{ stdenvNoCC, lib, fetchFromGitHub }:

let
  inherit (lib) licenses;

  # Thin wrapper over stdenvNoCC.mkDerivation.
  mkGem = attrs: stdenvNoCC.mkDerivation ({
    # "Static" name. Just like source packages.
    name = attrs.src.name;

    # Skip, as it may be accidentally triggered.
    configurePhase = ":";

    installPhase = ''
      runHook prePatch

      echo " :: Copying mrbgem"
      cp -vr . $out

      runHook postPatch
    '';
  } // attrs);
in
rec {
  mruby-dir = mkGem {
    src = fetchFromGitHub {
      repo = "mruby-dir";
      owner = "iij";
      rev = "89dceefa1250fb1ae868d4cb52498e9e24293cd1";
      sha256 = "0zrhiy9wmwmc9ls62iyb2z86j2ijqfn7rn4xfmrbrfxygczarsm9";
    };

    meta.license = licenses.mit;
  };

  mruby-dir-glob = mkGem {
    src = fetchFromGitHub {
      repo = "mruby-dir-glob";
      owner = "gromnitsky";
      rev = "334c040a2e2c4c2689f8c3440168011f64d57ada";
      sha256 = "1ji826s9mbwk6rmn5fccxp53hfgnq6ayaphv6ccznr0k6pim8cv5";
    };

    postPatch = ''
      # Disable all tests, they're not kind with gems :/
      rm -vrf test test.local
    '';

    patches = [
      ./mruby-dir-glob/0001-HACK-Removes-test-only-dependencies.patch
    ];

    requiredGems = [
      mruby-dir
      mruby-errno
      mruby-file-stat
    ];

    meta.license = licenses.mit;
  };

  mruby-env = mkGem {
    src = fetchFromGitHub {
      repo = "mruby-env";
      owner = "iij";
      rev = "056ae324451ef16a50c7887e117f0ea30921b71b";
      sha256 = "19fpp6lv8asjxhf0zraj15ds5fiskjz7zzcg0k64m5q0kzwra62w";
    };

    meta.license = licenses.mit;
  };

  mruby-erb = mkGem {
    src = fetchFromGitHub {
      repo = "mruby-erb";
      owner = "jbreeden";
      rev = "7ea27f1338fe5e971d818034d0163ca46ecd7d33";
      sha256 = "1ainldbh51wpsf8q62fgv1cg42sh5ykznr0dy0cchkab3rzkipf1";
    };

    requiredGems = [
      mruby-regexp-pcre
    ];

    meta.license = licenses.ruby;
  };

  mruby-errno = mkGem {
    src = fetchFromGitHub {
      repo = "mruby-errno";
      owner = "iij";
      rev = "b4415207ff6ea62360619c89a1cff83259dc4db0";
      sha256 = "12djcwjjw0fygai5kssxbfs3pzh3cpnq07h9m2h5b51jziw380xj";
    };

    meta.license = licenses.mit;
  };

  mruby-file-stat = mkGem {
    src = fetchFromGitHub {
      repo = "mruby-file-stat";
      owner = "ksss";
      rev = "aa474589f065c71d9e39ab8ba976f3bea6f9aac2";
      sha256 = "1clarmr67z133ivkbwla1a42wcjgj638j9w0mlv5n21mhim9rid5";
    };

    patches = [
      ./mruby-file-stat/0001-HACK-Rely-on-nixos-isms-for-.-configure.patch
    ];

    postPatch = ''
      substituteInPlace test/file-stat.rb \
        --replace 'dir = __FILE__[0..-18] # 18 = /test/file-stat.rb' \
        'skip "Fails in Nix sandbox"'
    '';

    meta.license = licenses.mit;
  };

  mruby-json = mkGem {
    src = fetchFromGitHub {
      repo = "mruby-json";
      owner = "mattn";
      rev = "054699892b0d681110e7348440cddb70a3fd671e";
      sha256 = "0pmlsjb5j2zdm1a1j1lah1nj3wn7bmy22z6nwqq5ydhj36rranf1";
    };

    meta.license = licenses.mit;
  };

  mruby-logger = mkGem {
    src = fetchFromGitHub {
      repo = "mruby-logger";
      owner = "katzer";
      rev = "5e703e5c2f11e92867a7d56292f1f0c7b4f42f69";
      sha256 = "0ip3mxpzyf9rswkh3wjc9nnml4gw1gzr50krbqhaz2mj10xdqfxw";
    };

    patches = [
      ./mruby-logger/0001-Skip-logger-test-with-read-only-source-directory.patch
    ];

    meta.license = licenses.mit;
  };

  mruby-open3 = mkGem {
    src = fetchFromGitHub {
      repo = "mruby-open3";
      owner = "mrbgems";
      rev = "5d343deeffc161d517d14deacb8b38c7bc5daef8";
      sha256 = "046xv1dqf2lh50sj7m74wdff5mhpvz5adhqziyrsia07rb5dcyl4";
    };

    requiredGems = [
      mruby-process
    ];

    meta.license = licenses.mit;
  };

  mruby-os = mkGem {
    src = fetchFromGitHub {
      repo = "mruby-os";
      owner = "appPlant";
      rev = "670eeb019e0abb657f5b9dbfd0ee993133edaa99";
      sha256 = "1whqhikiq8dkv9nsilsibcy5qw0xydxh6ysz6mjkp7vh0hpirlzs";
    };

    meta.license = licenses.mit;
  };

  mruby-process = mkGem {
    src = fetchFromGitHub {
      repo = "mruby-process";
      owner = "appPlant";
      rev = "d33886359dd2622994c4452997c2011b13463a6e";
      sha256 = "1q47v1mavdi12x3jrv5l58ax3kx83byxpn7nwbb4wxb4r4q23i0l";
    };

    patches =  [
      ./mruby-process/0001-dln-Fix-bad-environment-assumptions.patch
    ];

    postPatch = ''
      # Fixup a bad assumption about ability to write to (mruby) source tree
      substituteInPlace mrbgem.rake \
        --replace "File.join(dir, 'tmp')" '"/tmp/mruby-process"'

      # Fixup bad assumptions about interpreters in the test files
      substituteInPlace test/process.rb \
        --replace "/bin/bash" "$(type -P bash)"
    '';

    requiredGems = [
      mruby-env
      mruby-os
    ];

    meta.license = licenses.mit;
  };

  mruby-regexp-pcre = mkGem {
    src = fetchFromGitHub {
      repo = "mruby-regexp-pcre";
      owner = "iij";
      rev = "bcf0fb72f3baa2efb474232fd016edc021982d97";
      sha256 = "00bwca5as5hd0pgq2a7dw6c7g3h6k9xww72p5vni6zilhnl4kllj";
    };

    patches = [
      ./mruby-regexp-pcre/0001-Fix-String-match-removed-in-mruby-2.1.0.patch
    ];

    meta.license = licenses.mit;
  };

  mruby-require = mkGem {
    src = fetchFromGitHub {
      repo = "mruby-require";
      owner = "mattn";
      rev = "b2b95a27b8658c46c5cb05abd168e77a12aef2a4";
      sha256 = "09074m8c6szafs89xb8a1nhvc44jcj3hl8xcwgajzmkif39p72if";
    };

    patches = [
      ./mruby-require/0001-HACK-Skip-turning-gems-to-library-for-tests-output.patch
      ./mruby-require/0001-HACK-Prefer-first-target-if-host-is-not-present.patch
    ];

    meta.license = licenses.mit;
  };

  mruby-sha1 = mkGem {
    src = fetchFromGitHub {
      repo = "mruby-sha1";
      owner = "mattn";
      rev = "528419eefb415203b989650f7b792b3556e3d475";
      sha256 = "05y1l7pprwrnizbbhsgcss0863y4z5fqnz31qsngr344c50v79sh";
    };

    meta.license = licenses.gpl;
  };

  mruby-singleton = mkGem {
    src = fetchFromGitHub {
      repo = "mruby-singleton";
      owner = "ksss";
      rev = "73dd4bae1a47d82e49b8f85bf27f49ec4462052e";
      sha256 = "0yyf9vfsm46m2fi46f8w6ympkwzlaqnbpjkfnkzyapf94rg23g6i";
    };

    meta.licenses = licenses.mit;
  };
}