// etcp.h - ETCP Protocol Header (refactored based on etcp_protocol.txt)
#ifndef ETCP_H
#define ETCP_H

#include "etcp_connections.h"
#include "secure_channel.h"
#include "../lib/ll_queue.h"
#include <stdint.h>

#ifdef __cplusplus
extern "C" {
#endif

// Forward declarations
struct UTUN_INSTANCE;
struct UASYNC;

// ETCP packet section types (from protocol spec)
#define ETCP_SECTION_PAYLOAD    0x00  // Data payload
#define ETCP_SECTION_ACK        0x01  // ACK section
#define ETCP_SECTION_RETRANS    0x10  // Retransmission request base (0x10-0x2F)
#define ETCP_SECTION_TIMESTAMP  0x06  // Channel timestamp (example, adjust if needed)
#define ETCP_SECTION_MEAS_TS    0x07  // Measurement timestamp for bandwidth
#define ETCP_SECTION_MEAS_RESP  0x08  // Measurement response

// Inflight packet states
#define INFLIGHT_STATE_WAIT_ACK  0
#define INFLIGHT_STATE_WAIT_SEND 1

// Inflight packet structure
typedef struct inflight_packet {
    struct inflight_packet* next;
    uint16_t id;                   // Packet ID
    struct ETCP_LINK* last_link;   // Last sent link
    uint16_t last_timestamp;       // Last send timestamp
    uint8_t send_count;            // Number of sends
    uint8_t retrans_req_count;     // Number of retrans requests
    uint8_t state;                 // WAIT_ACK or WAIT_SEND
    uint8_t need_retrans;          // Flag for forced retrans
    uint8_t* data;                 // Packet data
    uint16_t data_len;             // Data length
    uint16_t payload_len;          // Payload length for window
} inflight_packet_t;

// RX packet for assembly linked list
typedef struct rx_packet {
    struct rx_packet* next;
    uint16_t id;
    uint16_t timestamp;
    uint8_t* data;                 // Assembled data (payload only)
    uint16_t data_len;
} rx_packet_t;

// ETCP connection structure (refactored)
struct ETCP_CONN {
    struct ETCP_CONN* next;
    int mtu;

    struct UTUN_INSTANCE* instance;

    // Links (channels) - linked list
    struct ETCP_LINK* links;
    
    // Crypto and state
    struct secure_channel crypto_ctx;
    
    // Peer info
    uint64_t peer_node_id;         // Peer node ID

    // Queues
    struct ll_queue* input_queue;  // Incoming packets to send
    struct ll_queue* output_queue; // Assembled outgoing packets

    // Inflight lists (two lists as per spec)
    inflight_packet_t* wait_ack_list;   // Waiting for ACK
    inflight_packet_t* wait_send_list;  // Waiting for send (retrans)

    // RX assembly list
    rx_packet_t* rx_list;          // Sorted by ID for gap detection

    // IDs and state
    uint16_t next_tx_id;           // Next TX ID
    uint16_t last_rx_id;           // Last received ID
    uint16_t last_delivered_id;    // Last delivered to output_queue

    // Pending ACKs and retrans
    uint16_t pending_ack_ids[32];
    uint16_t pending_ack_ts[32];   // Timestamps for ACKs
    uint8_t pending_ack_count;
    uint16_t pending_retrans_ids[32];
    uint8_t pending_retrans_count;

    // Metrics (RTT, jitter, etc.)
    uint16_t rtt_last;
    uint16_t rtt_avg_10;
    uint16_t rtt_avg_100;
    uint16_t jitter;
    uint32_t bytes_sent_total;
    uint32_t bytes_received_total;
    uint32_t retransmissions_count;

    // Window and inflight management
    uint32_t unacked_bytes;        // Current inflight bytes
    uint32_t window_size;          // Receive window
    uint32_t optimal_inflight;     // Sum over links

    // Timers
    void* retrans_timer;           // Retrans check timer
    void* ack_timer;               // ACK send timer

    // Bandwidth measurement state
    uint8_t burst_in_progress;     // Burst transmission flag
    uint16_t burst_start_id;       // Start ID for burst
    // ... (add more for meas_ts, meas_resp)

    // Statistics counters
    uint32_t ack_packets_count;      // Count of ACK packets received
    uint16_t last_rx_ack_id;         // Last ACK ID received
    uint16_t rtt_history[10];        // RTT history for jitter calculation (RTT_HISTORY_SIZE=10)
    uint8_t rtt_history_idx;         // Current index in RTT history
    uint32_t total_packets_sent;     // Total packets sent counter

    // Flags
    uint8_t wait_timeout_active;   // In wait timeout state
};

// Functions
struct ETCP_CONN* etcp_connection_create(struct UTUN_INSTANCE* instance);
void etcp_connection_close(struct ETCP_CONN* etcp);
void etcp_conn_reset(struct ETCP_CONN* etcp);

// Input from etcp_connections (decrypted packet)
void etcp_conn_input(struct ETCP_DGRAM* pkt);

// Request next packet for load balancer
struct ETCP_DGRAM* etcp_request_pkt(struct ETCP_CONN* etcp);

// Get stats
void etcp_get_stats(struct ETCP_CONN* etcp, size_t* packets_sent, size_t* packets_recv,
                    size_t* pool_allocs, size_t* pool_reuse);

uint16_t get_current_timestamp(void);

#ifdef __cplusplus
}
#endif

#endif // ETCP_H