#!/usr/bin/env elixir

# Direct test to the MPGS simulator to see what it expects and sends back
defmodule SimulatorTest do
  require Logger

  def test_raw_iso8583 do
    Logger.info("Testing raw ISO8583 message (no YSP framing)")
    host = "demo.ctrmv.com"
    port = 4444
    timeout = 5000

    # Simple 0200 (sale) request in raw ISO8583
    message = create_simple_0200()
    
    case :gen_tcp.connect(String.to_charlist(host), port, [:binary, active: false], timeout) do
      {:ok, socket} ->
        IO.puts("✅ Connected to #{host}:#{port}")
        
        # Send raw ISO8583
        case :gen_tcp.send(socket, message) do
          :ok ->
            IO.puts("✅ Sent #{byte_size(message)} bytes:")
            IO.puts("   Hex: #{Base.encode16(message)}")
            
            # Try to receive response
            case :gen_tcp.recv(socket, 0, timeout) do
              {:ok, response} ->
                IO.puts("✅ Received response (#{byte_size(response)} bytes):")
                IO.puts("   Hex: #{Base.encode16(response)}")
                IO.puts("\nResponse analysis:")
                analyze_response(response)
              
              {:error, :timeout} ->
                IO.puts("❌ TIMEOUT - Simulator did not respond within #{timeout}ms")
              
              {:error, reason} ->
                IO.puts("❌ ERROR receiving: #{inspect(reason)}")
            end
            
            :gen_tcp.close(socket)
          
          {:error, reason} ->
            IO.puts("❌ ERROR sending: #{inspect(reason)}")
            :gen_tcp.close(socket)
        end
      
      {:error, reason} ->
        IO.puts("❌ Connection failed to #{host}:#{port}: #{inspect(reason)}")
    end
  end

  defp create_simple_0200 do
    # Very simple raw ISO8583 0200 (sale)
    # MTI: 0200 (2 bytes)
    # Bitmap: 8 bytes (fields 2,3,4,11,12,13,14,41)
    # Fields:
    # - Field 2 (PAN): LLVAR 16 bytes
    # - Field 3 (Processing Code): 6 bytes
    # - Field 4 (Amount): 12 bytes (BCD)
    # - Field 11 (STAN): 6 bytes (BCD)
    # - Field 12 (Time): 6 bytes (BCD)
    # - Field 13 (Date): 4 bytes (BCD)
    # - Field 14 (Expiry): 4 bytes (BCD)
    # - Field 41 (Terminal ID): 8 bytes

    mti = "0200"
    
    # Bitmap for fields 2,3,4,11,12,13,14,41
    # Binary: 11110000 00000000 00000000 00001000 = 0xF0000008
    bitmap = <<0xF0, 0x00, 0x00, 0x08>>
    
    # Field 2 - PAN (16 bytes)
    field2 = "5559426552868466"
    field2_encoded = <<String.length(field2) :: 8>> <> field2
    
    # Field 3 - Processing code (6 bytes)
    field3 = "000000"
    
    # Field 4 - Amount (12 bytes BCD)
    field4 = "000000020000"
    
    # Field 11 - STAN (6 bytes BCD)
    field11 = "000063"
    
    # Field 12 - Time (6 bytes BCD)
    field12 = "045238"
    
    # Field 13 - Date (4 bytes BCD)
    field13 = "0605"
    
    # Field 14 - Expiry (4 bytes BCD)
    field14 = "2908"
    
    # Field 41 - Terminal ID (8 bytes)
    field41 = "12345671"
    
    message = mti <> bitmap <> field2_encoded <> field3 <> field4 <> field11 <> field12 <> field13 <> field14 <> field41
    
    IO.puts("Raw ISO8583 message created: #{byte_size(message)} bytes")
    message
  end

  defp analyze_response(data) when byte_size(data) >= 4 do
    # Try to detect response format
    case data do
      <<0x03, 0x25, _::binary>> ->
        IO.puts("   Format: YSP-framed (starts with BCD length 0325)")
      
      <<"0410", _::binary>> ->
        IO.puts("   Format: ISO8583 0410 (sale response)")
      
      <<"0430", _::binary>> ->
        IO.puts("   Format: ISO8583 0430 (reversal response)")
      
      _ ->
        # Try to decode as ISO8583
        case decode_iso_mti(data) do
          {:ok, mti} ->
            IO.puts("   Format: ISO8583 with MTI: #{mti}")
          
          :error ->
            IO.puts("   Format: Unknown - raw data")
            IO.inspect(data, limit: 50)
        end
    end
  end

  defp analyze_response(data) do
    IO.puts("   Response too short: #{byte_size(data)} bytes")
  end

  defp decode_iso_mti(<<mti1, mti2, _::binary>>) do
    {:ok, <<mti1, mti2>>}
  rescue
    _ -> :error
  end
end

# Run the test
SimulatorTest.test_raw_iso8583()