using OrderSupportTicket.Models;
using OrderSupportTicket.Models.Api;
using System;
using System.Threading.Tasks;

namespace OrderSupportTicket.Services;

/// <summary>
/// 工单业务服务，聚合工单 API 客户端与 SSE 实时服务。
/// </summary>
public sealed class TicketService : IDisposable
{
    private readonly TicketApiService _api;
    private readonly EventSourceTicketRealtimeService _realtime;
    private bool _disposed;

    /// <summary>
    /// 创建使用默认依赖的工单业务服务。
    /// </summary>
    public TicketService(bool ownsRealtime = true)
        : this(
            new TicketApiService(),
            new EventSourceTicketRealtimeService(),
            ownsRealtime)
    {
    }

    /// <summary>
    /// 创建工单业务服务。
    /// </summary>
    /// <param name="api">工单 API 客户端。</param>
    /// <param name="realtime">工单实时通知服务。</param>
    /// <param name="ownsRealtime">
    /// 是否由当前实例负责实时连接的停止与释放；共享连接应传入 false。
    /// </param>
    public TicketService(
        TicketApiService api,
        EventSourceTicketRealtimeService realtime,
        bool ownsRealtime = true)
    {
        _api = api ?? throw new ArgumentNullException(nameof(api));
        _realtime = realtime ?? throw new ArgumentNullException(nameof(realtime));
        OwnsRealtime = ownsRealtime;

        _realtime.NotificationReceived += OnNotificationReceived;
        _realtime.StateChanged += OnStateChanged;
    }

    /// <summary>
    /// 收到工单变更摘要通知时触发。
    /// </summary>
    public event EventHandler<TicketRealtimeNotificationEventArgs> NotificationReceived;

    /// <summary>
    /// SSE 连接状态变化时触发。
    /// </summary>
    public event EventHandler<TicketRealtimeStateChangedEventArgs> StateChanged;

    /// <summary>
    /// 当前 SSE 连接状态。
    /// </summary>
    public TicketRealtimeState RealtimeState => _realtime.State;

    /// <summary>
    /// 是否由当前服务实例管理实时连接的生命周期。
    /// </summary>
    public bool OwnsRealtime { get; }

    /// <summary>
    /// 校验工单页运行参数。
    /// </summary>
    public void ValidateOptions(TicketClientOptions options)
    {
        ThrowIfDisposed();
        TicketApiService.ValidateOptions(options);
    }

    /// <summary>
    /// 查询工单摘要列表。
    /// </summary>
    public Task<WorkOrderListResponse> GetWorkOrdersAsync(
        TicketClientOptions options,
        string wechatOrderId = null,
        string status = null,
        int limit = 20,
        string cursor = null)
    {
        ThrowIfDisposed();
        return _api.GetWorkOrdersAsync(
            options,
            wechatOrderId,
            status,
            limit,
            cursor);
    }

    /// <summary>
    /// 查询指定订单的公开留言板。
    /// </summary>
    public Task<WorkOrderMessagesResponse> GetMessagesAsync(
        TicketClientOptions options,
        string appId,
        string wechatOrderId,
        string before = null,
        int limit = 50)
    {
        ThrowIfDisposed();
        return _api.GetMessagesAsync(
            options,
            appId,
            wechatOrderId,
            before,
            limit);
    }

    /// <summary>
    /// 提交问题或创建工单。
    /// </summary>
    public Task<CreateWorkOrderResponse> CreateWorkOrderAsync(
        TicketClientOptions options,
        TicketOrderOption order,
        string description,
        string clientRequestId = null)
    {
        ThrowIfDisposed();
        return _api.CreateWorkOrderAsync(
            options,
            order,
            description,
            clientRequestId);
    }

    /// <summary>
    /// 提交客户留言。
    /// </summary>
    public Task<SendMessageResponse> SendMessageAsync(
        TicketClientOptions options,
        WorkOrderSummaryDto workOrder,
        string text,
        string clientMessageId,
        IList<MessageAttachmentReceipt> attachments = null)
    {
        ThrowIfDisposed();
        return _api.SendMessageAsync(
            options,
            workOrder,
            text,
            clientMessageId,
            attachments);
    }

    /// <summary>
    /// 申请单张图片的短时直传凭证。
    /// </summary>
    public Task<ImageUploadTicketResponse> CreateImageUploadTicketAsync(
        TicketClientOptions options,
        string appId,
        string wechatOrderId,
        string fileName,
        string mimeType,
        long size,
        string requestId = null)
    {
        ThrowIfDisposed();
        return _api.CreateImageUploadTicketAsync(
            options,
            appId,
            wechatOrderId,
            fileName,
            mimeType,
            size,
            requestId);
    }

    /// <summary>
    /// 将图片二进制直接上传到 COS，返回留言接口需要的回执。
    /// </summary>
    public Task<MessageAttachmentReceipt> UploadImageAsync(
        ImageUploadTicketDto upload,
        string filePath)
    {
        ThrowIfDisposed();
        return _api.UploadImageAsync(upload, filePath);
    }

    /// <summary>
    /// 标记当前订单留言已读。
    /// </summary>
    public Task MarkReadAsync(
        TicketClientOptions options,
        string appId,
        string wechatOrderId,
        int throughSequenceNo)
    {
        ThrowIfDisposed();
        return _api.MarkReadAsync(
            options,
            appId,
            wechatOrderId,
            throughSequenceNo);
    }

    /// <summary>
    /// 使用指定工单参数建立 SSE 连接。
    /// </summary>
    public async Task StartRealtime(TicketClientOptions options)
    {
        ThrowIfDisposed();
        ValidateOptions(options);
        await _realtime.Start(options);
    }

    /// <summary>
    /// 停止 SSE 连接；共享连接由宿主管理时，调用方应先检查 <see cref="OwnsRealtime"/>。
    /// </summary>
    public Task StopRealtimeAsync()
    {
        ThrowIfDisposed();
        return _realtime.StopAsync();
    }

    /// <summary>
    /// 停止并重新建立 SSE 连接。
    /// </summary>
    public async Task RestartRealtimeAsync(TicketClientOptions options)
    {
        ThrowIfDisposed();
        await _realtime.StopAsync();
        ThrowIfDisposed();
        await StartRealtime(options);
    }

    public void Dispose()
    {
        if (_disposed)
            return;
        _disposed = true;

        _realtime.NotificationReceived -= OnNotificationReceived;
        _realtime.StateChanged -= OnStateChanged;

        if (OwnsRealtime)
            _realtime.Dispose();
    }

    private void OnNotificationReceived(
        object sender,
        TicketRealtimeNotificationEventArgs args)
    {
        NotificationReceived?.Invoke(this, args);
    }

    private void OnStateChanged(
        object sender,
        TicketRealtimeStateChangedEventArgs args)
    {
        StateChanged?.Invoke(this, args);
    }

    private void ThrowIfDisposed()
    {
        if (_disposed)
            throw new ObjectDisposedException(nameof(TicketService));
    }
}