// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import 'dart:async';
import 'dart:io';

import 'package:async/async.dart';
import 'package:path/path.dart' as p;
import 'package:source_span/source_span.dart';
import 'package:yaml/yaml.dart';

import 'package:test_api/src/backend/group.dart'; // ignore: implementation_imports
import 'package:test_api/src/backend/invoker.dart'; // ignore: implementation_imports
import 'package:test_api/src/backend/runtime.dart'; // ignore: implementation_imports

import 'hack_register_platform.dart';
import 'platform.dart';
import 'runner_suite.dart';
import 'suite.dart';
import 'configuration.dart';
import 'load_exception.dart';
import 'load_suite.dart';
import 'parse_metadata.dart';
import 'plugin/customizable_platform.dart';
import 'plugin/environment.dart';
import 'vm/platform.dart';
import '../util/io.dart';

/// A class for finding test files and loading them into a runnable form.
class Loader {
  /// The test runner configuration.
  final _config = Configuration.current;

  /// All suites that have been created by the loader.
  final _suites = <RunnerSuite>{};

  /// Memoizers for platform plugins, indexed by the runtimes they support.
  final _platformPlugins = <Runtime, AsyncMemoizer<PlatformPlugin>>{};

  /// The functions to use to load [_platformPlugins].
  ///
  /// These are passed to the plugins' async memoizers when a plugin is needed.
  final _platformCallbacks = <Runtime, FutureOr<PlatformPlugin> Function()>{};

  /// A map of all runtimes registered in [_platformCallbacks], indexed by
  /// their string identifiers.
  final _runtimesByIdentifier = <String, Runtime>{};

  /// The user-provided settings for runtimes, as a list of settings that will
  /// be merged together using [CustomizablePlatform.mergePlatformSettings].
  final _runtimeSettings = <Runtime, List<YamlMap>>{};

  /// The user-provided settings for runtimes.
  final _parsedRuntimeSettings = <Runtime, Object>{};

  /// All plaforms supported by this [Loader].
  List<Runtime> get allRuntimes => List.unmodifiable(_platformCallbacks.keys);

  /// The runtime variables supported by this loader, in addition the default
  /// variables that are always supported.
  Iterable<String> get _runtimeVariables =>
      _platformCallbacks.keys.map((runtime) => runtime.identifier);

  /// Creates a new loader that loads tests on platforms defined in
  /// [Configuration.current].
  Loader() {
    _registerPlatformPlugin([Runtime.vm], () => VMPlatform());

    platformCallbacks.forEach((runtime, plugin) {
      _registerPlatformPlugin([runtime], plugin);
    });

    _registerCustomRuntimes();

    _config.validateRuntimes(allRuntimes);

    _registerRuntimeOverrides();
  }

  /// Registers a [PlatformPlugin] for [runtimes].
  void _registerPlatformPlugin(
      Iterable<Runtime> runtimes, FutureOr<PlatformPlugin> Function() plugin) {
    var memoizer = AsyncMemoizer<PlatformPlugin>();
    for (var runtime in runtimes) {
      _platformPlugins[runtime] = memoizer;
      _platformCallbacks[runtime] = plugin;
      _runtimesByIdentifier[runtime.identifier] = runtime;
    }
  }

  /// Registers user-defined runtimes from [Configuration.defineRuntimes].
  void _registerCustomRuntimes() {
    for (var customRuntime in _config.defineRuntimes.values) {
      if (_runtimesByIdentifier.containsKey(customRuntime.identifier)) {
        throw SourceSpanFormatException(
            wordWrap(
                'The platform "${customRuntime.identifier}" already exists. '
                'Use override_platforms to override it.'),
            customRuntime.identifierSpan);
      }

      var parent = _runtimesByIdentifier[customRuntime.parent];
      if (parent == null) {
        throw SourceSpanFormatException(
            'Unknown platform.', customRuntime.parentSpan);
      }

      var runtime = parent.extend(customRuntime.name, customRuntime.identifier);
      _platformPlugins[runtime] = _platformPlugins[parent]!;
      _platformCallbacks[runtime] = _platformCallbacks[parent]!;
      _runtimesByIdentifier[runtime.identifier] = runtime;

      _runtimeSettings[runtime] = [customRuntime.settings];
    }
  }

  /// Registers users' runtime settings from [Configuration.overrideRuntimes].
  void _registerRuntimeOverrides() {
    for (var settings in _config.overrideRuntimes.values) {
      var runtime = _runtimesByIdentifier[settings.identifier];
      _runtimeSettings
          .putIfAbsent(runtime!, () => [])
          .addAll(settings.settings);
    }
  }

  /// Returns the [Runtime] registered with this loader that's identified
  /// by [identifier], or `null` if none can be found.
  Runtime? findRuntime(String identifier) => _runtimesByIdentifier[identifier];

  /// Loads all test suites in [dir] according to [suiteConfig].
  ///
  /// This will load tests from files that match the global configuration's
  /// filename glob. Any tests that fail to load will be emitted as
  /// [LoadException]s.
  ///
  /// This emits [LoadSuite]s that must then be run to emit the actual
  /// [RunnerSuite]s defined in the file.
  Stream<LoadSuite> loadDir(String dir, SuiteConfiguration suiteConfig) {
    return StreamGroup.merge(
        Directory(dir).listSync(recursive: true).map((entry) {
      if (entry is! File ||
          !_config.filename.matches(p.basename(entry.path)) ||
          p.split(entry.path).contains('packages')) {
        return Stream.empty();
      }

      return loadFile(entry.path, suiteConfig);
    }));
  }

  /// Loads a test suite from the file at [path] according to [suiteConfig].
  ///
  /// This emits [LoadSuite]s that must then be run to emit the actual
  /// [RunnerSuite]s defined in the file.
  ///
  /// This will emit a [LoadException] if the file fails to load.
  Stream<LoadSuite> loadFile(
      String path, SuiteConfiguration suiteConfig) async* {
    try {
      suiteConfig = suiteConfig.merge(SuiteConfiguration.fromMetadata(
          parseMetadata(
              path, File(path).readAsStringSync(), _runtimeVariables.toSet())));
    } on ArgumentError catch (_) {
      // Ignore the analyzer's error, since its formatting is much worse than
      // the VM's or dart2js's.
    } on FormatException catch (error, stackTrace) {
      yield LoadSuite.forLoadException(LoadException(path, error), suiteConfig,
          stackTrace: stackTrace);
      return;
    }

    if (_config.suiteDefaults.excludeTags
        .evaluate(suiteConfig.metadata.tags.contains)) {
      return;
    }

    if (_config.pubServeUrl != null && !p.isWithin('test', path)) {
      yield LoadSuite.forLoadException(
          LoadException(
              path, 'When using "pub serve", all test files must be in test/.'),
          suiteConfig);
      return;
    }

    for (var runtimeName in suiteConfig.runtimes) {
      var runtime = findRuntime(runtimeName);
      assert(runtime != null, 'Unknown platform "$runtimeName".');

      var platform = currentPlatform(runtime!);
      if (!suiteConfig.metadata.testOn.evaluate(platform)) {
        continue;
      }

      var platformConfig = suiteConfig.forPlatform(platform);

      // Don't load a skipped suite.
      if (platformConfig.metadata.skip && !platformConfig.runSkipped) {
        yield LoadSuite.forSuite(RunnerSuite(
            const PluginEnvironment(),
            platformConfig,
            Group.root([LocalTest('(suite)', platformConfig.metadata, () {})],
                metadata: platformConfig.metadata),
            platform,
            path: path));
        continue;
      }

      var name =
          (platform.runtime.isJS && platformConfig.precompiledPath == null
                  ? 'compiling '
                  : 'loading ') +
              path;
      yield LoadSuite(name, platformConfig, platform, () async {
        var memo = _platformPlugins[platform.runtime]!;

        var retriesLeft = suiteConfig.metadata.retry;
        while (true) {
          try {
            var plugin =
                await memo.runOnce(_platformCallbacks[platform.runtime]!);
            _customizePlatform(plugin, platform.runtime);
            var suite = await plugin.load(path, platform, platformConfig,
                {'platformVariables': _runtimeVariables.toList()});
            if (suite != null) _suites.add(suite);
            return suite;
          } on Object catch (error, stackTrace) {
            if (retriesLeft > 0) {
              retriesLeft--;
              print('Retrying load of $path in 1s ($retriesLeft remaining)');
              await Future.delayed(Duration(seconds: 1));
              continue;
            }
            if (error is LoadException) {
              rethrow;
            }
            await Future.error(LoadException(path, error), stackTrace);
            return null;
          }
        }
      }, path: path);
    }
  }

  /// Passes user-defined settings to [plugin] if necessary.
  void _customizePlatform(PlatformPlugin plugin, Runtime runtime) {
    var parsed = _parsedRuntimeSettings[runtime];
    if (parsed != null) {
      (plugin as CustomizablePlatform).customizePlatform(runtime, parsed);
      return;
    }

    var settings = _runtimeSettings[runtime];
    if (settings == null) return;

    if (plugin is CustomizablePlatform) {
      parsed = settings
          .map(plugin.parsePlatformSettings)
          .reduce(plugin.mergePlatformSettings);
      plugin.customizePlatform(runtime, parsed);
      _parsedRuntimeSettings[runtime] = parsed;
    } else {
      String identifier;
      SourceSpan span;
      if (runtime.isChild) {
        identifier = runtime.parent!.identifier;
        span = _config.defineRuntimes[runtime.identifier]!.parentSpan;
      } else {
        identifier = runtime.identifier;
        span = _config.overrideRuntimes[runtime.identifier]!.identifierSpan;
      }

      throw SourceSpanFormatException(
          'The "$identifier" platform can\'t be customized.', span);
    }
  }

  Future closeEphemeral() async {
    await Future.wait(_platformPlugins.values.map((memo) async {
      if (!memo.hasRun) return;
      await (await memo.future).closeEphemeral();
    }));
  }

  /// Closes the loader and releases all resources allocated by it.
  Future close() => _closeMemo.runOnce(() async {
        await Future.wait([
          Future.wait(_platformPlugins.values.map((memo) async {
            if (!memo.hasRun) return;
            await (await memo.future).close();
          })),
          Future.wait(_suites.map((suite) => suite.close()))
        ]);

        _platformPlugins.clear();
        _platformCallbacks.clear();
        _suites.clear();
      });
  final _closeMemo = AsyncMemoizer();
}