api/email_utils.py

"""
Email utilities — send verification codes via Resend HTTP API (primary)
with SMTP fallback.
"""

import os
import random
import string
import socket
import smtplib
import logging
import threading
import requests as http_requests
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart

# ── Force IPv4 strictly to avoid Docker 'Errno 101 Network is unreachable' on IPv6 loops
_orig_getaddrinfo = socket.getaddrinfo
def _ipv4_only_getaddrinfo(*args, **kwargs):
    responses = _orig_getaddrinfo(*args, **kwargs)
    return [r for r in responses if r[0] == socket.AF_INET]
socket.getaddrinfo = _ipv4_only_getaddrinfo

logger = logging.getLogger(__name__)

# ── Brevo Configuration (preferred — bypasses HF SMTP firewall) ──────
BREVO_API_KEY = os.getenv("BREVO_API_KEY", "")
BREVO_FROM_EMAIL = os.getenv("BREVO_FROM_EMAIL", "bantaypahayag@gmail.com")
BREVO_FROM_NAME = os.getenv("BREVO_FROM_NAME", "BantayPahayag Verification")

# ── SMTP Configuration (fallback) ────────────────────────────────────
SMTP_HOST = os.getenv("SMTP_HOST", "smtp.gmail.com")
SMTP_PORT = int(os.getenv("SMTP_PORT", "587"))
SMTP_USER = os.getenv("SMTP_USER", "")
SMTP_PASSWORD = os.getenv("SMTP_PASSWORD", "")
SMTP_FROM_NAME = os.getenv("SMTP_FROM_NAME", "BantayPahayag")
SMTP_TIMEOUT = int(os.getenv("SMTP_TIMEOUT", "10"))  # seconds


def generate_verification_code(length: int = 6) -> str:
    """Generate a random numeric verification code."""
    return "".join(random.choices(string.digits, k=length))


# ═══════════════════════════════════════════════════════════════════════
#  BREVO HTTP API (Primary — works on Hugging Face Free Tier)
# ═══════════════════════════════════════════════════════════════════════

def _send_via_brevo(to_email: str, subject: str, html_body: str) -> bool:
    """Send email via Brevo HTTP API (port 443 — not blocked by HF)."""
    if not BREVO_API_KEY:
        logger.warning("BREVO_API_KEY not configured. Cannot send via Brevo.")
        return False

    try:
        resp = http_requests.post(
            "https://api.brevo.com/v3/smtp/email",
            headers={
                "api-key": BREVO_API_KEY,
                "Content-Type": "application/json",
                "Accept": "application/json"
            },
            json={
                "sender": {"name": BREVO_FROM_NAME, "email": BREVO_FROM_EMAIL},
                "to": [{"email": to_email}],
                "subject": subject,
                "htmlContent": html_body,
            },
            timeout=15,
        )
        if resp.status_code in (200, 201):
            logger.info("✅ Email sent via Brevo to %s (id: %s)", to_email, resp.json().get("messageId"))
            return True
        else:
            logger.error("Brevo API error %s: %s", resp.status_code, resp.text)
            return False
    except Exception as exc:
        logger.error("Brevo request failed: %s", exc)
        return False

    try:
        resp = http_requests.post(
            "https://api.resend.com/emails",
            headers={
                "Authorization": f"Bearer {RESEND_API_KEY}",
                "Content-Type": "application/json",
            },
            json={
                "from": RESEND_FROM,
                "to": [to_email],
                "subject": subject,
                "html": html_body,
            },
            timeout=15,
        )
        if resp.status_code in (200, 201):
            logger.info("✅ Email sent via Resend to %s (id: %s)", to_email, resp.json().get("id"))
            return True
        else:
            logger.error("Resend API error %s: %s", resp.status_code, resp.text)
            return False
    except Exception as exc:
        logger.error("Resend request failed: %s", exc)
        return False


# ═══════════════════════════════════════════════════════════════════════
#  SMTP FALLBACK (works on local dev, blocked on HF Free Tier)
# ═══════════════════════════════════════════════════════════════════════

def _send_via_smtp(to_email: str, subject: str, html_body: str, text_body: str) -> bool:
    """Send email via traditional SMTP. Works locally, blocked on HF."""
    if not SMTP_USER or not SMTP_PASSWORD:
        return False

    try:
        msg = MIMEMultipart("alternative")
        msg["Subject"] = subject
        msg["From"] = f"{SMTP_FROM_NAME} <{SMTP_USER}>"
        msg["To"] = to_email
        msg.attach(MIMEText(text_body, "plain"))
        msg.attach(MIMEText(html_body, "html"))

        with smtplib.SMTP(SMTP_HOST, SMTP_PORT, timeout=SMTP_TIMEOUT) as server:
            server.starttls()
            server.login(SMTP_USER, SMTP_PASSWORD)
            server.sendmail(SMTP_USER, to_email, msg.as_string())

        logger.info("✅ Email sent via SMTP to %s", to_email)
        return True
    except Exception as exc:
        logger.warning("SMTP failed for %s: %s", to_email, exc)
        return False


# ═══════════════════════════════════════════════════════════════════════
#  VERIFICATION EMAIL
# ═══════════════════════════════════════════════════════════════════════

def _build_verification_html(code: str, username: str = "") -> str:
    return f"""
    <div style="font-family: 'Segoe UI', Arial, sans-serif; max-width: 480px; margin: 0 auto;
                padding: 32px 24px; background: #ffffff; border-radius: 12px;
                border: 1px solid #e2e8f0;">
        <div style="text-align: center; margin-bottom: 24px;">
            <div style="display: inline-block; background: linear-gradient(135deg, #1E3A8A, #3B82F6);
                        color: white; font-size: 20px; font-weight: 800; padding: 12px 24px;
                        border-radius: 10px; letter-spacing: 0.5px;">
                BantayPahayag
            </div>
        </div>

        <h2 style="color: #0F172A; font-size: 22px; margin: 0 0 8px 0; text-align: center;">
            Verify Your Email
        </h2>

        <p style="color: #64748B; font-size: 14px; line-height: 1.6; text-align: center; margin: 0 0 24px 0;">
            Hi{' ' + username if username else ''}! Use the code below to verify your email address
            and activate your BantayPahayag account.
        </p>

        <div style="background: linear-gradient(135deg, #F8FAFC, #EFF6FF); border: 2px solid #3B82F6; border-radius: 12px;
                    padding: 24px; text-align: center; margin: 0 0 24px 0; box-shadow: 0 4px 6px -1px rgba(59, 130, 246, 0.1);">
            <div style="font-size: 38px; font-weight: 800; letter-spacing: 12px; color: #1E3A8A;
                        font-family: 'Outfit', 'Inter', 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;">
                {code}
            </div>
        </div>

        <p style="color: #94A3B8; font-size: 12px; text-align: center; margin: 0 0 8px 0;">
            This code expires in <strong>10 minutes</strong>.
        </p>
        <p style="color: #94A3B8; font-size: 12px; text-align: center; margin: 0;">
            If you didn't create a BantayPahayag account, you can safely ignore this email.
        </p>

        <hr style="border: none; border-top: 1px solid #e2e8f0; margin: 24px 0 16px 0;" />

        <p style="color: #CBD5E1; font-size: 11px; text-align: center; margin: 0;">
            BantayPahayag \u2014 News Verification System<br/>
            Cavite State University Thesis Project
        </p>
    </div>
    """


def _send_verification_email_worker(to_email: str, code: str, username: str = "") -> None:
    """Background worker: tries Resend first, then SMTP fallback."""
    # Always log the code for demo/debugging purposes
    logger.warning("==================================================================")
    logger.warning("   [VERIFICATION CODE]")
    logger.warning("   USER: %s", to_email)
    logger.warning("   CODE: %s", code)
    logger.warning("==================================================================")

    subject = f"BantayPahayag \u2014 Your Verification Code: {code}"
    html = _build_verification_html(code, username)

    # Try Brevo first (works on HF)
    if _send_via_brevo(to_email, subject, html):
        return

    # Fallback to SMTP (works locally)
    text_body = (
        f"BantayPahayag \u2014 Email Verification\n\n"
        f"Hi{' ' + username if username else ''}!\n\n"
        f"Your verification code is: {code}\n\n"
        f"This code expires in 10 minutes.\n\n"
        f"If you didn't create a BantayPahayag account, ignore this email."
    )
    if _send_via_smtp(to_email, subject, html, text_body):
        return

    logger.warning("All email channels failed for %s. Code is in logs above.", to_email)


def send_verification_email(to_email: str, code: str, username: str = "") -> bool:
    """Send verification email in a background thread (fire-and-forget)."""
    thread = threading.Thread(
        target=_send_verification_email_worker,
        args=(to_email, code, username),
        daemon=True,
    )
    thread.start()
    logger.info("Verification email queued for %s", to_email)
    return True


# ═══════════════════════════════════════════════════════════════════════
#  PASSWORD RESET EMAIL
# ═══════════════════════════════════════════════════════════════════════

def _build_reset_html(code: str, username: str = "") -> str:
    return f"""
    <div style="font-family: 'Segoe UI', Arial, sans-serif; max-width: 480px; margin: 0 auto;
                padding: 32px 24px; background: #ffffff; border-radius: 12px;
                border: 1px solid #e2e8f0;">
        <div style="text-align: center; margin-bottom: 24px;">
            <div style="display: inline-block; background: linear-gradient(135deg, #1E3A8A, #3B82F6);
                        color: white; font-size: 20px; font-weight: 800; padding: 12px 24px;
                        border-radius: 10px; letter-spacing: 0.5px;">
                BantayPahayag
            </div>
        </div>

        <h2 style="color: #0F172A; font-size: 22px; margin: 0 0 8px 0; text-align: center;">
            Reset Your Password
        </h2>

        <p style="color: #64748B; font-size: 14px; line-height: 1.6; text-align: center; margin: 0 0 24px 0;">
            Hi{' ' + username if username else ''}! You recently requested to reset your password.
            Use the code below to securely change it.
        </p>

        <div style="background: linear-gradient(135deg, #F8FAFC, #EFF6FF); border: 2px solid #3B82F6; border-radius: 12px;
                    padding: 24px; text-align: center; margin: 0 0 24px 0; box-shadow: 0 4px 6px -1px rgba(59, 130, 246, 0.1);">
            <div style="font-size: 38px; font-weight: 800; letter-spacing: 12px; color: #1E3A8A;
                        font-family: 'Outfit', 'Inter', 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;">
                {code}
            </div>
        </div>

        <p style="color: #94A3B8; font-size: 12px; text-align: center; margin: 0 0 8px 0;">
            This code expires in <strong>10 minutes</strong>.
        </p>
        <p style="color: #94A3B8; font-size: 12px; text-align: center; margin: 0;">
            If you did not request a password reset, you can safely ignore this email.
        </p>

        <hr style="border: none; border-top: 1px solid #e2e8f0; margin: 24px 0 16px 0;" />

        <p style="color: #CBD5E1; font-size: 11px; text-align: center; margin: 0;">
            BantayPahayag \u2014 News Verification System<br/>
            Cavite State University Thesis Project
        </p>
    </div>
    """


def _send_reset_email_worker(to_email: str, code: str, username: str = "") -> None:
    """Background worker: tries Resend first, then SMTP fallback."""
    # Always log the code for demo/debugging purposes
    logger.warning("==================================================================")
    logger.warning("   [PASSWORD RESET CODE]")
    logger.warning("   USER: %s", to_email)
    logger.warning("   CODE: %s", code)
    logger.warning("==================================================================")

    subject = f"BantayPahayag \u2014 Password Reset Code: {code}"
    html = _build_reset_html(code, username)

    # Try Brevo first (works on HF)
    if _send_via_brevo(to_email, subject, html):
        return

    # Fallback to SMTP (works locally)
    text_body = (
        f"BantayPahayag \u2014 Password Reset\n\n"
        f"Hi{' ' + username if username else ''}!\n\n"
        f"Your password reset code is: {code}\n\n"
        f"This code expires in 10 minutes.\n\n"
        f"If you did not request this, ignore this email."
    )
    if _send_via_smtp(to_email, subject, html, text_body):
        return

    logger.warning("All email channels failed for %s. Code is in logs above.", to_email)


def send_password_reset_email(to_email: str, code: str, username: str = "") -> bool:
    """Send password reset email in a background thread (fire-and-forget)."""
    thread = threading.Thread(
        target=_send_reset_email_worker,
        args=(to_email, code, username),
        daemon=True,
    )
    thread.start()
    logger.info("Password reset email queued for %s", to_email)
    return True