{ pkgs, lib }:

with lib;
rec {
  mozlz4 = pkgs.callPackage ./mozlz4.nix {};

  flattenAttrs = set:
    let recurse = k: v:
      if isAttrs v
      then mapAttrsToList (k': recurse "${k}.${k'}") v
      else nameValuePair k v;
    in listToAttrs (flatten (mapAttrsToList recurse set));

  mkValueString = v:
    if isInt v then toString v
    else if isString v then "\"${v}\""
    else if true == v then "true"
    else if false == v then "false"
    else abort "unsupported value type: ${builtins.typeOf v}";

  mkPrefs = settings: pkgs.writeText "prefs.js"
    ("// dummy line\n" +
    (lib.concatStringsSep "\n"
      (lib.mapAttrsToList (k: v: "pref(\"${k}\", ${mkValueString v}, locked);")
        (flattenAttrs settings))));

  toSearchConfig = settings: pkgs.runCommand "search.json.mozlz4" {} ''
    ${mozlz4.compress} < ${pkgs.writeText "search.json" (builtins.toJSON settings)} > $out
  '';

  profile = { preferences, search }: pkgs.runCommand "profile" {} ''
    mkdir $out
    ln -s ${toUserPrefs preferences} $out/user.js
    # ln -s ${toSearchConfig search} $out/search.json.mozlz4
    cp ${../search-with-qj.json.mozlz4} $out/search.json.mozlz4
  '';

  mkPolicies = policies: pkgs.writeText "policies.json" (builtins.toJSON {
    inherit policies;
  });

  mergeProfiles = profiles:
    let
      sanitise = args: {
        policies = args.policies or {};
        preferences = args.preferences or {};
      };
      sanitised = map sanitise profiles;
      final = lib.foldl lib.recursiveUpdate {} sanitised;
    in final;

  patchOmniJa = src: script: pkgs.runCommand "omni.ja" { } ''
    ${pkgs.unzip}/bin/unzip -q ${src}

    ${script}

    ${pkgs.zip}/bin/zip -qr9XD $out .
  '';

  bundle = { policies ? {}, preferences ? {}, patchOmniJaCommand ? "" }:
    let
      firefox = pkgs.firefox-unwrapped;
      policies' = mkPolicies policies;
      preferences' = mkPrefs preferences;
      patchedOmniJa = patchOmniJa "${firefox}/lib/firefox/browser/omni.ja" patchOmniJaCommand;
      patched = pkgs.runCommand "firefox-bundle" {
          nativeBuildInputs = [ pkgs.nix ];
          disallowedReferences = [ firefox ];
        } ''
        cp -r ${firefox} $out
        chmod -R +w $out
        # correct argv[0], which is used to locate distribution and defaults
        substituteInPlace $out/bin/firefox \
          --replace ${firefox} $out

        mkdir $out/lib/firefox/distribution
        cp ${policies'} $out/lib/firefox/distribution/policies.json
        cp ${preferences'} $out/lib/firefox/defaults/pref/99-custom.js
        cp ${patchedOmniJa} $out/lib/firefox/browser/omni.ja
      '';
      wrapped = (pkgs.wrapFirefox patched {
        browserName = "firefox";
        version = "custom";
      }) // { inherit policies preferences; };
    in wrapped;

  # This attempts to provide a start for deploying Nix-configured profiles to
  # systems which do not have Nix installed, and where /nix/store is undesired.
  # It does this by bundling all referenced store items into $out, and rewriting
  # references to those store items.
  export = { selfPath, policies ? {}, preferences ? {} }: pkgs.stdenv.mkDerivation rec {
    name = "firefox-profile-export";
    nativeBuildInputs = [ pkgs.jq ];

    allowedRequisites = [];

    buildCommand =
      let
        policyFile = mkPolicies policies;
        prefsFile = mkPrefs preferences;

        closure = pkgs.closureInfo {
          rootPaths = [
            policyFile prefsFile
          ];
        };
      in ''
      mkdir $out $out/store

      storePaths=$(cat ${closure}/store-paths)
      for p in $storePaths; do
        cp -a "$p" $out/store/"$(basename "$p" | sed -e 's|\([a-z0-9]\{32\}\)-||')"
      done

      mv $out/store/prefs.js $out/
      jq < $out/store/policies.json > $out/policies.json

      find $out -type f -print0 |
        xargs -0I{} -- sed -i -e "s|$NIX_STORE/\\([a-z0-9]\{32\}\\)-|${selfPath}/store/|g" "{}"
    '';
  };

  launcher = firefox: pkgs.writeShellScriptBin "firefox" ''
    # FF doesn't accept ro profiles, tries to create lockfile
    TMP_PROFILE="$(mktemp -d)"
    echo "$TMP_PROFILE"

    function finish() {
      echo deleting profile
      # rm -rv "$TMP_PROFILE"
    }
    trap finish EXIT
    # cp -r ''${profile} "$TMP_PROFILE"
    chmod u+rwx -R "$TMP_PROFILE"

    export MOZ_LOG=nsHttp:1
    export MOZ_LOG_FILE=ff
    # Make FF pay attention to services.settings.server
    # https://bugzilla.mozilla.org/show_bug.cgi?id=1598562
    export XPCSHELL_TEST_PROFILE_DIR=1

    ${firefox}/bin/firefox \
      --no-remote \
      --profile "$TMP_PROFILE" \
      "$@"
  '';
}