import tempfile
from io import BytesIO
from pathlib import Path
from unittest.mock import patch

from django.core.files.uploadedfile import SimpleUploadedFile
from django.test import TestCase, override_settings
from PIL import Image
from rest_framework.test import APIClient


def png_upload(color=(32, 64, 128), size=(4, 4), name="sample.png"):
    buffer = BytesIO()
    Image.new("RGB", size, color).save(buffer, format="PNG")
    return SimpleUploadedFile(name, buffer.getvalue(), content_type="image/png")


class ApiTests(TestCase):
    def setUp(self):
        self.tmp = tempfile.TemporaryDirectory()
        self.override = override_settings(MEDIA_ROOT=Path(self.tmp.name), IMAGE_SESSION_TTL_HOURS=1)
        self.override.enable()
        self.client = APIClient()

    def tearDown(self):
        self.override.disable()
        self.tmp.cleanup()

    def test_upload_and_process(self):
        upload = self.client.post("/api/images/", {"image": png_upload()}, format="multipart")
        self.assertEqual(upload.status_code, 201)
        session_id = upload.data["session_id"]
        self.assertEqual(len(upload.data["original_histogram"]), 256)

        processed = self.client.post(
            "/api/process/",
            {"session_id": session_id, "operation": "gamma", "params": {"gamma": 1, "c": 1}},
            format="json",
        )
        self.assertEqual(processed.status_code, 200)
        self.assertEqual(len(processed.data["processed_histogram"]), 256)
        self.assertTrue(processed.data["image_data"].startswith("data:image/png;base64,"))

    def test_invalid_kernel_rejected(self):
        upload = self.client.post("/api/images/", {"image": png_upload()}, format="multipart")
        processed = self.client.post(
            "/api/process/",
            {"session_id": upload.data["session_id"], "operation": "median_filter", "params": {"size": 4}},
            format="json",
        )
        self.assertEqual(processed.status_code, 400)

    @patch("processing.services.run_batch_job.delay")
    def test_batch_returns_job_id(self, delay):
        first = self.client.post("/api/images/", {"image": png_upload(name="a.png")}, format="multipart")
        second = self.client.post("/api/images/", {"image": png_upload(color=(96, 96, 96), name="b.png")}, format="multipart")
        response = self.client.post(
            "/api/batch/",
            {"operation": "average", "session_ids": [first.data["session_id"], second.data["session_id"]]},
            format="json",
        )
        self.assertEqual(response.status_code, 202)
        self.assertIn("job_id", response.data)
        delay.assert_called_once()