gradle-env.nix

# This file is generated by gradle2nix.
#
# Example usage (e.g. in default.nix):
#
#     with (import <nixpkgs> {});
#     let
#       buildGradle = callPackage ./gradle-env.nix {};
#     in
#       buildGradle {
#         envSpec = ./gradle-env.json;
#
#         src = ./.;
#
#         gradleFlags = [ "installDist" ];
#
#         installPhase = ''
#           mkdir -p $out
#           cp -r app/build/install/myproject $out
#         '';
#       }

{ lib
, stdenv
, buildEnv
, fetchs3
, fetchurl
, gradleGen
, writeText
, writeTextDir
}:

{
# Path to the environment spec generated by gradle2nix (e.g. gradle-env.json).
  envSpec
, pname ? null
, version ? null
, enableParallelBuilding ? true
# Arguments to Gradle used to build the project in buildPhase.
, gradleFlags ? [ "build" ]
# Gradle package to use instead of the one generated by gradle2nix.
, gradlePackage ? null
# Enable debugging for the Gradle build; this will cause Gradle to run a debug server
# and wait for a JVM debugging client to attach.
, enableDebug ? false
# Additional code to run in the Gradle init script (init.gradle).
, extraInit ? ""
# Override the default JDK used to run Gradle itself.
, buildJdk ? null
# Override functions which fetch dependency artifacts.
# Keys in this set are URL schemes such as "https" or "s3".
# Values are functions which take a dependency in the form
# `{ urls, sha256 }` and fetch into the Nix store. For example:
#
#   {
#     s3 = { urls, sha256 }: fetchs3 {
#       s3url = builtins.head urls;
#       inherit sha256;
#       region = "us-west-2";
#       credentials = {
#         access_key_id = "foo";
#         secret_access_key = "bar";
#       };
#     };
#   }
, fetchers ? { }
, ... } @ args:

let
  inherit (builtins)
    attrValues concatStringsSep filter fromJSON getAttr head match
    replaceStrings sort;

  inherit (lib)
    assertMsg concatMapStringsSep groupBy' hasSuffix hasPrefix last mapAttrs
    mapAttrsToList optionalString readFile removeSuffix unique versionAtLeast
    versionOlder;

  fetchers' = {
    http = fetchurl;
    https = fetchurl;
    s3 = { urls, sha256 }: fetchs3 {
      s3url = head urls;
      inherit sha256;
    };
  } // fetchers;

  # Fetch urls using the scheme for the first entry only; there isn't a
  # straightforward way to tell Nix to try multiple fetchers in turn
  # and short-circuit on the first successful fetch.
  fetch = { urls, sha256 }:
    let
      first = head urls;
      scheme = head (builtins.match "([a-z0-9+.-]+)://.*" first);
      fetch' = getAttr scheme fetchers';
      urls' = filter (hasPrefix scheme) urls;
    in
      fetch' { urls = urls'; inherit sha256; };

  mkDep = { name, path, urls, sha256, ... }: stdenv.mkDerivation {
    inherit name;

    src = fetch {
      inherit urls sha256;
    };

    phases = "installPhase";

    installPhase = ''
      mkdir -p $out/${path}
      ln -s $src $out/${path}/${name}
    '';
  };

  mkModuleMetadata = deps:
    let
      ids = filter
        (id: id.type == "pom")
        (map (dep: dep.id) deps);

      modules = groupBy'
        (meta: id:
          let
            isNewer = versionOlder meta.latest id.version;
            isNewerRelease =
              !(hasSuffix "-SNAPSHOT" id.version) &&
              versionOlder meta.release id.version;
          in {
            groupId = id.group;
            artifactId = id.name;
            latest = if isNewer then id.version else meta.latest;
            release = if isNewerRelease then id.version else meta.release;
            versions = meta.versions ++ [id.version];
          }
        )
        {
          latest = "";
          release = "";
          versions = [];
        }
        (id: "${replaceStrings ["."] ["/"] id.group}/${id.name}/maven-metadata.xml")
        ids;

    in
      attrValues (mapAttrs (path: meta:
        let
          versions' = sort versionOlder (unique meta.versions);
        in
          with meta; writeTextDir path ''
            <?xml version="1.0" encoding="UTF-8"?>
            <metadata modelVersion="1.1">
              <groupId>${groupId}</groupId>
              <artifactId>${artifactId}</artifactId>
              <versioning>
                ${optionalString (latest != "") "<latest>${latest}</latest>"}
                ${optionalString (release != "") "<release>${release}</release>"}
                <versions>
                  ${concatMapStringsSep "\n    " (v: "<version>${v}</version>") versions'}
                </versions>
              </versioning>
            </metadata>
          ''
      ) modules);

  mkSnapshotMetadata = deps:
    let
      snapshotDeps = filter (dep: dep ? build && dep ? timestamp) deps;

      modules = groupBy'
        (meta: dep:
          let
            id = dep.id;
            isNewer = dep.build > meta.buildNumber;
            # Timestamp values can be bogus, e.g. jitpack.io
            updated = if (match "[0-9]{8}\.[0-9]{6}" dep.timestamp) != null
                      then replaceStrings ["."] [""] dep.timestamp
                      else "";
          in {
            groupId = id.group;
            artifactId = id.name;
            version = id.version;
            timestamp = if isNewer then dep.timestamp else meta.timestamp;
            buildNumber = if isNewer then dep.build else meta.buildNumber;
            lastUpdated = if isNewer then updated else meta.lastUpdated;
            versions = meta.versions or [] ++ [{
              classifier = id.classifier or "";
              extension = id.extension;
              value = "${removeSuffix "-SNAPSHOT" id.version}-${dep.timestamp}-${toString dep.build}";
              updated = updated;
            }];
          }
        )
        {
          timestamp = "";
          buildNumber = -1;
          lastUpdated = "";
        }
        (dep: "${replaceStrings ["."] ["/"] dep.id.group}/${dep.id.name}/${dep.id.version}/maven-metadata.xml")
        snapshotDeps;

      mkSnapshotVersion = version: ''
        <snapshotVersion>
          ${optionalString (version.classifier != "") "<classifier>${version.classifier}</classifier>"}
          <extension>${version.extension}</extension>
          <value>${version.value}</value>
          ${optionalString (version.updated != "") "<updated>${version.updated}</updated>"}
        </snapshotVersion>
      '';

    in
      attrValues (mapAttrs (path: meta:
        with meta; writeTextDir path ''
          <?xml version="1.0" encoding="UTF-8"?>
          <metadata modelVersion="1.1">
            <groupId>${groupId}</groupId>
            <artifactId>${artifactId}</artifactId>
            <version>${version}</version>
            <versioning>
              <snapshot>
                ${optionalString (timestamp != "") "<timestamp>${timestamp}</timestamp>"}
                ${optionalString (buildNumber != -1) "<buildNumber>${toString buildNumber}</buildNumber>"}
              </snapshot>
              ${optionalString (lastUpdated != "") "<lastUpdated>${lastUpdated}</lastUpdated>"}
              <snapshotVersions>
                ${concatMapStringsSep "\n    " mkSnapshotVersion versions}
              </snapshotVersions>
            </versioning>
          </metadata>
        ''
      ) modules);

  mkRepo = project: type: deps: buildEnv {
    name = "${project}-gradle-${type}-env";
    paths = map mkDep deps ++ mkModuleMetadata deps ++ mkSnapshotMetadata deps;
  };

  mkInitScript = projectSpec: gradle:
    let
      repos = mapAttrs (mkRepo projectSpec.name) projectSpec.dependencies;
      hasDependencies = mapAttrs (type: deps: deps != []) projectSpec.dependencies;

      inSettings = pred: script:
        optionalString pred (
          if versionAtLeast gradle.version "6.0" then ''
            gradle.beforeSettings {
              ${script}
            }
          '' else ''
            gradle.settingsEvaluated {
              ${script}
            }
          ''
        );
    in
      assert (assertMsg (hasDependencies.settings -> versionAtLeast gradle.version "6.0") ''
        Project `${projectSpec.name}' has settings script dependencies, such as settings
        plugins, which are not supported by gradle2nix for Gradle versions prior to 6.0.

        Potential remedies:
        - Pass `--gradle-version=<version>' to the gradle2nix command.
        - Patch the `settings.gradle[.kts]' file to remove script dependencies.
      '');

      writeText "init.gradle" ''
        static def offlineRepo(RepositoryHandler repositories, String env, String path) {
            repositories.clear()
            repositories.maven {
                name "Nix''${env.capitalize()}MavenOffline"
                url path
                metadataSources {
                    it.gradleMetadata()
                    it.mavenPom()
                    it.artifact()
                }
            }
            repositories.ivy {
                name "Nix''${env.capitalize()}IvyOffline"
                url path
                layout "maven"
                metadataSources {
                    it.gradleMetadata()
                    it.ivyDescriptor()
                    it.artifact()
                }
            }
        }

        ${inSettings (hasDependencies.settings && (versionAtLeast gradle.version "6.0")) ''
          offlineRepo(it.buildscript.repositories, "settings", "${repos.settings}")
        ''}

        ${inSettings (hasDependencies.plugin) ''
            offlineRepo(it.pluginManagement.repositories, "plugin", "${repos.plugin}")
        ''}

        ${optionalString (hasDependencies.buildscript) ''
          gradle.projectsLoaded {
              allprojects {
                  buildscript {
                      offlineRepo(repositories, "buildscript", "${repos.buildscript}")
                  }
              }
          }
        ''}

        ${optionalString (hasDependencies.project) (
          if versionAtLeast gradle.version "6.8"
          then ''
            gradle.beforeSettings {
                it.dependencyResolutionManagement {
                    offlineRepo(repositories, "project", "${repos.project}")
                    repositoriesMode.set(RepositoriesMode.PREFER_SETTINGS)
                }
            }
          ''
          else ''
            gradle.projectsLoaded {
                allprojects {
                    offlineRepo(repositories, "project", "${repos.project}")
                }
            }
          ''
        )}

        ${extraInit}
      '';

  mkGradle = gradleSpec:
    gradleGen.gradleGen {
      inherit (gradleSpec) nativeVersion;

      name = "gradle-${gradleSpec.version}-${gradleSpec.type}";

      src = fetchurl {
        inherit (gradleSpec) url sha256;
      };
    } // {
      inherit (gradleSpec) version;
    };

  mkProjectEnv = projectSpec: rec {
    inherit (projectSpec) name path version;
    gradle = args.gradlePackage or mkGradle projectSpec.gradle;
    initScript = mkInitScript projectSpec gradle;
  };

  gradleEnv = mapAttrs
    (_: p: mkProjectEnv p)
    (fromJSON (readFile envSpec));

  projectEnv = gradleEnv."";
  pname = args.pname or projectEnv.name;
  version = args.version or projectEnv.version;

  buildProject = env: flags: ''
    cp ${env.initScript} "$GRADLE_USER_HOME/init.d"

    gradle --offline --no-daemon --no-build-cache \
      --info --full-stacktrace --warning-mode=all \
      ${optionalString enableParallelBuilding "--parallel"} \
      ${optionalString enableDebug "-Dorg.gradle.debug=true"} \
      ${optionalString (buildJdk != null) "-Dorg.gradle.java.home=${buildJdk.home}"} \
      --init-script ${env.initScript} \
      ${optionalString (env.path != "") ''-p "${env.path}"''} \
      ${concatStringsSep " " flags}
  '';

  buildIncludedProjects =
    concatStringsSep "\n" (mapAttrsToList
      (_: env: buildProject env [ "build" ])
      (removeAttrs gradleEnv [ "" ]));

  buildRootProject = buildProject projectEnv gradleFlags;

in stdenv.mkDerivation (args // {

  inherit pname version;

  nativeBuildInputs = (args.nativeBuildInputs or []) ++ [ projectEnv.gradle ];

  buildPhase = args.buildPhase or ''
    runHook preBuild

    (
    set -eux

    # Work around https://github.com/gradle/gradle/issues/1055
    TMPHOME="$(mktemp -d)"
    mkdir -p "$TMPHOME/init.d"
    export GRADLE_USER_HOME="$TMPHOME"

    ${buildIncludedProjects}
    ${buildRootProject}
    )

    runHook postBuild
  '';

  dontStrip = true;
})