// Copyright (c) 2016, 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.
@JS()
library dev_compiler.web.web_command;

import 'dart:async';
import 'dart:convert';
import 'dart:html' show HttpRequest;

import 'package:analyzer/dart/element/element.dart'
    show
        LibraryElement,
        ImportElement,
        ShowElementCombinator,
        HideElementCombinator;
import 'package:analyzer/file_system/file_system.dart' show ResourceUriResolver;
import 'package:analyzer/file_system/memory_file_system.dart'
    show MemoryResourceProvider;
import 'package:analyzer/src/context/context.dart' show AnalysisContextImpl;
import 'package:analyzer/src/summary/idl.dart' show PackageBundle;
import 'package:analyzer/src/summary/package_bundle_reader.dart'
    show
        SummaryDataStore,
        InSummaryUriResolver,
        InputPackagesResultProvider,
        InSummarySource;
import 'package:analyzer/src/dart/resolver/scope.dart' show Scope;

import 'package:args/command_runner.dart';

import 'package:dev_compiler/src/analyzer/context.dart' show AnalyzerOptions;
import 'package:dev_compiler/src/compiler/compiler.dart'
    show BuildUnit, CompilerOptions, JSModuleFile, ModuleCompiler;

import 'package:dev_compiler/src/compiler/module_builder.dart';
import 'package:js/js.dart';
import 'package:path/path.dart' as path;

typedef void MessageHandler(Object message);

@JS()
@anonymous
class CompileResult {
  external factory CompileResult(
      {String code, List<String> errors, bool isValid});
}

typedef CompileModule(String imports, String body, String libraryName,
    String existingLibrary, String fileName);

/// The command for invoking the modular compiler.
class WebCompileCommand extends Command {
  get name => 'compile';

  get description => 'Compile a set of Dart files into a JavaScript module.';
  final MessageHandler messageHandler;

  WebCompileCommand({MessageHandler messageHandler})
      : this.messageHandler = messageHandler ?? print {
    CompilerOptions.addArguments(argParser);
    AnalyzerOptions.addArguments(argParser);
  }

  @override
  Function run() {
    return requestSummaries;
  }

  void requestSummaries(String sdkUrl, List<String> summaryUrls,
      Function onCompileReady, Function onError) {
    HttpRequest.request(sdkUrl).then((sdkRequest) {
      var sdkResponse = sdkRequest.responseText;
      var sdkBytes = BASE64.decode(sdkResponse);

      // Map summary URLs to HttpRequests.
      var summaryRequests = summaryUrls
          .map((summary) => new Future(() => HttpRequest.request(summary)));

      Future.wait(summaryRequests).then((summaryResponses) {
        // Map summary responses to summary bytes.
        var summaryBytes = <List<int>>[];
        for (var response in summaryResponses) {
          summaryBytes.add(BASE64.decode(response.responseText));
        }

        var compileFn = setUpCompile(sdkBytes, summaryBytes, summaryUrls);
        onCompileReady(compileFn);
      }).catchError((error) => onError('Summaries failed to load: $error'));
    }).catchError(
        (error) => onError('Dart sdk summaries failed to load: $error'));
  }

  CompileModule setUpCompile(List<int> sdkBytes, List<List<int>> summaryBytes,
      List<String> summaryUrls) {
    var dartSdkSummaryPath = '/dart-sdk/lib/_internal/web_sdk.sum';

    var resourceProvider = new MemoryResourceProvider()
      ..newFileWithBytes(dartSdkSummaryPath, sdkBytes);

    var resourceUriResolver = new ResourceUriResolver(resourceProvider);

    var summaryDataStore = new SummaryDataStore([]);
    for (var i = 0; i < summaryBytes.length; i++) {
      var bytes = summaryBytes[i];
      var url = summaryUrls[i];
      var summaryBundle = new PackageBundle.fromBuffer(bytes);
      summaryDataStore.addBundle(url, summaryBundle);
    }
    var summaryResolver =
        new InSummaryUriResolver(resourceProvider, summaryDataStore);

    var fileResolvers = [summaryResolver, resourceUriResolver];

    var compiler = new ModuleCompiler(
        new AnalyzerOptions.basic(
            dartSdkPath: '/dart-sdk', dartSdkSummaryPath: dartSdkSummaryPath),
        analysisRoot: '/web-compile-root',
        fileResolvers: fileResolvers,
        resourceProvider: resourceProvider);

    var context = compiler.context as AnalysisContextImpl;
    context.resultProvider =
        new InputPackagesResultProvider(compiler.context, summaryDataStore);

    var compilerOptions = new CompilerOptions.fromArguments(argResults);

    CompileModule compileFn = (String imports, String body, String libraryName,
        String existingLibrary, String fileName) {
      // Create a new virtual File that contains the given Dart source.
      String sourceCode;
      if (existingLibrary == null) {
        sourceCode = imports + body;
      } else {
        var dir = path.dirname(existingLibrary);
        // Need to pull in all the imports from the existing library and
        // re-export all privates as privates in this library.
        var source = context.sourceFactory.forUri(existingLibrary);
        if (source == null) {
          throw "Unable to load source for library $existingLibrary";
        }

        LibraryElement libraryElement = context.computeLibraryElement(source);
        if (libraryElement == null) {
          throw "Unable to get library element.";
        }
        var sb = new StringBuffer(imports);
        sb.write('\n');

        // TODO(jacobr): we need to add a proper Analyzer flag specifing that
        // cross-library privates should be in scope instead of this hack.
        // We set the private name prefix for scope resolution to an invalid
        // character code so that the analyzer ignores normal Dart private
        // scoping rules for top level names allowing REPL users to access
        // privates in arbitrary libraries. The downside of this scheme is it is
        // possible to get errors if privates in the current library and
        // imported libraries happen to have exactly the same name.
        Scope.PRIVATE_NAME_PREFIX = -1;

        // We emulate running code in the context of an existing library by
        // importing that library and all libraries it imports.
        sb.write('import ${JSON.encode(existingLibrary)};\n');

        for (ImportElement importElement in libraryElement.imports) {
          if (importElement.uri == null) continue;
          var uri = importElement.uri;
          // dart: and package: uris are not relative but the path package
          // thinks they are. We have to provide absolute uris as our library
          // has a different directory than the library we are pretending to be.
          if (path.isRelative(uri) &&
              !uri.startsWith('package:') &&
              !uri.startsWith('dart:')) {
            uri = path.normalize(path.join(dir, uri));
          }
          sb.write('import ${JSON.encode(uri)}');
          if (importElement.prefix != null)
            sb.write(' as ${importElement.prefix.name}');
          for (var combinator in importElement.combinators) {
            if (combinator is ShowElementCombinator) {
              sb.write(' show ${combinator.shownNames.join(', ')}');
            } else if (combinator is HideElementCombinator) {
              sb.write(' hide ${combinator.hiddenNames.join(', ')}');
            } else {
              throw 'Unexpected element combinator';
            }
          }
          sb.write(';\n');
        }
        sb.write(body);
        sourceCode = sb.toString();
      }
      resourceProvider.newFile(fileName, sourceCode);

      var unit = new BuildUnit(libraryName, "", [fileName], _moduleForLibrary);

      JSModuleFile module = compiler.compile(unit, compilerOptions);

      var moduleCode = '';
      if (module.isValid) {
        moduleCode = module
            .getCode(ModuleFormat.legacy, unit.name, unit.name + '.map',
                singleOutFile: true)
            .code;
      }

      return new CompileResult(
          code: moduleCode, isValid: module.isValid, errors: module.errors);
    };

    return allowInterop(compileFn);
  }
}

// Given path, determine corresponding dart library.
String _moduleForLibrary(source) {
  if (source is InSummarySource) {
    return source.summaryPath.substring(1).replaceAll('.api.ds', '');
  }
  return source.toString().substring(1).replaceAll('.dart', '');
}

/// Thrown when the input source code has errors.
class CompileErrorException implements Exception {
  toString() => '\nPlease fix all errors before compiling (warnings are okay).';
}