using System.Collections.Generic;
using System.Threading.Tasks;
using ClaudeDo.Ui.Services;
using ClaudeDo.Ui.ViewModels.Conflicts;
using Xunit;

namespace ClaudeDo.Ui.Tests.ViewModels;

public class ConflictResolverViewModelTests
{
    private sealed class FakeWorker : StubWorkerClient
    {
        public string? WrittenPath;
        public string? WrittenContent;
        public bool Continued;
        public bool Aborted;
        public string ContinueStatus = "merged";

        public override Task<MergeResultDto> StartConflictMergeAsync(string taskId, string targetBranch)
            => Task.FromResult(new MergeResultDto("conflict", new[] { "README.md" }, null));

        public override Task<MergeConflictsDto> GetMergeConflictsAsync(string taskId)
            => Task.FromResult(new MergeConflictsDto(taskId, new[]
            {
                new ConflictFileDto("README.md", new[] { new ConflictHunkDto("ours\n", "theirs\n", "base\n") })
            }));

        public override Task WriteConflictResolutionAsync(string taskId, string path, string resolvedContent)
        {
            WrittenPath = path; WrittenContent = resolvedContent; return Task.CompletedTask;
        }

        public override Task<MergeResultDto> ContinueConflictMergeAsync(string taskId)
        {
            Continued = true;
            return Task.FromResult(new MergeResultDto(ContinueStatus, System.Array.Empty<string>(), null));
        }

        public override Task AbortConflictMergeAsync(string taskId) { Aborted = true; return Task.CompletedTask; }
    }

    [Fact]
    public async Task OpenAsync_LoadsConflicts_AndBlocksContinueUntilResolved()
    {
        var vm = new ConflictResolverViewModel(new FakeWorker(), "task-1");
        var hasConflicts = await vm.OpenAsync("main");

        Assert.True(hasConflicts);
        var file = Assert.Single(vm.Files);
        Assert.Equal("README.md", file.Path);
        Assert.False(vm.CanContinue);

        file.Hunks[0].AcceptIncomingCommand.Execute(null);
        Assert.True(vm.CanContinue);
    }

    [Fact]
    public async Task Continue_WritesComposedResolution_AndClosesOnMerged()
    {
        var worker = new FakeWorker();
        var vm = new ConflictResolverViewModel(worker, "task-1");
        var closed = false;
        vm.CloseRequested = () => closed = true;

        await vm.OpenAsync("main");
        vm.Files[0].Hunks[0].AcceptCurrentCommand.Execute(null);
        await vm.ContinueCommand.ExecuteAsync(null);

        Assert.Equal("README.md", worker.WrittenPath);
        Assert.Equal("ours\n", worker.WrittenContent);
        Assert.True(worker.Continued);
        Assert.True(closed);
    }

    [Fact]
    public async Task Continue_StaysOpenAndReportsError_WhenStillConflicted()
    {
        var worker = new FakeWorker { ContinueStatus = "conflict" };
        var vm = new ConflictResolverViewModel(worker, "task-1");
        var closed = false;
        vm.CloseRequested = () => closed = true;

        await vm.OpenAsync("main");
        vm.Files[0].Hunks[0].AcceptBothCommand.Execute(null);
        await vm.ContinueCommand.ExecuteAsync(null);

        Assert.False(closed);
        Assert.NotNull(vm.Error);
    }

    [Fact]
    public async Task Abort_CallsWorkerAndCloses()
    {
        var worker = new FakeWorker();
        var vm = new ConflictResolverViewModel(worker, "task-1");
        var closed = false;
        vm.CloseRequested = () => closed = true;

        await vm.AbortCommand.ExecuteAsync(null);

        Assert.True(worker.Aborted);
        Assert.True(closed);
    }
}