from uuid import uuid4

import pytest
from fastapi.testclient import TestClient
from sqlalchemy.orm import Session

from typing import Any, Dict, List

from models.simulation_result import SimulationResult
from services.simulation import run_simulation


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


def test_run_simulation_function_generates_samples():
    params: List[Dict[str, Any]] = [
        {"name": "grade", "value": 1.8, "distribution": "normal", "std_dev": 0.2},
        {
            "name": "recovery",
            "value": 0.9,
            "distribution": "uniform",
            "min": 0.8,
            "max": 0.95,
        },
    ]
    results = run_simulation(params, iterations=5, seed=123)
    assert isinstance(results, list)
    assert len(results) == 5
    assert results[0]["iteration"] == 1


def test_run_simulation_with_zero_iterations_returns_empty():
    params: List[Dict[str, Any]] = [
        {"name": "grade", "value": 1.2, "distribution": "normal"}
    ]
    results = run_simulation(params, iterations=0)
    assert results == []


@pytest.mark.parametrize(
    "parameter_payload,error_message",
    [
        ({"name": "missing-value"}, "Parameter at index 0 must include 'value'"),
        (
            {
                "name": "bad-dist",
                "value": 1.0,
                "distribution": "unsupported",
            },
            "Parameter 'bad-dist' has unsupported distribution 'unsupported'",
        ),
        (
            {
                "name": "uniform-range",
                "value": 1.0,
                "distribution": "uniform",
                "min": 5,
                "max": 5,
            },
            "Parameter 'uniform-range' requires 'min' < 'max' for uniform distribution",
        ),
        (
            {
                "name": "triangular-mode",
                "value": 5.0,
                "distribution": "triangular",
                "min": 1,
                "max": 3,
                "mode": 5,
            },
            "Parameter 'triangular-mode' mode must be within min/max bounds for triangular distribution",
        ),
    ],
)
def test_run_simulation_parameter_validation_errors(
    parameter_payload: Dict[str, Any], error_message: str
) -> None:
    with pytest.raises(ValueError) as exc:
        run_simulation([parameter_payload])
    assert str(exc.value) == error_message


def test_run_simulation_normal_std_dev_fallback():
    params: List[Dict[str, Any]] = [
        {
            "name": "std-dev-fallback",
            "value": 10.0,
            "distribution": "normal",
            "std_dev": 0,
        }
    ]
    results = run_simulation(params, iterations=3, seed=99)
    assert len(results) == 3
    assert all("result" in entry for entry in results)


def test_simulation_endpoint_no_params(client: TestClient):
    scenario_payload: Dict[str, Any] = {
        "name": f"NoParamScenario-{uuid4()}",
        "description": "No parameters run",
    }
    scenario_resp = client.post("/api/scenarios/", json=scenario_payload)
    assert scenario_resp.status_code == 200
    scenario_id = scenario_resp.json()["id"]

    resp = client.post(
        "/api/simulations/run",
        json={"scenario_id": scenario_id, "parameters": [], "iterations": 10},
    )
    assert resp.status_code == 400
    assert resp.json()["detail"] == "No parameters provided"


def test_simulation_endpoint_success(
    client: TestClient, db_session: Session
):
    scenario_payload: Dict[str, Any] = {
        "name": f"SimScenario-{uuid4()}",
        "description": "Simulation test",
    }
    scenario_resp = client.post("/api/scenarios/", json=scenario_payload)
    assert scenario_resp.status_code == 200
    scenario_id = scenario_resp.json()["id"]

    params: List[Dict[str, Any]] = [
        {"name": "param1", "value": 2.5, "distribution": "normal", "std_dev": 0.5}
    ]
    payload: Dict[str, Any] = {
        "scenario_id": scenario_id,
        "parameters": params,
        "iterations": 10,
        "seed": 42,
    }

    resp = client.post("/api/simulations/run", json=payload)
    assert resp.status_code == 200
    data = resp.json()
    assert data["scenario_id"] == scenario_id
    assert len(data["results"]) == 10
    assert data["summary"]["count"] == 10

    db_session.expire_all()
    persisted = (
        db_session.query(SimulationResult)
        .filter(SimulationResult.scenario_id == scenario_id)
        .all()
    )
    assert len(persisted) == 10


def test_simulation_endpoint_uses_stored_parameters(client: TestClient):
    scenario_payload: Dict[str, Any] = {
        "name": f"StoredParams-{uuid4()}",
        "description": "Stored parameter simulation",
    }
    scenario_resp = client.post("/api/scenarios/", json=scenario_payload)
    assert scenario_resp.status_code == 200
    scenario_id = scenario_resp.json()["id"]

    parameter_payload: Dict[str, Any] = {
        "scenario_id": scenario_id,
        "name": "grade",
        "value": 1.5,
    }
    param_resp = client.post("/api/parameters/", json=parameter_payload)
    assert param_resp.status_code == 200

    resp = client.post(
        "/api/simulations/run",
        json={"scenario_id": scenario_id, "iterations": 3, "seed": 7},
    )
    assert resp.status_code == 200
    data = resp.json()
    assert data["summary"]["count"] == 3
    assert len(data["results"]) == 3