using System;
using System.Threading.Tasks;
using ClaudeDo.Data.Models;
using ClaudeDo.Ui.Services;
using ClaudeDo.Ui.ViewModels;
using Xunit;

namespace ClaudeDo.Ui.Tests;

// Covers the MCP-driven-merge popup fix: a unit-merge conflict started by an MCP session
// (review_task/continue_merge) must not auto-open the in-app resolver — two parties editing the
// same shared checkout at once is how the original bug manifested. The UI-driven path (a human
// clicking Approve) keeps opening the resolver as before.
public class IslandsShellViewModelExternalMergeTests
{
    [Fact]
    public void ExternallyDriven_ShowsBanner()
    {
        var vm = new IslandsShellViewModel();

        vm.OnPlanningMergeConflict("plan1", "sub1", new[] { "file.txt" }, externallyDriven: true);

        Assert.True(vm.IsExternalMergeBannerVisible);
    }

    [Fact]
    public void UiDriven_DoesNotShowExternalBanner()
    {
        var vm = new IslandsShellViewModel();

        vm.OnPlanningMergeConflict("plan1", "sub1", new[] { "file.txt" }, externallyDriven: false);

        Assert.False(vm.IsExternalMergeBannerVisible);
    }

    [Fact]
    public void Aborted_ClearsBanner()
    {
        var vm = new IslandsShellViewModel();
        vm.OnPlanningMergeConflict("plan1", "sub1", Array.Empty<string>(), externallyDriven: true);
        Assert.True(vm.IsExternalMergeBannerVisible);

        vm.OnPlanningMergeAborted("plan1");

        Assert.False(vm.IsExternalMergeBannerVisible);
    }

    // Covers the unit-merge-error-propagation fix: a real merge failure (blocked/verify_failed/
    // untracked_collision) reaches the UI as a reason on PlanningMergeAborted, and must surface
    // in the footer strip rather than silently vanishing once the banner is cleared.
    [Fact]
    public void Aborted_WithReason_FlashesFooterError()
    {
        var vm = new IslandsShellViewModel();

        vm.OnPlanningMergeAborted("plan1", "child merge blocked: unrelated histories");

        Assert.Equal(WorkerLogLevel.Error, vm.WorkerLogLevel);
        Assert.Contains("child merge blocked: unrelated histories", vm.WorkerLogText);
        Assert.True(vm.IsWorkerLogVisible);
    }

    [Fact]
    public void Aborted_WithoutReason_DoesNotFlashFooterError()
    {
        var vm = new IslandsShellViewModel();

        vm.OnPlanningMergeAborted("plan1", null);

        Assert.False(vm.IsWorkerLogVisible);
    }

    [Fact]
    public void Completed_ClearsBanner()
    {
        var vm = new IslandsShellViewModel();
        vm.OnPlanningMergeConflict("plan1", "sub1", Array.Empty<string>(), externallyDriven: true);

        vm.OnPlanningMergeCompleted("plan1");

        Assert.False(vm.IsExternalMergeBannerVisible);
    }

    [Fact]
    public void UnrelatedPlanningTaskEnding_LeavesBannerVisible()
    {
        var vm = new IslandsShellViewModel();
        vm.OnPlanningMergeConflict("plan1", "sub1", Array.Empty<string>(), externallyDriven: true);

        vm.OnPlanningMergeCompleted("some-other-plan");

        Assert.True(vm.IsExternalMergeBannerVisible);
    }

    [Fact]
    public void LaterConflictOnSamePlanningTask_UpdatesInPlaceWithoutDuplicating()
    {
        var vm = new IslandsShellViewModel();
        vm.OnPlanningMergeConflict("plan1", "subA", Array.Empty<string>(), externallyDriven: true);
        vm.OnPlanningMergeConflict("plan1", "subB", Array.Empty<string>(), externallyDriven: true);
        Assert.True(vm.IsExternalMergeBannerVisible);

        // A single terminal event for that planning task clears it entirely — proves the second
        // conflict updated the same entry rather than piling up a second one.
        vm.OnPlanningMergeCompleted("plan1");

        Assert.False(vm.IsExternalMergeBannerVisible);
    }

    [Fact]
    public async Task OpenExternalMergeConflictCommand_NoPendingConflict_DoesNotThrow()
    {
        var vm = new IslandsShellViewModel();

        await vm.OpenExternalMergeConflictCommand.ExecuteAsync(null);
    }

    [Fact]
    public async Task OpenExternalMergeConflictCommand_NoDialogsWired_DoesNotThrow()
    {
        var vm = new IslandsShellViewModel();
        vm.OnPlanningMergeConflict("plan1", "sub1", Array.Empty<string>(), externallyDriven: true);

        // Dialogs/ConflictResolverFactory aren't wired in the test-only ctor — a deliberate
        // click must degrade gracefully rather than throw, same as the existing UI-driven path.
        await vm.OpenExternalMergeConflictCommand.ExecuteAsync(null);
    }

    private sealed class DirtyTargetWorker : StubWorkerClient
    {
        public override Task<MergeResultDto> StartConflictMergeAsync(string taskId, string targetBranch, bool autostash = false) =>
            Task.FromResult(new MergeResultDto("dirty_target", Array.Empty<string>(), "target working tree has uncommitted changes"));
    }

    [Fact]
    public async Task RequestConflictResolution_ResolverRefused_ShowsWhyInTheFooter()
    {
        // Regression: a refusal (dirty target, ...) left the resolver closed with no explanation anywhere.
        var vm = new IslandsShellViewModel
        {
            Dialogs = new RecordingDialogService(),
            ConflictResolverFactory = id => new ClaudeDo.Ui.ViewModels.Conflicts.ConflictResolverViewModel(new DirtyTargetWorker(), id),
        };

        await vm.RequestConflictResolutionAsync("t1", "main");

        Assert.Equal(WorkerLogLevel.Error, vm.WorkerLogLevel);
        Assert.Contains("uncommitted changes", vm.WorkerLogText);
    }
}