import os
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_migrate import Migrate
from flask_login import LoginManager
from flask_bcrypt import Bcrypt
from app.config import config

# Initialize extensions
db = SQLAlchemy()
migrate = Migrate()
login_manager = LoginManager()
bcrypt = Bcrypt()


def create_app(config_name='default'):
    """Application factory pattern."""
    app = Flask(__name__)
    
    # Load configuration
    app.config.from_object(config[config_name])

    # Logging first, so anything below can report problems.
    from app.services.logging_setup import configure_logging
    configure_logging(app)
    
    # Initialize extensions
    db.init_app(app)
    migrate.init_app(app, db)
    bcrypt.init_app(app)
    
    # Configure Flask-Login
    login_manager.init_app(app)
    login_manager.login_view = 'auth.login'
    login_manager.login_message = 'Please log in to access this page.'
    login_manager.login_message_category = 'info'
    
    # User loader for Flask-Login
    from app.models.user import User
    
    @login_manager.user_loader
    def load_user(user_id):
        return User.query.get(int(user_id))
    
    # Register blueprints
    from app.routes.auth import auth_bp
    from app.routes.main import main_bp
    from app.routes.sets import sets_bp
    from app.routes.instructions import instructions_bp
    from app.routes.admin import admin_bp
    from app.routes.extra_files import extra_files_bp
    from app.routes.moc import bp as moc_bp
    from app.routes.backup import backup_bp
    from app.routes.instruction_fetch import instruction_fetch_bp
    from app.routes.logs import logs_bp
    
    app.register_blueprint(auth_bp)
    app.register_blueprint(main_bp)
    app.register_blueprint(sets_bp)
    app.register_blueprint(instructions_bp)
    app.register_blueprint(admin_bp)
    app.register_blueprint(extra_files_bp)
    app.register_blueprint(moc_bp)
    app.register_blueprint(backup_bp)
    app.register_blueprint(instruction_fetch_bp)
    app.register_blueprint(logs_bp)
    
    # Import models to ensure they're registered with SQLAlchemy
    from app.models.user import User
    from app.models.set import Set
    from app.models.instruction import Instruction
    from app.models.extra_file import ExtraFile
    from app.models.set_share import SetShare
    from app.models.site_setting import SiteSetting
    from app.models.instruction_fetch import InstructionFetchJob
    from app.models.api_call import BricksetApiCall

    # Add any columns missing from an older database (additive only).
    if app.config.get('AUTO_SCHEMA_UPGRADE', True):
        from app.services.schema_upgrade import ensure_schema
        ensure_schema(app)

    # One place that decides who may see or change a set, covering every
    # set-scoped route in the app.
    from app.services.access import install_access_guard
    install_access_guard(app)

    # Create upload directories
    os.makedirs(os.path.join(app.config['UPLOAD_FOLDER'], 'pdfs'), exist_ok=True)
    os.makedirs(os.path.join(app.config['UPLOAD_FOLDER'], 'images'), exist_ok=True)
    os.makedirs(os.path.join(app.config['UPLOAD_FOLDER'], 'covers'), exist_ok=True)
    os.makedirs(os.path.join(app.config['UPLOAD_FOLDER'], 'thumbnails'), exist_ok=True)
    os.makedirs(os.path.join(app.config['UPLOAD_FOLDER'], 'extra_files'), exist_ok=True)

    # Create backup directory
    os.makedirs(app.config['BACKUP_FOLDER'], exist_ok=True)

    # Serve uploads from UPLOAD_FOLDER wherever it lives.
    # Stored paths are rendered as /static/uploads/<path>, which only works
    # by accident when UPLOAD_FOLDER sits inside app/static. This explicit
    # route takes precedence over Flask's static handler and keeps those
    # URLs valid when the folder is a mounted volume (e.g. /data/uploads).
    from flask import send_from_directory

    @app.route('/static/uploads/<path:filename>')
    def uploaded_file(filename):
        return send_from_directory(app.config['UPLOAD_FOLDER'], filename)

    # Register CLI commands (flask backup ... / flask instructions ...)
    from app.cli import register_cli
    register_cli(app)

    # Templates need to know whether to show owner-only links.
    @app.context_processor
    def inject_ownership():
        from app.services.ownership import is_owner
        try:
            return {'current_user_is_owner': is_owner()}
        except Exception:
            return {'current_user_is_owner': False}

    # Background ticker for the automatic instruction fetcher. It does
    # nothing at all until an admin enables it on the fetcher page.
    from app.services import fetch_worker
    fetch_worker.start(app)
    
    # Context processor for global template variables
    @app.context_processor
    def inject_global_vars():
        from app.services.brickset_api import BricksetAPI
        from datetime import datetime
        from app.models.site_setting import SiteSetting
        return {
            'app_name': 'LEGO Instructions Manager',
            'brickset_available': BricksetAPI.is_configured(),
            'current_year': datetime.now().year,
            'allow_registration': SiteSetting.get_bool('allow_registration', True)
        }
    
    return app