using System.Collections.ObjectModel;
using System.Collections.Specialized;
using System.IO;
using System.Linq;
using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using ClaudeDo.Data;
using ClaudeDo.Ui.Localization;
using ClaudeDo.Ui.Services;
using ClaudeDo.Ui.ViewModels.MissionControl;
using Microsoft.EntityFrameworkCore;

namespace ClaudeDo.Ui.ViewModels;

public sealed partial class MissionControlViewModel : ViewModelBase, IDisposable
{
    private readonly IDbContextFactory<ClaudeDoDbContext> _dbFactory;
    private readonly IWorkerClient _worker;
    private readonly Action<string, string, DateTime> _onTaskStarted;
    private readonly Action<string, string, string, DateTime> _onTaskFinished;
    private readonly Action<string> _onTaskUpdated;
    private readonly Action _onConnectionRestored;

    // Embedded ConPTY sessions (task-based only) — a manual cockpit detached from the
    // review/merge/status machinery.
    public ObservableCollection<ConPtyPaneViewModel> ConPtySessions { get; } = new();

    // Mirror of ConPtySessions typed as the pane abstraction so the layout toggle (grid/tabs)
    // binds one contract rather than a ConPTY-specific type.
    public ObservableCollection<IMissionControlPane> Panes { get; } = new();

    [ObservableProperty] private int _columnCount = 1;

    [ObservableProperty]
    [NotifyPropertyChangedFor(nameof(LayoutToggleLabel))]
    private bool _isFocusMode;

    [ObservableProperty] private IMissionControlPane? _focusedPane;

    public string LayoutToggleLabel => Loc.T(IsFocusMode ? "missionControl.overviewMode" : "missionControl.focusMode");

    /// <summary>Surfaces a Command Center failure (e.g. a ConPTY launch spec fetch) — the shell
    /// wires this into the footer error strip, same as the island view models' ErrorReported.</summary>
    public event Action<string>? ErrorReported;

    public Action<string>? OpenInApp { get; set; }

    // View-layer seam: open the app Settings modal from the Mission Control window.
    public Action? OpenSettingsRequested { get; set; }

    public bool HasPanes => Panes.Count > 0;

    // Read-only view of the worker queue (tasks waiting to run), shown as a side strip.
    public ObservableCollection<QueuedTaskViewModel> Queued { get; } = new();
    public bool HasQueued => Queued.Count > 0;

    public UsagePillViewModel UsagePill { get; }

    public MissionControlViewModel(IDbContextFactory<ClaudeDoDbContext> dbFactory, IWorkerClient worker, UsagePillViewModel usagePill)
    {
        _dbFactory = dbFactory;
        _worker = worker;
        UsagePill = usagePill;

        ConPtySessions.CollectionChanged += OnConPtySessionsChanged;
        Panes.CollectionChanged += OnPanesChanged;

        _onTaskStarted = (slot, taskId, startedAt) => { _ = RefreshQueueAsync(); };
        _worker.TaskStartedEvent += _onTaskStarted;

        _onTaskFinished = (slot, taskId, status, finishedAt) => _ = RefreshQueueAsync();
        _worker.TaskFinishedEvent += _onTaskFinished;

        _onTaskUpdated = taskId => _ = RefreshQueueAsync();
        _worker.TaskUpdatedEvent += _onTaskUpdated;

        _onConnectionRestored = () => { _ = RefreshQueueAsync(); };
        _worker.ConnectionRestoredEvent += _onConnectionRestored;

        _ = RefreshQueueAsync();
    }

    internal async System.Threading.Tasks.Task RefreshQueueAsync()
    {
        try
        {
            await using var ctx = await _dbFactory.CreateDbContextAsync();
            var rows = await ctx.Tasks.AsNoTracking()
                .Where(t => t.Status == ClaudeDo.Data.Models.TaskStatus.Queued
                         || t.Status == ClaudeDo.Data.Models.TaskStatus.Running)
                .OrderBy(t => t.Status == ClaudeDo.Data.Models.TaskStatus.Running ? 0 : 1)
                .ThenBy(t => t.SortOrder).ThenBy(t => t.CreatedAt)
                .Select(t => new { t.Id, t.Title, t.BlockedByTaskId, t.Status })
                .ToListAsync();

            Queued.Clear();
            foreach (var r in rows)
            {
                var id = r.Id;
                Queued.Add(new QueuedTaskViewModel
                {
                    Id = id,
                    Title = r.Title ?? string.Empty,
                    IsBlocked = r.BlockedByTaskId != null,
                    IsRunning = r.Status == ClaudeDo.Data.Models.TaskStatus.Running,
                    OpenInAppCommand = new RelayCommand(() => OpenInApp?.Invoke(id)),
                });
            }
            OnPropertyChanged(nameof(HasQueued));
        }
        catch { /* best-effort queue refresh */ }
    }

    // Drop-to-queue: a task dragged from the main app onto Mission Control gets queued.
    public async System.Threading.Tasks.Task EnqueueTaskAsync(string taskId)
    {
        if (string.IsNullOrEmpty(taskId)) return;
        try
        {
            await using var db = await _dbFactory.CreateDbContextAsync();
            var entity = await db.Tasks.FirstOrDefaultAsync(t => t.Id == taskId);
            if (entity is null
                || entity.Status == ClaudeDo.Data.Models.TaskStatus.Running
                || entity.Status == ClaudeDo.Data.Models.TaskStatus.Queued)
                return;
            entity.Status = ClaudeDo.Data.Models.TaskStatus.Queued;
            await db.SaveChangesAsync();
            await _worker.WakeQueueAsync();
        }
        catch { /* best-effort enqueue */ }
        await RefreshQueueAsync();
    }

    [RelayCommand]
    private void OpenSettings() => OpenSettingsRequested?.Invoke();

    [RelayCommand]
    private void ToggleLayout() => IsFocusMode = !IsFocusMode;

    // Fetches the launch spec for a task's worktree and hosts an embedded ConPTY session as a
    // Command Center pane (task-based only).
    public async System.Threading.Tasks.Task OpenConPtySessionAsync(string taskId)
    {
        if (string.IsNullOrEmpty(taskId)) return;
        if (ConPtySessions.FirstOrDefault(s => s.TaskId == taskId) is { } existing)
        {
            FocusedPane = existing;
            return;
        }

        var title = taskId;
        try
        {
            await using var ctx = await _dbFactory.CreateDbContextAsync();
            var entity = await ctx.Tasks.AsNoTracking().FirstOrDefaultAsync(t => t.Id == taskId);
            if (entity?.Title is { Length: > 0 } t) title = t;
        }
        catch { /* best-effort title lookup */ }

        AddConPtyPane(new ConPtyPaneViewModel(taskId, title,
            () => DescribeAsync(() => _worker.GetInteractiveLaunchSpecAsync(taskId))));
    }

    // Starts (or resumes) a planning session and hosts it as an embedded ConPTY Command Center
    // pane — the ConPTY replacement for the old external wt planning window. Deduped by TaskId
    // like OpenConPtySessionAsync.
    public async System.Threading.Tasks.Task OpenPlanningConPtySessionAsync(string taskId, bool resume)
    {
        if (string.IsNullOrEmpty(taskId)) return;
        if (ConPtySessions.FirstOrDefault(s => s.TaskId == taskId) is { } existing)
        {
            FocusedPane = existing;
            return;
        }

        var title = taskId;
        try
        {
            await using var ctx = await _dbFactory.CreateDbContextAsync();
            var entity = await ctx.Tasks.AsNoTracking().FirstOrDefaultAsync(t => t.Id == taskId);
            if (entity?.Title is { Length: > 0 } t) title = t;
        }
        catch { /* best-effort title lookup */ }
        title += Loc.T("missionControl.planningTitleSuffix");

        AddConPtyPane(new ConPtyPaneViewModel(taskId, title, () => DescribeAsync(() => resume
            ? _worker.GetPlanningResumeLaunchSpecAsync(taskId)
            : _worker.GetPlanningStartLaunchSpecAsync(taskId))));
    }

    // Ad-hoc (task-less) ConPTY session in a user-chosen directory. Never deduped — every call
    // opens a fresh pane, unlike the task-based OpenConPtySessionAsync above.
    public System.Threading.Tasks.Task OpenAdHocConPtySessionAsync(string directory)
    {
        if (string.IsNullOrEmpty(directory)) return System.Threading.Tasks.Task.CompletedTask;

        var title = Path.GetFileName(directory.TrimEnd('\\', '/'));
        if (string.IsNullOrEmpty(title)) title = directory;

        AddConPtyPane(ConPtyPaneViewModel.CreateAdHoc(title,
            () => DescribeAsync(() => _worker.GetAdHocLaunchSpecAsync(directory))));
        return System.Threading.Tasks.Task.CompletedTask;
    }

    // List-handler session over a hand-picked set of tasks ("Let Claude handle it"). Task-based:
    // creates one new ClaudeDo task per run to own the session (title/diff/result), deduped by
    // TaskId like OpenConPtySessionAsync. The handler still merges the tasks it handles itself
    // (no worktree of its own) — see TaskEntity.HandlerBaseCommit/HandlerHeadCommit.
    public async System.Threading.Tasks.Task OpenMergeHelperConPtySessionAsync(string listId, IReadOnlyList<string> taskIds)
    {
        if (taskIds is not { Count: > 0 }) return;

        var title = Loc.T("missionControl.mergeHelperTitle");
        var listName = listId;
        try
        {
            await using var ctx = await _dbFactory.CreateDbContextAsync();
            var list = await ctx.Lists.AsNoTracking().FirstOrDefaultAsync(l => l.Id == listId);
            if (list?.Name is { Length: > 0 } name) { listName = name; title = $"{title} — {name}"; }
        }
        catch { /* best-effort title lookup */ }

        string taskId;
        try
        {
            taskId = await _worker.CreateMergeHelperTaskAsync(taskIds, listId,
                Loc.T("missionControl.mergeHelperTaskTitle", listName),
                Loc.T("missionControl.mergeHelperTaskDescriptionHeader"));
        }
        catch (Exception ex)
        {
            ErrorReported?.Invoke(Loc.T("missionControl.conptyLaunchFailed", ex.Message));
            return;
        }

        if (ConPtySessions.FirstOrDefault(s => s.TaskId == taskId) is { } existing)
        {
            FocusedPane = existing;
            return;
        }

        AddConPtyPane(new ConPtyPaneViewModel(taskId, title,
            () => DescribeAsync(() => _worker.GetMergeHelperLaunchSpecAsync(taskIds, listId))));
    }

    // Wires a freshly built pane and shows it immediately — the pane resolves its own launch spec,
    // so the tile is on screen (spinner running) while the worker is still preparing the worktree.
    private void AddConPtyPane(ConPtyPaneViewModel pane)
    {
        pane.ErrorReported += OnConPtyPaneError;
        pane.CloseRequested += CloseConPtySession;
        pane.SubmitForReviewRequested += OnPaneSubmitForReview;
        ConPtySessions.Add(pane);
        pane.Start();
    }

    private static async System.Threading.Tasks.Task<TerminalLaunchDescriptor> DescribeAsync(
        Func<System.Threading.Tasks.Task<LaunchSpec>> fetch)
    {
        var spec = await fetch();
        return new TerminalLaunchDescriptor(spec.Cwd, spec.Exe, spec.Args, spec.Env);
    }

    private void OnConPtyPaneError(string message)
        => ErrorReported?.Invoke(Loc.T("missionControl.conptyLaunchFailed", message));

    // Submit a task's hand-driven ConPTY work for review, then close the pane (the interactive
    // session is finished). The worker commits the worktree and moves the task to WaitingForReview.
    private async void OnPaneSubmitForReview(string taskId)
    {
        try
        {
            await _worker.SubmitTaskForReviewAsync(taskId);
            if (ConPtySessions.FirstOrDefault(s => s.TaskId == taskId) is { } pane)
                CloseConPtySession(pane);
        }
        catch (Exception ex)
        {
            ErrorReported?.Invoke(Loc.T("missionControl.submitForReviewFailed", ex.Message));
        }
    }

    private void CloseConPtySession(ConPtyPaneViewModel pane)
    {
        if (!ConPtySessions.Contains(pane)) return;
        pane.ErrorReported -= OnConPtyPaneError;
        pane.CloseRequested -= CloseConPtySession;
        ConPtySessions.Remove(pane);
        pane.Dispose();
    }

    // Mirrors ConPtySessions' add/remove 1:1 into Panes (typed as the pane abstraction).
    private void OnConPtySessionsChanged(object? sender, NotifyCollectionChangedEventArgs e)
    {
        switch (e.Action)
        {
            case NotifyCollectionChangedAction.Add:
                Panes.Insert(e.NewStartingIndex, (ConPtyPaneViewModel)e.NewItems![0]!);
                break;
            case NotifyCollectionChangedAction.Remove:
                Panes.RemoveAt(e.OldStartingIndex);
                break;
            default: // Reset
                Panes.Clear();
                break;
        }
    }

    private void OnPanesChanged(object? sender, NotifyCollectionChangedEventArgs e)
    {
        ColumnCount = Panes.Count switch
        {
            <= 1 => 1,
            <= 4 => 2,
            _    => 3,
        };
        OnPropertyChanged(nameof(HasPanes));
        if (e.Action == NotifyCollectionChangedAction.Add && e.NewItems?[0] is IMissionControlPane added)
            FocusedPane = added;
        else if (e.Action == NotifyCollectionChangedAction.Remove && ReferenceEquals(FocusedPane, e.OldItems?[0]))
            FocusedPane = Panes.LastOrDefault();
    }

    public void Dispose()
    {
        _worker.TaskStartedEvent -= _onTaskStarted;
        _worker.TaskFinishedEvent -= _onTaskFinished;
        _worker.TaskUpdatedEvent -= _onTaskUpdated;
        _worker.ConnectionRestoredEvent -= _onConnectionRestored;
        ConPtySessions.CollectionChanged -= OnConPtySessionsChanged;
        Panes.CollectionChanged -= OnPanesChanged;
        foreach (var c in ConPtySessions.ToList())
        {
            c.ErrorReported -= OnConPtyPaneError;
            c.CloseRequested -= CloseConPtySession;
            c.Dispose();
        }
        ConPtySessions.Clear();
        Panes.Clear();
    }
}

/// <summary>Read-only display row for a queued or running task in the Mission Control side strip.</summary>
public sealed class QueuedTaskViewModel
{
    public required string Id { get; init; }
    public required string Title { get; init; }
    public bool IsBlocked { get; init; }
    public bool IsRunning { get; init; }
    public IRelayCommand? OpenInAppCommand { get; init; }
}