"""End-to-end tests for the ``/interactive/*`` router."""

from __future__ import annotations

import json
from collections.abc import Iterable

import pytest
from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
from fastapi.testclient import TestClient
from openenv.core.env_server import create_fastapi_app

from physix.models import PhysiXAction, PhysiXObservation
from physix.server.app import build_app
from physix.server.environment import PhysiXEnvironment
from physix.server.interactive import (
    LlmModelInfo,
    LlmModelsResponse,
    LlmStepRequest,
    build_interactive_router,
)


@pytest.fixture
def client() -> TestClient:
    return TestClient(build_app())


def _build_app_with_stubbed_llm(
    completions: Iterable[str],
    *,
    models_response: LlmModelsResponse | None = None,
) -> FastAPI:
    """Build a clone of the production app whose LLM policy returns
    pre-canned completion strings in order.

    Each call to the policy pops the next completion off the deque, so a
    test that wants three turns supplies three strings. Optionally
    overrides the model lister so the ``/interactive/models`` route can
    be exercised without touching the real Ollama daemon.
    """
    queue = list(completions)

    def _stub_policy(_payload: LlmStepRequest):
        def _policy(_prompt: list[dict[str, str]]) -> str:
            if not queue:
                raise AssertionError("Stubbed LLM ran out of canned completions.")
            return queue.pop(0)

        return _policy

    def _stub_lister() -> LlmModelsResponse:
        return models_response or LlmModelsResponse(models=[])

    app = create_fastapi_app(
        env=PhysiXEnvironment,
        action_cls=PhysiXAction,
        observation_cls=PhysiXObservation,
    )
    app.add_middleware(
        CORSMiddleware,
        allow_origins=["http://localhost:5173"],
        allow_credentials=True,
        allow_methods=["*"],
        allow_headers=["*"],
    )
    app.include_router(
        build_interactive_router(
            policy_factory=_stub_policy,
            models_lister=_stub_lister,
        )
    )
    return app


# --- Catalogue ---


def test_systems_endpoint_returns_supported_systems_in_order(
    client: TestClient,
) -> None:
    from physix.systems.registry import SUPPORTED_SYSTEMS

    response = client.get("/interactive/systems")
    assert response.status_code == 200

    catalogue = response.json()
    returned_ids = [row["system_id"] for row in catalogue]
    assert returned_ids == list(SUPPORTED_SYSTEMS)

    system_ids = set(returned_ids)
    assert "projectile_drag" not in system_ids
    assert "charged_b_field" not in system_ids
    # Sanity check: the systems we pruned for plateauing on 7B must not
    # leak through either, since the whole point of the curriculum is to
    # hide them from the demo dropdown.
    assert "free_fall_drag" not in system_ids
    assert "damped_pendulum" not in system_ids


# --- Local model catalogue ---


def test_models_endpoint_returns_injected_list() -> None:
    """Frontend reads installed model tags from the server, not a hardcoded
    list. The route must surface whatever the lister reports."""
    canned = LlmModelsResponse(
        models=[
            LlmModelInfo(name="qwen2.5:7b", size_bytes=4_700_000_000, parameter_size="7.6B"),
            LlmModelInfo(name="qwen2.5:1.5b-instruct", size_bytes=986_000_000),
        ]
    )
    app = _build_app_with_stubbed_llm([], models_response=canned)
    with TestClient(app) as client:
        response = client.get("/interactive/models")

    assert response.status_code == 200, response.text
    body = response.json()
    assert body["error"] is None
    assert [m["name"] for m in body["models"]] == [
        "qwen2.5:7b",
        "qwen2.5:1.5b-instruct",
    ]
    assert body["models"][0]["parameter_size"] == "7.6B"


def test_models_endpoint_returns_empty_with_error_when_daemon_unavailable() -> None:
    """When Ollama is unreachable the route degrades to an empty list and
    surfaces a human-readable hint, instead of 5xx-ing the page."""
    canned = LlmModelsResponse(
        models=[],
        error="Could not reach the local Ollama daemon (test). Is 'ollama serve' running?",
    )
    app = _build_app_with_stubbed_llm([], models_response=canned)
    with TestClient(app) as client:
        response = client.get("/interactive/models")

    assert response.status_code == 200
    body = response.json()
    assert body["models"] == []
    assert "Ollama" in body["error"]


# --- Session lifecycle ---


def test_session_lifecycle_create_summary_delete(client: TestClient) -> None:
    """Create → reset observation → summary → delete → 404. The actual
    advancing of turn counter / format scoring / predicted overlay
    lives in the ``/llm-step`` tests below; this is the lifecycle
    skeleton (the only flow the UI actually exercises now that the
    manual ``/step`` route is gone)."""
    create = client.post(
        "/interactive/sessions",
        json={"system_id": "free_fall", "seed": 42, "max_turns": 4},
    )
    assert create.status_code == 200, create.text
    body = create.json()

    session_id = body["session_id"]
    assert isinstance(session_id, str) and session_id
    assert body["system"]["system_id"] == "free_fall"
    assert "tier" not in body["system"]  # tier is dropped from the public schema
    assert body["max_turns"] == 4
    assert body["observation"]["turn"] == 0
    assert body["observation"]["done"] is False
    assert len(body["observation"]["trajectory"]) == 100

    summary = client.get(f"/interactive/sessions/{session_id}").json()
    assert summary["turn"] == 0
    assert summary["max_turns"] == 4
    assert summary["done"] is False

    end = client.delete(f"/interactive/sessions/{session_id}")
    assert end.status_code == 204
    assert client.get(f"/interactive/sessions/{session_id}").status_code == 404


def test_unknown_system_id_returns_400(client: TestClient) -> None:
    response = client.post(
        "/interactive/sessions",
        json={"system_id": "no_such_system"},
    )
    assert response.status_code == 400


def test_unknown_session_id_returns_404() -> None:
    """Session-scoped routes return 404 for unknown ids, not 500."""
    app = _build_app_with_stubbed_llm([])
    with TestClient(app) as client:
        response = client.post(
            "/interactive/sessions/does-not-exist/llm-step",
            json={"model": "stub"},
        )
    assert response.status_code == 404


# --- LLM-step endpoint (with stubbed policy) ---


def test_llm_step_drives_a_turn_using_injected_policy() -> None:
    """The endpoint must call the policy, parse, step, and surface the raw."""
    app = _build_app_with_stubbed_llm(
        [json.dumps({"equation": "d2y/dt2 = -9.81", "rationale": "gravity"})]
    )
    with TestClient(app) as client:
        create = client.post(
            "/interactive/sessions",
            json={"system_id": "free_fall", "seed": 0, "max_turns": 4},
        ).json()
        session_id = create["session_id"]

        response = client.post(
            f"/interactive/sessions/{session_id}/llm-step",
            json={"model": "stub:1.5b", "temperature": 0.1, "max_tokens": 64},
        )

    assert response.status_code == 200, response.text
    body = response.json()
    assert body["model"] == "stub:1.5b"
    assert body["action"]["equation"] == "d2y/dt2 = -9.81"
    assert body["action"]["rationale"] == "gravity"
    assert body["observation"]["turn"] == 1
    assert body["observation"]["reward_breakdown"]["match"] >= 0.9
    assert body["predicted_trajectory"]
    assert body["latency_s"] >= 0.0
    assert "d2y/dt2" in body["raw_completion"]


def test_llm_step_runs_full_episode_with_three_canned_turns() -> None:
    """Multi-turn drive: each call pops the next completion, history grows."""
    completions = [
        json.dumps({"equation": "d2y/dt2 = -9.81", "rationale": "pure gravity"}),
        json.dumps({
            "equation": "d2y/dt2 = -9.81 + 0.1 * vy",
            "rationale": "linear drag",
        }),
        json.dumps({
            "equation": "d2y/dt2 = -9.81 + 0.05 * vy**2",
            "rationale": "quadratic drag",
        }),
    ]
    app = _build_app_with_stubbed_llm(completions)
    with TestClient(app) as client:
        session_id = client.post(
            "/interactive/sessions",
            json={"system_id": "free_fall_drag", "seed": 42, "max_turns": 8},
        ).json()["session_id"]

        bodies = []
        for _ in range(3):
            response = client.post(
                f"/interactive/sessions/{session_id}/llm-step",
                json={"model": "stub"},
            )
            assert response.status_code == 200, response.text
            bodies.append(response.json())

    assert [b["action"]["equation"] for b in bodies] == [
        "d2y/dt2 = -9.81",
        "d2y/dt2 = -9.81 + 0.1 * vy",
        "d2y/dt2 = -9.81 + 0.05 * vy**2",
    ]
    assert [b["observation"]["turn"] for b in bodies] == [1, 2, 3]
    # History accumulates across turns.
    assert len(bodies[-1]["observation"]["history"]) == 3


def test_llm_step_handles_unparseable_completion_as_format_zero() -> None:
    """If the model emits junk, the env scores it format=0, no 500."""
    app = _build_app_with_stubbed_llm(["I refuse to answer."])
    with TestClient(app) as client:
        session_id = client.post(
            "/interactive/sessions",
            json={"system_id": "simple_pendulum", "seed": 0, "max_turns": 4},
        ).json()["session_id"]
        response = client.post(
            f"/interactive/sessions/{session_id}/llm-step",
            json={"model": "stub"},
        )

    assert response.status_code == 200, response.text
    body = response.json()
    assert body["observation"]["reward_breakdown"]["format"] == 0.0
    assert body["predicted_trajectory"] == []
    assert body["raw_completion"] == "I refuse to answer."


def test_llm_step_after_budget_exhaustion_returns_409() -> None:
    """Once the env has consumed its budget, llm-step is rejected too."""
    canned = [
        json.dumps({"equation": "d2theta/dt2 = 0"}),
        json.dumps({"equation": "d2theta/dt2 = 0"}),
    ]
    app = _build_app_with_stubbed_llm(canned)
    with TestClient(app) as client:
        session_id = client.post(
            "/interactive/sessions",
            json={"system_id": "simple_pendulum", "seed": 1, "max_turns": 2},
        ).json()["session_id"]
        for _ in range(2):
            assert client.post(
                f"/interactive/sessions/{session_id}/llm-step",
                json={"model": "stub"},
            ).status_code == 200
        overflow = client.post(
            f"/interactive/sessions/{session_id}/llm-step",
            json={"model": "stub"},
        )

    assert overflow.status_code == 409


# --- CORS ---


def test_cors_preflight_for_dev_origin(client: TestClient) -> None:
    """OPTIONS preflight from the Vite dev server is allowed."""
    response = client.options(
        "/interactive/sessions",
        headers={
            "Origin": "http://localhost:5173",
            "Access-Control-Request-Method": "POST",
            "Access-Control-Request-Headers": "content-type",
        },
    )
    assert response.status_code in (200, 204), response.text
    assert response.headers["access-control-allow-origin"] == "http://localhost:5173"