"""The shipment API.

The portal form and the API must agree: the fields the buyer's page reads are
required, and a departure after the arrival is refused. The permission boundary
itself is swept in ``apps/core/tests.py``; these pin the serializer rules so the
API cannot accept what the ops form refuses.
"""
from django.contrib.auth import get_user_model
from django.test import TestCase
from rest_framework.test import APIClient

from apps.batches.models import ProcessingBatch

from .models import Shipment

User = get_user_model()


class ShipmentAPITests(TestCase):
    def setUp(self):
        self.ops = User.objects.create_user(
            email="ship-api-ops@ixg.local", password="pass1234", role="ops",
            full_name="Shipment API Ops", is_staff=True,
        )
        self.buyer = User.objects.create_user(
            email="ship-api-buyer@ixg.local", password="pass1234", role="buyer",
            full_name="Shipment API Buyer", is_staff=True,
        )
        self.batch = ProcessingBatch.objects.create(
            batch_reference="IXG-BATCH-API-SHIP-001", status="ready_to_ship",
        )
        self.shipment = Shipment.objects.create(
            batch=self.batch, status=Shipment.Status.BOOKED,
            vessel_name="MV API", container_ref="IXGU0000001",
            etd_nigeria="2026-09-15", eta_uk="2026-10-15",
        )
        self.client = APIClient()

    def payload(self, **overrides):
        data = {
            "batch": str(self.batch.pk),
            "status": "booked",
            "vessel_name": "MV API",
            "container_ref": "IXGU0000002",
            "etd_nigeria": "2026-09-20",
            "eta_uk": "2026-10-20",
        }
        data.update(overrides)
        return data

    def test_a_buyer_cannot_read_or_write_shipments(self):
        self.client.force_authenticate(user=self.buyer)
        self.assertEqual(self.client.get("/api/shipments/").status_code, 403)
        self.assertEqual(
            self.client.post("/api/shipments/", self.payload(), format="json").status_code,
            403,
        )

    def test_ops_can_create_a_shipment(self):
        self.client.force_authenticate(user=self.ops)
        response = self.client.post("/api/shipments/", self.payload(), format="json")
        self.assertEqual(response.status_code, 201)
        self.assertEqual(Shipment.objects.count(), 2)

    def test_each_required_field_is_refused_when_blank(self):
        self.client.force_authenticate(user=self.ops)
        for field in (
            "status", "vessel_name", "container_ref", "etd_nigeria", "eta_uk",
        ):
            with self.subTest(field=field):
                response = self.client.post(
                    "/api/shipments/", self.payload(**{field: ""}), format="json"
                )
                self.assertEqual(response.status_code, 400)
                self.assertIn(field, response.json())
        self.assertEqual(Shipment.objects.count(), 1)

    def test_a_departure_after_the_arrival_is_refused(self):
        self.client.force_authenticate(user=self.ops)
        response = self.client.post(
            "/api/shipments/",
            self.payload(etd_nigeria="2026-11-01", eta_uk="2026-10-01"),
            format="json",
        )
        self.assertEqual(response.status_code, 400)
        self.assertIn("eta_uk", response.json())
        self.assertEqual(Shipment.objects.count(), 1)

    def test_a_partial_status_change_does_not_require_the_other_fields(self):
        self.client.force_authenticate(user=self.ops)
        response = self.client.patch(
            f"/api/shipments/{self.shipment.pk}/",
            {"status": "in_transit"},
            format="json",
        )
        self.assertEqual(response.status_code, 200)
        self.shipment.refresh_from_db()
        self.assertEqual(self.shipment.status, Shipment.Status.IN_TRANSIT)