"""Stripe invoice + Checkout pay-link helpers. Requires FEATURE_EMAIL_SMS to send."""

from __future__ import annotations

import logging
from datetime import date

from django.conf import settings
from django.urls import reverse
from django.utils import timezone

from payments.models import Invoice

logger = logging.getLogger(__name__)


class PaymentsError(RuntimeError):
    pass


def _stripe():
    secret = (settings.STRIPE_SECRET_KEY or "").strip()
    if not secret:
        raise PaymentsError("STRIPE_SECRET_KEY is not configured")
    try:
        import stripe
    except ImportError as exc:
        raise PaymentsError("stripe package is not installed") from exc
    stripe.api_key = secret
    return stripe


def next_invoice_number() -> str:
    today = date.today().strftime("%Y%m%d")
    prefix = f"INV-{today}-"
    existing = Invoice.objects.filter(number__startswith=prefix).count()
    return f"{prefix}{existing + 1:03d}"


def create_checkout_session(invoice: Invoice, *, success_url: str, cancel_url: str) -> str:
    stripe = _stripe()
    session = stripe.checkout.Session.create(
        mode="payment",
        customer_email=invoice.contact.email or None,
        line_items=[
            {
                "quantity": 1,
                "price_data": {
                    "currency": (invoice.currency or "usd").lower(),
                    "unit_amount": invoice.amount_cents,
                    "product_data": {
                        "name": invoice.description or f"Invoice {invoice.number}",
                    },
                },
            }
        ],
        metadata={"invoice_id": str(invoice.pk), "invoice_number": invoice.number},
        success_url=success_url,
        cancel_url=cancel_url,
    )
    invoice.stripe_checkout_session_id = session.id
    invoice.hosted_invoice_url = session.url or ""
    invoice.status = Invoice.Status.OPEN
    invoice.save(
        update_fields=[
            "stripe_checkout_session_id",
            "hosted_invoice_url",
            "status",
            "updated_at",
        ]
    )
    return session.url or ""


def mark_paid(invoice: Invoice, *, stripe_id: str = "") -> None:
    invoice.status = Invoice.Status.PAID
    invoice.paid_at = timezone.now()
    if stripe_id and not invoice.stripe_invoice_id:
        invoice.stripe_invoice_id = stripe_id
    invoice.save(
        update_fields=["status", "paid_at", "stripe_invoice_id", "updated_at"]
    )


def send_invoice_email(invoice: Invoice, pay_url: str) -> bool:
    """Send pay-link email through Django mail (SMTP2GO)."""
    to_email = (invoice.contact.email or "").strip()
    if not to_email:
        raise PaymentsError("Contact has no email address")
    from django.core.mail import EmailMultiAlternatives

    name = invoice.contact.full_name or "there"
    amount = f"{invoice.amount} {invoice.currency.upper()}"
    subject = f"Invoice {invoice.number} from {settings.SITE_NAME}"
    text = (
        f"Hi {name},\n\n"
        f"Invoice {invoice.number} for {amount} is ready.\n"
        f"{invoice.description}\n\n"
        f"Pay securely: {pay_url}\n"
    )
    html = (
        f"<p>Hi {name},</p>"
        f"<p>Invoice <strong>{invoice.number}</strong> for "
        f"<strong>{amount}</strong> is ready.</p>"
        f"<p>{invoice.description}</p>"
        f'<p><a href="{pay_url}">Pay this invoice</a></p>'
    )
    mail = EmailMultiAlternatives(
        subject=subject,
        body=text,
        from_email=settings.DEFAULT_FROM_EMAIL,
        to=[to_email],
    )
    mail.attach_alternative(html, "text/html")
    mail.send(fail_silently=False)
    return True