import os
import logging
from logging.handlers import RotatingFileHandler
from flask import Flask
from werkzeug.middleware.proxy_fix import ProxyFix
from flask_sqlalchemy import SQLAlchemy
from flask_login import LoginManager
from flask_mail import Mail
from flask_migrate import Migrate
from flask_socketio import SocketIO
from config.config import config

db       = SQLAlchemy()
login_manager= LoginManager()
mail     = Mail()
migrate  = Migrate()
socketio = SocketIO()


def create_app(config_name=None):
    if config_name is None:
        config_name = os.environ.get('FLASK_ENV', 'production')

    app = Flask(__name__, template_folder='templates', static_folder='static')
    app.config.from_object(config.get(config_name, config['default']))

    # ── ProxyFix: trust one nginx proxy hop for real client IPs ───────────────
    app.wsgi_app = ProxyFix(app.wsgi_app, x_for=1, x_proto=1, x_host=1)

    # ── Extensions ────────────────────────────────────────────────────────────
    db.init_app(app)
    login_manager.init_app(app)
    mail.init_app(app)
    migrate.init_app(app, db)
    socketio.init_app(app, async_mode='eventlet', cors_allowed_origins='*')

    login_manager.login_view       = 'auth.login'
    login_manager.login_message    = 'Please log in to access this page.'
    login_manager.login_message_category = 'info'

    # ── Upload directory ──────────────────────────────────────────────────────
    upload_dir = app.config['UPLOAD_FOLDER']   # always absolute — set in config.py
    os.makedirs(upload_dir, exist_ok=True)

    # ── Logging ───────────────────────────────────────────────────────────────
    if not app.debug:
        os.makedirs('logs', exist_ok=True)
        file_handler = RotatingFileHandler(
            'logs/it_tickets.log', maxBytes=10_485_760, backupCount=10
        )
        file_handler.setFormatter(logging.Formatter(
            '%(asctime)s %(levelname)s: %(message)s [in %(pathname)s:%(lineno)d]'
        ))
        file_handler.setLevel(logging.INFO)
        app.logger.addHandler(file_handler)
    app.logger.setLevel(logging.INFO)
    app.logger.info('IT Ticket System startup')

    # ── Blueprints ────────────────────────────────────────────────────────────
    from app.routes.auth    import auth_bp
    from app.routes.tickets import tickets_bp
    from app.routes.admin   import admin_bp
    from app.routes.api     import api_bp
    from app.routes.chatbot import chatbot_bp

    app.register_blueprint(auth_bp)
    app.register_blueprint(tickets_bp)
    app.register_blueprint(admin_bp)
    app.register_blueprint(api_bp)
    app.register_blueprint(chatbot_bp)

    # ── User loader ───────────────────────────────────────────────────────────
    from app.models import User

    @login_manager.user_loader
    def load_user(user_id):
        return User.query.get(int(user_id))

    # ── Context processors ────────────────────────────────────────────────────
    @app.context_processor
    def inject_globals():
        from flask_login import current_user
        unread = 0
        if current_user.is_authenticated:
            from app.models import Notification
            unread = Notification.query.filter_by(
                user_id=current_user.id, is_read=False
            ).count()
        return dict(unread_notifications=unread)

    # ── DB initialisation (first run) ─────────────────────────────────────────
    with app.app_context():
        db.create_all()
        _seed_admin(app)

    return app


def _seed_admin(app):
    """Create the default admin account if none exists."""
    from app.models import User, UserRole
    if User.query.filter_by(role=UserRole.ADMIN).first():
        return
    admin = User(
        email     = app.config['ADMIN_EMAIL'],
        username  = 'admin',
        full_name = 'System Administrator',
        role      = UserRole.ADMIN,
        department= 'IT',
        is_active = True,
    )
    admin.set_password(app.config['ADMIN_PASSWORD'])
    db.session.add(admin)
    db.session.commit()
    app.logger.info(f'[SEED] Default admin account created: {admin.email}')