// 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.

library polymer.test.transfom.common;

import 'dart:async';

import 'package:barback/barback.dart';
import 'package:stack_trace/stack_trace.dart';
import 'package:unittest/unittest.dart';

String idToString(AssetId id) => '${id.package}|${id.path}';
AssetId idFromString(String s) {
  int index = s.indexOf('|');
  return new AssetId(s.substring(0, index), s.substring(index + 1));
}

/**
 * A helper package provider that has files stored in memory, also wraps
 * [Barback] to simply our tests.
 */
class TestHelper implements PackageProvider {
  /**
   * Maps from an asset string identifier of the form 'package|path' to the
   * file contents. 
   */
  final Map<String, String> files;
  final Iterable<String> packages;

  Barback barback;
  var errorSubscription;
  var resultSubscription;

  Future<Asset> getAsset(AssetId id) =>
      new Future.value(new Asset.fromString(id, files[idToString(id)]));
  TestHelper(List<List<Transformer>> transformers, Map<String, String> files)
      : files = files,
        packages = files.keys.map((s) => idFromString(s).package) {
    barback = new Barback(this);
    for (var p in packages) {
      barback.updateTransformers(p, transformers);
    }
    errorSubscription = barback.errors.listen((e) {
      var trace = getAttachedStackTrace(e);
      if (trace != null) {
        print(Trace.format(trace));
      }
      fail('error running barback: $e');
    });
    resultSubscription = barback.results.listen((result) {
      expect(result.succeeded, isTrue, reason: "${result.errors}");
    });
  }

  void tearDown() {
    errorSubscription.cancel();
    resultSubscription.cancel();
  }

  /**
   * Tells barback which files have changed, and thus anything that depends on
   * it on should be computed. By default mark all the input files.
   */
  void run([Iterable<String> paths]) {
    if (paths == null) paths = files.keys;
    barback.updateSources(paths.map(idFromString));
  }

  Future<String> operator [](String assetString){
    return barback.getAssetById(idFromString(assetString))
        .then((asset) => asset.readAsString());
  }

  Future check(String assetIdString, String content) {
    return this[assetIdString].then((value) {
      expect(value, content, reason: 'Final output of $assetIdString differs.');
    });
  }

  Future checkAll(Map<String, String> files) {
    var futures = [];
    files.forEach((k, v) {
      futures.add(check(k, v));
    });
    return Future.wait(futures);
  }
}

testPhases(String testName, List<List<Transformer>> phases,
    Map<String, String> inputFiles, Map<String, String> expectedFiles) {
  test(testName, () {
    var helper = new TestHelper(phases, inputFiles)..run();
    return helper.checkAll(expectedFiles).then((_) => helper.tearDown());
  });
}

const SHADOW_DOM_TAG =
    '<script src="packages/shadow_dom/shadow_dom.min.js"></script>\n';

const INTEROP_TAG = '<script src="packages/browser/interop.js"></script>\n';