#!/usr/bin/env python3
"""
Generate systemd service file for hermes-service.
Usage: python3 install-service.py [--user USER] [--group GROUP] [--install]
"""

import os
import sys
import argparse
import shutil

# Resolve paths dynamically
SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
SERVICE_MODULE = SCRIPT_DIR
MAIN_PY = os.path.join(SERVICE_MODULE, "main.py")

# Auto-detect Python venv if it exists
VENV_PYTHON = os.path.join(SERVICE_MODULE, ".venv", "bin", "python3")
SYSTEM_PYTHON = shutil.which("python3")

if os.path.exists(VENV_PYTHON):
    PYTHON_EXEC = VENV_PYTHON
else:
    PYTHON_EXEC = SYSTEM_PYTHON or "/usr/bin/python3"

PORT = 9121
USER = "hermesai"
GROUP = "hermesai"

SERVICE_CONTENT_TEMPLATE = """[Unit]
Description=Hermes Service - AI Agent HTTP API
After=network.target

[Service]
Type=simple
User={user}
Group={group}
WorkingDirectory={workdir}
ExecStart={python} {main_py}
Restart=always
RestartSec=5
StandardOutput=journal
StandardError=journal

# Environment
Environment="HOME={home}"
Environment="PYTHONUNBUFFERED=1"

# Security hardening
NoNewPrivileges=true
ProtectSystem=strict
ProtectHome=read-only
ReadWritePaths={users_path} {data_path}

[Install]
WantedBy=multi-user.target
"""


def generate(args):
    parser = argparse.ArgumentParser(description="Generate hermes-service systemd service")
    parser.add_argument("--user", default=USER, help="Run as this user (default: hermesai)")
    parser.add_argument("--group", default=GROUP, help="Run as this group (default: hermesai)")
    parser.add_argument("--port", type=int, default=PORT, help="Service port (default: 9121)")
    parser.add_argument("--install", action="store_true", help="Copy to /etc/systemd/system and enable")
    parser.add_argument("--output", default=None, help="Output file path (default: ./hermes-service.service)")
    args = parser.parse_args()

    return args


def main():
    args = generate(sys.argv[1:])

    user = args.user
    group = args.group
    port = args.port
    install = args.install
    service_name = "hermes-service"
    output = args.output or os.path.join(SERVICE_MODULE, f"{service_name}.service")

    # Validate
    if not os.path.exists(MAIN_PY):
        print(f"ERROR: main.py not found at {MAIN_PY}")
        sys.exit(1)

    # Generate service content
    content = SERVICE_CONTENT_TEMPLATE.format(
        user=user,
        group=group,
        workdir=SERVICE_MODULE,
        python=PYTHON_EXEC,
        main_py=MAIN_PY,
        home=os.environ.get('HOME', '/home/hermesai'),
        users_path=os.path.join(os.environ.get('HOME', '/home/hermesai'), 'users'),
        data_path=os.path.join(SERVICE_MODULE, 'data'),
    )

    # Write service file
    with open(output, "w") as f:
        f.write(content)

    print(f"Service file written to: {output}")
    print(f"  Python:     {PYTHON_EXEC}")
    print(f"  WorkingDir: {SERVICE_MODULE}")
    print(f"  User/Group: {user}/{group}")
    print(f"  Port:       {port}")
    print(f"  Main:       {MAIN_PY}")
    print()

    if install:
        dest = f"/etc/systemd/system/{service_name}.service"
        if os.geteuid() != 0:
            print(f"ERROR: --install requires root privileges. Run with sudo.")
            sys.exit(1)

        shutil.copy2(output, dest)
        os.chmod(dest, 0o644)
        print(f"Installed to: {dest}")
        print()
        print("Next steps:")
        print(f"  sudo systemctl daemon-reload")
        print(f"  sudo systemctl enable {service_name}")
        print(f"  sudo systemctl start {service_name}")
        print(f"  sudo systemctl status {service_name}")
    else:
        print("To install and enable:")
        print(f"  sudo python3 {os.path.basename(__file__)} --install")


if __name__ == "__main__":
    main()