import { content } from "@deadhead/content";
import { describe, expect, it } from "vitest";
import { emergencyFuel, fuelPriceAt, tripFuel, type ShipState } from "../src/index";

const { config } = content;
const courier = content.shipModel("courier")!;
const [earth, moon] = [content.location("earth")!, content.location("moon")!];
const discoveredIds = new Set(["earth", "moon"]);
/** A Courier at the Moon: its only discovered way out is Earth. */
const legToEarth = tripFuel(courier, moon, earth, config);
const moonPrice = fuelPriceAt(moon, config);
const atMoon = (fuelFu: number, inFlight = false): ShipState => ({
  id: "s1",
  modelId: "courier",
  locationId: "moon",
  inFlight,
  tank: { fuelFu, avgPrice: moonPrice },
});

describe("emergency fuel (Step 15.5, decision 0.5.99)", () => {
  it("is offered when the tank can't reach anywhere and the credits can't buy the shortfall", () => {
    const offer = emergencyFuel({ ship: atMoon(1), credits: 0, discoveredIds }, content);
    expect(offer).not.toBeNull();
    // Exactly the cheapest leg's fuel minus what is on board, at 2.5 × the local price.
    expect(offer!.amountFu).toBeCloseTo(legToEarth - 1);
    expect(offer!.price).toBeCloseTo(moonPrice * 2.5);
    expect(offer!.cost).toBe(Math.round((legToEarth - 1) * moonPrice * 2.5));
  });

  it("is not offered when the tank can already reach somewhere", () => {
    expect(
      emergencyFuel({ ship: atMoon(legToEarth), credits: 0, discoveredIds }, content),
    ).toBeNull();
  });

  it("is not offered when the player can afford the fuel", () => {
    const shortfallCost = Math.ceil((legToEarth - 1) * moonPrice);
    expect(
      emergencyFuel({ ship: atMoon(1), credits: shortfallCost, discoveredIds }, content),
    ).toBeNull();
    expect(
      emergencyFuel({ ship: atMoon(1), credits: shortfallCost - 1, discoveredIds }, content),
    ).not.toBeNull();
  });

  it("is not offered in flight", () => {
    expect(emergencyFuel({ ship: atMoon(1, true), credits: 0, discoveredIds }, content)).toBeNull();
  });

  it("covers only the cheapest leg when there are several ways out", () => {
    // From Earth, the Moon is the cheapest leg for a Clipper (Mars costs far more).
    const clipper = content.shipModel("clipper")!;
    const ship: ShipState = {
      id: "s2",
      modelId: "clipper",
      locationId: "earth",
      inFlight: false,
      tank: { fuelFu: 0, avgPrice: 0 },
    };
    const offer = emergencyFuel(
      { ship, credits: 0, discoveredIds: new Set(["earth", "moon", "mars"]) },
      content,
    );
    expect(offer!.amountFu).toBeCloseTo(tripFuel(clipper, earth, moon, config));
  });
});