using CanonSharp.Common.LexicalAnalyzer;

namespace CanonSharp.Tests.LexicalAnalyzerTests;

public class RegularExpressionTests
{
    [Fact]
    public void KleeneTest()
    {
        RegularExpression expression = RegularExpression.Concatenate(
            RegularExpression.Kleene(RegularExpression.Single('a')),
            RegularExpression.Single('b'));

        NondeterministicFiniteAutomation automation = expression.Convert2Nfa();

        automation.Start.Transactions.TryGetValue(EmptyChar.Empty, out HashSet<NondeterministicState>? next);
        Assert.NotNull(next);

        Assert.Contains(next, s => s.Transactions.ContainsKey(new EmptyChar('a')));
        Assert.Contains(next, s => s.Transactions.ContainsKey(new EmptyChar('b')));
    }

    [Fact]
    public void AlternateTest()
    {
        RegularExpression expression = RegularExpression.Alternate(
            RegularExpression.Kleene(RegularExpression.Single('a')),
            RegularExpression.Single('b'));

        NondeterministicFiniteAutomation automation = expression.Convert2Nfa();

        automation.Start.Transactions.TryGetValue(EmptyChar.Empty, out HashSet<NondeterministicState>? next);
        Assert.NotNull(next);

        Assert.Contains(next, s => s.Transactions.ContainsKey(new EmptyChar('b')));

        NondeterministicState? state = (from item in next
            where item.Transactions[EmptyChar.Empty].Count == 2
            select item).FirstOrDefault();
        Assert.NotNull(state);

        Assert.Contains(state.Transactions[EmptyChar.Empty],
            s => s.Transactions.ContainsKey(new EmptyChar('a')));
    }

    [Fact]
    public void ConvertTest()
    {
        RegularExpression expression = RegularExpression.Alternate(
            RegularExpression.Kleene(RegularExpression.Single('a')),
            RegularExpression.Single('b'));

        NondeterministicFiniteAutomation automation = expression.Convert2Nfa();
        DeterministicFiniteAutomation dfa = DeterministicFiniteAutomation.Create(automation);

        DeterministicState state2 = dfa.Start.Transaction['a'];
        Assert.Equal(state2, state2.Transaction['a']);

        DeterministicState state3 = dfa.Start.Transaction['b'];
        Assert.Empty(state3.Transaction);

        Assert.Equal(3, dfa.FinalStates.Count);
    }

    [Fact]
    public void NondeterministicStateSetTest()
    {
        Dictionary<NondeterministicStateSet, char> map = [];

        NondeterministicState key1 = new();
        NondeterministicState key2 = new();

        map.Add(new NondeterministicStateSet([key1, key2]), 'a');

        Assert.Equal('a', map[new NondeterministicStateSet([key2, key1])]);
    }
}