## Copyright © 2026 Olaf Kolkman
## SPDX-License-Identifier: GPL-3.0-or-later

from email.message import EmailMessage
from smtplib import SMTP
import json

from backend.app.core.config import settings
from backend.app.database import get_connection


def get_smtp_settings() -> dict:
    values = {
        'smtp_host': settings.smtp_host,
        'smtp_port': settings.smtp_port,
        'smtp_username': settings.smtp_username,
        'smtp_password': settings.smtp_password,
        'smtp_from': settings.smtp_from,
        'smtp_use_tls': settings.smtp_use_tls,
    }
    with get_connection() as conn:
        row = conn.execute('SELECT value FROM app_settings WHERE name = ?', ('smtp',)).fetchone()
    if row:
        values.update(json.loads(row['value']))
    return values


def save_smtp_settings(values: dict) -> None:
    with get_connection() as conn:
        conn.execute(
            '''INSERT INTO app_settings (name, value, updated_at) VALUES (?, ?, CURRENT_TIMESTAMP)
               ON CONFLICT(name) DO UPDATE SET value = excluded.value, updated_at = CURRENT_TIMESTAMP''',
            ('smtp', json.dumps(values)),
        )
        conn.commit()


def smtp_configured(smtp_values: dict | None = None) -> bool:
    smtp = smtp_values or get_smtp_settings()
    return bool(smtp['smtp_host'] and smtp['smtp_from'])


def send_message(email: str, subject: str, body: str, smtp_values: dict | None = None) -> None:
    smtp = smtp_values or get_smtp_settings()
    if not smtp_configured(smtp):
        raise RuntimeError('SMTP is not configured; set LINKLOG_SMTP_HOST and LINKLOG_SMTP_FROM')

    message = EmailMessage()
    message['Subject'] = subject
    message['From'] = smtp['smtp_from']
    message['To'] = email
    message.set_content(body)

    with SMTP(smtp['smtp_host'], smtp['smtp_port'], timeout=10) as connection:
        if smtp['smtp_use_tls']:
            connection.starttls()
        if smtp['smtp_username']:
            connection.login(smtp['smtp_username'], smtp['smtp_password'])
        connection.send_message(message)


def send_verification_email(email: str, username: str, verification_url: str) -> None:
    send_message(
        email,
        'Verify your LinkLog email address',
        f'Hello {username},\n\n'
        f'Verify your LinkLog email address by opening this link:\n{verification_url}\n\n'
        f'This link expires in {settings.email_verification_expiry_hours} hours.\n',
    )


def send_test_email(email: str, smtp_values: dict | None = None) -> None:
    send_message(
        email,
        'LinkLog SMTP test',
        'This is a test message from LinkLog. SMTP is configured correctly.\n',
        smtp_values,
    )


def send_password_reset_email(email: str, username: str, reset_url: str) -> None:
    send_message(
        email,
        'Reset your LinkLog password',
        f'Hello {username},\n\n'
        f'Reset your LinkLog password by opening this link:\n{reset_url}\n\n'
        f'This link expires in {settings.password_reset_expiry_hours} hours.\n',
    )