// Copyright (c) 2013, 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.

/// A library for compiling Dart code and manipulating analyzer parse trees.
import 'dart:async';
import 'dart:io';
import 'dart:isolate';

import 'package:analyzer/analyzer.dart';
import 'package:barback/barback.dart';
import 'package:compiler_unsupported/compiler.dart' as compiler;
import 'package:compiler_unsupported/src/filenames.dart' show appendSlash;
import 'package:path/path.dart' as p;

import 'exceptions.dart';
import 'io.dart';
import 'log.dart' as log;

/// Interface to communicate with dart2js.
///
/// This is basically an amalgamation of dart2js's
/// [compiler.CompilerInputProvider], [compiler.CompilerOutputProvider], and
/// [compiler.DiagnosticHandler] function types so that we can provide them
/// as a single unit.
abstract class CompilerProvider {
  /// The URI to the root directory where "dart:" libraries can be found.
  ///
  /// This is used as the base URL to generate library URLs that are then sent
  /// back to [provideInput].
  Uri get libraryRoot;

  /// Given [uri], responds with a future that completes to the contents of
  /// the input file at that URI.
  ///
  /// The future can complete to a string or a list of bytes.
  Future provideInput(Uri uri);

  /// Reports a diagnostic message from dart2js to the user.
  void handleDiagnostic(
      Uri uri, int begin, int end, String message, compiler.Diagnostic kind);

  /// Given a [name] (which will be "" for the entrypoint) and a file extension,
  /// returns an [EventSink] that dart2js can write to to emit an output file.
  EventSink<String> provideOutput(String name, String extension);
}

/// Compiles [entrypoint] to JavaScript (or to Dart if [toDart] is true) as
/// well as any ancillary outputs dart2js creates.
///
/// Uses [provider] to communcate between dart2js and the caller. Returns a
/// future that completes when compilation is done.
///
/// By default, the package root is assumed to be adjacent to [entrypoint], but
/// if [packageRoot] is passed that will be used instead.
Future compile(String entrypoint, CompilerProvider provider,
    {Iterable<String> commandLineOptions,
    bool checked: false,
    bool csp: false,
    bool minify: true,
    bool verbose: false,
    Map<String, String> environment,
    String packageRoot,
    bool analyzeAll: false,
    bool preserveUris: false,
    bool suppressWarnings: false,
    bool suppressHints: false,
    bool suppressPackageWarnings: true,
    bool terse: false,
    bool includeSourceMapUrls: false,
    bool toDart: false,
    String platformBinaries}) async {
  // dart2js chokes on relative paths. Including "/./" can also confuse it, so
  // we normalize as well.
  entrypoint = p.normalize(p.absolute(entrypoint));

  var options = <String>['--categories=Client,Server'];
  if (checked) options.add('--enable-checked-mode');
  if (csp) options.add('--csp');
  if (minify) options.add('--minify');
  if (verbose) options.add('--verbose');
  if (analyzeAll) options.add('--analyze-all');
  if (preserveUris) options.add('--preserve-uris');
  if (suppressWarnings) options.add('--suppress-warnings');
  if (suppressHints) options.add('--suppress-hints');
  if (!suppressPackageWarnings) options.add('--show-package-warnings');
  if (terse) options.add('--terse');
  if (toDart) options.add('--output-type=dart');
  if (platformBinaries != null) {
    options.add('--platform-binaries=$platformBinaries');
  }

  var sourceUrl = p.toUri(entrypoint);
  options.add("--out=$sourceUrl.js");

  // Add the source map URLs.
  if (includeSourceMapUrls) {
    options.add("--source-map=$sourceUrl.js.map");
  }

  if (environment == null) environment = {};
  if (commandLineOptions != null) options.addAll(commandLineOptions);

  if (packageRoot == null) {
    packageRoot = p.join(p.dirname(entrypoint), 'packages');
  } else {
    packageRoot = p.normalize(p.absolute(packageRoot));
  }

  await compiler.compile(
      p.toUri(entrypoint),
      provider.libraryRoot,
      p.toUri(appendSlash(packageRoot)),
      provider.provideInput,
      provider.handleDiagnostic,
      options,
      provider.provideOutput,
      environment);
}

/// Returns whether [dart] looks like an entrypoint file.
bool isEntrypoint(CompilationUnit dart) {
  // Allow two or fewer arguments so that entrypoints intended for use with
  // [spawnUri] get counted.
  //
  // TODO(nweiz): this misses the case where a Dart file doesn't contain main(),
  // but it parts in another file that does.
  return dart.declarations.any((node) {
    return node is FunctionDeclaration &&
        node.name.name == "main" &&
        node.functionExpression.parameters.parameters.length <= 2;
  });
}

/// Returns whether [dart] contains a [PartOfDirective].
bool isPart(CompilationUnit dart) =>
    dart.directives.any((directive) => directive is PartOfDirective);

/// Efficiently parses the import and export directives in [contents].
///
/// If [name] is passed, it's used as the filename for error reporting.
List<UriBasedDirective> parseImportsAndExports(String contents, {String name}) {
  var collector = new _DirectiveCollector();
  parseDirectives(contents, name: name).accept(collector);
  return collector.directives;
}

/// A simple visitor that collects import and export nodes.
class _DirectiveCollector extends GeneralizingAstVisitor {
  final directives = <UriBasedDirective>[];

  visitUriBasedDirective(UriBasedDirective node) => directives.add(node);
}

/// Runs [code] in an isolate.
///
/// [code] should be the contents of a Dart entrypoint. It may contain imports;
/// they will be resolved in the same context as the host isolate. [message] is
/// passed to the [main] method of the code being run; the caller is responsible
/// for using this to establish communication with the isolate.
///
/// [packageRoot] controls the package root of the isolate. It may be either a
/// [String] or a [Uri].
///
/// If [snapshot] is passed, the isolate will be loaded from that path if it
/// exists. Otherwise, a snapshot of the isolate's code will be saved to that
/// path once the isolate is loaded.
Future runInIsolate(String code, message,
    {packageRoot, String snapshot}) async {
  if (snapshot != null && fileExists(snapshot)) {
    log.fine("Spawning isolate from $snapshot.");
    if (packageRoot != null) packageRoot = Uri.parse(packageRoot.toString());
    try {
      // Make the snapshot URI absolute to work around sdk#8440.
      await Isolate.spawnUri(p.toUri(p.absolute(snapshot)), [], message,
          packageRoot: packageRoot);
      return;
    } on IsolateSpawnException catch (error) {
      log.fine("Couldn't load existing snapshot $snapshot:\n$error");
      // Do nothing, we will regenerate the snapshot below.
    }
  }

  await withTempDir((dir) async {
    var dartPath = p.join(dir, 'runInIsolate.dart');
    writeTextFile(dartPath, code, dontLogContents: true);
    await Isolate.spawnUri(p.toUri(p.absolute(dartPath)), [], message,
        packageRoot: packageRoot);

    if (snapshot == null) return;

    ensureDir(p.dirname(snapshot));
    var snapshotArgs = <String>[];
    if (packageRoot != null) snapshotArgs.add('--package-root=$packageRoot');
    snapshotArgs.addAll(['--snapshot=$snapshot', dartPath]);
    var result = await runProcess(Platform.executable, snapshotArgs);

    if (result.success) return;

    // Don't emit a fatal error here, since we don't want to crash the
    // otherwise successful isolate load.
    log.warning("Failed to compile a snapshot to "
        "${p.relative(snapshot)}:\n" +
        result.stderr.join("\n"));
  });
}

/// Snapshots the Dart executable at [executableUrl] to a snapshot at
/// [snapshotPath].
///
/// If [packagesFile] is passed, it's used to resolve `package:` URIs in the
/// executable. Otherwise, a `packages/` directory or a package spec is inferred
/// from the executable's location.
///
/// If [id] is passed, it's used to describe the executable in logs and error
/// messages.
Future snapshot(Uri executableUrl, String snapshotPath,
    {Uri packagesFile, AssetId id}) async {
  var name = log.bold(id == null
      ? executableUrl.toString()
      : "${id.package}:${p.url.basenameWithoutExtension(id.path)}");

  var args = ['--snapshot=$snapshotPath', executableUrl.toString()];
  if (packagesFile != null) args.insert(0, "--packages=$packagesFile");
  var result = await runProcess(Platform.executable, args);

  if (result.success) {
    log.message("Precompiled $name.");
  } else {
    throw new ApplicationException(
        log.yellow("Failed to precompile $name:\n") + result.stderr.join('\n'));
  }
}