import math
from typing import Any, Dict, List

import pytest

from fastapi.testclient import TestClient

from services.reporting import generate_report


def test_generate_report_empty():
    report = generate_report([])
    assert report == {
        "count": 0,
        "mean": 0.0,
        "median": 0.0,
        "min": 0.0,
        "max": 0.0,
        "std_dev": 0.0,
        "variance": 0.0,
        "percentile_10": 0.0,
        "percentile_90": 0.0,
        "percentile_5": 0.0,
        "percentile_95": 0.0,
        "value_at_risk_95": 0.0,
        "expected_shortfall_95": 0.0,
    }


def test_generate_report_with_values():
    values: List[Dict[str, float]] = [
        {"iteration": 1, "result": 10.0},
        {"iteration": 2, "result": 20.0},
        {"iteration": 3, "result": 30.0},
    ]
    report = generate_report(values)
    assert report["count"] == 3
    assert math.isclose(float(report["mean"]), 20.0)
    assert math.isclose(float(report["median"]), 20.0)
    assert math.isclose(float(report["min"]), 10.0)
    assert math.isclose(float(report["max"]), 30.0)
    assert math.isclose(float(report["std_dev"]), 8.1649658, rel_tol=1e-6)
    assert math.isclose(float(report["variance"]), 66.6666666, rel_tol=1e-6)
    assert math.isclose(float(report["percentile_10"]), 12.0)
    assert math.isclose(float(report["percentile_90"]), 28.0)
    assert math.isclose(float(report["percentile_5"]), 11.0)
    assert math.isclose(float(report["percentile_95"]), 29.0)
    assert math.isclose(float(report["value_at_risk_95"]), 11.0)
    assert math.isclose(float(report["expected_shortfall_95"]), 10.0)


def test_generate_report_single_value():
    report = generate_report(
        [
            {"iteration": 1, "result": 42.0},
        ]
    )
    assert report["count"] == 1
    assert report["std_dev"] == 0.0
    assert report["variance"] == 0.0
    assert report["percentile_10"] == 42.0
    assert report["expected_shortfall_95"] == 42.0


def test_generate_report_ignores_invalid_entries():
    raw_values: List[Any] = [
        {"iteration": 1, "result": 10.0},
        "not-a-mapping",
        {"iteration": 2},
        {"iteration": 3, "result": None},
        {"iteration": 4, "result": 20},
    ]
    report = generate_report(raw_values)
    assert report["count"] == 2
    assert math.isclose(float(report["mean"]), 15.0)
    assert math.isclose(float(report["min"]), 10.0)
    assert math.isclose(float(report["max"]), 20.0)


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


def test_reporting_endpoint_invalid_input(client: TestClient):
    resp = client.post("/api/reporting/summary", json={})
    assert resp.status_code == 400
    assert resp.json()["detail"] == "Invalid input format"


def test_reporting_endpoint_success(client: TestClient):
    input_data: List[Dict[str, float]] = [
        {"iteration": 1, "result": 10.0},
        {"iteration": 2, "result": 20.0},
        {"iteration": 3, "result": 30.0},
    ]
    resp = client.post("/api/reporting/summary", json=input_data)
    assert resp.status_code == 200
    data: Dict[str, Any] = resp.json()
    assert data["count"] == 3
    assert math.isclose(float(data["mean"]), 20.0)
    assert math.isclose(float(data["variance"]), 66.6666666, rel_tol=1e-6)
    assert math.isclose(float(data["value_at_risk_95"]), 11.0)
    assert math.isclose(float(data["expected_shortfall_95"]), 10.0)


validation_error_cases: List[tuple[List[Any], str]] = [
    (["not-a-dict"], "Entry at index 0 must be an object"),
    ([{"iteration": 1}], "Entry at index 0 must include numeric 'result'"),
    (
        [{"iteration": 1, "result": "bad"}],
        "Entry at index 0 must include numeric 'result'",
    ),
]


@pytest.mark.parametrize("payload,expected_detail", validation_error_cases)
def test_reporting_endpoint_validation_errors(
    client: TestClient, payload: List[Any], expected_detail: str
):
    resp = client.post("/api/reporting/summary", json=payload)
    assert resp.status_code == 400
    assert resp.json()["detail"] == expected_detail