import { ReaderCommand } from '../types';
import { calculateCRC16, getCRCBytes } from '../utils/crc16';

export class RfidProtocol {
  /**
   * Constructs a command frame: [Len, Adr, Cmd, Data..., CRC_LSB, CRC_MSB]
   */
  static buildCommand(address: number, cmd: ReaderCommand, data: number[] = []): Uint8Array {
    const len = data.length + 4; // Len byte itself is not included in length value logic usually, but manual says: "Len equals length of Data[] plus 4"
    
    // Frame except CRC
    const frameHeader = [len, address, cmd, ...data];
    
    // Calculate CRC on [Len, Adr, Cmd, Data...]
    const crc = calculateCRC16(new Uint8Array(frameHeader));
    const [lsb, msb] = getCRCBytes(crc);
    
    return new Uint8Array([...frameHeader, lsb, msb]);
  }

  /**
   * Helper to interpret status codes from the reader
   */
  static getStatusDescription(status: number): string {
    switch (status) {
      case 0x00: return "Success";
      case 0x01: return "Return before Inventory finished";
      case 0x02: return "Inventory Timeout";
      case 0x03: return "More data follows";
      case 0x04: return "Reader memory full";
      case 0x05: return "Access Password Error";
      case 0x09: return "Kill Tag Error";
      case 0x0A: return "Kill Password cannot be zero";
      case 0x0B: return "Tag does not support command";
      case 0x0C: return "Access Password cannot be zero (Locked)";
      case 0x0D: return "Tag is protected, cannot set again";
      case 0x0E: return "Tag is unprotected, no need to reset";
      case 0x10: return "Locked bytes, write fail";
      case 0x11: return "Cannot lock tag";
      case 0x12: return "Already locked, cannot lock again";
      case 0x13: return "Save Parameter Failed";
      case 0x14: return "Cannot adjust power";
      case 0x15: return "Return before Inventory finished (6B)";
      case 0x16: return "Inventory Timeout (6B)";
      case 0x17: return "More data follows (6B)";
      case 0x18: return "Reader memory full (6B)";
      case 0x19: return "Not Support Command or Access Password Error";
      case 0xF9: return "Command Execution Error";
      case 0xFA: return "Poor Communication / Tag Inoperable";
      case 0xFB: return "No Tag Operable";
      case 0xFC: return "Tag Returned Error Code"; // Check data for specific code
      case 0xFD: return "Command Length Wrong";
      case 0xFE: return "Illegal Command / CRC Error";
      case 0xFF: return "Parameter Error";
      case 0x30: return "Communication Error";
      default: return `Unknown Status (0x${status.toString(16).toUpperCase().padStart(2, '0')})`;
    }
  }

  /**
   * Helper to interpret EPC C1G2 Tag specific error codes (Status 0xFC)
   */
  static getTagErrorDescription(errorCode: number): string {
    switch (errorCode) {
      case 0x00: return "Other error";
      case 0x03: return "Memory overrun or EPC length not supported";
      case 0x04: return "Memory locked";
      case 0x0B: return "Insufficient power";
      case 0x0F: return "Non-specific error";
      default: return `Unknown Tag Error (0x${errorCode.toString(16).toUpperCase().padStart(2, '0')})`;
    }
  }
}