#ifndef NFC_PROTOCOL_H
#define NFC_PROTOCOL_H

#include <Arduino.h>

// Communication protocol definitions
#define MAX_NFC_DATA_SIZE 256
#define ESPNOW_CHANNEL 1
#define PAIRING_TIMEOUT_MS 30000
#define HEARTBEAT_INTERVAL_MS 1000
#define MAX_RETRY_ATTEMPTS 3

// Message types
enum MessageType {
    MSG_PAIRING_REQUEST = 0x01,
    MSG_PAIRING_RESPONSE = 0x02,
    MSG_NFC_DATA = 0x03,
    MSG_HEARTBEAT = 0x04,
    MSG_ERROR = 0x05,
    MSG_ACK = 0x06
};

// NFC data structure
struct NFCData {
    uint8_t uid[10];          // NFC UID (max 10 bytes)
    uint8_t uid_length;       // Actual UID length
    uint8_t sak;              // Select Acknowledge
    uint8_t atqa[2];          // Answer to Request Type A
    uint8_t raw_data[MAX_NFC_DATA_SIZE];  // Raw NFC data
    uint16_t data_length;     // Actual data length
    uint32_t timestamp;       // Capture timestamp
    uint8_t tag_type;         // NFC tag type
};

// Communication message structure
struct CommMessage {
    uint8_t type;             // Message type
    uint8_t sequence;         // Sequence number
    uint16_t payload_size;    // Payload size
    union {
        NFCData nfc_data;
        uint8_t raw_payload[sizeof(NFCData)];
    };
    uint16_t checksum;        // Message integrity check
};

// Device roles
enum DeviceRole {
    ROLE_LISTENER = 1,
    ROLE_EMULATOR = 2
};

// Status codes
enum StatusCode {
    STATUS_OK = 0,
    STATUS_ERROR = 1,
    STATUS_TIMEOUT = 2,
    STATUS_INVALID_DATA = 3,
    STATUS_NOT_PAIRED = 4
};

// Function prototypes
uint16_t calculateChecksum(const uint8_t* data, size_t length);
bool validateMessage(const CommMessage* msg);
void printNFCData(const NFCData* data);

#endif // NFC_PROTOCOL_H