#!/usr/bin/env elixir

Mix.install([])

defmodule BCDTPDUTest do
  import Bitwise

  def bcd_to_binary(bcd_string, byte_length) when is_binary(bcd_string) and is_integer(byte_length) do
    try do
      # Pad with leading zeros to ensure even length
      padded = bcd_string
      |> String.pad_leading(byte_length * 2, "0")
      |> String.slice(0, byte_length * 2)
      
      # Convert each pair of digits to BCD byte
      binary = padded
      |> String.graphemes()
      |> Enum.chunk_every(2)
      |> Enum.map(fn [high, low] -> 
        (String.to_integer(high) <<< 4) ||| String.to_integer(low)
      end)
      |> :binary.list_to_bin()
      
      {:ok, binary}
    rescue
      _ -> {:error, :invalid_bcd}
    end
  end

  def test_bcd_tpdu do
    IO.puts("🔍 Testing BCD TPDU Processing")
    
    # Your TPDU pattern from configuration
    tpdu_pattern = "6000782000"
    expected_bytes = 5
    
    IO.puts("TPDU Pattern: #{tpdu_pattern}")
    IO.puts("Expected bytes: #{expected_bytes}")
    
    # Convert BCD pattern to binary
    case bcd_to_binary(tpdu_pattern, expected_bytes) do
      {:ok, pattern_binary} ->
        pattern_hex = Base.encode16(pattern_binary)
        IO.puts("✅ BCD pattern converted to binary successfully")
        IO.puts("   Pattern binary (hex): #{pattern_hex}")
        IO.puts("   Pattern binary size: #{byte_size(pattern_binary)} bytes")
        
        # Your actual packet data
        packet_hex = "60007820000400703C078000C282051648549806007367400000000000000050000000220912500917310500510000078200313233343536373131323334353637383930313233343500817B226F72696744617465223A223230323530393137222C226F7269674D7469223A2230323030222C226F7269675472616365223A22303030303232222C226F72696754696D65223A22303931323530227D3738340028950500800400009F1E0832333733303030319F100706011203A0A80200063030303030311234567812345678"
        
        case Base.decode16(packet_hex) do
          {:ok, packet_data} ->
            IO.puts("\n📦 Processing actual packet:")
            IO.puts("   Total packet size: #{byte_size(packet_data)} bytes")
            
            # Extract first 5 bytes (TPDU)
            <<tpdu_data::binary-size(5), remaining_data::binary>> = packet_data
            tpdu_hex = Base.encode16(tpdu_data)
            
            IO.puts("   Extracted TPDU (hex): #{tpdu_hex}")
            IO.puts("   Pattern expected (hex): #{pattern_hex}")
            
            if tpdu_data == pattern_binary do
              IO.puts("✅ TPDU matches BCD pattern perfectly!")
              IO.puts("   Remaining ISO data: #{byte_size(remaining_data)} bytes")
              
              # Show first part of ISO data
              iso_start = Base.encode16(binary_part(remaining_data, 0, min(10, byte_size(remaining_data))))
              IO.puts("   ISO data starts with: #{iso_start}")
            else
              IO.puts("❌ TPDU does not match pattern")
              IO.puts("   This suggests the data might not be BCD encoded")
            end
            
          :error ->
            IO.puts("❌ Failed to decode packet hex")
        end
        
      {:error, reason} ->
        IO.puts("❌ Failed to convert BCD pattern: #{inspect(reason)}")
    end
  end
end

BCDTPDUTest.test_bcd_tpdu()