using System;
using Amphora;
using Glass.Editing;
using UnitTestSharp;

namespace Glass.UnitTests.Editing
{
    public class CharRunTests : TestFixture
    {
        public class AppendTests : TestFixture
        {
            public void StartsEmpty()
            {
                CheckEqual(0, new CharRun().Length);
            }

            public void AddsAtTheEnd()
            {
                var run = new CharRun();

                run.Append("xabcx", 1, 3);
                run.Append("yzy", 1, 1);

                CheckEqual("abcz", run.ToString());
            }

            public void AView_AddsOnlyItsOwnCharacters()
            {
                var run = new CharRun();
                run.Append("12", 0, 2);

                run.Append(new StringView("xabcx", 1, 4));

                CheckEqual("12abc", run.ToString());
            }

            public void ADefaultView_AddsNothing()
            {
                var run = new CharRun();
                run.Append("12", 0, 2);

                run.Append(default(StringView));

                CheckEqual("12", run.ToString());
            }

            public void GrowsPastItsFirstRoom()
            {
                var run = new CharRun();

                run.Append(new string('a', 40), 0, 40);

                CheckEqual(40, run.Length);
                CheckEqual(new string('a', 40), run.ToString());
            }
        }

        public class PrependTests : TestFixture
        {
            public void AddsAtTheStart()
            {
                var run = new CharRun();
                run.Append("cd", 0, 2);

                run.Prepend("xabx", 1, 2);

                CheckEqual("abcd", run.ToString());
            }

            public void AView_AddsOnlyItsOwnCharacters()
            {
                var run = new CharRun();
                run.Append("12", 0, 2);

                run.Prepend(new StringView("xabcx", 1, 4));

                CheckEqual("abc12", run.ToString());
            }

            public void ADefaultView_AddsNothing()
            {
                var run = new CharRun();
                run.Append("12", 0, 2);

                run.Prepend(default(StringView));

                CheckEqual("12", run.ToString());
            }

            public void GrowsPastItsFirstRoom()
            {
                var run = new CharRun();
                run.Append(new string('a', 40), 0, 40);

                run.Prepend(new string('b', 100), 0, 100);

                CheckEqual(140, run.Length);
                CheckEqual(new string('b', 100) + new string('a', 40), run.ToString());
            }
        }

        public class ClearTests : TestFixture
        {
            public void Empties()
            {
                var run = new CharRun();
                run.Append("abc", 0, 3);

                run.Clear();

                CheckEqual(0, run.Length);
            }

            public void KeepsTheRoomOfASmallRun()
            {
                var run = new CharRun();
                run.Append("abc", 0, 3);
                int capacity = run.Capacity;

                run.Clear();

                CheckEqual(capacity, run.Capacity);
            }

            public void GivesBackRoomBeyondWhatItKeeps()
            {
                var run = new CharRun();
                run.Append(new string('a', CharRun.RetainedCapacity + 1), 0, CharRun.RetainedCapacity + 1);

                run.Clear();

                Check(run.Capacity <= CharRun.RetainedCapacity);
            }
        }

        public class FirstCodePointTests : TestFixture
        {
            public void IsTheFirstChar()
            {
                var run = new CharRun();
                run.Append("abc", 0, 3);

                CheckEqual('a', run.FirstCodePoint);
            }

            public void JoinsASurrogatePair()
            {
                var run = new CharRun();
                string text = char.ConvertFromUtf32(0x20BB7) + "a";
                run.Append(text, 0, text.Length);

                CheckEqual(0x20BB7, run.FirstCodePoint);
            }

            public void OfAnEmptyRun_Throws()
            {
                CheckThrow(typeof(InvalidOperationException));
                GC.KeepAlive(new CharRun().FirstCodePoint);
            }
        }

        public class LastCodePointTests : TestFixture
        {
            public void IsTheLastChar()
            {
                var run = new CharRun();
                run.Append("abc", 0, 3);

                CheckEqual('c', run.LastCodePoint);
            }

            public void JoinsASurrogatePair()
            {
                var run = new CharRun();
                string text = "a" + char.ConvertFromUtf32(0x20BB7);
                run.Append(text, 0, text.Length);

                CheckEqual(0x20BB7, run.LastCodePoint);
            }

            public void OfAnEmptyRun_Throws()
            {
                CheckThrow(typeof(InvalidOperationException));
                GC.KeepAlive(new CharRun().LastCodePoint);
            }
        }

        public class AppendToTests : TestFixture
        {
            public void AddsTheCharsHeldToTheBuilder()
            {
                var run = new CharRun();
                run.Append("xabx", 1, 2);
                var builder = new System.Text.StringBuilder("1");

                run.AppendTo(builder);

                CheckEqual("1ab", builder.ToString());
            }

            public void OfAnEmptyRun_AddsNothing()
            {
                var builder = new System.Text.StringBuilder("1");

                new CharRun().AppendTo(builder);

                CheckEqual("1", builder.ToString());
            }
        }

        public class AsViewTests : TestFixture
        {
            public void ViewsTheCharsHeldAndNotTheSpareRoom()
            {
                var run = new CharRun();
                run.Append("xabx", 1, 2);

                CheckEqual("ab", run.AsView().ToString());
            }

            public void OfAnEmptyRun_IsEmpty()
            {
                CheckEqual(0, new CharRun().AsView().Length);
            }
        }

        public class CapacityTests : TestFixture
        {
            public void GrowsWithTheChars()
            {
                var run = new CharRun();

                run.Append(new string('a', 100), 0, 100);

                Check(run.Capacity >= 100);
            }
        }

        public class ToStringTests : TestFixture
        {
            public void OfAnEmptyRun_IsEmpty()
            {
                CheckEqual("", new CharRun().ToString());
            }

            public void IsTheCharsHeld()
            {
                var run = new CharRun();
                run.Append("xabx", 1, 2);

                CheckEqual("ab", run.ToString());
            }
        }
    }
}