"""Runtime configuration for the mail API.

Loads environment variables once at import time, validates required values,
and exposes a frozen :class:`Settings` dataclass plus module-level constants
for compatibility with code that still imports the legacy names.
"""

from __future__ import annotations

import logging
import logging.handlers
import os
import re
import sys
from dataclasses import dataclass
from pathlib import Path

import resend


# ── Logging ──────────────────────────────────────────────────────────────────

def setup_logging() -> logging.Logger:
    log_dir = Path(os.environ.get("LOG_DIR", "logs"))
    log_dir.mkdir(parents=True, exist_ok=True)
    log_file = log_dir / "mail-api.log"

    fmt = logging.Formatter(
        "%(asctime)s %(levelname)-8s %(name)s: %(message)s",
        datefmt="%d/%m/%Y %H:%M:%S %Z",
    )

    root = logging.getLogger()
    root.setLevel(logging.DEBUG)
    for handler in list(root.handlers):
        root.removeHandler(handler)

    console = logging.StreamHandler(sys.stdout)
    console.setLevel(logging.INFO)
    console.setFormatter(fmt)
    root.addHandler(console)

    rotating = logging.handlers.RotatingFileHandler(
        log_file, maxBytes=2_000_000, backupCount=5, encoding="utf-8"
    )
    rotating.setLevel(logging.DEBUG)
    rotating.setFormatter(fmt)
    root.addHandler(rotating)

    log = logging.getLogger("mail-api")
    log.info("Logging initialised → console=INFO, file=%s (DEBUG, rotating)", log_file)
    return log


logger = setup_logging()


# ── Settings ─────────────────────────────────────────────────────────────────

DEV_MODE = os.environ.get("DEV_MODE", "").strip().lower() in {"1", "true", "yes"}

REQUIRED_ENV = {
    "RESEND_API_KEY": "API key from https://resend.com/api-keys",
    "OWNER_EMAIL": "Email address that receives new lead notifications",
}


def _parse_email_env_list(*values: str | None) -> list[str]:
    emails: list[str] = []
    seen: set[str] = set()
    for raw in values:
        if not raw:
            continue
        for part in re.split(r"[;,\s]+", raw.strip()):
            normalized = part.strip().lower()
            if normalized and normalized not in seen:
                seen.add(normalized)
                emails.append(normalized)
    return emails


@dataclass(frozen=True)
class Settings:
    resend_api_key: str
    owner_email: str
    cp_admin_emails: tuple[str, ...]
    from_email: str
    reply_to: str
    owner_bcc: str
    client_bcc: str
    enable_general_enquiries: bool
    max_attempts: int
    form_min_seconds: int
    form_max_seconds: int
    rate_limit_window_seconds: int
    rate_limit_max_per_ip: int
    rate_limit_max_per_email: int
    rate_limit_min_interval_seconds: int
    email_send_timeout_seconds: int


def _load_settings() -> Settings:
    if DEV_MODE:
        owner_email = os.environ.get("OWNER_EMAIL", "dev@localhost").strip().lower()
        return Settings(
            resend_api_key=os.environ.get("RESEND_API_KEY", "dev"),
            owner_email=owner_email,
            cp_admin_emails=tuple(_parse_email_env_list(
                owner_email,
                os.environ.get("SECONDARY_CP_EMAIL"),
                os.environ.get("SECONDARY_CP_EMAILS"),
            )),
            from_email=os.environ.get("FROM_EMAIL", "GoodWalk <info@goodwalk.co.nz>"),
            reply_to=os.environ.get("REPLY_TO", "info@goodwalk.co.nz"),
            owner_bcc="",
            client_bcc="",
            enable_general_enquiries=False,
            max_attempts=3,
            form_min_seconds=1,
            form_max_seconds=7200,
            rate_limit_window_seconds=900,
            rate_limit_max_per_ip=50,
            rate_limit_max_per_email=50,
            rate_limit_min_interval_seconds=1,
            email_send_timeout_seconds=20,
        )

    missing = [(name, hint) for name, hint in REQUIRED_ENV.items() if not os.environ.get(name)]
    if missing:
        lines = [
            "",
            "Mail API cannot start — required environment variables are not set:",
            "",
        ]
        for name, hint in missing:
            lines.append(f"  • {name}  ({hint})")
        lines += [
            "",
            "Set them in your shell and try again. For example, in PowerShell:",
            "",
        ]
        for name, _ in missing:
            lines.append(f'  $env:{name} = "..."')
        lines.append("")
        message = "\n".join(lines)
        logger.critical("Startup aborted: missing env vars: %s", [n for n, _ in missing])
        print(message, file=sys.stderr)
        sys.exit(1)

    owner_email = os.environ["OWNER_EMAIL"].strip().lower()
    return Settings(
        resend_api_key=os.environ["RESEND_API_KEY"],
        owner_email=owner_email,
        cp_admin_emails=tuple(_parse_email_env_list(
            owner_email,
            os.environ.get("SECONDARY_CP_EMAIL"),
            os.environ.get("SECONDARY_CP_EMAILS"),
        )),
        from_email=os.environ.get("FROM_EMAIL", "GoodWalk <info@goodwalk.co.nz>"),
        reply_to=os.environ.get("REPLY_TO", "info@goodwalk.co.nz"),
        owner_bcc=os.environ.get("OWNER_BCC", "example@example.com").strip(),
        client_bcc=os.environ.get("CLIENT_BCC", "").strip(),
        enable_general_enquiries=os.environ.get("ENABLE_GENERAL_ENQUIRIES", "false").strip().lower()
            in {"1", "true", "yes", "on", "enabled"},
        max_attempts=max(1, int(os.environ.get("MAIL_MAX_ATTEMPTS", "3"))),
        form_min_seconds=max(1, int(os.environ.get("FORM_MIN_SECONDS", "4"))),
        form_max_seconds=max(60, int(os.environ.get("FORM_MAX_SECONDS", "7200"))),
        rate_limit_window_seconds=max(60, int(os.environ.get("RATE_LIMIT_WINDOW_SECONDS", "900"))),
        rate_limit_max_per_ip=max(1, int(os.environ.get("RATE_LIMIT_MAX_PER_IP", "5"))),
        rate_limit_max_per_email=max(1, int(os.environ.get("RATE_LIMIT_MAX_PER_EMAIL", "3"))),
        rate_limit_min_interval_seconds=max(1, int(os.environ.get("RATE_LIMIT_MIN_INTERVAL_SECONDS", "20"))),
        email_send_timeout_seconds=max(5, int(os.environ.get("EMAIL_SEND_TIMEOUT_SECONDS", "20"))),
    )


settings = _load_settings()
resend.api_key = settings.resend_api_key

APP_VERSION = os.environ.get("APP_VERSION", "unknown")
AUTH_CODE_TTL_SECONDS = max(60, int(os.environ.get("AUTH_CODE_TTL_SECONDS", "600")))
AUTH_SESSION_TTL_SECONDS = max(3600, int(os.environ.get("AUTH_SESSION_TTL_SECONDS", str(7 * 24 * 3600))))
AUTH_CODE_MAX_ATTEMPTS = 5
AUTH_CODE_REQUESTS_PER_HOUR = 5
AUTH_IP_MAX_FAILURES = max(3, int(os.environ.get("AUTH_IP_MAX_FAILURES", "10")))
AUTH_IP_FAILURE_WINDOW = max(60, int(os.environ.get("AUTH_IP_FAILURE_WINDOW", "600")))
AUTH_IP_BLOCK_DURATION = max(60, int(os.environ.get("AUTH_IP_BLOCK_DURATION", "3600")))
BIRTHDAY_CHECK_INTERVAL_SECONDS = max(3600, int(os.environ.get("BIRTHDAY_CHECK_INTERVAL_SECONDS", str(12 * 3600))))


def _split_csv_env(name: str, default: str) -> tuple[str, ...]:
    # Treat empty-string env (e.g. compose `${VAR:-}`) the same as "unset" so
    # an unset compose key falls back to the default, not to an empty allowlist.
    raw = (os.environ.get(name) or "").strip() or default
    parts = [p.strip() for p in raw.split(",")]
    return tuple(p for p in parts if p)


CORS_ALLOWED_ORIGINS = _split_csv_env(
    "CORS_ALLOWED_ORIGINS",
    "https://goodwalk.co.nz,https://www.goodwalk.co.nz,https://clients.goodwalk.co.nz,https://cp.goodwalk.co.nz",
)
TRUSTED_HOSTS = _split_csv_env(
    "TRUSTED_HOSTS",
    "goodwalk.co.nz,www.goodwalk.co.nz,clients.goodwalk.co.nz,cp.goodwalk.co.nz,localhost,127.0.0.1",
)
# Hard cap on request body size. Signed contracts include a base64 PNG of the
# signature (~30 KB) plus form fields, so 2 MB is a generous ceiling.
MAX_REQUEST_BODY_BYTES = max(64 * 1024, int((os.environ.get("MAX_REQUEST_BODY_BYTES") or str(2 * 1024 * 1024)).strip() or str(2 * 1024 * 1024)))

_DATA_DIR = Path(os.environ.get("DATA_DIR", "data"))
ALLOWED_EMAILS_FILE = _DATA_DIR / "allowed_emails.json"
CLIENT_PROFILES_FILE = _DATA_DIR / "client_profiles.json"
DRAFTS_FILE = _DATA_DIR / "drafts.json"
# Legacy seed lives OUTSIDE the data volume — it's shipped in the image so a
# fresh deploy always carries the same baked-in copy. On boot the mail-api
# merges this dict into _client_profiles, adding any emails that aren't
# already present. It never overwrites a live entry.
LEGACY_SEED_FILE = Path(
    os.environ.get("LEGACY_SEED_FILE", "/app/legacy-clients-seed.json")
)

LOGO_URL = "https://www.goodwalk.co.nz/images/goodwalk-auckland-dog-walking-logo.png"

# ── Legacy module constants (kept for compatibility with the existing main.py) ──

OWNER_EMAIL = settings.owner_email
CP_ADMIN_EMAILS = set(settings.cp_admin_emails)
OWNER_BCC = settings.owner_bcc
CLIENT_BCC = settings.client_bcc
FROM_EMAIL = settings.from_email
REPLY_TO = settings.reply_to
ENABLE_GENERAL_ENQUIRIES = settings.enable_general_enquiries
MAX_SEND_ATTEMPTS = settings.max_attempts
FORM_MIN_SECONDS = settings.form_min_seconds
FORM_MAX_SECONDS = settings.form_max_seconds
RATE_LIMIT_WINDOW_SECONDS = settings.rate_limit_window_seconds
RATE_LIMIT_MAX_PER_IP = settings.rate_limit_max_per_ip
RATE_LIMIT_MAX_PER_EMAIL = settings.rate_limit_max_per_email
RATE_LIMIT_MIN_INTERVAL_SECONDS = settings.rate_limit_min_interval_seconds
EMAIL_SEND_TIMEOUT_SECONDS = settings.email_send_timeout_seconds

# Owner-BCC placeholder used by deploy.env.template; treat it as "unset" for the smoke email.
STARTUP_TEST_RECIPIENT = OWNER_BCC if OWNER_BCC and OWNER_BCC.lower() != "example@example.com" else ""

# Shared secret presented by the deploy script's post-deploy form smoke tests.
# When set, requests carrying a matching X-Deploy-Smoke header short-circuit the
# form handlers before any email/db side effects so production submissions stay
# clean. When unset, the bypass is fully disabled.
DEPLOY_SMOKE_SECRET = (os.environ.get("DEPLOY_SMOKE_SECRET") or "").strip()

logger.info(
    "Mail API config: version=%r timezone=%r from=%r reply_to=%r owner=%r cp_admins=%r owner_bcc=%r client_bcc=%r general_enquiries=%r max_attempts=%d form_min=%ss form_max=%ss rate_window=%ss per_ip=%d per_email=%d min_interval=%ss send_timeout=%ss",
    APP_VERSION,
    os.environ.get("TZ", "system-default"),
    FROM_EMAIL,
    REPLY_TO,
    OWNER_EMAIL,
    sorted(CP_ADMIN_EMAILS),
    OWNER_BCC,
    CLIENT_BCC,
    ENABLE_GENERAL_ENQUIRIES,
    MAX_SEND_ATTEMPTS,
    FORM_MIN_SECONDS,
    FORM_MAX_SECONDS,
    RATE_LIMIT_WINDOW_SECONDS,
    RATE_LIMIT_MAX_PER_IP,
    RATE_LIMIT_MAX_PER_EMAIL,
    RATE_LIMIT_MIN_INTERVAL_SECONDS,
    EMAIL_SEND_TIMEOUT_SECONDS,
)