import logging
import os
from flask import Flask
from app.config import config
from app.extensions import db, login_manager, migrate, csrf
from app.utils.formatters import format_currency, format_percent, format_large_number


def _setup_logging(app):
    """
    Ensure app.* module loggers emit at INFO level.

    Under Gunicorn the root logger already has handlers (pointing to Gunicorn's
    error log / stderr) but its level is WARNING, so INFO records are dropped
    before they reach any handler.  We fix that by:
      1. Reusing Gunicorn's handlers on the 'app' namespace logger so records
         go to the same destination as Gunicorn's own logs.
      2. Falling back to a plain stderr StreamHandler in dev / direct-run mode.
    """
    import sys

    app_log = logging.getLogger('app')
    app_log.setLevel(logging.INFO)

    if app_log.handlers:
        return  # already configured (e.g. running tests)

    gunicorn_handlers = logging.getLogger('gunicorn.error').handlers
    if gunicorn_handlers:
        # Running under Gunicorn — attach its handlers so our logs land in the
        # same error log file that Gunicorn writes to.
        for h in gunicorn_handlers:
            app_log.addHandler(h)
    else:
        # Dev / direct python run — stderr is fine.
        handler = logging.StreamHandler(sys.stderr)
        handler.setFormatter(logging.Formatter(
            '%(asctime)s %(levelname)s %(name)s: %(message)s'
        ))
        app_log.addHandler(handler)

    app_log.propagate = False  # avoid double-printing via root


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

    app = Flask(__name__)
    app.config.from_object(config[config_name])

    # Wire app.* loggers into Gunicorn's error log (or stderr in dev).
    # basicConfig is a no-op under Gunicorn because Gunicorn already
    # installed root handlers before our app is imported — so we must
    # attach handlers explicitly.
    _setup_logging(app)

    db.init_app(app)
    login_manager.init_app(app)
    migrate.init_app(app, db)
    csrf.init_app(app)

    from app.routes.auth import auth_bp
    from app.routes.dashboard import dashboard_bp
    from app.routes.accounts import accounts_bp
    from app.routes.categories import categories_bp
    from app.routes.transactions import transactions_bp
    from app.routes.budgets import budgets_bp
    from app.routes.goals import goals_bp
    from app.routes.investments import investments_bp
    from app.routes.ai import ai_bp
    from app.routes.reports import reports_bp
    from app.routes.settings import settings_bp
    from app.routes.teller import teller_bp

    app.register_blueprint(auth_bp)
    app.register_blueprint(dashboard_bp)
    app.register_blueprint(accounts_bp)
    app.register_blueprint(categories_bp)
    app.register_blueprint(transactions_bp)
    app.register_blueprint(budgets_bp)
    app.register_blueprint(goals_bp)
    app.register_blueprint(investments_bp)
    app.register_blueprint(ai_bp)
    app.register_blueprint(reports_bp)
    app.register_blueprint(settings_bp)
    app.register_blueprint(teller_bp)

    with app.app_context():
        from app.models import (
            User, Account, Category, Receipt, RecurringRule,
            Transaction, Budget, Goal, GoalContribution,
            Investment, InvestmentTransaction, NetWorthSnapshot,
            AiInsight, FxRate
        )
        from app.models.teller_enrollment import TellerEnrollment, TellerAccount

    app.jinja_env.globals['format_currency'] = format_currency
    app.jinja_env.globals['format_percent'] = format_percent
    app.jinja_env.globals['format_large_number'] = format_large_number

    @app.template_filter('currency')
    def currency_filter(value, symbol=None):
        return format_currency(value, symbol)

    @app.template_filter('percent')
    def percent_filter(value):
        return format_percent(value)

    @app.template_filter('shares')
    def shares_filter(value):
        """Format share quantity — strips trailing zeros, keeps up to 8 decimal places."""
        try:
            f = float(value)
        except (TypeError, ValueError):
            return '0'
        # Format to 8 decimal places then strip trailing zeros
        s = '{:.8f}'.format(f).rstrip('0').rstrip('.')
        return s if s else '0'

    return app