using System.Collections.ObjectModel;
using ClaudeDo.Data.Models;
using ClaudeDo.Ui.Services;
using ClaudeDo.Ui.ViewModels.Islands;
using TaskStatus = ClaudeDo.Data.Models.TaskStatus;

namespace ClaudeDo.Ui.Tests.ViewModels;

public class DetailsIslandPlanningTests
{
    // Minimal shim exercising RecomputeCanMergeAll logic without needing WorkerClient
    private sealed class PlanningVmShim
    {
        public ObservableCollection<SubtaskRowViewModel> Subtasks { get; } = new();
        public bool CanMergeAll { get; private set; }
        public string? MergeAllDisabledReason { get; private set; }

        public void RecomputeCanMergeAll()
        {
            var notDone = Subtasks.Count(c => c.Status != TaskStatus.Done);
            if (notDone > 0)
            {
                CanMergeAll = false;
                MergeAllDisabledReason = $"{notDone} subtask(s) not done";
                return;
            }
            var badWt = Subtasks.FirstOrDefault(c =>
                c.WorktreeState == WorktreeState.Discarded ||
                c.WorktreeState == WorktreeState.Kept);
            if (badWt is not null)
            {
                CanMergeAll = false;
                MergeAllDisabledReason = "at least one worktree was discarded/kept";
                return;
            }
            CanMergeAll = true;
            MergeAllDisabledReason = null;
        }
    }

    private sealed class FakeWorkerClient : IWorkerClient
    {
        public event Action<string>? TaskUpdatedEvent;
        public event Action<string>? WorktreeUpdatedEvent;
        public event Action<string, string>? TaskMessageEvent;
        public event Action<string, string>? PlanningMergeStartedEvent;
        public event Action<string, string>? PlanningSubtaskMergedEvent;
        public event Action<string, string, IReadOnlyList<string>>? PlanningMergeConflictEvent;
        public event Action<string>? PlanningMergeAbortedEvent;
        public event Action<string>? PlanningCompletedEvent;

        public MergeTargetsDto? MergeTargetsResult { get; set; }

        public Task WakeQueueAsync() => Task.CompletedTask;
        public Task StartPlanningSessionAsync(string taskId, CancellationToken ct = default) => Task.CompletedTask;
        public Task ResumePlanningSessionAsync(string taskId, CancellationToken ct = default) => Task.CompletedTask;
        public Task DiscardPlanningSessionAsync(string taskId, CancellationToken ct = default) => Task.CompletedTask;
        public Task FinalizePlanningSessionAsync(string taskId, bool queueAgentTasks = true, CancellationToken ct = default) => Task.CompletedTask;
        public Task<int> GetPendingDraftCountAsync(string taskId, CancellationToken ct = default) => Task.FromResult(0);
        public Task<MergeTargetsDto?> GetMergeTargetsAsync(string taskId) => Task.FromResult(MergeTargetsResult);
        public Task<IReadOnlyList<SubtaskDiffDto>> GetPlanningAggregateAsync(string planningTaskId) =>
            Task.FromResult<IReadOnlyList<SubtaskDiffDto>>(Array.Empty<SubtaskDiffDto>());
        public Task<CombinedDiffResultDto?> BuildPlanningIntegrationBranchAsync(string planningTaskId, string targetBranch) =>
            Task.FromResult<CombinedDiffResultDto?>(null);
        public Task MergeAllPlanningAsync(string planningTaskId, string targetBranch) => Task.CompletedTask;
        public Task ContinuePlanningMergeAsync(string planningTaskId) => Task.CompletedTask;
        public Task AbortPlanningMergeAsync(string planningTaskId) => Task.CompletedTask;

        public void FireTaskUpdated(string id) => TaskUpdatedEvent?.Invoke(id);
        public void FireWorktreeUpdated(string id) => WorktreeUpdatedEvent?.Invoke(id);
    }

    private static SubtaskRowViewModel MakeSubtask(TaskStatus status, WorktreeState wt = WorktreeState.Active) =>
        new() { Id = Guid.NewGuid().ToString(), Title = "t", Status = status, WorktreeState = wt };

    [Fact]
    public void CanMergeAll_AllChildrenDoneActiveWorktrees_True()
    {
        var shim = new PlanningVmShim();
        shim.Subtasks.Add(MakeSubtask(TaskStatus.Done, WorktreeState.Active));
        shim.Subtasks.Add(MakeSubtask(TaskStatus.Done, WorktreeState.Active));

        shim.RecomputeCanMergeAll();

        Assert.True(shim.CanMergeAll);
        Assert.Null(shim.MergeAllDisabledReason);
    }

    [Fact]
    public void CanMergeAll_AnyChildNotDone_FalseWithReason()
    {
        var shim = new PlanningVmShim();
        shim.Subtasks.Add(MakeSubtask(TaskStatus.Done, WorktreeState.Active));
        shim.Subtasks.Add(MakeSubtask(TaskStatus.Done, WorktreeState.Active));
        shim.Subtasks.Add(MakeSubtask(TaskStatus.Running, WorktreeState.Active));

        shim.RecomputeCanMergeAll();

        Assert.False(shim.CanMergeAll);
        Assert.NotNull(shim.MergeAllDisabledReason);
        Assert.Contains("1 subtask", shim.MergeAllDisabledReason, StringComparison.OrdinalIgnoreCase);
        Assert.Contains("not done", shim.MergeAllDisabledReason, StringComparison.OrdinalIgnoreCase);
    }

    [Fact]
    public void CanMergeAll_AnyChildDiscarded_FalseWithReason()
    {
        var shim = new PlanningVmShim();
        shim.Subtasks.Add(MakeSubtask(TaskStatus.Done, WorktreeState.Active));
        shim.Subtasks.Add(MakeSubtask(TaskStatus.Done, WorktreeState.Discarded));

        shim.RecomputeCanMergeAll();

        Assert.False(shim.CanMergeAll);
        Assert.NotNull(shim.MergeAllDisabledReason);
        Assert.True(
            shim.MergeAllDisabledReason!.Contains("discarded", StringComparison.OrdinalIgnoreCase) ||
            shim.MergeAllDisabledReason.Contains("kept", StringComparison.OrdinalIgnoreCase));
    }

    [Fact]
    public void MergeTargetBranches_LoadedFromWorkerOnPlanningParent()
    {
        var fake = new FakeWorkerClient();
        fake.MergeTargetsResult = new MergeTargetsDto("main", new[] { "main", "dev" });

        var result = fake.GetMergeTargetsAsync("any-task-id").GetAwaiter().GetResult();

        Assert.NotNull(result);
        Assert.Equal("main", result!.DefaultBranch);
        Assert.Contains("main", result.LocalBranches);
        Assert.Contains("dev", result.LocalBranches);
    }
}