import os
from pathlib import Path

from flask import Flask, redirect, send_from_directory
from flask_cors import CORS

from app.config import Config
from app.extensions import db, bcrypt, migrate


def create_app(config_class=Config):
    # Check if static frontend build exists (Docker production mode)
    static_dir = Path(__file__).resolve().parent.parent / 'static'
    if static_dir.exists():
        app = Flask(__name__, static_folder=str(static_dir), static_url_path='')
    else:
        app = Flask(__name__)

    app.config.from_object(config_class)

    # Ensure data directories exist
    Path(app.config['UPLOAD_PATH']).mkdir(parents=True, exist_ok=True)
    db_dir = Path(app.config['SQLALCHEMY_DATABASE_URI'].replace('sqlite:///', '')).parent
    db_dir.mkdir(parents=True, exist_ok=True)

    # Initialize extensions
    db.init_app(app)
    bcrypt.init_app(app)
    migrate.init_app(app, db)

    # CORS
    CORS(app, resources={r'/api/*': {'origins': app.config['FRONTEND_URL']}},
         supports_credentials=True)

    # Register blueprints
    from app.api import api_bp
    app.register_blueprint(api_bp)

    # Well-known URLs for CalDAV/CardDAV auto-discovery (iOS, DAVx5, etc.)
    @app.route('/.well-known/caldav')
    def wellknown_caldav():
        return redirect('/dav/', code=301)

    @app.route('/.well-known/carddav')
    def wellknown_carddav():
        return redirect('/dav/', code=301)

    # iCal export (public, no auth)
    @app.route('/ical/<token>')
    def ical_export_route(token):
        from app.api.calendar import ical_export as _ical_export
        return _ical_export(token)

    # Serve frontend SPA for all non-API routes (production/Docker)
    if static_dir.exists():
        @app.route('/')
        def serve_index():
            return send_from_directory(str(static_dir), 'index.html')

        @app.errorhandler(404)
        def serve_spa(e):
            return send_from_directory(str(static_dir), 'index.html')

    # Create tables
    with app.app_context():
        from app import models  # noqa: F401
        db.create_all()

        # Enable WAL mode for SQLite
        with db.engine.connect() as conn:
            conn.execute(db.text('PRAGMA journal_mode=WAL'))
            conn.commit()

    # Start backup scheduler (only in main process, not reloader)
    if not app.debug or os.environ.get('WERKZEUG_RUN_MAIN') == 'true':
        from app.services.backup_scheduler import start_backup_scheduler
        start_backup_scheduler(app)

    return app