import os
from pathlib import Path
from datetime import timedelta

BASE_DIR = Path(__file__).resolve().parent.parent

# Load a .env file if present (development convenience; production uses real env vars)
try:
    from dotenv import load_dotenv
    load_dotenv(BASE_DIR / '.env')
except ImportError:
    pass

# ── Core ───────────────────────────────────────────────────────────────────────

SECRET_KEY = os.environ.get(
    'DJANGO_SECRET_KEY',
    'django-insecure-dev-secret-key-change-in-production-xyz123',
)

DEBUG = os.environ.get('DJANGO_DEBUG', 'True').lower() in ('true', '1', 'yes')

ALLOWED_HOSTS = [
    h.strip()
    for h in os.environ.get('DJANGO_ALLOWED_HOSTS', 'localhost,127.0.0.1').split(',')
    if h.strip()
]

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'rest_framework',
    'oauth2_provider',
    'corsheaders',
    'api',
]

MIDDLEWARE = [
    'corsheaders.middleware.CorsMiddleware',
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
    'oauth2_provider.middleware.OAuth2TokenMiddleware',
]

ROOT_URLCONF = 'config.urls'

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [BASE_DIR / 'templates'],
        'APP_DIRS': True,
        'OPTIONS': {
            'context_processors': [
                'django.template.context_processors.debug',
                'django.template.context_processors.request',
                'django.contrib.auth.context_processors.auth',
                'django.contrib.messages.context_processors.messages',
            ],
        },
    },
]

WSGI_APPLICATION = 'config.wsgi.application'

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': BASE_DIR / 'db.sqlite3',
    }
}

AUTH_PASSWORD_VALIDATORS = [
    {'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator'},
    {'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator'},
    {'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator'},
    {'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator'},
]

LANGUAGE_CODE = 'en-us'
TIME_ZONE = 'UTC'
USE_I18N = True
USE_TZ = True

STATIC_URL = 'static/'
STATIC_ROOT = BASE_DIR / 'staticfiles'

DEFAULT_AUTO_FIELD = 'django.db.models.BigAutoField'

# ── Auth redirects ─────────────────────────────────────────────────────────────

LOGIN_URL = '/accounts/login/'
LOGIN_REDIRECT_URL = '/o/authorize/'
LOGOUT_REDIRECT_URL = os.environ.get('LOGOUT_REDIRECT_URL', 'http://localhost:5173/')

# ── Django REST Framework ──────────────────────────────────────────────────────

REST_FRAMEWORK = {
    'DEFAULT_AUTHENTICATION_CLASSES': [
        'oauth2_provider.contrib.rest_framework.OAuth2Authentication',
    ],
    'DEFAULT_PERMISSION_CLASSES': [
        'rest_framework.permissions.IsAuthenticated',
    ],
}

# ── Django OAuth Toolkit ───────────────────────────────────────────────────────

OAUTH2_PROVIDER = {
    'PKCE_REQUIRED': True,
    'ACCESS_TOKEN_EXPIRE_SECONDS': 3600,
    'REFRESH_TOKEN_EXPIRE_SECONDS': 60 * 60 * 24 * 7,
    'ROTATE_REFRESH_TOKEN': True,
    'SCOPES': {
        'read': 'Read access',
        'write': 'Write access',
    },
    'DEFAULT_SCOPES': ['read'],
    'ALLOWED_REDIRECT_URI_SCHEMES': ['http', 'https'],
}

AUTHENTICATION_BACKENDS = [
    'oauth2_provider.backends.OAuth2Backend',
    'django.contrib.auth.backends.ModelBackend',
]

# ── CORS ───────────────────────────────────────────────────────────────────────
# In production the frontend is co-located (same origin), so CORS isn't needed.
# Keep it configured here so the dev setup (Vite on :5173) still works.

CORS_ALLOWED_ORIGINS = [
    o.strip()
    for o in os.environ.get(
        'CORS_ALLOWED_ORIGINS',
        'http://localhost:5173,http://127.0.0.1:5173',
    ).split(',')
    if o.strip()
]
CORS_ALLOW_CREDENTIALS = True
CORS_ALLOW_HEADERS = [
    'accept',
    'accept-encoding',
    'authorization',
    'content-type',
    'dnt',
    'origin',
    'user-agent',
    'x-csrftoken',
    'x-requested-with',
]

# ── WebAuthn / Touch ID ────────────────────────────────────────────────────────
# RP_ID must be the effective domain of the origin (no port, no scheme).
# WEBAUTHN_ORIGIN must be the exact origin browsers will use to reach the app.

WEBAUTHN_RP_ID = os.environ.get('WEBAUTHN_RP_ID', 'localhost')
WEBAUTHN_ORIGIN = os.environ.get('WEBAUTHN_ORIGIN', 'http://localhost:5173')

# ── Production HTTPS hardening ─────────────────────────────────────────────────
# These only activate when DEBUG=False.  Assumes nginx terminates TLS and sets
# the X-Forwarded-Proto header before proxying to Gunicorn/Django.

if not DEBUG:
    SECURE_PROXY_SSL_HEADER = ('HTTP_X_FORWARDED_PROTO', 'https')
    SECURE_HSTS_SECONDS = 31536000
    SECURE_HSTS_INCLUDE_SUBDOMAINS = True
    SECURE_HSTS_PRELOAD = True
    SESSION_COOKIE_SECURE = True
    CSRF_COOKIE_SECURE = True