"""
config.py
=========
Centralised application configuration.

All environment variable reads happen here — once, at startup.
Blueprints and helpers that need a config value use:

    from flask import current_app
    value = current_app.config['KEY']

Or for values needed at module import time (before app context):

    from config import Config
    value = Config.COMPANY_NAME
"""

import os
from datetime import timedelta


class Config:
    # ------------------------------------------------------------------ #
    # Core Flask
    # ------------------------------------------------------------------ #
    SECRET_KEY = os.environ.get('SECRET_KEY', 'change-me-in-production')
    SQLALCHEMY_DATABASE_URI = os.environ.get('DATABASE_URL', '')
    SQLALCHEMY_TRACK_MODIFICATIONS = (
        os.environ.get('SQLALCHEMY_TRACK_MODIFICATIONS', 'False').lower() == 'true'
    )
    TEMPLATES_AUTO_RELOAD = (
        os.environ.get('TEMPLATES_AUTO_RELOAD', 'True').lower() == 'true'
    )
    DEBUG = os.environ.get('DEBUG', 'False').lower() == 'true'

    # ------------------------------------------------------------------ #
    # SQLAlchemy connection pool (read from .env; safe defaults)
    # ------------------------------------------------------------------ #
    SQLALCHEMY_ENGINE_OPTIONS = {
        'pool_size':    int(os.environ.get('SQLALCHEMY_ENGINE_OPTIONS_POOL_SIZE',    '10')),
        'pool_timeout': int(os.environ.get('SQLALCHEMY_ENGINE_OPTIONS_POOL_TIMEOUT', '20')),
        'pool_recycle': int(os.environ.get('SQLALCHEMY_ENGINE_OPTIONS_POOL_RECYCLE', '3600')),
        'max_overflow': int(os.environ.get('SQLALCHEMY_ENGINE_OPTIONS_MAX_OVERFLOW', '20')),
    }

    # ------------------------------------------------------------------ #
    # Session / cookies
    # ------------------------------------------------------------------ #
    # Remember Me lifetime, and the maximum age Flask accepts for ANY session
    # cookie. Logins without Remember Me end after 10 hours in app.py
    # (adjust_session_lifetime) — do not lower this to get that, or Remember Me
    # cookies stop loading.
    PERMANENT_SESSION_LIFETIME = timedelta(days=30)
    SESSION_COOKIE_SECURE = (
        os.environ.get('SESSION_COOKIE_SECURE', 'false').lower() == 'true'
    )
    SESSION_COOKIE_HTTPONLY = (
        os.environ.get('SESSION_COOKIE_HTTPONLY', 'true').lower() == 'true'
    )
    SESSION_COOKIE_SAMESITE = os.environ.get('SESSION_COOKIE_SAMESITE', 'Lax')

    # ------------------------------------------------------------------ #
    # Application identity
    # ------------------------------------------------------------------ #
    COMPANY_NAME    = os.environ.get('COMPANY_NAME',    'QR Code Management System')
    CONTRACT_NAME   = os.environ.get('CONTRACT_NAME',   'Default Contract')

    # ------------------------------------------------------------------ #
    # File uploads
    # ------------------------------------------------------------------ #
    UPLOAD_FOLDER   = os.environ.get('UPLOAD_FOLDER', '/tmp')

    # ------------------------------------------------------------------ #
    # Photo verification
    # ------------------------------------------------------------------ #
    PHOTO_VERIFICATION_ENABLED = (
        os.environ.get('ENABLE_PHOTO_VERIFICATION', 'true').lower() == 'true'
    )
    DISTANCE_THRESHOLD_FOR_VERIFICATION = float(
        os.environ.get('PHOTO_VERIFICATION_DISTANCE_THRESHOLD', '0.3')
    )
    VERIFICATION_PHOTO_MAX_SIZE = int(
        os.environ.get('VERIFICATION_PHOTO_MAX_SIZE', str(5 * 1024 * 1024))
    )

    # ------------------------------------------------------------------ #
    # Request size limits
    # ------------------------------------------------------------------ #
    # Flask 3.1 rejects any non-file form field larger than MAX_FORM_MEMORY_SIZE
    # (default 500 KB) with HTTP 413. The verification photo is sent as a base64
    # TEXT field, so this follows the photo limit (+1 MB for the other fields).
    MAX_FORM_MEMORY_SIZE = VERIFICATION_PHOTO_MAX_SIZE + 1024 * 1024
    # Whole-request cap (Excel imports, photos). Nginx client_max_body_size
    # must be at least this, or Nginx rejects larger uploads first.
    MAX_CONTENT_LENGTH = int(os.environ.get('MAX_UPLOAD_SIZE_MB', '50')) * 1024 * 1024

    # ------------------------------------------------------------------ #
    # Check-in interval
    # ------------------------------------------------------------------ #
    TIME_INTERVAL = int(os.environ.get('TIME_INTERVAL', '30'))

    # ------------------------------------------------------------------ #
    # Export by Building — filtered sheet + weekly hours summary
    # ------------------------------------------------------------------ #
    # Comma-separated base employee IDs (project managers) removed from the
    # "Filtered Report" and "Weekly Hours by Location" sheets.
    BUILDING_SUMMARY_EXCLUDED_EMPLOYEE_IDS = [
        e.strip() for e in os.environ.get(
            'BUILDING_SUMMARY_EXCLUDED_EMPLOYEE_IDS', '4921,4944,4816,3979'
        ).split(',') if e.strip()
    ]

    # ------------------------------------------------------------------ #
    # Server
    # ------------------------------------------------------------------ #
    FLASK_HOST  = os.environ.get('FLASK_HOST',  '0.0.0.0')
    FLASK_PORT  = int(os.environ.get('FLASK_PORT', '5000'))
    THREADED    = os.environ.get('THREADED', 'True').lower() == 'true'

    # Number of reverse proxies in front of the app (Nginx = 1; Cloudflare in
    # front of Nginx = 2). ProxyFix reads the real client IP from that many
    # X-Forwarded-For hops. 0 = not behind a proxy (local development only).
    TRUSTED_PROXY_COUNT = int(os.environ.get('TRUSTED_PROXY_COUNT', '1'))

    # Public base URL of this deployment (e.g. https://qr.govservicesinc.com).
    # Used for QR images generated at startup, where there is no request.
    QR_BASE_URL = os.environ.get('QR_BASE_URL', '').strip()

    # ------------------------------------------------------------------ #
    # Default admin (used only on first boot)
    # ------------------------------------------------------------------ #
    DEFAULT_ADMIN_PASSWORD = os.environ.get('DEFAULT_ADMIN_PASSWORD', 'admin123')

    # ------------------------------------------------------------------ #
    # Remote (legacy) MySQL server — read-only source for Legacy Attendance
    # ------------------------------------------------------------------ #
    REMOTE_DB_HOST     = os.environ.get('REMOTE_DB_HOST', '')
    REMOTE_DB_PORT     = int(os.environ.get('REMOTE_DB_PORT', '3306'))
    REMOTE_DB_USERNAME = os.environ.get('REMOTE_DB_USERNAME', '')
    REMOTE_DB_PASSWORD = os.environ.get('REMOTE_DB_PASSWORD', '')
    REMOTE_DB_NAME     = os.environ.get('REMOTE_DB_NAME', '')


class DevelopmentConfig(Config):
    DEBUG = True
    SESSION_COOKIE_SECURE = False


class ProductionConfig(Config):
    DEBUG = False
    TEMPLATES_AUTO_RELOAD = False


# Active config selected by environment variable
_config_map = {
    'development': DevelopmentConfig,
    'production':  ProductionConfig,
    'default':     Config,
}

def get_config():
    """Return the active Config class based on FLASK_ENV."""
    env = os.environ.get('FLASK_ENV', 'default').lower()
    return _config_map.get(env, Config)