reaper-control/mcp/tests/test_sysex_loopback.py

"""
Phase 0: SysEx Loopback Validation Test.

Tests whether MIDI SysEx messages can travel through the Windows MIDI Services
loopback port "FL_MCP" from the MCP server to the FL Studio controller script.

Usage:
    python test_sysex_loopback.py

Requires:
    - FL Studio running with FL_MCP controller script loaded
    - Windows MIDI Services loopback ports "FL_MCP 0" (input) and "FL_MCP 1" (output)
"""

from __future__ import annotations

import sys
import time

try:
    import mido
except ImportError:
    print("ERROR: mido not installed. Run: pip install mido")
    sys.exit(1)


def send_sysex_raw(output, data):
    """Send raw SysEx bytes via mido."""
    msg = mido.Message("sysex", data=bytes(data))
    output.send(msg)


def test_simple_sysex():
    """Test 1: Send F0 7D 48 69 F7 ("Hi") and expect it back."""
    print("\n=== Test 1: Simple SysEx Echo ===")
    output_name = None
    input_name = None

    for name in mido.get_output_names():
        if "FL_MCP" in name and "1" in name:
            output_name = name
            break
    for name in mido.get_input_names():
        if "FL_MCP" in name and "0" in name:
            input_name = name
            break

    if not output_name:
        print("FAIL: FL_MCP output port (FL_MCP 1) not found")
        print("Available outputs:", mido.get_output_names())
        return False
    if not input_name:
        print("FAIL: FL_MCP input port (FL_MCP 0) not found")
        print("Available inputs:", mido.get_input_names())
        return False

    print(f"Output: {output_name}")
    print(f"Input:  {input_name}")

    try:
        output = mido.open_output(output_name)
        input_port = mido.open_input(input_name)
    except Exception as e:
        print(f"FAIL: Cannot open ports: {e}")
        return False

    # Send "Hi" ping: F0 7D 48 69 F7
    # (0x48='H', 0x69='i')
    ping_data = [0xF0, 0x7D, 0x48, 0x69, 0xF7]
    print(f"Sending: {' '.join(f'{b:02X}' for b in ping_data)}")
    send_sysex_raw(output, ping_data[1:-1])  # mido adds F0/F7

    print("Waiting 5s for echo...")
    timeout = 5.0
    start = time.time()
    received = None
    while time.time() - start < timeout:
        msg = input_port.receive(timeout=0.1)
        if msg and msg.type == "sysex":
            received = list(msg.bytes())
            break

    output.close()
    input_port.close()

    if received:
        print(f"Received: {' '.join(f'{b:02X}' for b in received)}")
        if received[0] == 0xF0 and received[-1] == 0xF7 and received[1] == 0x7D:
            print("PASS: Simple SysEx loopback works!")
            return True
        print(f"UNKNOWN: Received but unexpected bytes: {received}")
        return False
    else:
        print("FAIL: No message received within timeout")
        return False


def test_json_command():
    """Test 2: Send a proper JSON command via nibble encoding."""
    print("\n=== Test 2: JSON Command SysEx ===")
    import json

    output_name = None
    input_name = None
    for name in mido.get_output_names():
        if "FL_MCP" in name and "1" in name:
            output_name = name
            break
    for name in mido.get_input_names():
        if "FL_MCP" in name and "0" in name:
            input_name = name
            break

    if not output_name or not input_name:
        print("SKIP: FL_MCP ports not available for JSON test")
        return False

    try:
        output = mido.open_output(output_name)
        input_port = mido.open_input(input_name)
    except Exception as e:
        print(f"SKIP: Cannot open ports: {e}")
        return False

    # Encode ping command: {"cmd":"ping","params":{"ts":1}}
    payload = json.dumps({"cmd": "ping", "params": {"ts": 1}}).encode("utf-8")
    print(f"JSON payload: {payload}")

    # Nibble encode
    nibbles = []
    for byte in payload:
        nibbles.append((byte >> 4) & 0x0F)
        nibbles.append(byte & 0x0F)

    sysex_data = [0xF0, 0x7D] + nibbles + [0xF7]
    print(f"SysEx: {' '.join(f'{b:02X}' for b in sysex_data)}")

    send_sysex_raw(output, sysex_data[1:-1])
    print("Waiting 5s for response...")

    timeout = 5.0
    start = time.time()
    received = None
    while time.time() - start < timeout:
        msg = input_port.receive(timeout=0.1)
        if msg and msg.type == "sysex":
            received = list(msg.bytes())
            break

    output.close()
    input_port.close()

    if received:
        print(f"Received: {' '.join(f'{b:02X}' for b in received)}")
        # Decode nibbles
        if received[1] == 0x7D:
            nibble_data = received[2:-1]
            result = bytearray()
            for i in range(0, len(nibble_data), 2):
                if i + 1 < len(nibble_data):
                    result.append(((nibble_data[i] & 0x0F) << 4) | (nibble_data[i + 1] & 0x0F))
            decoded = result.decode("utf-8")
            print(f"Decoded JSON: {decoded}")
            print("PASS: JSON command roundtrip works!")
            return True
    else:
        print("FAIL: No response within timeout")
        return False


def list_ports():
    """List all available MIDI ports."""
    print("\n=== Available MIDI Ports ===")
    print("Inputs:")
    for p in mido.get_input_names():
        print(f"  {p}")
    print("Outputs:")
    for p in mido.get_output_names():
        print(f"  {p}")


if __name__ == "__main__":
    print("FL Studio MCP — SysEx Loopback Validation")
    print("=========================================")
    list_ports()

    test1 = test_simple_sysex()
    test2 = test_json_command()

    print("\n=== Summary ===")
    print(f"Simple SysEx:  {'PASS' if test1 else 'FAIL'}")
    print(f"JSON Command:  {'PASS' if test2 else 'FAIL'}")

    if test1 and test2:
        print("\nSysEx loopback is functional. Phase 1-4 can proceed.")
        sys.exit(0)
    else:
        print("\nSysEx loopback FAILED. Phase 1-4 ABORTED — pivot required.")
        sys.exit(1)