using ZB.MOM.WW.ScadaBridge.Commons.Entities.Templates;
using ZB.MOM.WW.ScadaBridge.Commons.Types.Templates;

namespace ZB.MOM.WW.ScadaBridge.TemplateEngine.Tests;

/// <summary>
/// Gitea #66: member add/update validation now runs the analysis walkers over a template's
/// inheritance chain + composition closure instead of the whole library. These tests pin that
/// the closure is (a) sufficient — every walker answer is identical to the whole-graph answer,
/// for every template in a graph with chains, nested and diamond compositions, a derived
/// module, cycles, dangling edges and unrelated look-alikes — and (b) actually smaller.
/// </summary>
public class TemplateAnalysisClosureTests
{
    // Ids of the fixture graph.
    private const int Grand = 1, Parent = 2, Child = 3, ModA = 4, ModB = 5, ModBBase = 6, Inner = 7;
    private const int CycX = 8, CycY = 9, Dangling = 10;
    private const int Twin = 18, TwinParent = 19, TwinGrand = 20;

    private static readonly List<Template> Graph = BuildGraph();

    private static List<Template> BuildGraph()
    {
        var memberId = 1000;
        Template T(int id, string name, int? parent = null, params string[] attrs)
        {
            var t = new Template(name) { Id = id, ParentTemplateId = parent };
            foreach (var a in attrs)
                t.Attributes.Add(new TemplateAttribute(a) { Id = memberId++, TemplateId = id, IsLocked = a.StartsWith('L') });
            return t;
        }

        void Compose(Template owner, Template module, string slot) =>
            owner.Compositions.Add(new TemplateComposition(slot) { Id = memberId++, TemplateId = owner.Id, ComposedTemplateId = module.Id });

        var grand = T(Grand, "Grand", null, "LSpeed", "Shared");
        var parent = T(Parent, "Parent", Grand, "Flow");
        var child = T(Child, "Child", Parent, "Shared", "m1.Level"); // overrides + a would-be collision
        var modA = T(ModA, "ModA", null, "Level", "Temp");
        var modB = T(ModB, "ModB", ModBBase, "Base1");                // derived module (placeholder row)
        var modBBase = T(ModBBase, "ModBBase", null, "Base1", "OnlyInBase");
        var inner = T(Inner, "Inner", null, "Deep");
        modB.Alarms.Add(new TemplateAlarm("HiHi") { Id = memberId++, TemplateId = ModB });
        modA.Scripts.Add(new TemplateScript("Calc", string.Empty) { Id = memberId++, TemplateId = ModA, IsLocked = true });

        Compose(parent, modA, "m1");
        Compose(child, modB, "m2");
        Compose(child, modA, "m1b");        // diamond: ModA reached by two paths
        Compose(modA, inner, "inner");

        var cycX = T(CycX, "CycX", null, "X");
        var cycY = T(CycY, "CycY", null, "Y");
        Compose(cycX, cycY, "y");
        Compose(cycY, cycX, "x");           // composition cycle

        var dangling = T(Dangling, "Dangling", 998, "D");
        dangling.Compositions.Add(new TemplateComposition("ghost") { Id = memberId++, TemplateId = Dangling, ComposedTemplateId = 999 });

        // A template reached first as a module and then as a chain member: its parent must still load.
        var twinGrand = T(TwinGrand, "TwinGrand", null, "G");
        var twinParent = T(TwinParent, "TwinParent", TwinGrand, "P");
        var twin = T(Twin, "Twin", TwinParent, "S");
        Compose(twin, twinParent, "t");

        var all = new List<Template> { grand, parent, child, modA, modB, modBBase, inner, cycX, cycY, dangling, twinGrand, twinParent, twin };

        // Unrelated library content with colliding member names — must never be loaded.
        for (var i = 0; i < 5; i++)
            all.Add(T(11 + i, $"Unrelated{i}", i == 0 ? null : 11, "Shared", "Level", "m1.Level"));

        return all;
    }

    private static Task<IReadOnlyList<Template>> InMemoryClosure(int id, List<IReadOnlyCollection<int>>? batches = null) =>
        TemplateAnalysisClosure.CollectAsync(id, (ids, _) =>
        {
            batches?.Add(ids);
            return Task.FromResult<IReadOnlyList<Template>>(Graph.Where(t => ids.Contains(t.Id)).ToList());
        });

    public static IEnumerable<object[]> EveryTemplate() => Graph.Select(t => new object[] { t.Id });

    /// <summary>Resolver and collision detector give the same answer from the closure as from the whole graph.</summary>
    /// <param name="templateId">Template under analysis.</param>
    /// <returns>A task that represents the asynchronous operation.</returns>
    [Theory]
    [MemberData(nameof(EveryTemplate))]
    public async Task Walkers_AnswerIdenticallyFromClosure(int templateId)
    {
        var closure = await InMemoryClosure(templateId);
        var template = Graph.Single(t => t.Id == templateId);

        Assert.Equal(
            TemplateResolver.ResolveAllMembers(templateId, Graph),
            TemplateResolver.ResolveAllMembers(templateId, closure));
        Assert.Equal(
            CollisionDetector.DetectCollisions(template, Graph),
            CollisionDetector.DetectCollisions(template, closure));

        foreach (var member in TemplateResolver.ResolveAllMembers(templateId, Graph))
        {
            Assert.Equal(
                TemplateResolver.FindMemberByCanonicalName(member.CanonicalName, templateId, Graph),
                TemplateResolver.FindMemberByCanonicalName(member.CanonicalName, templateId, closure));
        }
    }

    /// <summary>The fixture really exercises a collision, so the equality above is not vacuous.</summary>
    [Fact]
    public void Fixture_ChildHasACompositionCollision()
    {
        var child = Graph.Single(t => t.Id == Child);
        Assert.NotEmpty(CollisionDetector.DetectCollisions(child, Graph));
    }

    /// <summary>The closure is exactly the chain plus composition closure — no module ancestors, no unrelated templates.</summary>
    /// <returns>A task that represents the asynchronous operation.</returns>
    [Fact]
    public async Task Closure_IsChainPlusCompositionClosureOnly()
    {
        var closure = await InMemoryClosure(Child);

        Assert.Equal(
            new[] { Grand, Parent, Child, ModA, ModB, Inner }.OrderBy(i => i),
            closure.Select(t => t.Id).OrderBy(i => i));
        Assert.DoesNotContain(closure, t => t.Id == ModBBase); // a module's parent chain is never walked
        Assert.True(closure.Count < Graph.Count);
    }

    /// <summary>A template reached as a module before it is reached as a chain member still expands its parent.</summary>
    /// <returns>A task that represents the asynchronous operation.</returns>
    [Fact]
    public async Task Closure_ModuleThatIsAlsoAChainMember_StillClimbsItsParent()
    {
        var closure = await InMemoryClosure(Twin);
        Assert.Equal(new[] { Twin, TwinParent, TwinGrand }.OrderBy(i => i), closure.Select(t => t.Id).OrderBy(i => i));
    }

    /// <summary>Cycles terminate and dangling ids are skipped.</summary>
    /// <returns>A task that represents the asynchronous operation.</returns>
    [Fact]
    public async Task Closure_TerminatesOnCyclesAndSkipsDanglingEdges()
    {
        Assert.Equal(new[] { CycX, CycY }, (await InMemoryClosure(CycX)).Select(t => t.Id).OrderBy(i => i));
        Assert.Equal(new[] { Dangling }, (await InMemoryClosure(Dangling)).Select(t => t.Id));
        Assert.Empty(await InMemoryClosure(424242));
    }

    /// <summary>One batch per closure depth, and no id is ever requested twice.</summary>
    /// <returns>A task that represents the asynchronous operation.</returns>
    [Fact]
    public async Task Closure_LoadsOneBatchPerDepth_NeverRequestsAnIdTwice()
    {
        var batches = new List<IReadOnlyCollection<int>>();
        await InMemoryClosure(Child, batches);

        // Depth 0: Child; depth 1: Parent, ModB, ModA; depth 2: Grand, Inner.
        Assert.Equal(3, batches.Count);
        var requested = batches.SelectMany(b => b).ToList();
        Assert.Equal(requested.Count, requested.Distinct().Count());
    }
}