// Copyright (c) 2012, 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 matcher.iterable_matchers;

import 'core_matchers.dart';
import 'description.dart';
import 'interfaces.dart';
import 'util.dart';

/// Returns a matcher which matches [Iterable]s in which all elements
/// match the given [matcher].
Matcher everyElement(matcher) => new _EveryElement(wrapMatcher(matcher));

class _EveryElement extends _IterableMatcher {
  final Matcher _matcher;

  _EveryElement(Matcher this._matcher);

  bool matches(item, Map matchState) {
    if (item is! Iterable) {
      return false;
    }
    var i = 0;
    for (var element in item) {
      if (!_matcher.matches(element, matchState)) {
        addStateInfo(matchState, {'index': i, 'element': element});
        return false;
      }
      ++i;
    }
    return true;
  }

  Description describe(Description description) =>
      description.add('every element(').addDescriptionOf(_matcher).add(')');

  Description describeMismatch(item, Description mismatchDescription,
                               Map matchState, bool verbose) {
    if (matchState['index'] != null) {
      var index = matchState['index'];
      var element = matchState['element'];
      mismatchDescription.add('has value ').addDescriptionOf(element).
          add(' which ');
      var subDescription = new StringDescription();
      _matcher.describeMismatch(element, subDescription, matchState['state'],
          verbose);
      if (subDescription.length > 0) {
        mismatchDescription.add(subDescription.toString());
      } else {
        mismatchDescription.add("doesn't match ");
        _matcher.describe(mismatchDescription);
      }
      mismatchDescription.add(' at index $index');
      return mismatchDescription;
    }
    return super.describeMismatch(item, mismatchDescription,
          matchState, verbose);
  }
}

/// Returns a matcher which matches [Iterable]s in which at least one
/// element matches the given [matcher].
Matcher anyElement(matcher) => new _AnyElement(wrapMatcher(matcher));

class _AnyElement extends _IterableMatcher {
  final Matcher _matcher;

  _AnyElement(this._matcher);

  bool matches(item, Map matchState) {
    return item.any((e) => _matcher.matches(e, matchState));
  }

  Description describe(Description description) =>
      description.add('some element ').addDescriptionOf(_matcher);
}

/// Returns a matcher which matches [Iterable]s that have the same
/// length and the same elements as [expected], in the same order.
///
/// This is equivalent to [equals] but does not recurse.
Matcher orderedEquals(Iterable expected) => new _OrderedEquals(expected);

class _OrderedEquals extends Matcher {
  final Iterable _expected;
  Matcher _matcher;

  _OrderedEquals(this._expected) {
    _matcher = equals(_expected, 1);
  }

  bool matches(item, Map matchState) =>
      (item is Iterable) && _matcher.matches(item, matchState);

  Description describe(Description description) =>
      description.add('equals ').addDescriptionOf(_expected).add(' ordered');

  Description describeMismatch(item, Description mismatchDescription,
                               Map matchState, bool verbose) {
    if (item is !Iterable) {
      return mismatchDescription.add('is not an Iterable');
    } else {
      return _matcher.describeMismatch(item, mismatchDescription,
          matchState, verbose);
    }
  }
}

/// Returns a matcher which matches [Iterable]s that have the same length and
/// the same elements as [expected], but not necessarily in the same order.
///
/// Note that this is O(n^2) so should only be used on small objects.
Matcher unorderedEquals(Iterable expected) => new _UnorderedEquals(expected);

class _UnorderedEquals extends _UnorderedMatches {
  final List _expectedValues;

  _UnorderedEquals(Iterable expected)
      : super(expected.map(equals)),
        _expectedValues = expected.toList();

  Description describe(Description description) =>
    description
        .add('equals ')
        .addDescriptionOf(_expectedValues)
        .add(' unordered');
}

/// Iterable matchers match against [Iterable]s. We add this intermediate
/// class to give better mismatch error messages than the base Matcher class.
abstract class _IterableMatcher extends Matcher {
  const _IterableMatcher();
  Description describeMismatch(item, Description mismatchDescription,
                               Map matchState, bool verbose) {
    if (item is! Iterable) {
      return mismatchDescription.
          addDescriptionOf(item).
          add(' not an Iterable');
    } else {
      return super.describeMismatch(item, mismatchDescription, matchState,
          verbose);
    }
  }
}

/// Returns a matcher which matches [Iterable]s whose elements match the
/// matchers in [expected], but not necessarily in the same order.
///
///  Note that this is `O(n^2)` and so should only be used on small objects.
Matcher unorderedMatches(Iterable expected) => new _UnorderedMatches(expected);

class _UnorderedMatches extends Matcher {
  final List<Matcher> _expected;

  _UnorderedMatches(Iterable expected)
      : _expected = expected.map(wrapMatcher).toList();

  String _test(item) {
    if (item is! Iterable) return 'not iterable';
    item = item.toList();

    // Check the lengths are the same.
    if (_expected.length > item.length) {
      return 'has too few elements (${item.length} < ${_expected.length})';
    } else if (_expected.length < item.length) {
      return 'has too many elements (${item.length} > ${_expected.length})';
    }

    var matched = new List<bool>.filled(item.length, false);
    var expectedPosition = 0;
    for (var expectedMatcher in _expected) {
      var actualPosition = 0;
      var gotMatch = false;
      for (var actualElement in item) {
        if (!matched[actualPosition]) {
          if (expectedMatcher.matches(actualElement, {})) {
            matched[actualPosition] = gotMatch = true;
            break;
          }
        }
        ++actualPosition;
      }

      if (!gotMatch) {
        return new StringDescription()
            .add('has no match for ')
            .addDescriptionOf(expectedMatcher)
            .add(' at index ${expectedPosition}')
            .toString();
      }

      ++expectedPosition;
    }
    return null;
  }

  bool matches(item, Map mismatchState) => _test(item) == null;

  Description describe(Description description) =>
    description
      .add('matches ')
      .addAll('[', ', ', ']', _expected)
      .add(' unordered');

  Description describeMismatch(item, Description mismatchDescription,
                               Map matchState, bool verbose) =>
      mismatchDescription.add(_test(item));
}

/// A pairwise matcher for [Iterable]s.
///
/// The [comparator] function, taking an expected and an actual argument, and
/// returning whether they match, will be applied to each pair in order.
/// [description] should be a meaningful name for the comparator.
Matcher pairwiseCompare(Iterable expected, bool comparator(a, b),
    String description) =>
        new _PairwiseCompare(expected, comparator, description);

typedef bool _Comparator(a, b);

class _PairwiseCompare extends _IterableMatcher {
  final Iterable _expected;
  final _Comparator _comparator;
  final String _description;

  _PairwiseCompare(this._expected, this._comparator, this._description);

  bool matches(item, Map matchState) {
    if (item is! Iterable) return false;
    if (item.length != _expected.length) return false;
    var iterator = item.iterator;
    var i = 0;
    for (var e in _expected) {
      iterator.moveNext();
      if (!_comparator(e, iterator.current)) {
        addStateInfo(matchState, {'index': i, 'expected': e,
            'actual': iterator.current});
        return false;
      }
      i++;
    }
    return true;
  }

  Description describe(Description description) =>
      description.add('pairwise $_description ').addDescriptionOf(_expected);

  Description describeMismatch(item, Description mismatchDescription,
                               Map matchState, bool verbose) {
    if (item is !Iterable) {
      return mismatchDescription.add('is not an Iterable');
    } else if (item.length != _expected.length) {
      return mismatchDescription.
          add('has length ${item.length} instead of ${_expected.length}');
    } else {
      return mismatchDescription.
          add('has ').
          addDescriptionOf(matchState["actual"]).
          add(' which is not $_description ').
          addDescriptionOf(matchState["expected"]).
          add(' at index ${matchState["index"]}');
    }
  }
}