"""
API contract tests (#1074).

The pipeline is stubbed out — these cover the auth boundary and the request
guards, which is where a mistake is a security problem rather than an
accuracy problem. Model behaviour is the spike's job, not a unit test's.
"""

import pytest
from fastapi.testclient import TestClient

TOKEN = "test-token-not-a-secret"


class StubPipeline:
    dim = 512

    def process(self, image_bytes: bytes):
        if image_bytes == b"undecodable":
            raise ValueError("Image could not be decoded")
        return [
            {
                "bbox": [10.0, 20.0, 30.0, 40.0],
                "score": 0.99,
                "landmarks": [[1.0, 2.0]] * 5,
                "yaw": 0.0,
                "pitch": 0.0,
                "blur": 123.4,
                "embedding": [0.1] * 512,
            }
        ]


@pytest.fixture
def client(monkeypatch):
    from app import config, main

    monkeypatch.setattr(config, "TOKEN", TOKEN)
    monkeypatch.setattr(main.config, "TOKEN", TOKEN)
    monkeypatch.setattr(main, "FacePipeline", StubPipeline)

    with TestClient(main.app) as c:
        yield c


def _image_file(data: bytes = b"fake-jpeg-bytes"):
    return {"image": ("photo.jpg", data, "image/jpeg")}


class TestAuth:
    def test_health_needs_no_token(self, client):
        # The compose healthcheck calls this without a secret.
        r = client.get("/health")
        assert r.status_code == 200
        assert r.json() == {"status": "ok"}

    def test_info_without_token_is_401(self, client):
        assert client.get("/info").status_code == 401

    def test_info_with_wrong_token_is_401(self, client):
        r = client.get("/info", headers={"X-Face-ML-Token": "wrong"})
        assert r.status_code == 401

    def test_faces_without_token_is_401(self, client):
        r = client.post("/faces", files=_image_file())
        assert r.status_code == 401

    def test_401_body_leaks_nothing(self, client):
        # A prober should not learn whether the header name was even right.
        r = client.post("/faces", files=_image_file())
        assert r.json() == {"detail": "Unauthorized"}

    def test_startup_refuses_an_empty_token(self, monkeypatch):
        from app import config, main

        monkeypatch.setattr(config, "TOKEN", "")
        monkeypatch.setattr(main.config, "TOKEN", "")
        monkeypatch.setattr(main, "FacePipeline", StubPipeline)

        # Running open is the one failure mode this service must not have.
        with pytest.raises(RuntimeError, match="FACE_ML_TOKEN"):
            with TestClient(main.app):
                pass


class TestInfo:
    def test_reports_the_model_identity_the_backend_stores(self, client):
        from app import config

        r = client.get("/info", headers={"X-Face-ML-Token": TOKEN})
        assert r.status_code == 200
        body = r.json()
        assert body["model_version"] == config.MODEL_VERSION
        assert body["dim"] == 512


class TestFaces:
    def test_returns_faces_with_the_model_version(self, client):
        from app import config

        r = client.post(
            "/faces", files=_image_file(), headers={"X-Face-ML-Token": TOKEN}
        )
        assert r.status_code == 200
        body = r.json()
        assert body["model_version"] == config.MODEL_VERSION
        assert len(body["faces"]) == 1
        assert len(body["faces"][0]["embedding"]) == 512
        assert body["faces"][0]["bbox"] == [10.0, 20.0, 30.0, 40.0]

    def test_empty_upload_is_400(self, client):
        r = client.post(
            "/faces", files=_image_file(b""), headers={"X-Face-ML-Token": TOKEN}
        )
        assert r.status_code == 400

    def test_undecodable_image_is_400_not_500(self, client):
        # 4xx matters: the backend must mark the photo failed rather than
        # retry it forever, which is what it does for 5xx.
        r = client.post(
            "/faces",
            files=_image_file(b"undecodable"),
            headers={"X-Face-ML-Token": TOKEN},
        )
        assert r.status_code == 400

    def test_oversize_upload_is_413(self, client, monkeypatch):
        from app import main

        monkeypatch.setattr(main.config, "MAX_IMAGE_BYTES", 10)
        r = client.post(
            "/faces",
            files=_image_file(b"x" * 100),
            headers={"X-Face-ML-Token": TOKEN},
        )
        assert r.status_code == 413