#!/usr/bin/env python3
"""Send one explicit SMTP delivery test email using local .env settings."""

import argparse
import os
import smtplib
import ssl
import sys
from datetime import datetime, timezone
from email.message import EmailMessage
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():
    parser = argparse.ArgumentParser(description="Send an Eternity Project SMTP test email.")
    parser.add_argument("--to", required=True, help="Recipient email address")
    args = parser.parse_args()

    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)}")

    message = EmailMessage()
    message["Subject"] = "Eternity Project SMTP verification"
    message["From"] = os.environ["MAIL_FROM"]
    message["To"] = args.to
    message.set_content(
        f"SMTP delivery verification completed at {datetime.now(timezone.utc).isoformat()}.\n"
        "You can now test password-reset delivery from the application."
    )

    try:
        with smtplib.SMTP(os.environ["MAIL_HOST"], int(os.environ["MAIL_PORT"]), timeout=15) as client:
            client.ehlo()
            client.starttls(context=ssl.create_default_context())
            client.ehlo()
            client.login(os.environ["MAIL_USERNAME"], os.environ["MAIL_PASSWORD"])
            client.send_message(message)
    except (OSError, smtplib.SMTPException) as error:
        print(f"SMTP_TEST_FAILED: {error}", file=sys.stderr)
        return 1

    print(f"SMTP_TEST_SENT_TO={args.to}")
    return 0


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