"""
app/enrollment/mailer.py
------------------------
The enrollment confirmation email.

Sent to the requester after a submission is stored. One job, and it must never
be able to break that: the record is already safely on disk before this runs,
so every failure path here is logged and swallowed. A bounced confirmation must
not cost the customer their enrollment.

Sending happens on a background thread (rule 14 — never block the HTTP
response), and the From identity comes from branded_sender() so it stays an
SMTP-authorized address that actually delivers (rules 64 / 76).

This is the only part of app/enrollment that touches shared mail
infrastructure; it still imports no models and writes no DB row.
"""

import logging
import threading

from flask import current_app, render_template

logger = logging.getLogger(__name__)


def _text_body(record, people):
    """Plain-text alternative — some recipients see only this."""
    lines = [
        f'Hi {record.get("request_by") or "there"},',
        '',
        'Thank you — we have received your JQC enrollment form.',
        '',
        f'Reference: {record.get("id")}',
        f'Project:   {record.get("project_name")}',
        '',
        f'People to be set up ({len(people)}):',
    ]
    for i, person in enumerate(people, start=1):
        lines.append(
            f'  {i}. {person["name"]} — {person["role_label"]} — {person["email"]}'
        )
    lines += [
        '',
        'Our team will create these accounts. Each person will receive their own '
        'email invitation with sign-in instructions.',
        '',
        'If anything above is wrong, simply reply to this email and we will '
        'correct it.',
        '',
        'JQC by L.T Services, Inc',
    ]
    return '\n'.join(lines)


def send_confirmation(record, base_url=None):
    """Email the requester a copy of what they submitted. Never raises."""
    email = (record.get('requester_email') or '').strip()
    if not email:
        return

    if not current_app.config.get('MAIL_SERVER'):
        logger.warning('ENROLLMENT EMAIL SKIPPED | no MAIL_SERVER | id=%s',
                       record.get('id'))
        return

    try:
        from flask_mail import Message
        from app import mail
        from app.utils.mail_utils import branded_sender
        from . import schema

        effective_base = (base_url
                          or current_app.config.get('APP_BASE_URL', '')).rstrip('/')
        people = schema.people_of(record)

        msg = Message(
            subject    = f'[JQC] Enrollment received — {record.get("project_name")}',
            sender     = branded_sender(effective_base),
            recipients = [email],
            body       = _text_body(record, people),
            html       = render_template('enrollment/email_confirmation.html',
                                         record=record, people=people,
                                         schema=schema),
        )

        app = current_app._get_current_object()

        def _send():
            with app.app_context():
                try:
                    mail.send(msg)
                    logger.info('ENROLLMENT EMAIL SENT | to=%s | id=%s',
                                email, record.get('id'))
                except Exception as exc:
                    logger.error('ENROLLMENT EMAIL FAILED | to=%s | id=%s | error=%s',
                                 email, record.get('id'), exc)

        threading.Thread(target=_send, daemon=True).start()

    except Exception:
        # Building the message failed (bad template, mail misconfigured, …).
        # The submission is already saved — log it and move on.
        logger.exception('ENROLLMENT EMAIL BUILD FAILED | id=%s', record.get('id'))