ANSCMSCORE/anscloud-common/include/anscloud/common/i_message_broker.h

#pragma once
//=============================================================================
// IMessageBroker - Abstract interface for message broker operations
// 
// Your existing RabbitMQ C++ API implements this interface.
// The SDK (DeviceAgent / GatewayAgent) depends only on this abstraction,
// not on any concrete AMQP library.
//=============================================================================

#ifndef ANSCLOUD_COMMON_I_MESSAGE_BROKER_H
#define ANSCLOUD_COMMON_I_MESSAGE_BROKER_H

#include <string>
#include <functional>
#include <memory>
#include <cstdint>

namespace anscloud {

// Forward declare
struct BrokerConfig;

//-----------------------------------------------------------------------------
// Message received from broker
//-----------------------------------------------------------------------------
struct BrokerMessage {
    std::string exchange;
    std::string routing_key;
    std::string body;              // JSON payload
    std::string correlation_id;    // For RPC matching
    std::string reply_to;          // Reply queue/routing key
    std::string message_id;
    std::string content_type;      // "application/json"
    uint64_t    delivery_tag = 0;
    bool        redelivered = false;
};

//-----------------------------------------------------------------------------
// Publish options
//-----------------------------------------------------------------------------
struct PublishOptions {
    std::string correlation_id;
    std::string reply_to;
    std::string message_id;
    std::string content_type = "application/json";
    bool persistent = true;
    int  expiration_ms = 0;        // 0 = no expiry (TTL)
};

//-----------------------------------------------------------------------------
// Callback types
//-----------------------------------------------------------------------------
using MessageCallback     = std::function<void(const BrokerMessage& msg)>;
using ConnectionCallback  = std::function<void(bool connected)>;
using ErrorCallback       = std::function<void(const std::string& error)>;

//=============================================================================
// IMessageBroker - Pure virtual interface
//
// Your existing RabbitMQ C++ API creates a class that inherits from this:
//
//   class MyRabbitMQBroker : public anscloud::IMessageBroker {
//       // ... implement all pure virtual methods using your existing API
//   };
//
//=============================================================================
class IMessageBroker {
public:
    virtual ~IMessageBroker() = default;

    //--- Connection lifecycle ------------------------------------------------
    virtual bool connect(const std::string& host, int port,
                         const std::string& username, const std::string& password,
                         const std::string& vhost) = 0;
    virtual void disconnect() = 0;
    virtual bool is_connected() const = 0;

    //--- Exchange & Queue declarations (idempotent) --------------------------
    virtual bool declare_exchange(const std::string& name,
                                  const std::string& type = "topic",
                                  bool durable = true) = 0;

    virtual bool declare_queue(const std::string& name,
                               bool durable = true,
                               bool exclusive = false,
                               bool auto_delete = false) = 0;

    virtual bool bind_queue(const std::string& queue,
                            const std::string& exchange,
                            const std::string& routing_key) = 0;

    //--- Publishing ----------------------------------------------------------
    virtual bool publish(const std::string& exchange,
                         const std::string& routing_key,
                         const std::string& body,
                         const PublishOptions& options = {}) = 0;

    //--- Consuming -----------------------------------------------------------
    // Start consuming from a queue. Messages delivered via callback.
    // Returns a consumer tag (string) that can be used to cancel.
    virtual std::string start_consuming(const std::string& queue,
                                        MessageCallback callback,
                                        bool auto_ack = true) = 0;

    // Cancel a consumer by tag
    virtual void cancel_consumer(const std::string& consumer_tag) = 0;

    // Process pending messages (call from event loop).
    // timeout_ms: max time to wait for messages. 0 = non-blocking poll.
    // Returns number of messages processed.
    virtual int process_messages(int timeout_ms = 100) = 0;

    //--- Callbacks -----------------------------------------------------------
    virtual void on_connected(ConnectionCallback cb) = 0;
    virtual void on_error(ErrorCallback cb) = 0;
};

//=============================================================================
// Factory function type - your application provides this
//=============================================================================
using BrokerFactory = std::function<std::unique_ptr<IMessageBroker>()>;

} // namespace anscloud

#endif // ANSCLOUD_COMMON_I_MESSAGE_BROKER_H