"""POST /v1/systemone: Jev wire shape, straight passthrough to DecisionEngine.predict.
Contract: intern-decision-serve.contract.md § POST /v1/systemone"""
import threading
import time
from concurrent.futures import ThreadPoolExecutor

import pytest
from fastapi.testclient import TestClient

from fake_engine import FakeEngine
from intern_decision_serve.app import create_app
from intern_decision_serve.config import Settings
from intern_decision_serve.errors import OutOfMemory

TOKEN = "t" * 40
AUTH = {"Authorization": f"Bearer {TOKEN}"}

CHOICE = {"type": "choice", "instructions": "Did it pass?",
          "criteria": {"yes": "It passed.", "no": "It did not pass at all."}}
NOUL = {"type": "noul", "instructions": "Is the deploy healthy?"}
SCORE = {"type": "score", "instructions": "How risky?", "criteria": ["low", "medium", "high"]}


def make_client(engine=None, **overrides):
    return TestClient(create_app(Settings(api_token=TOKEN, **overrides), engine or FakeEngine()))


def body(**over):
    b = {"state": "The deploy finished at 14:00.", "model": "jev-latest", "questions": {"decision": CHOICE}}
    b.update(over)
    return b


# ---------------------------------------------------------------- happy paths

def test_choice_request_is_passed_straight_through_and_the_engine_answer_is_returned():
    engine = FakeEngine()
    response = make_client(engine).post("/v1/systemone", json=body(), headers=AUTH)
    assert response.status_code == 200
    native, _ = FakeEngine().predict(engine.calls[0])
    # straight through: only state+questions reach predict, model is not forwarded, the question
    # dict is untouched (no semif mapping: no A=id:description conversion, no field rename)
    assert engine.calls == [{"state": "The deploy finished at 14:00.", "questions": {"decision": CHOICE}}]
    out = response.json()
    assert out["answers"] == native["answers"]
    assert out["answers"]["decision"]["type"] == "choice"
    assert out["answers"]["decision"]["choice"] in ("yes", "no")
    assert out["usage"] == native["usage"]
    # a STRING: JevBench's runner hashes the value into its manifest (a dict broke it on the
    # 0.1.1 first run) and real clients compare it; the string names the real model and revision
    assert out["model"] == "Intern-Decision-4B@" + "0" * 40


def test_noul_question_needs_no_criteria_and_answers_with_a_probability():
    engine = FakeEngine()
    response = make_client(engine).post("/v1/systemone", json=body(questions={"q": NOUL}), headers=AUTH)
    assert response.status_code == 200
    assert engine.calls == [{"state": "The deploy finished at 14:00.", "questions": {"q": NOUL}}]
    answer = response.json()["answers"]["q"]
    assert answer["type"] == "noul" and answer["noul"] == 0.75


def test_score_question_with_a_list_of_levels_returns_probabilities_over_the_levels():
    engine = FakeEngine()
    response = make_client(engine).post("/v1/systemone", json=body(questions={"q": SCORE}), headers=AUTH)
    assert response.status_code == 200
    answer = response.json()["answers"]["q"]
    assert answer["type"] == "score"
    assert set(answer["probabilities"]) == {"0", "1", "2"}
    assert abs(sum(answer["probabilities"].values()) - 1.0) < 1e-9


def test_any_number_of_questions_up_to_16_is_ONE_call_so_they_share_one_prompt():
    engine = FakeEngine()
    questions = {f"q{i}": NOUL for i in range(16)}
    response = make_client(engine).post("/v1/systemone", json=body(questions=questions), headers=AUTH)
    assert response.status_code == 200
    assert len(engine.calls) == 1 and len(engine.calls[0]["questions"]) == 16


def test_the_model_field_is_accepted_with_any_value_and_ignored():
    engine = FakeEngine()
    for model in ("jev-latest", "anything-else", 7, None):
        response = make_client(engine).post("/v1/systemone", json=body(model=model), headers=AUTH)
        assert response.status_code == 200


class NoUsageEngine(FakeEngine):
    def predict(self, request):
        response, sha = super().predict(request)
        response.pop("usage")
        return response, sha


def test_an_engine_that_reports_no_usage_yields_an_empty_usage_object():
    response = make_client(NoUsageEngine()).post("/v1/systemone", json=body(), headers=AUTH)
    assert response.status_code == 200
    assert response.json()["usage"] == {}


# ---------------------------------------------------------------- refusals

@pytest.mark.parametrize("headers", [{}, {"Authorization": "Bearer wrong"}, {"Authorization": TOKEN}])
def test_without_the_right_bearer_a_systemone_post_is_401_and_never_reaches_the_engine(headers):
    engine = FakeEngine()
    response = make_client(engine).post("/v1/systemone", json=body(), headers=headers)
    assert response.status_code == 401
    assert response.json()["error"]["code"] == "unauthorized"
    assert engine.calls == []


@pytest.mark.parametrize("images", [["a.png"], [], "a.png"])
def test_images_any_value_at_all_is_422_before_the_engine_runs(images):
    engine = FakeEngine()
    response = make_client(engine).post("/v1/systemone", json=body(images=images), headers=AUTH)
    assert response.status_code == 422
    assert response.json()["error"]["code"] == "invalid_request"
    assert "images not supported" in response.json()["error"]["message"]
    assert engine.calls == []


def test_17_questions_is_422_not_a_chunked_2_call_request():
    engine = FakeEngine()
    questions = {f"q{i}": NOUL for i in range(17)}
    response = make_client(engine).post("/v1/systemone", json=body(questions=questions), headers=AUTH)
    assert response.status_code == 422
    assert "16" in response.json()["error"]["message"]
    assert engine.calls == []


def test_zero_questions_is_422():
    response = make_client().post("/v1/systemone", json=body(questions={}), headers=AUTH)
    assert response.status_code == 422


def test_a_body_that_is_not_json_or_has_no_questions_is_422():
    client = make_client()
    assert client.post("/v1/systemone", content=b"{nope", headers={**AUTH, "content-type": "application/json"}
                       ).status_code == 422
    assert client.post("/v1/systemone", json={"state": "s"}, headers=AUTH).status_code == 422


class TokenLimitEngine(FakeEngine):
    """Stands in for the model's own pre-forward check: predict raises ValueError, never a tensor."""
    def predict(self, request):
        self.calls.append(request)
        raise ValueError("Example has 7169 tokens, above 7168; truncation is forbidden")


def test_over_max_tokens_is_422_from_the_models_own_before_the_forward_check():
    response = make_client(TokenLimitEngine(), max_tokens=7168).post("/v1/systemone", json=body(), headers=AUTH)
    assert response.status_code == 422
    assert "7169" in response.json()["error"]["message"]


# ---------------------------------------------------------------- queue and memory

class SlowEngine(FakeEngine):
    def __init__(self):
        super().__init__()
        self.entered, self.release = threading.Event(), threading.Event()

    def predict(self, request):
        self.entered.set()
        assert self.release.wait(5)
        return super().predict(request)


def test_more_than_max_queue_systemone_posts_get_429_busy():
    engine = SlowEngine()
    with make_client(engine, max_queue=1) as client, ThreadPoolExecutor(2) as pool:
        held = pool.submit(client.post, "/v1/systemone", json=body(), headers=AUTH)
        assert engine.entered.wait(5)
        time.sleep(0.2)
        extra = client.post("/v1/systemone", json=body(), headers=AUTH)
        assert extra.status_code == 429 and extra.json()["error"]["code"] == "busy"
        engine.release.set()
        assert held.result().status_code == 200


class OomOnceEngine(FakeEngine):
    def __init__(self):
        super().__init__()
        self.raised = False

    def predict(self, request):
        if not self.raised:
            self.raised, _ = True, self.calls.append(request)
            raise OutOfMemory("CUDA out of memory.")
        return super().predict(request)


def test_an_oom_is_503_with_the_contract_envelope_and_the_next_request_succeeds():
    engine = OomOnceEngine()
    client = make_client(engine)
    first = client.post("/v1/systemone", json=body(), headers=AUTH)
    assert first.status_code == 503 and first.json()["error"]["code"] == "out_of_memory"
    second = client.post("/v1/systemone", json=body(), headers=AUTH)
    assert second.status_code == 200


def test_systemone_runs_on_the_same_single_inference_thread_as_decide():
    seen = []

    class ThreadSpy(FakeEngine):
        def predict(self, request):
            seen.append(threading.current_thread().name)
            return super().predict(request)

    client = make_client(ThreadSpy())
    client.post("/v1/systemone", json=body(), headers=AUTH)
    client.post("/decide", json={"id": "r", "state": "s", "question": "q?", "options":
                                 [{"id": "a", "description": "x"}, {"id": "b", "description": "yy"}]},
                headers=AUTH)
    assert len(set(seen)) == 1 and seen[0].startswith("inference")


# ---------------------------------------------------------------- /health

def test_health_advertises_the_systemone_surface_and_its_limits():
    out = make_client(max_tokens=7168).get("/health").json()
    assert set(out["endpoints"]) == {"/decide", "/decide/shared", "/v1/systemone"}
    assert out["systemone"] == {"max_questions": 16, "chunking": "none",
                                "images": "not supported", "max_tokens": 7168}