using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using RabbitMQ.Client;
using TakeoutSaaS.Module.Messaging.Abstractions;
using TakeoutSaaS.Module.Messaging.Options;
using TakeoutSaaS.Module.Messaging.Serialization;

namespace TakeoutSaaS.Module.Messaging.Services;

/// <summary>
/// RabbitMQ 消息发布实现。
/// </summary>
public sealed class RabbitMqMessagePublisher(RabbitMqConnectionFactory connectionFactory, IOptionsMonitor<RabbitMqOptions> optionsMonitor, JsonMessageSerializer serializer, ILogger<RabbitMqMessagePublisher> logger)
    : IMessagePublisher, IAsyncDisposable
{
    private IConnection? _connection;
    private IChannel? _channel;
    private bool _disposed;

    /// <inheritdoc />
    public async Task PublishAsync<T>(string routingKey, T message, CancellationToken cancellationToken = default)
    {
        // 1. 确保通道可用
        await EnsureChannelAsync(cancellationToken);
        var options = optionsMonitor.CurrentValue;

        var channel = _channel ?? throw new InvalidOperationException("RabbitMQ channel is not available.");
        // 2. 声明交换机
        await channel.ExchangeDeclareAsync(options.Exchange, options.ExchangeType, durable: true, autoDelete: false, cancellationToken: cancellationToken);
        // 3. 序列化消息并设置属性
        var body = serializer.Serialize(message);
        var props = new BasicProperties
        {
            ContentType = "application/json",
            DeliveryMode = DeliveryModes.Persistent,
            MessageId = Guid.NewGuid().ToString("N")
        };

        // 4. 发布消息
        await channel.BasicPublishAsync(options.Exchange, routingKey, mandatory: false, props, body, cancellationToken);
        logger.LogDebug("发布消息到交换机 {Exchange} RoutingKey {RoutingKey}", options.Exchange, routingKey);
    }

    private async Task EnsureChannelAsync(CancellationToken cancellationToken)
    {
        if (_channel != null && _channel.IsOpen)
        {
            return;
        }

        _connection ??= await connectionFactory.CreateConnectionAsync(cancellationToken);
        _channel = await _connection.CreateChannelAsync(cancellationToken: cancellationToken);
    }

    /// <summary>
    /// 释放 RabbitMQ 资源。
    /// </summary>
    public ValueTask DisposeAsync()
    {
        if (_disposed)
        {
            return ValueTask.CompletedTask;
        }

        _disposed = true;
        _channel?.Dispose();
        _connection?.Dispose();
        return ValueTask.CompletedTask;
    }
}