using Antlr4.Runtime;
using Shouldly;

namespace InkBlot.Tests;

public class LexerTest
{
    private readonly TokenEqualityComparer _tokenEqualityComparer = new();

    private IToken T(string text, int type)
    {
        return new SimpleToken(text, type);
    }

    [Fact]
    public void TestSimpleTokens()
    {
        var tokens = GetTokens("testTest15");
        tokens.ShouldBe([
            T("testTest15", InkBlotAntlrGrammarLexer.IDENTIFIER),
            T("<EOF>", InkBlotAntlrGrammarLexer.Eof)
        ], _tokenEqualityComparer);
    }

    [Fact]
    public void TestDivertForLexer()
    {
        var divertTokens = GetTokens("<- threadName");
        divertTokens.ShouldBe([
            T("<-", InkBlotAntlrGrammarLexer.THREAD_ARROW),
            T(" ", InkBlotAntlrGrammarLexer.WS),
            T("threadName", InkBlotAntlrGrammarLexer.IDENTIFIER),
            T("<EOF>", InkBlotAntlrGrammarLexer.Eof)
        ], _tokenEqualityComparer);
    }

    private static IList<IToken> GetTokens(string text)
    {
        var fileReader = new InMemoryFileReader([
            ("main.ink", text)
        ]);
        var tokensStream = InkBlotParser.GetTokenStream(fileReader, "main.ink");
        tokensStream.Fill();
        var tokens = tokensStream.GetTokens();
        return tokens;
    }

    private class TokenEqualityComparer : IEqualityComparer<IToken>
    {
        public bool Equals(IToken? x, IToken? y)
        {
            if (ReferenceEquals(x, y)) return true;
            if (x is null) return false;
            if (y is null) return false;
            return x.Text == y.Text && x.Type == y.Type;
        }

        public int GetHashCode(IToken obj)
        {
            return HashCode.Combine(obj.Text, obj.Type);
        }
    }

    private class SimpleToken(string text, int type) : IToken
    {
        public string Text { get; } = text;
        public int Type { get; } = type;
        public int Line => 0;
        public int Column => 0;
        public int Channel => 0;
        public int TokenIndex => 0;
        public int StartIndex => 0;
        public int StopIndex => 0;
        public ITokenSource TokenSource => null!;
        public ICharStream InputStream => null!;

        public override string ToString()
        {
            return $"['{Text}',<{Type}>]";
        }
    }
}