"""EasyPost-style rates/labels plus Pirate Ship CSV export."""

from __future__ import annotations

import csv
import io
import logging
from decimal import Decimal

import requests
from django.conf import settings

from shipping.models import Shipment
from shop.models import Order

logger = logging.getLogger(__name__)


class ShippingError(RuntimeError):
    pass


def _easypost_key() -> str:
    return (getattr(settings, "EASYPOST_API_KEY", "") or "").strip()


def quote_rates(shipment: Shipment) -> list[dict]:
    """Return carrier rates. Uses EasyPost when configured; otherwise a USPS stub."""
    key = _easypost_key()
    if not key:
        rates = [
            {
                "id": "stub-usps-ground",
                "carrier": "USPS",
                "service": "GroundAdvantage",
                "rate": "5.40",
                "currency": "USD",
            },
            {
                "id": "stub-usps-priority",
                "carrier": "USPS",
                "service": "Priority",
                "rate": "9.80",
                "currency": "USD",
            },
        ]
        shipment.rates = rates
        shipment.status = Shipment.Status.RATED
        shipment.save(update_fields=["rates", "status", "updated_at"])
        return rates

    addr = shipment.order.shipping_address or {}
    response = requests.post(
        "https://api.easypost.com/v2/shipments",
        auth=(key, ""),
        json={
            "shipment": {
                "to_address": {
                    "name": shipment.order.customer_name or shipment.order.email,
                    "street1": addr.get("line1") or "",
                    "street2": addr.get("line2") or "",
                    "city": addr.get("city") or "",
                    "state": addr.get("state") or "",
                    "zip": addr.get("zip") or "",
                    "country": addr.get("country") or "US",
                },
                "from_address": {
                    "name": settings.SITE_NAME,
                    "street1": getattr(settings, "SHIP_FROM_LINE1", "") or "",
                    "city": getattr(settings, "SHIP_FROM_CITY", "") or "",
                    "state": getattr(settings, "SHIP_FROM_STATE", "") or "",
                    "zip": getattr(settings, "SHIP_FROM_ZIP", "") or "",
                    "country": "US",
                },
                "parcel": {"weight": shipment.weight_oz},
            }
        },
        timeout=20,
    )
    response.raise_for_status()
    data = response.json()
    rates = data.get("rates") or []
    shipment.provider_shipment_id = data.get("id") or ""
    shipment.rates = rates
    shipment.status = Shipment.Status.RATED
    shipment.save(
        update_fields=["provider_shipment_id", "rates", "status", "updated_at"]
    )
    return rates


def buy_label(shipment: Shipment, *, rate_id: str = "") -> Shipment:
    rates = shipment.rates or quote_rates(shipment)
    chosen = None
    if rate_id:
        chosen = next((r for r in rates if str(r.get("id")) == str(rate_id)), None)
    if chosen is None and rates:
        chosen = rates[0]
    if chosen is None:
        raise ShippingError("No shipping rates available.")

    key = _easypost_key()
    if key and shipment.provider_shipment_id:
        response = requests.post(
            f"https://api.easypost.com/v2/shipments/{shipment.provider_shipment_id}/buy",
            auth=(key, ""),
            json={"rate": {"id": chosen.get("id")}},
            timeout=20,
        )
        response.raise_for_status()
        data = response.json()
        postage = data.get("postage_label") or {}
        tracking = data.get("tracking_code") or ""
        shipment.label_url = postage.get("label_url") or ""
        shipment.tracking_number = tracking
    else:
        shipment.tracking_number = f"STUB{shipment.order.number[-6:]}"
        shipment.label_url = ""

    shipment.carrier = chosen.get("carrier") or ""
    shipment.service = chosen.get("service") or ""
    try:
        shipment.rate_amount = Decimal(str(chosen.get("rate") or "0"))
    except Exception:
        shipment.rate_amount = None
    shipment.status = Shipment.Status.LABELED
    shipment.save(
        update_fields=[
            "carrier",
            "service",
            "tracking_number",
            "label_url",
            "rate_amount",
            "status",
            "updated_at",
        ]
    )
    return shipment


def create_shipment_for_order(order: Order, *, weight_oz: int = 16) -> Shipment:
    if order.status not in {Order.Status.PAID, Order.Status.FULFILLED}:
        raise ShippingError("Ship paid orders only.")
    return Shipment.objects.create(order=order, weight_oz=weight_oz)


def pirate_ship_csv(orders=None) -> str:
    """CSV Pirate Ship can map: name, address, city, state, zip, email."""
    if orders is None:
        shipped = Shipment.objects.filter(
            status=Shipment.Status.LABELED
        ).values_list("order_id", flat=True)
        orders = Order.objects.filter(status=Order.Status.PAID).exclude(pk__in=shipped)
    buffer = io.StringIO()
    writer = csv.writer(buffer)
    writer.writerow(
        [
            "Order Number",
            "Name",
            "Address 1",
            "Address 2",
            "City",
            "State",
            "Zip",
            "Country",
            "Email",
        ]
    )
    for order in orders:
        addr = order.shipping_address or {}
        writer.writerow(
            [
                order.number,
                order.customer_name or order.email,
                addr.get("line1") or "",
                addr.get("line2") or "",
                addr.get("city") or "",
                addr.get("state") or "",
                addr.get("zip") or "",
                addr.get("country") or "US",
                order.email,
            ]
        )
    return buffer.getvalue()