension.extensionUuid extension))
      builtins.listToAttrs
    ];

  # Map the list of extensions to an attrset based on the pname as key, which is more human readable than the UUID
  # We also take care of conflict renaming in here
  mapReadableNames = extensionsList: lib.trivial.pipe extensionsList [
    # Filter out all extensions that map to null
    (lib.filter (extension:
      !(
        (builtins.hasAttr extension.extensionUuid extensionRenames)
        && ((builtins.getAttr extension.extensionUuid extensionRenames) == null)
      )
    ))
    # Map all extensions to their pname, with potential overwrites
    (map (extension:
      lib.nameValuePair (extensionRenames.${extension.extensionUuid} or extension.extensionPortalSlug) extension
    ))
    builtins.listToAttrs
  ];

in rec {
  inherit buildShellExtension;

  gnome38Extensions = mapUuidNames (produceExtensionsList "38");
  gnome40Extensions = mapUuidNames (produceExtensionsList "40");

  gnomeExtensions = lib.recurseIntoAttrs (
    (mapReadableNames (produceExtensionsList "40"))
    // (callPackage ./manuallyPackaged.nix {})
    // lib.optionalAttrs (config.allowAliases or true) {
      unite-shell = gnomeExtensions.unite; # added 2021-01-19
      arc-menu = gnomeExtensions.arcmenu; # added 2021-02-14

      nohotcorner = throw "gnomeExtensions.nohotcorner removed since 2019-10-09: Since 3.34, it is a part of GNOME Shell configurable through GNOME Tweaks.";
      mediaplayer = throw "gnomeExtensions.mediaplayer deprecated since 2019-09-23: retired upstream https://github.com/JasonLG1979/gnome-shell-extensions-mediaplayer/blob/master/README.md";
    }
  );
}