import os
from datetime import timedelta
from dotenv import load_dotenv
from sqlalchemy.pool import StaticPool

# Load .env from the project root (only takes effect locally; no-op in production
# if variables are already set in the environment)
load_dotenv()

basedir = os.path.abspath(os.path.dirname(__file__))


def _require_env(key: str) -> str:
    """Return the value of a required environment variable, raising if absent."""
    value = os.environ.get(key)
    if not value:
        raise RuntimeError(
            f"Required environment variable '{key}' is not set. "
            f"Add it to your .env file (development) or server environment (production)."
        )
    return value


class Config:
    # ── Security ────────────────────────────────────────────────────────────
    # SECRET_KEY must be set externally — no insecure fallback.
    SECRET_KEY = _require_env('SECRET_KEY')

    # ── Database ────────────────────────────────────────────────────────────
    # DATABASE_URL must be set externally — no hardcoded credentials.
    SQLALCHEMY_DATABASE_URI = _require_env('DATABASE_URL')
    SQLALCHEMY_TRACK_MODIFICATIONS = False
    SQLALCHEMY_ECHO = False

    # ── File uploads ────────────────────────────────────────────────────────
    UPLOAD_FOLDER = os.path.join(basedir, 'app/static/uploads')
    MAX_CONTENT_LENGTH = 50 * 1024 * 1024   # 50 MB
    ALLOWED_EXTENSIONS = {'png', 'jpg', 'jpeg', 'gif'}

    # ── Storage backend (R2 migration) ──────────────────────────────────────
    # 'local' (default) = files under app/static/uploads, served via url_for('static').
    # 's3'   = Cloudflare R2 / S3-compatible (added Phase 2). Flip via env only.
    STORAGE_BACKEND = os.environ.get('STORAGE_BACKEND', 'local')

    # Cloudflare R2 — only used when STORAGE_BACKEND=s3.
    R2_ENDPOINT_URL      = os.environ.get('R2_ENDPOINT_URL')
    R2_ACCESS_KEY_ID     = os.environ.get('R2_ACCESS_KEY_ID')
    R2_SECRET_ACCESS_KEY = os.environ.get('R2_SECRET_ACCESS_KEY')
    R2_BUCKET            = os.environ.get('R2_BUCKET')
    R2_PRESIGN_TTL       = int(os.environ.get('R2_PRESIGN_TTL', '86400'))   # seconds (24h)
    # When true, media_url HEADs the object and falls back to a local static URL
    # if it's missing (belt-and-suspenders during an early/partial cutover).
    # Off by default — cutover is gated on full verification, so objects exist.
    R2_MEDIA_FALLBACK    = os.environ.get('R2_MEDIA_FALLBACK', 'false').lower() == 'true'

    # ── Photo capture-time / geo overlay ────────────────────────────────────
    # When true (default), POST /api/v1/photos/upload burns a timestamp + GPS
    # bar into the image before storing it. Set false to store raw uploads.
    PHOTO_STAMP_ENABLED = os.environ.get('PHOTO_STAMP_ENABLED', 'true').lower() == 'true'

    # ── Session / cookies ───────────────────────────────────────────────────
    PERMANENT_SESSION_LIFETIME = timedelta(hours=24)
    # Secure by default — subclasses must explicitly opt out for local dev.
    SESSION_COOKIE_SECURE   = True
    SESSION_COOKIE_HTTPONLY = True
    SESSION_COOKIE_SAMESITE = 'Lax'

    # ── Mail ────────────────────────────────────────────────────────────────
    # ── Application base URL (used in email links) ─────────────────────────
    APP_BASE_URL         = os.environ.get('APP_BASE_URL', '')
    MAIL_DEFAULT_SENDER  = os.environ.get('MAIL_DEFAULT_SENDER', 'noreply@janitorialqc.local')

    # ── Digest email secret token (used to authenticate cron trigger) ────────
    DIGEST_SECRET        = os.environ.get('DIGEST_SECRET')

    # ── Photo retention (data minimization — GDPR Art. 5(1)(e)) ─────────────
    # Unset (None) by default: no automatic photo deletion happens unless the
    # operator opts in. When set, /notifications/purge-old-photos deletes
    # photo files (not the issue record) for RESOLVED issues older than this
    # many days.
    PHOTO_RETENTION_DAYS = int(os.environ['PHOTO_RETENTION_DAYS']) if os.environ.get('PHOTO_RETENTION_DAYS') else None

    # ── Google Maps (used for GPS map on inspection view) ────────────────────
    GOOGLE_MAPS_API_KEY  = os.environ.get('GOOGLE_MAPS_API_KEY', '')

    MAIL_SERVER   = os.environ.get('MAIL_SERVER')
    MAIL_USERNAME = os.environ.get('MAIL_USERNAME')
    MAIL_PASSWORD = os.environ.get('MAIL_PASSWORD')

    # ── SSL vs STARTTLS selection ────────────────────────────────────────────
    # Port 465 = implicit SSL  → MAIL_USE_SSL=True,  MAIL_USE_TLS=False
    # Port 587 = STARTTLS      → MAIL_USE_SSL=False, MAIL_USE_TLS=True
    # The two flags are mutually exclusive; setting both True breaks Flask-Mail.
    _mail_port    = int(os.environ.get('MAIL_PORT') or 587)
    MAIL_PORT     = _mail_port
    MAIL_USE_SSL  = _mail_port == 465
    MAIL_USE_TLS  = not MAIL_USE_SSL   # STARTTLS only when NOT using implicit SSL


class DevelopmentConfig(Config):
    DEBUG = True
    SQLALCHEMY_ECHO = True
    # Allow HTTP cookies during local development (HTTP, not HTTPS)
    SESSION_COOKIE_SECURE = False


class ProductionConfig(Config):
    DEBUG = False
    # Inherits SESSION_COOKIE_SECURE = True from Config — no override needed.


class TestingConfig(Config):
    """Config for the automated test suite (pytest).

    Uses an in-memory SQLite database with a StaticPool so the single
    connection — and therefore the schema created by db.create_all() — persists
    across every request the test client makes within one app instance. CSRF and
    rate limiting are disabled so tests can POST directly, and mail is
    suppressed. DEBUG=True short-circuits the file-logging block in create_app()
    so the suite never writes to logs/jqc.log.
    """
    TESTING = True
    DEBUG   = True

    SQLALCHEMY_DATABASE_URI = 'sqlite://'   # in-memory
    SQLALCHEMY_ENGINE_OPTIONS = {
        'connect_args': {'check_same_thread': False},
        'poolclass':    StaticPool,
    }

    WTF_CSRF_ENABLED      = False
    RATELIMIT_ENABLED     = False
    MAIL_SUPPRESS_SEND    = True
    SESSION_COOKIE_SECURE = False


config = {
    'development': DevelopmentConfig,
    'production':  ProductionConfig,
    'testing':     TestingConfig,
    'default':     DevelopmentConfig,
}