"""
Email integration configuration.

Reads from the same env-var surface as the rest of the CRM (server.py style),
no pydantic/dotenv magic — stdlib only.
"""

import os
from dataclasses import dataclass
from typing import Optional

# Reuse the CRM's data dir so backups and email storage live together.
_PROJECT_DIR = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
_DEFAULT_DATA_DIR = os.path.join(_PROJECT_DIR, "data")


def _bool_env(name: str, default: bool = False) -> bool:
    v = os.environ.get(name, "").strip().lower()
    if v in ("1", "true", "yes", "on"):
        return True
    if v in ("0", "false", "no", "off"):
        return False
    return default


def _int_env(name: str, default: int) -> int:
    try:
        return int(os.environ.get(name, str(default)))
    except (TypeError, ValueError):
        return default


@dataclass(frozen=True)
class EmailConfig:
    # Master kill switch. When False, scheduler doesn't start and routes
    # return 503. Migrations are still applied (so schema is ready).
    enabled: bool

    # Primary auth path. "dwd" means service account / domain-wide delegation.
    # "oauth" means per-user refresh tokens. DWD is default; OAuth is the
    # pluggable fallback.
    primary_auth: str

    # DWD specifics
    dwd_key_path: Optional[str]
    workspace_domain: Optional[str]

    # OAuth specifics (used for fallback + admin UI)
    oauth_client_id: Optional[str]
    oauth_client_secret: Optional[str]
    oauth_redirect_uri: Optional[str]

    # Encryption key (base64) for OAuth refresh-token-at-rest encryption.
    # Required whenever oauth path is in use. DWD path never persists tokens.
    secret_key_b64: Optional[str]

    # Sync scheduling
    sync_interval_sec: int
    backfill_page_size: int
    max_attachment_mb: int
    max_parallel_attachment_downloads: int

    # Storage
    data_dir: str
    attachments_dir: str
    secrets_dir: str

    # Rate limit / retry
    rate_limit_units_per_sec_per_account: int
    retry_max_attempts: int
    retry_initial_delay_sec: float
    retry_max_delay_sec: float

    # Gmail history retention — if we fall this far behind, switch to date
    # backfill since Gmail may have pruned history records.
    history_stale_days: int


def load() -> EmailConfig:
    data_dir = os.environ.get("CRM_DATA_DIR", _DEFAULT_DATA_DIR)
    return EmailConfig(
        enabled=_bool_env("CRM_GMAIL_INTEGRATION_ENABLED", False),
        primary_auth=os.environ.get("CRM_GMAIL_AUTH_METHOD", "dwd").lower(),
        dwd_key_path=os.environ.get("CRM_GMAIL_SA_KEY_PATH") or None,
        workspace_domain=os.environ.get("CRM_GMAIL_WORKSPACE_DOMAIN") or None,
        oauth_client_id=os.environ.get("CRM_GMAIL_OAUTH_CLIENT_ID") or None,
        oauth_client_secret=os.environ.get("CRM_GMAIL_OAUTH_CLIENT_SECRET") or None,
        oauth_redirect_uri=os.environ.get("CRM_GMAIL_OAUTH_REDIRECT_URI") or None,
        secret_key_b64=os.environ.get("CRM_GMAIL_SECRET_KEY") or None,
        sync_interval_sec=_int_env("CRM_GMAIL_SYNC_INTERVAL_MIN", 180) * 60,
        backfill_page_size=_int_env("CRM_GMAIL_BACKFILL_PAGE_SIZE", 500),
        max_attachment_mb=_int_env("CRM_GMAIL_MAX_ATTACHMENT_MB", 50),
        max_parallel_attachment_downloads=_int_env("CRM_GMAIL_ATTACH_CONCURRENCY", 4),
        data_dir=data_dir,
        attachments_dir=os.path.join(data_dir, "email_attachments"),
        secrets_dir=os.path.join(data_dir, "secrets"),
        rate_limit_units_per_sec_per_account=_int_env("CRM_GMAIL_RATE_UNITS_SEC", 150),
        retry_max_attempts=_int_env("CRM_GMAIL_RETRY_MAX", 5),
        retry_initial_delay_sec=float(os.environ.get("CRM_GMAIL_RETRY_INITIAL_SEC", "1.0")),
        retry_max_delay_sec=float(os.environ.get("CRM_GMAIL_RETRY_MAX_SEC", "60.0")),
        history_stale_days=_int_env("CRM_GMAIL_HISTORY_STALE_DAYS", 5),
    )


# Singleton. Reload with `reload_config()` if env changes (mostly for tests).
CONFIG = load()


def reload_config() -> EmailConfig:
    global CONFIG
    CONFIG = load()
    return CONFIG