"""platform/mailer — the outbound email port (SD-0001 §6.2).

A one-method port `send(to, subject, body)` with two adapters: `LogMailer` (dev/tests —
the message lands in the app log and an in-memory outbox tests read back, §6.8) and the
deployed `SmtpMailer` (relay coordinates from configuration, INV-8). The adapter is chosen
by configuration at startup, so no deployment shape lives in the domain. LogMailer logs the
full body on purpose: that is PUC-10's "local dev channel" — the one-time code reaches the
developer in the terminal. SmtpMailer never logs the body or the recipient (INV-3 / §6.6
log hygiene) and raises MailerError on delivery failure (INV-9 → the §6.4 502).
"""
from __future__ import annotations

import hashlib
import logging
import smtplib
from dataclasses import dataclass
from email.message import EmailMessage
from typing import Protocol

from app.platform import config

logger = logging.getLogger("ecomm.mailer")


class MailerError(Exception):
    """Delivery failed — the relay refused or was unreachable (INV-9)."""


@dataclass(frozen=True)
class SentMessage:
    to: str
    subject: str
    body: str


class Mailer(Protocol):
    """The outbound-message port. Raises on delivery failure (INV-9 → §6.4 502)."""

    def send(self, to: str, subject: str, body: str) -> None: ...


class LogMailer:
    """Dev/test adapter: records to an in-memory outbox and logs the message (PUC-10)."""

    def __init__(self) -> None:
        self.outbox: list[SentMessage] = []

    def send(self, to: str, subject: str, body: str) -> None:
        self.outbox.append(SentMessage(to=to, subject=subject, body=body))
        # Full body incl. the code — the local dev channel. Dev/test only (never deployed).
        logger.info("LogMailer -> %s | %s\n%s", to, subject, body)


class SmtpMailer:
    """Deployed adapter: real mail over an SMTP relay (STARTTLS + login by default).

    Logs only a hashed recipient — never the address, subject, or body (§6.6).
    """

    def __init__(self, host: str, port: int, user: str, password: str, sender: str, starttls: bool) -> None:
        self._host, self._port = host, port
        self._user, self._password = user, password
        self._sender, self._starttls = sender, starttls

    def send(self, to: str, subject: str, body: str) -> None:
        msg = EmailMessage()
        msg["To"] = to
        msg["From"] = self._sender
        msg["Subject"] = subject
        msg.set_content(body)
        to_hash = hashlib.sha256(to.encode("utf-8")).hexdigest()[:8]
        try:
            with smtplib.SMTP(self._host, self._port, timeout=10) as smtp:
                if self._starttls:
                    smtp.starttls()
                if self._user:
                    smtp.login(self._user, self._password)
                smtp.send_message(msg)
        except Exception as exc:
            logger.warning("smtp send FAILED to=%s: %s", to_hash, type(exc).__name__)
            raise MailerError(str(exc)) from exc
        logger.info("smtp sent to=%s", to_hash)


def build_mailer(kind: str) -> Mailer:
    """Select the mailer adapter by configured kind (config.mailer_kind(), INV-8)."""
    if kind == "log":
        return LogMailer()
    if kind == "smtp":
        return SmtpMailer(
            host=config.smtp_host(),
            port=config.smtp_port(),
            user=config.smtp_user(),
            password=config.smtp_password(),
            sender=config.smtp_from(),
            starttls=config.smtp_starttls(),
        )
    raise ValueError(f"unknown mailer kind: {kind!r}")