using System;
using Amphora;
using Glass.Text;
using UnitTestSharp;

namespace Glass.UnitTests.Text
{
    public class StyleCursorTests : TestFixture
    {
        public static DynamicArray<StyleSpan> Spans(params (int start, int end)[] ranges)
        {
            var returnMe = new DynamicArray<StyleSpan>(capacity: ranges.Length);
            foreach ((int start, int end) in ranges)
            {
                returnMe.Add(new StyleSpan(start, end, new TextStyle()));
            }

            return returnMe;
        }

        public class SpanAtTests : TestFixture
        {
            public void NullSpans_HoldNothing()
            {
                var cursor = new StyleCursor(null);

                CheckEqual(-1, cursor.SpanAt(0));
                CheckEqual(-1, cursor.SpanAt(5));
            }

            public void NoSpans_HoldNothing()
            {
                var cursor = new StyleCursor(Spans());

                CheckEqual(-1, cursor.SpanAt(0));
            }

            public void CharacterInsideASpan_IsThatSpan()
            {
                var cursor = new StyleCursor(Spans((2, 5)));

                CheckEqual(0, cursor.SpanAt(3));
            }

            public void SpansStart_IsInside()
            {
                var cursor = new StyleCursor(Spans((2, 5)));

                CheckEqual(0, cursor.SpanAt(2));
            }

            public void SpansEnd_IsOutside()
            {
                var cursor = new StyleCursor(Spans((2, 5)));

                CheckEqual(-1, cursor.SpanAt(5));
            }

            public void CharacterBeforeTheFirstSpan_HoldsNothing()
            {
                var cursor = new StyleCursor(Spans((2, 5)));

                CheckEqual(-1, cursor.SpanAt(1));
            }

            public void CharacterBetweenSpans_HoldsNothing()
            {
                var cursor = new StyleCursor(Spans((0, 2), (4, 6)));

                CheckEqual(-1, cursor.SpanAt(3));
            }

            public void WalkingTheText_FindsEachCharactersSpan()
            {
                var cursor = new StyleCursor(Spans((1, 3), (3, 4), (6, 8)));
                var found = new int[9];

                for (int i = 0; i < found.Length; ++i)
                {
                    found[i] = cursor.SpanAt(i);
                }

                CheckEqual(new[] { -1, 0, 0, 1, -1, -1, 2, 2, -1 }, found);
            }

            public void AskingTheSameCharacterAgain_FindsTheSameSpan()
            {
                var cursor = new StyleCursor(Spans((1, 3)));
                cursor.SpanAt(1);

                CheckEqual(0, cursor.SpanAt(1));
            }

            public void SkippingPastSpans_FindsTheLaterOne()
            {
                var cursor = new StyleCursor(Spans((0, 1), (2, 3), (4, 5)));

                CheckEqual(2, cursor.SpanAt(4));
            }

            public void OverlappingSpans_TheFirstOneStillHoldingTheCharacterWins()
            {
                var cursor = new StyleCursor(Spans((0, 10), (5, 7)));

                CheckEqual(0, cursor.SpanAt(6));
                CheckEqual(0, cursor.SpanAt(9));
            }

            public void AfterAnOverlappedSpanEnds_FindsTheOneThatOutlastedIt()
            {
                var cursor = new StyleCursor(Spans((0, 4), (2, 8)));
                cursor.SpanAt(3);

                CheckEqual(1, cursor.SpanAt(5));
            }

            public void AnEarlierCharacter_Throws()
            {
                var cursor = new StyleCursor(Spans((0, 10)));
                cursor.SpanAt(5);

                CheckThrow(typeof(ArgumentOutOfRangeException));
                cursor.SpanAt(4);
            }

            public void AnEarlierCharacterWithNoSpans_Throws()
            {
                var cursor = new StyleCursor(null);
                cursor.SpanAt(5);

                CheckThrow(typeof(ArgumentOutOfRangeException));
                cursor.SpanAt(4);
            }
        }
    }
}