package org.hamcrest.collection;

import org.hamcrest.Description;
import org.hamcrest.Matcher;
import org.hamcrest.TypeSafeDiagnosingMatcher;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;

import static org.hamcrest.core.IsEqual.equalTo;

/**
 * Tests if an iterable contains matching elements in any order.
 *
 * @param <T> the type of items in the iterable.
 */
public class IsIterableContainingInAnyOrder<T> extends TypeSafeDiagnosingMatcher<Iterable<? extends T>> {

    private final Collection<Matcher<? super T>> matchers;

    /**
     * Constructor, best called from one of the static "<code>containsInAnyOrder</code>" factory methods.
     * @param matchers the matchers
     * @see #containsInAnyOrder(Object[])
     * @see #containsInAnyOrder(Collection)
     * @see #containsInAnyOrder(Matcher[])
     */
    public IsIterableContainingInAnyOrder(Collection<Matcher<? super T>> matchers) {
        this.matchers = matchers;
    }

    @Override
    protected boolean matchesSafely(Iterable<? extends T> items, Description mismatchDescription) {
      final Matching<T> matching = new Matching<>(matchers, mismatchDescription);
      for (T item : items) {
        if (! matching.matches(item)) {
          return false;
        }
      }

      return matching.isFinished(items);
    }

    @Override
    public void describeTo(Description description) {
      description.appendText("iterable with items ")
          .appendList("[", ", ", "]", matchers)
          .appendText(" in any order");
    }

    private static class Matching<S> {
      private final Collection<Matcher<? super S>> matchers;
      private final Description mismatchDescription;

      public Matching(Collection<Matcher<? super S>> matchers, Description mismatchDescription) {
        this.matchers = new ArrayList<>(matchers);
        this.mismatchDescription = mismatchDescription;
      }

      public boolean matches(S item) {
        if (matchers.isEmpty()) {
          mismatchDescription.appendText("no match for: ").appendValue(item);
          return false;
        }
        return isMatched(item);
      }

      public boolean isFinished(Iterable<? extends S> items) {
        if (matchers.isEmpty()) {
          return true;
        }
        mismatchDescription
          .appendText("no item matches: ").appendList("", ", ", "", matchers)
          .appendText(" in ").appendValueList("[", ", ", "]", items);
        return false;
      }

      private boolean isMatched(S item) {
        for (Matcher<? super S>  matcher : matchers) {
          if (matcher.matches(item)) {
            matchers.remove(matcher);
            return true;
          }
        }
        mismatchDescription.appendText("not matched: ").appendValue(item);
        return false;
      }
    }

    /**
     * <p>
     * Creates an order agnostic matcher for {@link Iterable}s that matches when a single pass over
     * the examined {@link Iterable} yields a series of items, each satisfying one matcher anywhere
     * in the specified matchers.  For a positive match, the examined iterable must be of the same
     * length as the number of specified matchers.
     * </p>
     * <p>
     * N.B. each of the specified matchers will only be used once during a given examination, so be
     * careful when specifying matchers that may be satisfied by more than one entry in an examined
     * iterable.
     * </p>
     * <p>
     * For example:
     * </p>
     * <pre>assertThat(Arrays.asList("foo", "bar"), containsInAnyOrder(equalTo("bar"), equalTo("foo")))</pre>
     *
     * @param <T>
     *     the matcher type.
     * @param itemMatchers
     *     a list of matchers, each of which must be satisfied by an item provided by an examined {@link Iterable}
     * @return The matcher.
     */
    @SafeVarargs
    public static <T> Matcher<Iterable<? extends T>> containsInAnyOrder(Matcher<? super T>... itemMatchers) {
        List<Matcher<? super T>> itemMatchersList = Arrays.asList(itemMatchers);
        return containsInAnyOrder(itemMatchersList);
    }

    /**
     * <p>
     * Creates an order agnostic matcher for {@link Iterable}s that matches when a single pass over
     * the examined {@link Iterable} yields a series of items, each logically equal to one item
     * anywhere in the specified items. For a positive match, the examined iterable
     * must be of the same length as the number of specified items.
     * </p>
     * <p>
     * N.B. each of the specified items will only be used once during a given examination, so be
     * careful when specifying items that may be equal to more than one entry in an examined
     * iterable.
     * </p>
     * <p>
     * For example:
     * </p>
     * <pre>assertThat(Arrays.asList("foo", "bar"), containsInAnyOrder("bar", "foo"))</pre>
     *
     * @param <T>
     *     the matcher type.
     * @param items
     *     the items that must equal the items provided by an examined {@link Iterable} in any order
     * @return The matcher.
     */
    @SafeVarargs
    public static <T> Matcher<Iterable<? extends T>> containsInAnyOrder(T... items) {
        List<Matcher<? super T>> matchers = new ArrayList<>();
        for (T item : items) {
            matchers.add(equalTo(item));
        }

        return new IsIterableContainingInAnyOrder<>(matchers);
    }

    /**
     * <p>
     * Creates an order agnostic matcher for {@link Iterable}s that matches when a single pass over
     * the examined {@link Iterable} yields a series of items, each satisfying one matcher anywhere
     * in the specified collection of matchers.  For a positive match, the examined iterable
     * must be of the same length as the specified collection of matchers.
     * </p>
     * <p>
     * N.B. each matcher in the specified collection will only be used once during a given
     * examination, so be careful when specifying matchers that may be satisfied by more than
     * one entry in an examined iterable.
     * </p>
     * <p>For example:</p>
     * <pre>assertThat(Arrays.asList("foo", "bar"), containsInAnyOrder(Arrays.asList(equalTo("bar"), equalTo("foo"))))</pre>
     *
     * @param <T>
     *     the matcher type.
     * @param itemMatchers
     *     a list of matchers, each of which must be satisfied by an item provided by an examined {@link Iterable}
     * @return The matcher.
     */
    public static <T> Matcher<Iterable<? extends T>> containsInAnyOrder(Collection<Matcher<? super T>> itemMatchers) {
        return new IsIterableContainingInAnyOrder<>(itemMatchers);
    }

}
