import os
from datetime import timedelta
from dotenv import load_dotenv

# 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

    # ── Multi-tenancy (MT-1) ─────────────────────────────────────────────────
    # Master switch. When False (default) the app behaves EXACTLY as the
    # single-tenant deployment: no Host resolution, every query uses
    # SQLALCHEMY_DATABASE_URI. Flip to True only after tenants are registered
    # in the control plane (see MULTI_TENANT_PLAN.md). The control plane env
    # vars (CONTROL_DATABASE_URL, CONTROL_FERNET_KEY) are only required when
    # this is True.
    MULTI_TENANT_ENABLED = os.environ.get(
        'MULTI_TENANT_ENABLED', 'false'
    ).strip().lower() in ('1', 'true', 'yes', 'on')
    # Path prefixes that bypass the tenant gate even when enabled (e.g. health
    # checks). '/static/' is always exempt. Comma-separated in the environment.
    MULTI_TENANT_EXEMPT_PATHS = [
        p.strip() for p in os.environ.get('MULTI_TENANT_EXEMPT_PATHS', '').split(',')
        if p.strip()
    ]
    # Apex domain for the public marketing/landing page. When MULTI_TENANT_ENABLED
    # is True, requests to this host (and its www. variant) are served the landing
    # page instead of being resolved to a tenant. Mirrors TENANT_BASE_DOMAIN used
    # by the provisioner to build <slug>.<base> subdomains.
    TENANT_BASE_DOMAIN = os.environ.get('TENANT_BASE_DOMAIN', 'jqc.app')
    # Per-tenant SQLAlchemy engine pool tuning (see MULTI_TENANT_PLAN.md §4).
    # MT-21: defaults lowered from 5/5 to 2/3. Backend connections scale as
    # workers × cached-tenants × (pool_size + max_overflow); at the old
    # defaults 8 workers × 32 tenants would reserve 2560 connections against a
    # MySQL max_connections that defaults to 151.
    TENANT_ENGINE_POOL_SIZE    = int(os.environ.get('TENANT_ENGINE_POOL_SIZE', 2))
    TENANT_ENGINE_MAX_OVERFLOW = int(os.environ.get('TENANT_ENGINE_MAX_OVERFLOW', 3))
    TENANT_ENGINE_POOL_RECYCLE = int(os.environ.get('TENANT_ENGINE_POOL_RECYCLE', 1800))
    # MT-21: hard cap on cached per-tenant engines per worker process. Beyond
    # this the least-recently-used engine is disposed and rebuilt on demand.
    # 0 disables the bound (previous behaviour — not recommended).
    TENANT_ENGINE_CACHE_MAX    = int(os.environ.get('TENANT_ENGINE_CACHE_MAX', 32))

    # ── 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, MT-2) ────────────────────────────────
    # 'local' (default) = files under app/static/uploads, served via url_for('static').
    # 's3'   = Cloudflare R2 / S3-compatible. Flip via env only, per tenant, in MT-8.
    # Object keys are tenant-prefixed inside the backend; DB paths never change.
    STORAGE_BACKEND = os.environ.get('STORAGE_BACKEND', 'local')

    # Cloudflare R2 — only used when STORAGE_BACKEND=s3 (inert until MT-8).
    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 the legacy
    # unprefixed key, then a local static URL, if it's missing (belt-and-braces
    # 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 (MT-12) ────────────────────────────
    # 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.
    # Global, not per-tenant: the overlay is evidence provenance, which every
    # tenant wants and none should be able to switch off from the UI. Promote to
    # a TenantSettings column only if a tenant ever has a real reason to opt out.
    PHOTO_STAMP_ENABLED = os.environ.get('PHOTO_STAMP_ENABLED', 'true').lower() == 'true'

    # ── Web portal design (MT-16) ───────────────────────────────────────────
    # Fallback design for users who have never chosen one. A stored
    # users.ui_theme ALWAYS wins, so this only affects accounts that have not
    # touched the switcher.
    #
    # Defaults to 'classic' — deliberately NOT ST's 'modern'. ST is
    # single-tenant and could decide for its own users; MT serves tenants who
    # never saw the A/B test, and flipping every user of every tenant to a new
    # UI on a migration is not a change to make on their behalf. New tenants can
    # be provisioned with DEFAULT_UI_THEME=modern, and any user can opt in from
    # the account menu at any time.
    DEFAULT_UI_THEME = os.environ.get('DEFAULT_UI_THEME', 'classic').strip().lower()

    # ── Photo retention (MT-13) ─────────────────────────────────────────────
    # Days after an issue is RESOLVED before its photo FILES are deleted by
    # POST /notifications/purge-old-photos. Unset (None) = the purge is a no-op.
    # Deliberately opt-in, not a default: this is a data-minimization policy the
    # operator chooses (GDPR Art. 5(1)(e) storage limitation), and some tenants
    # have longer contractual/audit retention of their own. Applies per tenant —
    # the cron is invoked once per tenant Host, like check-sla.
    PHOTO_RETENTION_DAYS = (
        int(os.environ['PHOTO_RETENTION_DAYS'])
        if os.environ.get('PHOTO_RETENTION_DAYS') else None
    )

    # ── Issue comment visibility (TEMPORARY — Aug 2026) ──────────────────────
    # True  = every comment on an issue is visible to everyone, customers
    #         included; the per-comment is_customer_visible flag is ignored
    #         when READING.
    # False = phase22 behaviour — customers see only comments explicitly shared
    #         with them.
    #
    # The flag is still WRITTEN on every comment, so flipping this back to
    # 'false' restores the old behaviour exactly, with no data to repair.
    # Set COMMENTS_VISIBLE_TO_ALL=false in the environment to revert.
    COMMENTS_VISIBLE_TO_ALL = os.environ.get(
        'COMMENTS_VISIBLE_TO_ALL', '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')

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

    # ── Stripe / Billing (MT-8) ──────────────────────────────────────────────
    # BILLING_ENABLED=false by default — inert until explicitly flipped.
    # Flip to true only after STRIPE_* keys are set and plans have stripe_price_id.
    BILLING_ENABLED         = os.environ.get('BILLING_ENABLED', 'false').strip().lower() in ('1', 'true', 'yes', 'on')
    STRIPE_SECRET_KEY       = os.environ.get('STRIPE_SECRET_KEY')
    STRIPE_PUBLISHABLE_KEY  = os.environ.get('STRIPE_PUBLISHABLE_KEY')
    STRIPE_WEBHOOK_SECRET   = os.environ.get('STRIPE_WEBHOOK_SECRET')
    STRIPE_PRICE_STARTER    = os.environ.get('STRIPE_PRICE_STARTER')
    STRIPE_PRICE_PRO        = os.environ.get('STRIPE_PRICE_PRO')
    STRIPE_PRICE_ENTERPRISE = os.environ.get('STRIPE_PRICE_ENTERPRISE')

    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.


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