using System;
using System.Collections.Generic;
using StellaOps.Signals.Models;
using StellaOps.Signals.Services;
using Xunit;

public class ReachabilityFactDigestCalculatorTests
{
    [Fact]
    public void Compute_ReturnsDeterministicDigest_ForEquivalentFacts()
    {
        var factA = new ReachabilityFactDocument
        {
            CallgraphId = "cg-1",
            Subject = new ReachabilitySubject { Component = "demo", Version = "1.0.0" },
            SubjectKey = "demo|1.0.0",
            EntryPoints = new List<string> { "svc.main", "app.main" },
            States = new List<ReachabilityStateDocument>
            {
                new() { Target = "a", Reachable = true, Confidence = 0.9, Bucket = "runtime", Weight = 0.45, Path = new List<string> { "app.main", "a" }, Evidence = new ReachabilityEvidenceDocument { RuntimeHits = new List<string> { "a" } } },
                new() { Target = "b", Reachable = false, Confidence = 0.3, Bucket = "unreachable", Weight = 0.1, Path = new List<string> { "app.main", "b" } }
            },
            RuntimeFacts = new List<RuntimeFactDocument>
            {
                new() { SymbolId = "a", HitCount = 2 }
            },
            Metadata = new Dictionary<string, string?>(StringComparer.Ordinal) { { "tenant", "tenant-default" } },
            ComputedAt = DateTimeOffset.Parse("2025-12-09T00:00:00Z")
        };

        var factB = new ReachabilityFactDocument
        {
            CallgraphId = "cg-1",
            Subject = new ReachabilitySubject { Component = "demo", Version = "1.0.0" },
            SubjectKey = "demo|1.0.0",
            EntryPoints = new List<string> { "app.main", "svc.main" }, // reversed
            States = new List<ReachabilityStateDocument>
            {
                new() { Target = "b", Reachable = false, Confidence = 0.3, Bucket = "unreachable", Weight = 0.1, Path = new List<string> { "app.main", "b" } },
                new() { Target = "a", Reachable = true, Confidence = 0.9, Bucket = "runtime", Weight = 0.45, Path = new List<string> { "app.main", "a" }, Evidence = new ReachabilityEvidenceDocument { RuntimeHits = new List<string> { "a" } } }
            },
            RuntimeFacts = new List<RuntimeFactDocument>
            {
                new() { SymbolId = "a", HitCount = 2 }
            },
            Metadata = new Dictionary<string, string?>(StringComparer.Ordinal) { { "tenant", "tenant-default" } },
            ComputedAt = DateTimeOffset.Parse("2025-12-09T00:00:00Z")
        };

        var digestA = ReachabilityFactDigestCalculator.Compute(factA);
        var digestB = ReachabilityFactDigestCalculator.Compute(factB);

        Assert.StartsWith("sha256:", digestA, StringComparison.Ordinal);
        Assert.Equal(digestA, digestB);
    }
}