import logging
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText

import aiosmtplib

from app.config import settings

logger = logging.getLogger(__name__)


async def send_email(to: str, subject: str, html_body: str) -> bool:
    """Send HTML email via SMTP. Returns True on success."""
    if not settings.smtp_host:
        logger.info(f"SMTP not configured, skipping email to {to}: {subject}")
        return False

    msg = MIMEMultipart("alternative")
    msg["From"] = f"{settings.smtp_from_name} <{settings.smtp_from_email}>"
    msg["To"] = to
    msg["Subject"] = subject
    msg.attach(MIMEText(html_body, "html"))

    try:
        await aiosmtplib.send(
            msg,
            hostname=settings.smtp_host,
            port=settings.smtp_port,
            username=settings.smtp_user,
            password=settings.smtp_password,
            use_tls=True,
        )
        return True
    except Exception as e:
        logger.error(f"Failed to send email to {to}: {e}")
        return False


async def send_registration_notification(
    admin_email: str, student_name: str, class_name: str
):
    html = f"""
    <h2>New Registration Pending Approval</h2>
    <p><strong>{student_name}</strong> has registered for <strong>{class_name}</strong>.</p>
    <p>Please log in to HKU ICB to review and approve.</p>
    """
    await send_email(admin_email, "HKU ICB: New Registration", html)


async def send_approval_notification(student_email: str, approved: bool):
    status_text = "approved" if approved else "rejected"
    html = f"""
    <h2>Registration {status_text.capitalize()}</h2>
    <p>Your registration has been <strong>{status_text}</strong>.</p>
    {"<p>You can now log in to HKU ICB.</p>" if approved else ""}
    """
    await send_email(
        student_email, f"HKU ICB: Registration {status_text.capitalize()}", html
    )


async def send_class_notification_email(
    emails: list[str],
    subject: str,
    title: str,
    body: str,
    action_url: str | None = None,
):
    """Send a styled notification email to class members."""
    action_html = ""
    if action_url:
        action_html = f"""
        <div style="margin-top: 20px;">
            <a href="{action_url}" style="display:inline-block;padding:10px 24px;background:#111827;color:#fff;border-radius:6px;text-decoration:none;font-size:14px;">
                查看详情
            </a>
        </div>
        """
    html = f"""
    <div style="max-width:600px;margin:0 auto;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;color:#1f2937;">
        <div style="padding:24px 0;border-bottom:2px solid #111827;">
            <h1 style="margin:0;font-size:20px;color:#111827;">HKU ICB</h1>
        </div>
        <div style="padding:24px 0;">
            <h2 style="margin:0 0 12px;font-size:18px;">{title}</h2>
            <div style="font-size:14px;line-height:1.6;color:#4b5563;">{body}</div>
            {action_html}
        </div>
        <div style="padding:16px 0;border-top:1px solid #e5e7eb;font-size:12px;color:#9ca3af;">
            此邮件由系统自动发送，请勿直接回复。
        </div>
    </div>
    """
    for email in emails:
        await send_email(email, subject, html)