#!/usr/bin/env python3
"""
SetupManager — first-run wizard backend for PIC.

Handles validation, locking, and atomic completion of the initial setup
wizard.  Called by api/routes/setup.py.
"""

import fcntl
import logging
import os
import re
from typing import Any, Dict, List

logger = logging.getLogger(__name__)

# Top 30 representative IANA time zones shown in the wizard
AVAILABLE_TIMEZONES = [
    'UTC',
    'America/New_York',
    'America/Chicago',
    'America/Denver',
    'America/Los_Angeles',
    'America/Anchorage',
    'America/Honolulu',
    'America/Sao_Paulo',
    'America/Argentina/Buenos_Aires',
    'America/Toronto',
    'America/Vancouver',
    'America/Mexico_City',
    'Europe/London',
    'Europe/Paris',
    'Europe/Berlin',
    'Europe/Madrid',
    'Europe/Rome',
    'Europe/Amsterdam',
    'Europe/Moscow',
    'Europe/Istanbul',
    'Africa/Cairo',
    'Africa/Johannesburg',
    'Asia/Dubai',
    'Asia/Kolkata',
    'Asia/Bangkok',
    'Asia/Shanghai',
    'Asia/Tokyo',
    'Asia/Seoul',
    'Australia/Sydney',
    'Pacific/Auckland',
]

AVAILABLE_SERVICES = [
    'email',
    'calendar',
    'files',
    'wireguard',
]

VALID_DOMAIN_MODES = {'pic_ngo', 'cloudflare', 'duckdns', 'http01', 'lan'}

CELL_NAME_RE = re.compile(r'^[a-z][a-z0-9-]{1,30}$')


class SetupManager:
    """Manages the first-run setup wizard state and completion."""

    def __init__(self, config_manager, auth_manager):
        self.config_manager = config_manager
        self.auth_manager = auth_manager

    # ── state helpers ─────────────────────────────────────────────────────

    def is_setup_complete(self) -> bool:
        """Return True if setup has already been completed."""
        return bool(self.config_manager.get_identity().get('setup_complete', False))

    def get_setup_status(self) -> Dict[str, Any]:
        """Return current setup status and wizard metadata."""
        return {
            'complete': self.is_setup_complete(),
            'available_services': AVAILABLE_SERVICES,
            'available_timezones': AVAILABLE_TIMEZONES,
        }

    # ── validation ────────────────────────────────────────────────────────

    def validate_cell_name(self, name: str) -> List[str]:
        """Validate a proposed cell name.  Returns a list of error strings."""
        errors: List[str] = []
        if not name:
            errors.append('Cell name is required.')
            return errors
        if not CELL_NAME_RE.match(name):
            errors.append(
                'Cell name must start with a lowercase letter, be 2–31 characters, '
                'and contain only lowercase letters, digits, and hyphens.'
            )
        if name.startswith('-') or name.endswith('-'):
            errors.append('Cell name must not start or end with a hyphen.')
        return errors

    def validate_password(self, password: str) -> List[str]:
        """Validate admin password strength.  Returns a list of error strings."""
        errors: List[str] = []
        if not password:
            errors.append('Password is required.')
            return errors
        if len(password) < 12:
            errors.append('Password must be at least 12 characters long.')
        if not re.search(r'[A-Z]', password):
            errors.append('Password must contain at least one uppercase letter.')
        if not re.search(r'[a-z]', password):
            errors.append('Password must contain at least one lowercase letter.')
        if not re.search(r'\d', password):
            errors.append('Password must contain at least one digit.')
        return errors

    # ── main completion ───────────────────────────────────────────────────

    def complete_setup(self, payload: Dict[str, Any]) -> Dict[str, Any]:
        """Run all validation, then atomically complete the setup wizard.

        Returns ``{'success': True, 'redirect': '/login'}`` on success or
        ``{'success': False, 'errors': [...]}`` on any failure.
        """
        errors: List[str] = []

        # ── validate inputs ────────────────────────────────────────────────
        cell_name = payload.get('cell_name', '')
        password = payload.get('password', '')
        domain_mode = payload.get('domain_mode', '')
        timezone = payload.get('timezone', '')
        services_enabled = payload.get('services_enabled', [])
        ddns_provider = payload.get('ddns_provider', 'none')

        errors.extend(self.validate_cell_name(cell_name))
        errors.extend(self.validate_password(password))

        if domain_mode not in VALID_DOMAIN_MODES:
            errors.append(
                f"domain_mode must be one of: {', '.join(sorted(VALID_DOMAIN_MODES))}."
            )
        if not timezone or not isinstance(timezone, str):
            errors.append('timezone is required.')
        if not isinstance(services_enabled, list):
            errors.append('services_enabled must be a list.')

        if errors:
            return {'success': False, 'errors': errors}

        # ── acquire file lock to prevent double-completion ─────────────────
        lock_path = os.path.join(
            os.environ.get('DATA_DIR', '/app/data'), 'api', '.setup.lock'
        )
        try:
            os.makedirs(os.path.dirname(lock_path), exist_ok=True)
        except OSError:
            pass

        try:
            lock_fd = open(lock_path, 'w')
            fcntl.flock(lock_fd, fcntl.LOCK_EX)
        except OSError as exc:
            logger.error(f'Could not acquire setup lock: {exc}')
            return {'success': False, 'errors': ['Setup lock could not be acquired. Try again.']}

        try:
            # Re-check inside lock
            if self.is_setup_complete():
                return {'success': False, 'errors': ['Setup has already been completed.']}

            # ── create or update admin user ────────────────────────────────
            # The installer may have bootstrapped an admin account from a
            # generated password. The wizard's job is to set the real password,
            # so update it if the account already exists.
            ok = self.auth_manager.create_user(
                username='admin',
                password=password,
                role='admin',
            )
            if not ok:
                ok = self.auth_manager.update_password('admin', password)
            if not ok:
                return {'success': False, 'errors': ['Failed to set admin password.']}

            # ── persist identity fields ────────────────────────────────────
            self.config_manager.set_identity_field('cell_name', cell_name)
            self.config_manager.set_identity_field('domain_mode', domain_mode)
            self.config_manager.set_identity_field('timezone', timezone)
            self.config_manager.set_identity_field('services_enabled', services_enabled)
            self.config_manager.set_identity_field('ddns_provider', ddns_provider)

            # NOTE: DDNS registration is deferred to Phase 3.
            # For now we just store ddns_provider in config.
            logger.info(
                'DDNS registration skipped (Phase 1). '
                'DDNS registration will happen in Phase 3. '
                f'ddns_provider={ddns_provider!r} stored in identity config.'
            )

            # ── mark setup complete (must be last) ─────────────────────────
            self.config_manager.set_identity_field('setup_complete', True)

            logger.info(f"Setup completed. cell_name={cell_name!r}, domain_mode={domain_mode!r}")
            return {'success': True, 'redirect': '/login'}

        finally:
            try:
                fcntl.flock(lock_fd, fcntl.LOCK_UN)
                lock_fd.close()
            except Exception:
                pass