// 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.

library services.common_server_impl;

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

import 'package:crypto/crypto.dart';
import 'package:logging/logging.dart';
import 'package:pedantic/pedantic.dart';

import '../version.dart';
import 'analysis_server.dart';
import 'common.dart';
import 'compiler.dart';
import 'flutter_web.dart';
import 'protos/dart_services.pb.dart' as proto;
import 'pub.dart';
import 'sdk_manager.dart';
import 'server_cache.dart';

const Duration _standardExpiration = Duration(hours: 1);
final Logger log = Logger('common_server');

class BadRequest implements Exception {
  String cause;

  BadRequest(this.cause);
}

abstract class ServerContainer {
  String get version;
}

class CommonServerImpl {
  final String sdkPath;
  final FlutterWebManager flutterWebManager;
  final ServerContainer container;
  final ServerCache cache;

  Compiler compiler;
  AnalysisServerWrapper analysisServer;
  AnalysisServerWrapper flutterAnalysisServer;

  bool get analysisServersRunning =>
      analysisServer.analysisServer != null &&
      flutterAnalysisServer.analysisServer != null;

  // If non-null, this value indicates that the server is starting/restarting
  // and holds the time at which that process began. If null, the server is
  // ready to handle requests.
  DateTime _restartingSince = DateTime.now();

  bool get isRestarting => (_restartingSince != null);

  // If the server has been trying and failing to restart for more than a half
  // hour, something is seriously wrong.
  bool get isHealthy => (_restartingSince == null ||
      DateTime.now().difference(_restartingSince).inMinutes < 30);

  CommonServerImpl(
    this.sdkPath,
    this.flutterWebManager,
    this.container,
    this.cache,
  ) {
    hierarchicalLoggingEnabled = true;
    log.level = Level.ALL;
  }

  Future<void> init() async {
    log.info('Beginning CommonServer init().');
    analysisServer = AnalysisServerWrapper(sdkPath, flutterWebManager);
    flutterAnalysisServer = AnalysisServerWrapper(
        flutterWebManager.flutterSdk.sdkPath, flutterWebManager);

    compiler =
        Compiler(SdkManager.sdk, SdkManager.flutterSdk, flutterWebManager);

    await analysisServer.init();
    log.info('Dart analysis server initialized.');

    await flutterAnalysisServer.init();
    log.info('Flutter analysis server initialized.');

    unawaited(analysisServer.onExit.then((int code) {
      log.severe('analysisServer exited, code: $code');
      if (code != 0) {
        exit(code);
      }
    }));

    unawaited(flutterAnalysisServer.onExit.then((int code) {
      log.severe('flutterAnalysisServer exited, code: $code');
      if (code != 0) {
        exit(code);
      }
    }));

    _restartingSince = null;

    await flutterWebManager.warmup();
    await compiler.warmup();
    await analysisServer.warmup();
    await flutterAnalysisServer.warmup();
  }

  Future<void> restart() async {
    log.warning('Restarting CommonServer');
    await shutdown();
    log.info('Analysis Servers shutdown');

    await init();
    log.warning('Restart complete');
  }

  Future<dynamic> shutdown() {
    _restartingSince = DateTime.now();

    return Future.wait(<Future<dynamic>>[
      analysisServer.shutdown(),
      flutterAnalysisServer.shutdown(),
      compiler.dispose(),
      Future<dynamic>.sync(cache.shutdown)
    ]).timeout(const Duration(minutes: 1));
  }

  Future<proto.AnalysisResults> analyze(proto.SourceRequest request) {
    if (!request.hasSource()) {
      throw BadRequest('Missing parameter: \'source\'');
    }

    return _analyze(request.source);
  }

  Future<proto.CompileResponse> compile(proto.CompileRequest request) {
    if (!request.hasSource()) {
      throw BadRequest('Missing parameter: \'source\'');
    }

    return _compileDart2js(request.source,
        returnSourceMap: request.returnSourceMap ?? false);
  }

  Future<proto.CompileDDCResponse> compileDDC(proto.CompileDDCRequest request) {
    if (!request.hasSource()) {
      throw BadRequest('Missing parameter: \'source\'');
    }

    return _compileDDC(request.source);
  }

  Future<proto.CompleteResponse> complete(proto.SourceRequest request) {
    if (!request.hasSource()) {
      throw BadRequest('Missing parameter: \'source\'');
    }
    if (!request.hasOffset()) {
      throw BadRequest('Missing parameter: \'offset\'');
    }

    return _complete(request.source, request.offset);
  }

  Future<proto.FixesResponse> fixes(proto.SourceRequest request) {
    if (!request.hasSource()) {
      throw BadRequest('Missing parameter: \'source\'');
    }
    if (!request.hasOffset()) {
      throw BadRequest('Missing parameter: \'offset\'');
    }

    return _fixes(request.source, request.offset);
  }

  Future<proto.AssistsResponse> assists(proto.SourceRequest request) {
    if (!request.hasSource()) {
      throw BadRequest('Missing parameter: \'source\'');
    }
    if (!request.hasOffset()) {
      throw BadRequest('Missing parameter: \'offset\'');
    }

    return _assists(request.source, request.offset);
  }

  Future<proto.FormatResponse> format(proto.SourceRequest request) {
    if (!request.hasSource()) {
      throw BadRequest('Missing parameter: \'source\'');
    }

    return _format(request.source, request.offset ?? 0);
  }

  Future<proto.DocumentResponse> document(proto.SourceRequest request) {
    if (!request.hasSource()) {
      throw BadRequest('Missing parameter: \'source\'');
    }
    if (!request.hasOffset()) {
      throw BadRequest('Missing parameter: \'offset\'');
    }

    return _document(request.source, request.offset);
  }

  Future<proto.VersionResponse> version(proto.VersionRequest _) =>
      Future<proto.VersionResponse>.value(_version());

  Future<proto.AnalysisResults> _analyze(String source) async {
    await _checkPackageReferencesInitFlutterWeb(source);

    try {
      final watch = Stopwatch()..start();

      final results = await getCorrectAnalysisServer(source).analyze(source);
      final lineCount = source.split('\n').length;
      final ms = watch.elapsedMilliseconds;
      log.info('PERF: Analyzed $lineCount lines of Dart in ${ms}ms.');
      return results;
    } catch (e, st) {
      log.severe('Error during _analyze on "$source"', e, st);
      await restart();
      rethrow;
    }
  }

  Future<proto.CompileResponse> _compileDart2js(
    String source, {
    bool returnSourceMap = false,
  }) async {
    try {
      await _checkPackageReferencesInitFlutterWeb(source);

      final sourceHash = _hashSource(source);
      final memCacheKey = '%%COMPILE:v0'
          ':returnSourceMap:$returnSourceMap:source:$sourceHash';

      final result = await checkCache(memCacheKey);
      if (result != null) {
        log.info('CACHE: Cache hit for compileDart2js');
        final resultObj = const JsonDecoder().convert(result);
        final response = proto.CompileResponse()
          ..result = resultObj['compiledJS'] as String;
        if (resultObj['sourceMap'] != null) {
          response.sourceMap = resultObj['sourceMap'] as String;
        }
        return response;
      }

      log.info('CACHE: MISS for compileDart2js');
      final watch = Stopwatch()..start();

      final results =
          await compiler.compile(source, returnSourceMap: returnSourceMap);

      if (results.hasOutput) {
        final lineCount = source.split('\n').length;
        final outputSize = (results.compiledJS.length / 1024).ceil();
        final ms = watch.elapsedMilliseconds;
        log.info('PERF: Compiled $lineCount lines of Dart into '
            '${outputSize}kb of JavaScript in ${ms}ms using dart2js.');
        final sourceMap = returnSourceMap ? results.sourceMap : null;

        final cachedResult = const JsonEncoder().convert(<String, String>{
          'compiledJS': results.compiledJS,
          'sourceMap': sourceMap,
        });
        // Don't block on cache set.
        unawaited(setCache(memCacheKey, cachedResult));
        final compileResponse = proto.CompileResponse();
        compileResponse.result = results.compiledJS;
        if (sourceMap != null) {
          compileResponse.sourceMap = sourceMap;
        }
        return compileResponse;
      } else {
        final problems = results.problems;
        final errors = problems.map(_printCompileProblem).join('\n');
        throw BadRequest(errors);
      }
    } catch (e, st) {
      if (e is! BadRequest) {
        log.severe('Error during compile (dart2js) on "$source"', e, st);
      }
      rethrow;
    }
  }

  Future<proto.CompileDDCResponse> _compileDDC(String source) async {
    try {
      await _checkPackageReferencesInitFlutterWeb(source);

      final sourceHash = _hashSource(source);
      final memCacheKey = '%%COMPILE_DDC:v0:source:$sourceHash';

      final result = await checkCache(memCacheKey);
      if (result != null) {
        log.info('CACHE: Cache hit for compileDDC');
        final resultObj = const JsonDecoder().convert(result);
        return proto.CompileDDCResponse()
          ..result = resultObj['compiledJS'] as String
          ..modulesBaseUrl = resultObj['modulesBaseUrl'] as String;
      }

      log.info('CACHE: MISS for compileDDC');
      final watch = Stopwatch()..start();

      final results = await compiler.compileDDC(source);

      if (results.hasOutput) {
        final lineCount = source.split('\n').length;
        final outputSize = (results.compiledJS.length / 1024).ceil();
        final ms = watch.elapsedMilliseconds;
        log.info('PERF: Compiled $lineCount lines of Dart into '
            '${outputSize}kb of JavaScript in ${ms}ms using DDC.');

        final cachedResult = const JsonEncoder().convert(<String, String>{
          'compiledJS': results.compiledJS,
          'modulesBaseUrl': results.modulesBaseUrl,
        });
        // Don't block on cache set.
        unawaited(setCache(memCacheKey, cachedResult));
        return proto.CompileDDCResponse()
          ..result = results.compiledJS
          ..modulesBaseUrl = results.modulesBaseUrl;
      } else {
        final problems = results.problems;
        final errors = problems.map(_printCompileProblem).join('\n');
        throw BadRequest(errors);
      }
    } catch (e, st) {
      if (e is! BadRequest) {
        log.severe('Error during compile (DDC) on "$source"', e, st);
      }
      rethrow;
    }
  }

  Future<proto.DocumentResponse> _document(String source, int offset) async {
    await _checkPackageReferencesInitFlutterWeb(source);

    final watch = Stopwatch()..start();
    try {
      var docInfo =
          await getCorrectAnalysisServer(source).dartdoc(source, offset);
      docInfo ??= <String, String>{};
      log.info('PERF: Computed dartdoc in ${watch.elapsedMilliseconds}ms.');
      return proto.DocumentResponse()..info.addAll(docInfo);
    } catch (e, st) {
      log.severe('Error during _document on "$source" at $offset', e, st);
      await restart();
      rethrow;
    }
  }

  proto.VersionResponse _version() => proto.VersionResponse()
    ..sdkVersion = SdkManager.sdk.version
    ..sdkVersionFull = SdkManager.sdk.versionFull
    ..runtimeVersion = vmVersion
    ..servicesVersion = servicesVersion
    ..appEngineVersion = container.version
    ..flutterDartVersion = SdkManager.flutterSdk.version
    ..flutterDartVersionFull = SdkManager.flutterSdk.versionFull
    ..flutterVersion = SdkManager.flutterSdk.flutterVersion;

  Future<proto.CompleteResponse> _complete(String source, int offset) async {
    await _checkPackageReferencesInitFlutterWeb(source);

    final watch = Stopwatch()..start();
    try {
      final response =
          await getCorrectAnalysisServer(source).complete(source, offset);
      log.info('PERF: Computed completions in ${watch.elapsedMilliseconds}ms.');
      return response;
    } catch (e, st) {
      log.severe('Error during _complete on "$source" at $offset', e, st);
      await restart();
      rethrow;
    }
  }

  Future<proto.FixesResponse> _fixes(String source, int offset) async {
    try {
      await _checkPackageReferencesInitFlutterWeb(source);

      final watch = Stopwatch()..start();
      final response =
          await getCorrectAnalysisServer(source).getFixes(source, offset);
      log.info('PERF: Computed fixes in ${watch.elapsedMilliseconds}ms.');
      return response;
    } catch (e, st) {
      log.severe('Error during _fixes on "$source" at $offset', e, st);
      await restart();
      rethrow;
    }
  }

  Future<proto.AssistsResponse> _assists(String source, int offset) async {
    try {
      await _checkPackageReferencesInitFlutterWeb(source);

      final watch = Stopwatch()..start();
      final response =
          await getCorrectAnalysisServer(source).getAssists(source, offset);
      log.info('PERF: Computed assists in ${watch.elapsedMilliseconds}ms.');
      return response;
    } catch (e, st) {
      log.severe('Error during _assists on "$source" at $offset', e, st);
      await restart();
      rethrow;
    }
  }

  Future<proto.FormatResponse> _format(String source, int offset) async {
    try {
      final watch = Stopwatch()..start();

      final response =
          await getCorrectAnalysisServer(source).format(source, offset);
      log.info('PERF: Computed format in ${watch.elapsedMilliseconds}ms.');
      return response;
    } catch (e, st) {
      log.severe('Error during _format on "$source" at $offset', e, st);
      await restart();
      rethrow;
    }
  }

  Future<String> checkCache(String query) => cache.get(query);

  Future<void> setCache(String query, String result) =>
      cache.set(query, result, expiration: _standardExpiration);

  /// Check that the set of packages referenced is valid.
  ///
  /// If there are uses of package:flutter, ensure that support there is
  /// initialized.
  Future<void> _checkPackageReferencesInitFlutterWeb(String source) async {
    final imports = getAllImportsFor(source);

    if (flutterWebManager.hasUnsupportedImport(imports)) {
      throw BadRequest(
          'Unsupported input: ${flutterWebManager.getUnsupportedImport(imports)}');
    }

    if (flutterWebManager.usesFlutterWeb(imports)) {
      try {
        await flutterWebManager.initFlutterWeb();
      } catch (e) {
        log.warning('unable to init package:flutter: $e');
        return;
      }
    }
  }

  AnalysisServerWrapper getCorrectAnalysisServer(String source) {
    final imports = getAllImportsFor(source);
    return flutterWebManager.usesFlutterWeb(imports)
        ? flutterAnalysisServer
        : analysisServer;
  }
}

String _printCompileProblem(CompilationProblem problem) => problem.message;

String _hashSource(String str) {
  return sha1.convert(str.codeUnits).toString();
}