"""
MeshBay Hub — email sending via localhost Postfix.

Postfix listens on loopback only (inet_interfaces = loopback-only), so no
authentication is needed. See docs/MAIL-SERVER.md for the full setup.
"""

import logging
import smtplib
from email.message import EmailMessage

log = logging.getLogger(__name__)

_hub_domain: str = "meshbay.org"
_hub_url: str = "https://meshbay.org"


def configure(hub_id: str) -> None:
    global _hub_domain, _hub_url
    _hub_domain = hub_id
    _hub_url = f"https://{hub_id}"


def _send(msg: EmailMessage) -> bool:
    try:
        with smtplib.SMTP("localhost", 25, timeout=10) as s:
            s.send_message(msg)
        return True
    except Exception:
        log.exception("Failed to send email to %s", msg["To"])
        return False


def send_verification_code(to: str, code: str, recovery_key: str | None = None) -> None:
    """
    Registration verification e-mail. When `recovery_key` is given it is
    appended to the body so the recipient's mailbox becomes the backup for it
    (docs/auth-confirm.md §4.4).

    `recovery_key` is a **pass-through**: it is generated on the client, never
    stored anywhere on the hub, and never logged — only whether one was present.
    """
    body = (
        f"Your verification code is: {code}\n"
        "\n"
        "Enter this code to verify your email address.\n"
        "This code expires in 24 hours.\n"
    )
    if recovery_key:
        body += (
            "\n"
            "---- Account recovery key ----\n"
            "\n"
            "Keep this message. If you ever forget your passphrase, this key is\n"
            "what restores your access to your groups. It is not stored on the\n"
            f"server and nobody at {_hub_domain} can recover it for you.\n"
            "\n"
            f"    {recovery_key}\n"
        )
    body += (
        "\n"
        "If you did not create a MeshBay account, ignore this email.\n"
        "\n"
        f"{_hub_url}\n"
    )
    msg = EmailMessage()
    msg["From"] = f"noreply@{_hub_domain}"
    msg["To"] = to
    msg["Subject"] = f"MeshBay — Your verification code: {code}"
    msg.set_content(body)
    _send(msg)
    log.info("Verification code sent to %s (recovery_key=%s)",
             _mask_email(to), bool(recovery_key))


def send_email_change_code(to: str, code: str) -> None:
    msg = EmailMessage()
    msg["From"] = f"noreply@{_hub_domain}"
    msg["To"] = to
    msg["Subject"] = f"MeshBay — Confirm your new email: {code}"
    msg.set_content(
        f"Your verification code is: {code}\n"
        "\n"
        "Enter this code to confirm your new email address.\n"
        "This code expires in 24 hours.\n"
        "\n"
        "If you did not request this change, ignore this email.\n"
        "\n"
        f"{_hub_url}\n"
    )
    _send(msg)
    log.info("Email change code sent to %s", _mask_email(to))


def send_password_reset_code(to: str, code: str) -> None:
    """
    Passphrase-reset code (docs/auth-confirm.md §4.2). This only re-opens hub
    login; it recovers no group content — that needs the recovery key.
    """
    msg = EmailMessage()
    msg["From"] = f"noreply@{_hub_domain}"
    msg["To"] = to
    msg["Subject"] = f"MeshBay — Passphrase reset code: {code}"
    msg.set_content(
        f"Your passphrase reset code is: {code}\n"
        "\n"
        "Enter it to set a new passphrase. This code expires in 1 hour.\n"
        "\n"
        "This restores your sign-in only. If you also have your recovery key,\n"
        "you can restore access to your groups in the same step.\n"
        "\n"
        "If you did not request this, ignore this email — your account is\n"
        "unchanged.\n"
        "\n"
        f"{_hub_url}\n"
    )
    _send(msg)
    log.info("Passphrase reset code sent to %s", _mask_email(to))


def send_invite_notification(
    to: str, code: str, inviter: str, group_name: str,
) -> None:
    msg = EmailMessage()
    msg["From"] = f"noreply@{_hub_domain}"
    msg["To"] = to
    msg["Subject"] = f"MeshBay — {inviter} invited you to {group_name}"
    msg.set_content(
        f"{inviter} invited you to the group \"{group_name}\" on MeshBay.\n"
        "\n"
        f"Your one-time code is: {code}\n"
        "\n"
        "Open the group and enter this code when prompted.\n"
        "The code works once and expires in 7 days.\n"
        "\n"
        f"{_hub_url}\n"
    )
    _send(msg)
    log.info("Invite notification sent to %s", _mask_email(to))


def _mask_email(email: str) -> str:
    local, _, domain = email.partition("@")
    if len(local) <= 2:
        return f"{'*' * len(local)}@{domain}"
    return f"{local[0]}{'*' * (len(local) - 2)}{local[-1]}@{domain}"