#!/usr/bin/env python3
"""Verify SMTP connectivity and authentication without sending email."""

import os
import smtplib
import ssl
import sys
from pathlib import Path

REQUIRED_SETTINGS = ("MAIL_HOST", "MAIL_PORT", "MAIL_USERNAME", "MAIL_PASSWORD", "MAIL_FROM")


def load_dotenv(path):
    if not path.is_file():
        raise RuntimeError("Missing .env. Copy .env.example to .env and enter the SMTP settings.")
    for line in path.read_text(encoding="utf-8").splitlines():
        line = line.strip()
        if not line or line.startswith("#"):
            continue
        key, separator, value = line.partition("=")
        if separator and key.strip():
            os.environ.setdefault(key.strip(), value.strip().strip('"').strip("'"))


def main():
    project_root = Path(__file__).resolve().parent.parent
    load_dotenv(project_root / ".env")
    missing = [setting for setting in REQUIRED_SETTINGS if not os.environ.get(setting)]
    if missing:
        raise RuntimeError(f"Missing required SMTP settings: {', '.join(missing)}")

    host = os.environ["MAIL_HOST"]
    port = int(os.environ["MAIL_PORT"])
    username = os.environ["MAIL_USERNAME"]
    password = os.environ["MAIL_PASSWORD"]
    context = ssl.create_default_context()

    try:
        with smtplib.SMTP(host, port, timeout=15) as client:
            client.ehlo()
            client.starttls(context=context)
            client.ehlo()
            client.login(username, password)
    except (OSError, smtplib.SMTPException) as error:
        print(f"SMTP_CONNECTION_FAILED: {error}", file=sys.stderr)
        return 1

    print(f"SMTP_CONNECTION_OK: {host}:{port} authenticated as {username}")
    return 0


if __name__ == "__main__":
    try:
        raise SystemExit(main())
    except (RuntimeError, ValueError) as error:
        print(f"SMTP_CONFIGURATION_ERROR: {error}", file=sys.stderr)
        raise SystemExit(2)