using ClaudeDo.Data;
using ClaudeDo.Data.Models;
using ClaudeDo.Data.Repositories;
using ClaudeDo.Localization;
using ClaudeDo.Ui.Localization;
using ClaudeDo.Ui.ViewModels.Islands;
using Microsoft.EntityFrameworkCore;

namespace ClaudeDo.Ui.Tests.ViewModels;

/// <summary>
/// Sidebar folders: grouping on load, the folder badge, and the two ways a list changes folder
/// (dropped onto a row in another container, dropped onto a folder header).
/// </summary>
public class ListsIslandFolderTests : IDisposable
{
    private readonly string _dbPath;

    public ListsIslandFolderTests()
    {
        _dbPath = Path.Combine(Path.GetTempPath(), $"claudedo_lists_folders_test_{Guid.NewGuid():N}.db");
        using var ctx = NewContext();
        ctx.Database.EnsureCreated();

        var dir = AppContext.BaseDirectory;
        while (dir is not null && !Directory.Exists(Path.Combine(dir, "src", "ClaudeDo.Localization", "locales")))
            dir = Path.GetDirectoryName(dir);
        Loc.Current = new Localizer(
            LocaleStore.Load(Path.Combine(dir!, "src", "ClaudeDo.Localization", "locales")), "en");
    }

    public void Dispose()
    {
        foreach (var suffix in new[] { "", "-wal", "-shm" })
            try { File.Delete(_dbPath + suffix); } catch { }
    }

    private ClaudeDoDbContext NewContext()
    {
        var opts = new DbContextOptionsBuilder<ClaudeDoDbContext>()
            .UseSqlite($"Data Source={_dbPath}")
            .Options;
        return new ClaudeDoDbContext(opts);
    }

    private sealed class FakeWorker : StubWorkerClient
    {
        public override bool IsConnected => true;
    }

    private async Task SeedAsync(string? folderId = null, params (string Id, string Name, int Sort)[] lists) =>
        await SeedAsync(folderId, 0, lists);

    private async Task SeedAsync(string? folderId, int folderSort, params (string Id, string Name, int Sort)[] lists)
    {
        await using var db = NewContext();
        if (folderId is not null)
            db.ListFolders.Add(new ListFolderEntity { Id = folderId, Name = $"Folder {folderId}", SortOrder = folderSort, CreatedAt = DateTime.UtcNow });
        foreach (var (id, name, sort) in lists)
            db.Lists.Add(new ListEntity { Id = id, Name = name, SortOrder = sort, CreatedAt = DateTime.UtcNow, FolderId = folderId });
        await db.SaveChangesAsync();
    }

    private async Task SeedTaskAsync(string listId, int number)
    {
        await using var db = NewContext();
        db.Tasks.Add(new TaskEntity
        {
            Id = Guid.NewGuid().ToString("N"),
            Number = number,
            ListId = listId,
            Title = "T",
            Status = Data.Models.TaskStatus.Idle,
            CreatedAt = DateTime.UtcNow,
        });
        await db.SaveChangesAsync();
    }

    private ListsIslandViewModel NewVm() => new(new TestDbFactory(NewContext), worker: new FakeWorker());

    [Fact]
    public async Task LoadAsync_puts_lists_into_their_folder_and_leaves_the_rest_at_the_top_level()
    {
        await SeedAsync("f1", ("inside", "Inside", 0));
        await SeedAsync(null, ("outside", "Outside", 1));

        var vm = NewVm();
        await vm.LoadAsync();

        var folder = Assert.Single(vm.Folders);
        Assert.Equal("Inside", Assert.Single(folder.Lists).Name);
        Assert.Equal("Outside", Assert.Single(vm.RootLists).Name);
        // UserLists stays the flat superset — counts and row refreshes work over it.
        Assert.Equal(2, vm.UserLists.Count);
    }

    [Fact]
    public async Task Folder_count_is_the_sum_of_its_lists()
    {
        await SeedAsync("f1", ("a", "A", 0), ("b", "B", 1));
        await SeedTaskAsync("a", 1);
        await SeedTaskAsync("b", 2);
        await SeedTaskAsync("b", 3);

        var vm = NewVm();
        await vm.LoadAsync();

        Assert.Equal(3, Assert.Single(vm.Folders).Count);
    }

    [Fact]
    public async Task MoveToFolderAsync_moves_a_top_level_list_into_the_folder_and_persists_it()
    {
        await SeedAsync("f1", ("inside", "Inside", 0));
        await SeedAsync(null, ("mover", "Mover", 1));

        var vm = NewVm();
        await vm.LoadAsync();
        var mover = vm.RootLists.Single(r => r.Id == "user:mover");

        await vm.MoveToFolderAsync(mover, vm.Folders[0]);

        Assert.Empty(vm.RootLists);
        Assert.Equal(2, vm.Folders[0].Lists.Count);
        Assert.Equal("f1", mover.FolderId);

        await using var db = NewContext();
        Assert.Equal("f1", (await db.Lists.AsNoTracking().FirstAsync(l => l.Id == "mover")).FolderId);
    }

    [Fact]
    public async Task MoveToFolderAsync_with_no_folder_takes_a_list_back_out()
    {
        await SeedAsync("f1", ("inside", "Inside", 0));

        var vm = NewVm();
        await vm.LoadAsync();
        var row = vm.Folders[0].Lists.Single();

        await vm.MoveToFolderAsync(row, null);

        Assert.Empty(vm.Folders[0].Lists);
        Assert.Same(row, Assert.Single(vm.RootLists));
        Assert.Null(row.FolderId);

        await using var db = NewContext();
        Assert.Null((await db.Lists.AsNoTracking().FirstAsync(l => l.Id == "inside")).FolderId);
    }

    [Fact]
    public async Task ReorderAsync_onto_a_row_in_another_container_also_changes_the_folder()
    {
        await SeedAsync("f1", ("inside", "Inside", 0));
        await SeedAsync(null, ("mover", "Mover", 1));

        var vm = NewVm();
        await vm.LoadAsync();
        var mover = vm.RootLists.Single();
        var inside = vm.Folders[0].Lists.Single();

        await vm.ReorderAsync(mover, inside, placeBelow: false);

        Assert.Empty(vm.RootLists);
        Assert.Equal(["Mover", "Inside"], vm.Folders[0].Lists.Select(l => l.Name));
        Assert.Equal("f1", mover.FolderId);

        await using var db = NewContext();
        var stored = await db.Lists.AsNoTracking().ToListAsync();
        Assert.Equal("f1", stored.Single(l => l.Id == "mover").FolderId);
        // sort_order is one sequence over the whole sidebar, folders included: f1 takes 0, its
        // two children 1 and 2.
        Assert.Equal(0, (await db.ListFolders.AsNoTracking().FirstAsync(f => f.Id == "f1")).SortOrder);
        Assert.Equal(1, stored.Single(l => l.Id == "mover").SortOrder);
        Assert.Equal(2, stored.Single(l => l.Id == "inside").SortOrder);
    }

    [Fact]
    public async Task DropAsync_reorders_folders_among_each_other_and_persists_it()
    {
        await SeedAsync("f1", folderSort: 0);
        await SeedAsync("f2", folderSort: 1);

        var vm = NewVm();
        await vm.LoadAsync();
        var (first, second) = (vm.Folders[0], vm.Folders[1]);

        await vm.DropAsync(second, first, placeBelow: false);

        Assert.Equal([second, first], vm.Folders);
        await using var db = NewContext();
        var stored = await db.ListFolders.AsNoTracking().ToListAsync();
        Assert.Equal(0, stored.Single(f => f.Id == second.Id).SortOrder);
        Assert.Equal(1, stored.Single(f => f.Id == first.Id).SortOrder);

        // And it survives a reload — the load path merges folders and lists by sort_order.
        var reloaded = NewVm();
        await reloaded.LoadAsync();
        Assert.Equal([second.Id, first.Id], reloaded.Folders.Select(f => f.Id));
    }

    [Fact]
    public async Task DropAsync_puts_a_list_above_a_folder_at_the_top_level()
    {
        await SeedAsync("f1", ("inside", "Inside", 1));
        await SeedAsync(null, ("mover", "Mover", 2));

        var vm = NewVm();
        await vm.LoadAsync();
        var folder = vm.Folders[0];
        var mover = vm.RootLists.Single();

        await vm.DropAsync(mover, folder, placeBelow: false);

        Assert.Equal(new object[] { mover, folder }, vm.TopLevel);
        Assert.Null(mover.FolderId);

        var reloaded = NewVm();
        await reloaded.LoadAsync();
        Assert.Equal(["user:mover", "f1"], reloaded.TopLevel.Select(i =>
            i is ListNavItemViewModel l ? l.Id : ((ListFolderNavItemViewModel)i).Id));
    }

    [Fact]
    public async Task DropAsync_never_nests_a_folder_in_a_folder()
    {
        await SeedAsync("f1", 0, ("inside", "Inside", 1));
        await SeedAsync("f2", folderSort: 2);

        var vm = NewVm();
        await vm.LoadAsync();
        var inside = vm.Folders[0].Lists.Single();
        var f2 = vm.Folders[1];

        await vm.DropAsync(f2, inside, placeBelow: true);

        Assert.Equal(2, vm.TopLevel.Count);
        Assert.Single(vm.Folders[0].Lists);
    }

    [Fact]
    public async Task ReorderAsync_within_a_folder_keeps_the_folder()
    {
        await SeedAsync("f1", ("a", "A", 0), ("b", "B", 1));

        var vm = NewVm();
        await vm.LoadAsync();
        var a = vm.Folders[0].Lists[0];
        var b = vm.Folders[0].Lists[1];

        await vm.ReorderAsync(b, a, placeBelow: false);

        Assert.Equal(["B", "A"], vm.Folders[0].Lists.Select(l => l.Name));
        Assert.All(vm.Folders[0].Lists, l => Assert.Equal("f1", l.FolderId));
    }

    [Fact]
    public async Task ToggleFolder_flips_and_persists_the_collapse_state()
    {
        await SeedAsync("f1", ("inside", "Inside", 0));

        var vm = NewVm();
        await vm.LoadAsync();
        var folder = vm.Folders[0];
        Assert.False(folder.IsCollapsed);

        vm.ToggleFolderCommand.Execute(folder);
        await Task.Delay(100);

        Assert.True(folder.IsCollapsed);
        await using var db = NewContext();
        Assert.True((await db.ListFolders.AsNoTracking().FirstAsync(f => f.Id == "f1")).IsCollapsed);

        // And the state survives a reload.
        var reloaded = NewVm();
        await reloaded.LoadAsync();
        Assert.True(reloaded.Folders[0].IsCollapsed);
    }

    [Fact]
    public async Task ToggleFolder_rapid_double_click_both_toggles_land()
    {
        // Bug F1 (docs/test-session-2026-09-16.md): the command used to be an async
        // [RelayCommand], so AsyncRelayCommand's own CanExecute lock swallowed the second click
        // while the first one's DB write was still in flight. Firing two toggles back-to-back
        // (no await between them) reproduces exactly that window.
        await SeedAsync("f1", ("inside", "Inside", 0));

        var vm = NewVm();
        await vm.LoadAsync();
        var folder = vm.Folders[0];
        Assert.False(folder.IsCollapsed);

        vm.ToggleFolderCommand.Execute(folder);
        vm.ToggleFolderCommand.Execute(folder);
        await Task.Delay(100);

        // Two flips land back on the original (visible) state...
        Assert.False(folder.IsCollapsed);
        // ...and the DB ends up agreeing with it, not with the stale mid-flight value.
        await using var db = NewContext();
        Assert.False((await db.ListFolders.AsNoTracking().FirstAsync(f => f.Id == "f1")).IsCollapsed);
    }

    [Fact]
    public async Task RemoveFromFolder_command_is_the_context_menu_route_out()
    {
        await SeedAsync("f1", ("inside", "Inside", 0));

        var vm = NewVm();
        await vm.LoadAsync();
        var row = vm.Folders[0].Lists.Single();

        await vm.RemoveFromFolderCommand.ExecuteAsync(row);

        Assert.Null(row.FolderId);
        Assert.Single(vm.RootLists);
    }
}