#!/usr/bin/env python3
"""
setup.py — First-time setup for Bastebin.

What this does:
  1. Checks that a supported Python version is available.
  2. Creates a virtual environment at .venv/ (if absent).
  3. Installs all dependencies from requirements.txt into the venv.
  4. Initialises the SQLite database (creates the pastes table).
  5. Warns if config.json contains the default secret key.

Usage:
    python setup.py
"""

import os
import subprocess
import sys

MIN_PYTHON = (3, 11)
BASE_DIR   = os.path.dirname(os.path.abspath(__file__))
VENV_DIR   = os.path.join(BASE_DIR, '.venv')
REQS_FILE  = os.path.join(BASE_DIR, 'requirements.txt')
CONFIG     = os.path.join(BASE_DIR, 'config.json')


# ── Helpers ───────────────────────────────────────────────────────────────────

def _step(msg: str) -> None:
    print(f'\n  {msg}')


def _ok(msg: str = 'done') -> None:
    print(f'    ✓ {msg}')


def _warn(msg: str) -> None:
    print(f'    ⚠  {msg}')


def _fail(msg: str) -> None:
    print(f'\n  ✗ {msg}')
    sys.exit(1)


def _venv_python() -> str:
    return os.path.join(VENV_DIR, 'bin', 'python')


def _venv_pip() -> str:
    return os.path.join(VENV_DIR, 'bin', 'pip')


def _run(*args: str, capture: bool = False) -> subprocess.CompletedProcess:
    return subprocess.run(
        args,
        check=True,
        capture_output=capture,
        text=True,
    )


# ── Steps ─────────────────────────────────────────────────────────────────────

def check_python() -> None:
    _step('Checking Python version...')
    if sys.version_info < MIN_PYTHON:
        _fail(
            f'Python {MIN_PYTHON[0]}.{MIN_PYTHON[1]}+ is required '
            f'(found {sys.version.split()[0]}).'
        )
    _ok(f'Python {sys.version.split()[0]}')


def create_venv() -> None:
    _step('Setting up virtual environment...')
    if os.path.isfile(_venv_python()):
        _ok('.venv already exists — skipping creation')
        return
    _run(sys.executable, '-m', 'venv', VENV_DIR)
    _ok(f'Created {VENV_DIR}')


def install_dependencies() -> None:
    _step('Installing dependencies...')
    if not os.path.isfile(REQS_FILE):
        _fail(f'requirements.txt not found at {REQS_FILE}')
    _run(_venv_pip(), 'install', '--quiet', '--upgrade', 'pip')
    _run(_venv_pip(), 'install', '--quiet', '-r', REQS_FILE)
    _ok('All packages installed')


def initialise_database() -> None:
    _step('Initialising database...')
    # Import app inside the venv's Python so the correct packages are used.
    result = _run(
        _venv_python(),
        '-c',
        'import sys; sys.path.insert(0, "."); from app import init_db; init_db(); print("ok")',
        capture=True,
    )
    if 'ok' in result.stdout:
        _ok('Database ready')
    else:
        _warn('Database initialisation produced unexpected output — check manually.')


def check_secret_key() -> None:
    _step('Checking configuration...')
    try:
        import json
        with open(CONFIG, encoding='utf-8') as f:
            cfg = json.load(f)
        key = cfg.get('server', {}).get('secret_key', '')
        if key in ('', 'change-this-to-a-long-random-secret', 'change-me'):
            _warn(
                'config.json still has the default secret_key. '
                'Set a long, random value before deploying to production.'
            )
        else:
            _ok('Secret key looks good')
    except (FileNotFoundError, Exception) as e:
        _warn(f'Could not read config.json: {e}')


# ── Entry point ───────────────────────────────────────────────────────────────

def main() -> None:
    print('─' * 50)
    print('  Bastebin setup')
    print('─' * 50)

    check_python()
    create_venv()
    install_dependencies()
    initialise_database()
    check_secret_key()

    print()
    print('─' * 50)
    print('  Setup complete.')
    print()
    print('  Start the server:')
    print('    python production.py start')
    print()
    print('  Stop the server:')
    print('    python production.py stop')
    print('─' * 50)
    print()


if __name__ == '__main__':
    main()