#include "nfc_protocol.h"

uint16_t calculateChecksum(const uint8_t* data, size_t length) {
    uint16_t checksum = 0;
    for (size_t i = 0; i < length; i++) {
        checksum += data[i];
    }
    return checksum;
}

bool validateMessage(const CommMessage* msg) {
    if (msg == nullptr) return false;
    
    // Calculate checksum excluding the checksum field itself
    size_t data_size = sizeof(CommMessage) - sizeof(msg->checksum);
    uint16_t calculated_checksum = calculateChecksum((const uint8_t*)msg, data_size);
    
    return calculated_checksum == msg->checksum;
}

void printNFCData(const NFCData* data) {
    if (data == nullptr) return;
    
    Serial.println("=== NFC Data ===");
    Serial.print("UID: ");
    for (int i = 0; i < data->uid_length; i++) {
        if (data->uid[i] < 0x10) Serial.print("0");
        Serial.print(data->uid[i], HEX);
        if (i < data->uid_length - 1) Serial.print(" ");
    }
    Serial.println();
    
    Serial.print("UID Length: ");
    Serial.println(data->uid_length);
    
    Serial.print("SAK: 0x");
    if (data->sak < 0x10) Serial.print("0");
    Serial.println(data->sak, HEX);
    
    Serial.print("ATQA: 0x");
    if (data->atqa[0] < 0x10) Serial.print("0");
    Serial.print(data->atqa[0], HEX);
    Serial.print(" 0x");
    if (data->atqa[1] < 0x10) Serial.print("0");
    Serial.println(data->atqa[1], HEX);
    
    Serial.print("Tag Type: ");
    Serial.println(data->tag_type);
    
    Serial.print("Data Length: ");
    Serial.println(data->data_length);
    
    Serial.print("Timestamp: ");
    Serial.println(data->timestamp);
    
    if (data->data_length > 0) {
        Serial.print("Raw Data: ");
        for (int i = 0; i < data->data_length && i < 32; i++) {
            if (data->raw_data[i] < 0x10) Serial.print("0");
            Serial.print(data->raw_data[i], HEX);
            Serial.print(" ");
        }
        if (data->data_length > 32) {
            Serial.print("... (truncated)");
        }
        Serial.println();
    }
    Serial.println("================");
}