using ClaudeDo.Data;
using ClaudeDo.Data.Models;
using ClaudeDo.Worker.Planning;
using ClaudeDo.Worker.Tests.Infrastructure;
using Microsoft.EntityFrameworkCore;
using TaskStatus = ClaudeDo.Data.Models.TaskStatus;

namespace ClaudeDo.Worker.Tests.Planning;

public sealed class PlanningChainCoordinatorTests : IDisposable
{
    private readonly DbFixture _db = new();
    private readonly TestDbContextFactory _factory;
    private readonly PlanningChainCoordinator _sut;
    private readonly string _listId;

    public PlanningChainCoordinatorTests()
    {
        _factory = _db.CreateFactory();
        _sut = new PlanningChainCoordinator(_factory);
        _listId = Guid.NewGuid().ToString();
        using var ctx = _factory.CreateDbContext();
        ctx.Lists.Add(new ListEntity
        {
            Id = _listId,
            Name = "Test",
            CreatedAt = DateTime.UtcNow,
            DefaultCommitType = "chore",
        });
        ctx.SaveChanges();
    }

    public void Dispose() => _db.Dispose();

    private async Task SeedPlanningFamilyAsync(string parentId, int childCount)
    {
        await using var ctx = _factory.CreateDbContext();
        ctx.Tasks.Add(new TaskEntity
        {
            Id = parentId,
            ListId = _listId,
            Title = "Parent",
            CreatedAt = DateTime.UtcNow,
            Status = TaskStatus.Planned,
        });
        for (int i = 0; i < childCount; i++)
        {
            ctx.Tasks.Add(new TaskEntity
            {
                Id = $"{parentId}-c{i}",
                ListId = _listId,
                Title = $"Child {i}",
                CreatedAt = DateTime.UtcNow,
                Status = TaskStatus.Manual,
                ParentTaskId = parentId,
                SortOrder = i,
            });
        }
        await ctx.SaveChangesAsync();
    }

    private async Task<List<TaskEntity>> GetChildrenAsync(string parentId)
    {
        await using var ctx = _factory.CreateDbContext();
        return await ctx.Tasks
            .AsNoTracking()
            .Where(t => t.ParentTaskId == parentId)
            .OrderBy(t => t.SortOrder)
            .ToListAsync();
    }

    [Fact]
    public async Task QueueSubtasksSequentially_SetsFirstQueued_RestWaiting()
    {
        await SeedPlanningFamilyAsync("P", 3);

        await _sut.QueueSubtasksSequentiallyAsync("P", default);

        var kids = await GetChildrenAsync("P");
        Assert.Equal(TaskStatus.Queued, kids[0].Status);
        Assert.Equal(TaskStatus.Waiting, kids[1].Status);
        Assert.Equal(TaskStatus.Waiting, kids[2].Status);
    }

    [Fact]
    public async Task OnChildDone_FlipsNextWaitingToQueued()
    {
        await SeedPlanningFamilyAsync("P", 3);
        await _sut.QueueSubtasksSequentiallyAsync("P", default);

        // Simulate first child finishing Done.
        await using (var ctx = _factory.CreateDbContext())
        {
            var first = await ctx.Tasks.FirstAsync(t => t.Id == "P-c0");
            first.Status = TaskStatus.Done;
            await ctx.SaveChangesAsync();
        }

        var advanced = await _sut.OnChildFinishedAsync("P-c0", TaskStatus.Done, default);

        Assert.Equal("P-c1", advanced);
        var kids = await GetChildrenAsync("P");
        Assert.Equal(TaskStatus.Done, kids[0].Status);
        Assert.Equal(TaskStatus.Queued, kids[1].Status);
        Assert.Equal(TaskStatus.Waiting, kids[2].Status);
    }

    [Fact]
    public async Task OnChildFailed_DoesNotAdvanceChain()
    {
        await SeedPlanningFamilyAsync("P", 3);
        await _sut.QueueSubtasksSequentiallyAsync("P", default);

        await using (var ctx = _factory.CreateDbContext())
        {
            var first = await ctx.Tasks.FirstAsync(t => t.Id == "P-c0");
            first.Status = TaskStatus.Failed;
            await ctx.SaveChangesAsync();
        }

        var advanced = await _sut.OnChildFinishedAsync("P-c0", TaskStatus.Failed, default);

        Assert.Null(advanced);
        var kids = await GetChildrenAsync("P");
        Assert.Equal(TaskStatus.Failed, kids[0].Status);
        Assert.Equal(TaskStatus.Waiting, kids[1].Status);
        Assert.Equal(TaskStatus.Waiting, kids[2].Status);
    }

    [Fact]
    public async Task OnChildDone_LastChild_ReturnsNull()
    {
        await SeedPlanningFamilyAsync("P", 2);
        await _sut.QueueSubtasksSequentiallyAsync("P", default);

        // Mark both done, simulating chain reaching the end.
        await using (var ctx = _factory.CreateDbContext())
        {
            foreach (var t in ctx.Tasks.Where(t => t.ParentTaskId == "P"))
                t.Status = TaskStatus.Done;
            await ctx.SaveChangesAsync();
        }

        var advanced = await _sut.OnChildFinishedAsync("P-c1", TaskStatus.Done, default);

        Assert.Null(advanced);
    }

    [Fact]
    public async Task QueueSubtasksSequentially_RejectsNonManualChildren()
    {
        await SeedPlanningFamilyAsync("P", 2);
        // Corrupt one child to be already Queued.
        await using (var ctx = _factory.CreateDbContext())
        {
            var first = await ctx.Tasks.FirstAsync(t => t.Id == "P-c0");
            first.Status = TaskStatus.Queued;
            await ctx.SaveChangesAsync();
        }

        await Assert.ThrowsAsync<InvalidOperationException>(
            () => _sut.QueueSubtasksSequentiallyAsync("P", default));
    }
}