import os
from pathlib import Path
from datetime import timedelta
from dotenv import load_dotenv
from django.core.exceptions import ImproperlyConfigured

load_dotenv()

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

_INSECURE_DEFAULT_SECRET = 'django-insecure-change-me'
SECRET_KEY = os.getenv('SECRET_KEY', _INSECURE_DEFAULT_SECRET)

DEBUG = os.getenv('DEBUG', 'False').lower() in ('true', '1', 'yes')

if not DEBUG and SECRET_KEY == _INSECURE_DEFAULT_SECRET:
    raise ImproperlyConfigured(
        "SECRET_KEY must be set via environment when DEBUG is False. "
        "Set a strong random value in the SECRET_KEY env var."
    )

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

# Deployment (HF Spaces + Neon): a single DATABASE_URL takes precedence when
# set. Locally it is unset, so the explicit DB_* settings below are used
# unchanged. dj_database_url is imported lazily so local dev needn't install it.
if os.getenv('DATABASE_URL'):
    import dj_database_url
    DATABASES = {
        'default': dj_database_url.parse(
            os.getenv('DATABASE_URL'), conn_max_age=0, ssl_require=True,
        )
    }
else:
    DATABASES = {
        'default': {
            'ENGINE': 'django.db.backends.postgresql',
            'NAME': os.getenv('DB_NAME', 'gapguide_db'),
            'USER': os.getenv('DB_USER', 'postgres'),
            'PASSWORD': os.getenv('DB_PASSWORD', 'postgres'),
            'HOST': os.getenv('DB_HOST', 'localhost'),
            'PORT': os.getenv('DB_PORT', '5432'),
        }
    }

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'django.contrib.postgres',

    'rest_framework',
    'rest_framework_simplejwt',
    'rest_framework_simplejwt.token_blacklist',
    'corsheaders',
    'drf_spectacular',
    'django_filters',

    'apps.accounts',
    'apps.skills',
    'apps.roles',
    'apps.analysis',
    'apps.resources',
    'apps.progress',
]

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    # WhiteNoise serves static files (Django admin / DRF) in the container with
    # no nginx. Must sit immediately after SecurityMiddleware. No-op locally
    # under runserver (DEBUG=True serves static via staticfiles finders).
    'whitenoise.middleware.WhiteNoiseMiddleware',
    'corsheaders.middleware.CorsMiddleware',
    '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',
]

ROOT_URLCONF = 'config.urls'

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [],
        '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'

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/'
# collectstatic target (used in the container build). Non-manifest WhiteNoise
# storage → no collectstatic required for local `runserver`.
STATIC_ROOT = BASE_DIR / 'staticfiles'
STORAGES = {
    "default": {"BACKEND": "django.core.files.storage.FileSystemStorage"},
    "staticfiles": {"BACKEND": "whitenoise.storage.CompressedStaticFilesStorage"},
}
DEFAULT_AUTO_FIELD = 'django.db.models.BigAutoField'

AUTH_USER_MODEL = 'accounts.User'

REST_FRAMEWORK = {
    'DEFAULT_AUTHENTICATION_CLASSES': (
        'rest_framework_simplejwt.authentication.JWTAuthentication',
    ),
    'DEFAULT_PERMISSION_CLASSES': (
        'rest_framework.permissions.IsAuthenticated',
    ),
    'DEFAULT_SCHEMA_CLASS': 'drf_spectacular.openapi.AutoSchema',
    'DEFAULT_THROTTLE_CLASSES': (
        'rest_framework.throttling.ScopedRateThrottle',
    ),
    'DEFAULT_THROTTLE_RATES': {
        'login': '10/minute',
        'register': '20/hour',
        # F28 — the resume-parse endpoint runs the full NER chain (expensive).
        # ScopedRateThrottle is a no-op until BOTH this rate key and the view's
        # throttle_scope='resume_parse' exist; a missing/typo'd key here raises
        # ImproperlyConfigured (500) on every parse, so keep them in lockstep.
        'resume_parse': os.getenv('THROTTLE_RESUME', '30/hour'),
    },
}

SIMPLE_JWT = {
    'ACCESS_TOKEN_LIFETIME': timedelta(minutes=30),
    'REFRESH_TOKEN_LIFETIME': timedelta(days=1),
    'ROTATE_REFRESH_TOKENS': True,
    'BLACKLIST_AFTER_ROTATION': True,
    'UPDATE_LAST_LOGIN': True,
    'ALGORITHM': 'HS256',
    'AUTH_HEADER_TYPES': ('Bearer',),
}

CORS_ALLOWED_ORIGINS = [o.strip() for o in os.getenv('CORS_ALLOWED_ORIGINS', 'http://localhost:5173').split(',') if o.strip()]

# F27 — production hardening. Applied only when DEBUG is off (dev runs plain
# http on localhost). `python manage.py check --deploy` (with a prod-like env:
# DEBUG=False + a real SECRET_KEY + ALLOWED_HOSTS) verifies these resolve the
# W004/W008/W012/W016 warnings. SECURE_PROXY_SSL_HEADER requires the upstream
# proxy to set X-Forwarded-Proto (else SECURE_SSL_REDIRECT can loop).
if not DEBUG:
    # Env-toggle: behind HF Spaces' HTTPS edge we start this False to avoid a
    # redirect loop if the proxy doesn't forward X-Forwarded-Proto. SECURE_PROXY_
    # SSL_HEADER stays always-on (harmless if absent, correct if present) so
    # request.is_secure() — and thus secure cookies / admin login — works.
    SECURE_SSL_REDIRECT = os.getenv('SECURE_SSL_REDIRECT', 'True').lower() in ('true', '1', 'yes')
    SECURE_PROXY_SSL_HEADER = ('HTTP_X_FORWARDED_PROTO', 'https')
    SECURE_HSTS_SECONDS = 31536000  # 1 year
    SECURE_HSTS_INCLUDE_SUBDOMAINS = True
    SECURE_HSTS_PRELOAD = True
    SESSION_COOKIE_SECURE = True
    CSRF_COOKIE_SECURE = True
    CSRF_TRUSTED_ORIGINS = [
        o.strip() for o in os.getenv('CSRF_TRUSTED_ORIGINS', '').split(',')
        if o.strip()
    ]

# Resume parser caps at 5 MB (see apps.accounts.resume_parser.MAX_PDF_BYTES).
# Raise Django's defaults (both are 2.5 MB) so 3–5 MB PDFs stay in memory
# instead of silently spooling to /tmp during parse.
FILE_UPLOAD_MAX_MEMORY_SIZE = 6 * 1024 * 1024
DATA_UPLOAD_MAX_MEMORY_SIZE = 6 * 1024 * 1024

SPECTACULAR_SETTINGS = {
    'TITLE': 'GapGuide API',
    'DESCRIPTION': 'API documentation for GapGuide - Skill Gap Analysis Platform',
    'VERSION': '1.0.0',
    # Four fields expose the same (BEGINNER, INTERMEDIATE, ADVANCED) choice set:
    # Skill.difficulty_level, UserSkill.user_level, RoleSkill.required_level, and
    # Resource.difficulty_level. Without explicit overrides drf-spectacular emits
    # a "multiple names for same choice set" warning on schema build.
    'ENUM_NAME_OVERRIDES': {
        'DifficultyLevelEnum': 'apps.skills.models.Skill.DIFFICULTY_CHOICES',
    },
}

# F30 — logging. Console always + a rotating file. The NER layers log under
# apps.accounts.* so handlers attach to the 'apps' logger (a django-only config
# would miss them). RotatingFileHandler opens its file at construction, so the
# log dir must exist first (module-level mkdir guard).
_LOG_DIR = BASE_DIR / 'logs'
try:
    _LOG_DIR.mkdir(parents=True, exist_ok=True)
except OSError:
    # Read-only / restricted FS: don't crash settings import. The file handler
    # opens lazily (delay=True); the console handler is always available.
    pass
LOGGING = {
    'version': 1,
    'disable_existing_loggers': False,
    'formatters': {
        'verbose': {'format': '{asctime} {levelname} {name}: {message}', 'style': '{'},
    },
    'handlers': {
        'console': {'class': 'logging.StreamHandler', 'formatter': 'verbose'},
        'file': {
            'class': 'logging.handlers.RotatingFileHandler',
            'filename': str(_LOG_DIR / 'gapguide.log'),
            'maxBytes': 5 * 1024 * 1024,
            'backupCount': 3,
            'formatter': 'verbose',
            'delay': True,  # open the file on first emit, not at import time
        },
    },
    'root': {'handlers': ['console', 'file'], 'level': 'INFO'},
    'loggers': {
        'apps': {'handlers': ['console', 'file'], 'level': 'INFO', 'propagate': False},
        'django': {'handlers': ['console', 'file'], 'level': 'WARNING', 'propagate': False},
    },
}