from __future__ import annotations

from datetime import date, timedelta

import pandas as pd

from app.services.analytics_service import AnalyticsService


class StubWarehouseClient:
    def fetch_daily_sales(self) -> pd.DataFrame:
        today = date.today()
        rows = []
        for i in range(120):
            day = today - timedelta(days=120 - i)
            rows.append(
                {
                    "sale_date": day.isoformat(),
                    "revenue": 1000 + (i * 5),
                    "cost": 500 + (i * 2),
                    "quantity": 40 + i,
                    "orders": 5 + (i % 4),
                    "source": "stub",
                }
            )
        return pd.DataFrame(rows)

    def fetch_product_performance(self) -> pd.DataFrame:
        return pd.DataFrame(
            [
                {
                    "product_id": "A1",
                    "product_name": "Alpha",
                    "category_name": "CatA",
                    "revenue": 12000,
                    "cost": 6000,
                    "quantity": 400,
                    "orders": 150,
                    "source": "stub",
                },
                {
                    "product_id": "B1",
                    "product_name": "Beta",
                    "category_name": "CatB",
                    "revenue": 9000,
                    "cost": 8500,
                    "quantity": 300,
                    "orders": 110,
                    "source": "stub",
                },
            ]
        )

    def fetch_customer_performance(self) -> pd.DataFrame:
        return pd.DataFrame(
            [
                {
                    "customer_id": "C1",
                    "customer_name": "Contoso",
                    "revenue": 15000,
                    "orders": 80,
                    "source": "stub",
                }
            ]
        )


def test_forecast_has_expected_horizon() -> None:
    service = AnalyticsService(StubWarehouseClient())  # type: ignore[arg-type]
    forecast = service.get_forecast(horizon_days=15)
    assert len(forecast) == 15
    assert "predicted_revenue" in forecast[0]


def test_rankings_are_sorted() -> None:
    service = AnalyticsService(StubWarehouseClient())  # type: ignore[arg-type]
    rankings = service.get_rankings(top_n=2)
    assert len(rankings) == 2
    assert rankings[0]["score"] >= rankings[1]["score"]