using System.IO;
using UnitTestSharp;
using Vellum;

namespace Amphora.Vellum.UnitTests
{
    public class StringViewConverterTests : TestFixture
    {
        public static SaveSession Session()
        {
            return SaveConverters.For(typeof(StringViewConverterTests).Assembly).CreateSession();
        }

        public static StringView ThroughLuaText(StringView value)
        {
            SaveSession session = Session();
            SaveNode save = SaveNode.NewTable();
            save.Entries["value"] = session.ToNode(value, typeof(StringView));
            SaveNode read = LuaSaveFormat.Parse(LuaSaveFormat.Format(save));
            return (StringView)session.FromNode(read.RequireEntry("value"), typeof(StringView));
        }

        /// <summary>
        /// Returns a saved view of <paramref name="text"/> running from <paramref name="startIndex"/> to
        /// <paramref name="endIndex"/>.
        /// </summary>
        public static SaveNode Saved(string text, string startIndex, string endIndex)
        {
            SaveNode returnMe = SaveNode.NewTable();
            returnMe.Entries[StringViewConverter.TextKey] = SaveNode.OfText(text);
            returnMe.Entries[StringViewConverter.StartIndexKey] = SaveNode.OfText(startIndex);
            returnMe.Entries[StringViewConverter.EndIndexKey] = SaveNode.OfText(endIndex);
            return returnMe;
        }

        public static StringView Loaded(SaveNode node)
        {
            return (StringView)Session().FromNode(node, typeof(StringView));
        }

        public class WriteTests : TestFixture
        {
            public void WholeString_IsTheStringAndItsFullRange()
            {
                SaveNode node = Session().ToNode(new StringView("hello"), typeof(StringView));

                CheckEqual("hello", node.RequireEntry("text").Text);
                CheckEqual("0", node.RequireEntry("startIndex").Text);
                CheckEqual("5", node.RequireEntry("endIndex").Text);
            }

            public void ViewOfPartOfAString_IsTheWholeStringAndWhereItRuns()
            {
                SaveNode node = Session().ToNode(new StringView("hello world", 6, 11), typeof(StringView));

                CheckEqual("hello world", node.RequireEntry("text").Text);
                CheckEqual("6", node.RequireEntry("startIndex").Text);
                CheckEqual("11", node.RequireEntry("endIndex").Text);
            }

            public void EmptyView_KeepsItsPlaceInTheString()
            {
                SaveNode node = Session().ToNode(new StringView("hello", 2, 2), typeof(StringView));

                CheckEqual("hello", node.RequireEntry("text").Text);
                CheckEqual("2", node.RequireEntry("startIndex").Text);
                CheckEqual("2", node.RequireEntry("endIndex").Text);
            }

            public void DefaultView_IsAViewOfAnEmptyString()
            {
                SaveNode node = Session().ToNode(default(StringView), typeof(StringView));

                CheckEqual("", node.RequireEntry("text").Text);
                CheckEqual("0", node.RequireEntry("startIndex").Text);
                CheckEqual("0", node.RequireEntry("endIndex").Text);
            }

            public void ViewsOfOneString_ShareTheNodeOfThatString()
            {
                SaveSession session = Session();
                string text = new string('s', 4);
                SaveNode whole = session.ToNode(new StringView(text), typeof(StringView));
                SaveNode part = session.ToNode(new StringView(text, 1, 3), typeof(StringView));
                SaveNode plain = session.ToNode(text, typeof(string));

                CheckTrue(ReferenceEquals(plain, whole.RequireEntry("text")));
                CheckTrue(ReferenceEquals(plain, part.RequireEntry("text")));
            }

            public void ViewsOfEqualStringsThatAreTwoObjects_DoNotShare()
            {
                SaveSession session = Session();
                SaveNode first = session.ToNode(new StringView(new string('s', 4)), typeof(StringView));
                SaveNode second = session.ToNode(new StringView(new string('s', 4)), typeof(StringView));

                CheckFalse(ReferenceEquals(first.RequireEntry("text"), second.RequireEntry("text")));
            }
        }

        public class ReadTests : TestFixture
        {
            public void SavedView_KeepsItsTextAndRange()
            {
                StringView loaded = Loaded(Saved("hello world", "6", "11"));

                CheckEqual("hello world", loaded.Text);
                CheckEqual(6, loaded.StartIndex);
                CheckEqual(11, loaded.EndIndex);
                CheckEqual("world", loaded.ToString());
            }

            public void ViewOfPartOfAString_RoundTripsWithItsPlace()
            {
                var original = new StringView("hello world", 6, 11);
                StringView loaded = ThroughLuaText(original);

                CheckTrue(original == loaded);
                CheckEqual(6, loaded.StartIndex);
                CheckEqual(11, loaded.EndIndex);
            }

            public void DefaultView_LoadsAsAViewOfAnEmptyString()
            {
                StringView loaded = ThroughLuaText(default(StringView));

                CheckEqual("", loaded.Text);
                CheckEqual(0, loaded.Length);
            }

            public void AwkwardCharacters_SurviveLuaText()
            {
                var original = new StringView("say \"hi\"\r\n\ttab \\ end", 4, 8);

                CheckEqual(original.Text, ThroughLuaText(original).Text);
                CheckEqual(original.ToString(), ThroughLuaText(original).ToString());
            }

            public void ViewsOfOneStringSavedInAFile_LoadOverOneString()
            {
                SaveSession saving = Session();
                string text = new string('s', 6);
                SaveNode save = SaveNode.NewTable();
                save.Entries["text"] = saving.ToNode(text, typeof(string));
                save.Entries["first"] = saving.ToNode(new StringView(text, 0, 2), typeof(StringView));
                save.Entries["second"] = saving.ToNode(new StringView(text, 3, 6), typeof(StringView));

                SaveNode read = LuaSaveFormat.Parse(LuaSaveFormat.Format(save));
                SaveSession loading = Session();
                var loadedText = (string)loading.FromNode(read.RequireEntry("text"), typeof(string));
                var first = (StringView)loading.FromNode(read.RequireEntry("first"), typeof(StringView));
                var second = (StringView)loading.FromNode(read.RequireEntry("second"), typeof(StringView));

                CheckTrue(ReferenceEquals(loadedText, first.Text));
                CheckTrue(ReferenceEquals(loadedText, second.Text));
                CheckEqual(3, second.Length);
            }

            public void EndBeforeStart_Throws()
            {
                CheckThrow(typeof(InvalidDataException));
                Loaded(Saved("hello", "4", "2"));
            }

            public void IndexPastTheText_Throws()
            {
                CheckThrow(typeof(InvalidDataException));
                Loaded(Saved("hello", "0", "6"));
            }

            public void NegativeIndex_Throws()
            {
                CheckThrow(typeof(InvalidDataException));
                Loaded(Saved("hello", "-1", "2"));
            }

            public void MissingEntry_Throws()
            {
                SaveNode node = Saved("hello", "0", "5");
                node.Entries.Remove("endIndex");

                CheckThrow(typeof(InvalidDataException));
                Loaded(node);
            }

            public void IndexOfTheWrongShape_IsReportedUnderItsKey()
            {
                string message = "";
                try
                {
                    Loaded(Saved("hello", "one", "5"));
                }
                catch (InvalidDataException exception)
                {
                    message = exception.Message;
                }

                CheckTrue(message.StartsWith("startIndex: ", System.StringComparison.Ordinal));
            }

            public void NullText_Throws()
            {
                SaveNode node = Saved("hello", "0", "5");
                node.Entries["text"] = SaveNode.Null;

                CheckThrow(typeof(InvalidDataException));
                Loaded(node);
            }

            public void NodeThatIsNotATable_Throws()
            {
                CheckThrow(typeof(InvalidDataException));
                Loaded(SaveNode.OfText("hello"));
            }

            public void NullForAStringView_Throws()
            {
                CheckThrow(typeof(InvalidDataException));
                Session().FromNode(SaveNode.Null, typeof(StringView));
            }

            public void NullForANullableStringView_IsNull()
            {
                CheckNull(Session().FromNode(SaveNode.Null, typeof(StringView?)));
            }
        }

        public class TryListChildrenTests : TestFixture
        {
            public void StringView_ListsNothingAndSucceeds()
            {
                SaveNode node = Session().ToNode(new StringView("hello", 1, 3), typeof(StringView));
                var children = new ChildList();

                CheckTrue(new StringViewConverter().TryListChildren(node, children));
                CheckEqual(0, children.Count);
            }

            public void NodeWithoutText_ReturnsFalse()
            {
                CheckFalse(new StringViewConverter().TryListChildren(SaveNode.NewTable(), new ChildList()));
            }

            public void NodeThatIsNotATable_ReturnsFalse()
            {
                CheckFalse(new StringViewConverter().TryListChildren(SaveNode.OfText("3"), new ChildList()));
            }
        }
    }
}