using StellaOps.Signals.Lattice;
using Xunit;

namespace StellaOps.Signals.Tests;

public class ReachabilityLatticeTests
{
    [Theory]
    [InlineData(ReachabilityLatticeState.Unknown, ReachabilityLatticeState.StaticallyReachable, ReachabilityLatticeState.StaticallyReachable)]
    [InlineData(ReachabilityLatticeState.StaticallyReachable, ReachabilityLatticeState.StaticallyUnreachable, ReachabilityLatticeState.Contested)]
    [InlineData(ReachabilityLatticeState.StaticallyReachable, ReachabilityLatticeState.RuntimeObserved, ReachabilityLatticeState.ConfirmedReachable)]
    [InlineData(ReachabilityLatticeState.StaticallyUnreachable, ReachabilityLatticeState.RuntimeUnobserved, ReachabilityLatticeState.ConfirmedUnreachable)]
    [InlineData(ReachabilityLatticeState.RuntimeObserved, ReachabilityLatticeState.StaticallyUnreachable, ReachabilityLatticeState.Contested)]
    [InlineData(ReachabilityLatticeState.ConfirmedReachable, ReachabilityLatticeState.ConfirmedUnreachable, ReachabilityLatticeState.Contested)]
    [InlineData(ReachabilityLatticeState.Contested, ReachabilityLatticeState.Unknown, ReachabilityLatticeState.Contested)]
    public void Join_ReturnsExpectedState(ReachabilityLatticeState a, ReachabilityLatticeState b, ReachabilityLatticeState expected)
    {
        var result = ReachabilityLattice.Join(a, b);
        Assert.Equal(expected, result);
    }

    [Theory]
    [InlineData(ReachabilityLatticeState.Unknown, ReachabilityLatticeState.StaticallyReachable, ReachabilityLatticeState.Unknown)]
    [InlineData(ReachabilityLatticeState.ConfirmedReachable, ReachabilityLatticeState.RuntimeObserved, ReachabilityLatticeState.RuntimeObserved)]
    [InlineData(ReachabilityLatticeState.Contested, ReachabilityLatticeState.StaticallyReachable, ReachabilityLatticeState.StaticallyReachable)]
    [InlineData(ReachabilityLatticeState.Contested, ReachabilityLatticeState.Unknown, ReachabilityLatticeState.Unknown)]
    public void Meet_ReturnsExpectedState(ReachabilityLatticeState a, ReachabilityLatticeState b, ReachabilityLatticeState expected)
    {
        var result = ReachabilityLattice.Meet(a, b);
        Assert.Equal(expected, result);
    }

    [Fact]
    public void Join_IsCommutative()
    {
        var states = Enum.GetValues<ReachabilityLatticeState>();
        foreach (var a in states)
        {
            foreach (var b in states)
            {
                Assert.Equal(ReachabilityLattice.Join(a, b), ReachabilityLattice.Join(b, a));
            }
        }
    }

    [Fact]
    public void Meet_IsCommutative()
    {
        var states = Enum.GetValues<ReachabilityLatticeState>();
        foreach (var a in states)
        {
            foreach (var b in states)
            {
                Assert.Equal(ReachabilityLattice.Meet(a, b), ReachabilityLattice.Meet(b, a));
            }
        }
    }

    [Fact]
    public void JoinAll_WithEmptySequence_ReturnsUnknown()
    {
        var result = ReachabilityLattice.JoinAll(Array.Empty<ReachabilityLatticeState>());
        Assert.Equal(ReachabilityLatticeState.Unknown, result);
    }

    [Fact]
    public void JoinAll_StopsEarlyOnContested()
    {
        var states = new[] { ReachabilityLatticeState.StaticallyReachable, ReachabilityLatticeState.Contested, ReachabilityLatticeState.Unknown };
        var result = ReachabilityLattice.JoinAll(states);
        Assert.Equal(ReachabilityLatticeState.Contested, result);
    }

    [Theory]
    [InlineData(true, false, false, ReachabilityLatticeState.StaticallyReachable)]
    [InlineData(false, false, false, ReachabilityLatticeState.StaticallyUnreachable)]
    [InlineData(null, false, false, ReachabilityLatticeState.Unknown)]
    [InlineData(true, true, true, ReachabilityLatticeState.ConfirmedReachable)]
    [InlineData(false, true, false, ReachabilityLatticeState.ConfirmedUnreachable)]
    [InlineData(false, true, true, ReachabilityLatticeState.Contested)]
    public void FromEvidence_ReturnsExpectedState(bool? staticReachable, bool hasRuntimeEvidence, bool runtimeObserved, ReachabilityLatticeState expected)
    {
        var result = ReachabilityLattice.FromEvidence(staticReachable, hasRuntimeEvidence, runtimeObserved);
        Assert.Equal(expected, result);
    }

    [Theory]
    [InlineData("entrypoint", false, ReachabilityLatticeState.ConfirmedReachable)]
    [InlineData("direct", false, ReachabilityLatticeState.StaticallyReachable)]
    [InlineData("direct", true, ReachabilityLatticeState.ConfirmedReachable)]
    [InlineData("runtime", false, ReachabilityLatticeState.RuntimeObserved)]
    [InlineData("unreachable", false, ReachabilityLatticeState.StaticallyUnreachable)]
    [InlineData("unreachable", true, ReachabilityLatticeState.Contested)]
    [InlineData("unknown", false, ReachabilityLatticeState.Unknown)]
    public void FromV0Bucket_ReturnsExpectedState(string bucket, bool hasRuntimeHits, ReachabilityLatticeState expected)
    {
        var result = ReachabilityLattice.FromV0Bucket(bucket, hasRuntimeHits);
        Assert.Equal(expected, result);
    }
}

public class ReachabilityLatticeStateExtensionsTests
{
    [Theory]
    [InlineData(ReachabilityLatticeState.Unknown, "U")]
    [InlineData(ReachabilityLatticeState.StaticallyReachable, "SR")]
    [InlineData(ReachabilityLatticeState.StaticallyUnreachable, "SU")]
    [InlineData(ReachabilityLatticeState.RuntimeObserved, "RO")]
    [InlineData(ReachabilityLatticeState.RuntimeUnobserved, "RU")]
    [InlineData(ReachabilityLatticeState.ConfirmedReachable, "CR")]
    [InlineData(ReachabilityLatticeState.ConfirmedUnreachable, "CU")]
    [InlineData(ReachabilityLatticeState.Contested, "X")]
    public void ToCode_ReturnsExpectedCode(ReachabilityLatticeState state, string expectedCode)
    {
        Assert.Equal(expectedCode, state.ToCode());
    }

    [Theory]
    [InlineData("U", ReachabilityLatticeState.Unknown)]
    [InlineData("SR", ReachabilityLatticeState.StaticallyReachable)]
    [InlineData("SU", ReachabilityLatticeState.StaticallyUnreachable)]
    [InlineData("RO", ReachabilityLatticeState.RuntimeObserved)]
    [InlineData("RU", ReachabilityLatticeState.RuntimeUnobserved)]
    [InlineData("CR", ReachabilityLatticeState.ConfirmedReachable)]
    [InlineData("CU", ReachabilityLatticeState.ConfirmedUnreachable)]
    [InlineData("X", ReachabilityLatticeState.Contested)]
    [InlineData("invalid", ReachabilityLatticeState.Unknown)]
    [InlineData("", ReachabilityLatticeState.Unknown)]
    [InlineData(null, ReachabilityLatticeState.Unknown)]
    public void FromCode_ReturnsExpectedState(string? code, ReachabilityLatticeState expected)
    {
        Assert.Equal(expected, ReachabilityLatticeStateExtensions.FromCode(code));
    }

    [Theory]
    [InlineData(ReachabilityLatticeState.ConfirmedUnreachable, "unreachable")]
    [InlineData(ReachabilityLatticeState.StaticallyUnreachable, "unreachable")]
    [InlineData(ReachabilityLatticeState.RuntimeUnobserved, "unreachable")]
    [InlineData(ReachabilityLatticeState.ConfirmedReachable, "runtime")]
    [InlineData(ReachabilityLatticeState.RuntimeObserved, "runtime")]
    [InlineData(ReachabilityLatticeState.StaticallyReachable, "direct")]
    [InlineData(ReachabilityLatticeState.Unknown, "unknown")]
    [InlineData(ReachabilityLatticeState.Contested, "unknown")]
    public void ToV0Bucket_ReturnsExpectedBucket(ReachabilityLatticeState state, string expectedBucket)
    {
        Assert.Equal(expectedBucket, state.ToV0Bucket());
    }

}