using Microsoft.EntityFrameworkCore;
using ZB.MOM.WW.ScadaBridge.Commons.Entities.Templates;
using ZB.MOM.WW.ScadaBridge.Commons.Types.Templates;
using ZB.MOM.WW.ScadaBridge.ConfigurationDatabase.Repositories;

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

/// <summary>
/// Gitea #86: <see cref="TemplateEngineRepository.GetTemplateReconcileClosureAsync"/> reads only a
/// template's derived subtree + inheritance chain — tracked and fully included, the same shape as
/// <see cref="TemplateEngineRepository.GetAllTemplatesAsync"/> — instead of the whole library.
/// Asserted against real SQL on SQLite with the reader commands recorded.
/// </summary>
public class TemplateReconcileClosureRepositoryTests : IDisposable
{
    private const int UnrelatedTemplates = 40;
    private const string Body = "/* script body the reconcile compares and copies */";

    private readonly SqlReaderCommandRecorder _recorder = new();
    private readonly ScadaBridgeDbContext _context;
    private readonly TemplateEngineRepository _repository;

    /// <summary>Initializes the test class with an in-memory context and repository.</summary>
    public TemplateReconcileClosureRepositoryTests()
    {
        _context = SqliteTestHelper.CreateInMemoryContext(_recorder);
        _repository = new TemplateEngineRepository(_context, new TemplateGraphWatermark());
    }

    /// <summary>Releases the resources held by this test class.</summary>
    public void Dispose()
    {
        _context.Database.CloseConnection();
        _context.Dispose();
    }

    private async Task<Template> AddAsync(string name, int? parentId = null)
    {
        var t = new Template(name) { ParentTemplateId = parentId };
        t.Attributes.Add(new TemplateAttribute($"{name}Attr1"));
        t.Attributes.Add(new TemplateAttribute($"{name}Attr2"));
        t.Scripts.Add(new TemplateScript($"{name}Script", Body));
        _context.Templates.Add(t);
        await _context.SaveChangesAsync();
        return t;
    }

    private sealed record Seeded(int Root, int Base, int Mid, int Leaf, int Leaf3, int Sibling, int Module);

    private async Task<Seeded> SeedAsync()
    {
        var root = await AddAsync("Root");
        var @base = await AddAsync("Base", root.Id);
        var mid = await AddAsync("Mid", @base.Id);
        var leaf = await AddAsync("Leaf", mid.Id);
        var leaf3 = await AddAsync("Leaf3", @base.Id);
        var sibling = await AddAsync("Sibling", root.Id); // Base's sibling: not in Base's closure
        var module = await AddAsync("Module");
        _context.Set<TemplateComposition>().Add(
            new TemplateComposition("m") { TemplateId = @base.Id, ComposedTemplateId = module.Id });
        await _context.SaveChangesAsync();

        for (var i = 0; i < UnrelatedTemplates; i++)
            await AddAsync($"Unrelated{i}");

        _context.ChangeTracker.Clear();
        _recorder.Reset();
        return new Seeded(root.Id, @base.Id, mid.Id, leaf.Id, leaf3.Id, sibling.Id, module.Id);
    }

    /// <summary>
    /// The closure is exactly the subtree + chain — 5 templates instead of 47 — loaded tracked
    /// with script bodies and every child collection, in one load per subtree depth + chain level.
    /// </summary>
    /// <returns>A task that represents the asynchronous operation.</returns>
    [Fact]
    public async Task Closure_ReadsOnlySubtreeAndChain_TrackedAndFullyIncluded()
    {
        var ids = await SeedAsync();

        var whole = await _repository.GetAllTemplatesAsync();
        var wholeQueries = _recorder.Commands.Count;
        _context.ChangeTracker.Clear();
        _recorder.Reset();

        var closure = await _repository.GetTemplateReconcileClosureAsync(ids.Base);
        var closureQueries = _recorder.Commands.Count;

        Assert.Equal(
            new[] { ids.Root, ids.Base, ids.Mid, ids.Leaf, ids.Leaf3 }.OrderBy(i => i),
            closure.Select(t => t.Id).OrderBy(i => i));
        Assert.Equal(7 + UnrelatedTemplates, whole.Count);
        Assert.Equal(10, closure.Sum(t => t.Attributes.Count));

        // Four full loads — children of {Base} and of {Mid, Leaf3}; chain Base, Root — each one
        // split-query set like the whole-graph load, plus the empty children-of-{Leaf} probe whose
        // includes never run. More round trips than the single whole-graph load, but each is
        // bounded by the closure, not the library.
        Assert.Equal(4 * wholeQueries + 1, closureQueries);

        // Same shape the reconcile writes through: tracked, script bodies present, compositions loaded.
        Assert.Equal(5, _context.ChangeTracker.Entries<Template>().Count());
        Assert.All(closure.SelectMany(t => t.Scripts), s => Assert.Equal(Body, s.Code));
        Assert.Single(closure.Single(t => t.Id == ids.Base).Compositions);
        Assert.DoesNotContain(closure, t => t.Id == ids.Module || t.Id == ids.Sibling);
    }

    /// <summary>
    /// The common case — a template nobody derives from — costs one children probe that returns
    /// no rows, and loads and tracks nothing.
    /// </summary>
    /// <returns>A task that represents the asynchronous operation.</returns>
    [Fact]
    public async Task Closure_NoDescendants_SingleProbe_LoadsNothing()
    {
        var ids = await SeedAsync();

        var closure = await _repository.GetTemplateReconcileClosureAsync(ids.Leaf);

        Assert.Empty(closure);
        Assert.Single(_recorder.Commands);
        Assert.Empty(_context.ChangeTracker.Entries());
        Assert.Empty(await _repository.GetTemplateReconcileClosureAsync(987654));
    }
}