import { describe, it, expect, vi, beforeEach, type MockInstance } from "vitest";
import { AutoRacingSimulator } from "../auto-racing-simulator";
import { F1_RACE_POINTS, INDYCAR_RACE_POINTS } from "../race-points";

vi.mock("~/database/context", () => ({
  database: vi.fn(),
}));

vi.mock("~/models/participant-season-result", () => ({
  getSeasonResults: vi.fn(),
}));

vi.mock("~/models/participant-expected-value", () => ({
  getAllParticipantEVsForSeason: vi.fn(),
}));

vi.mock("~/models/season-races", () => ({
  countSeasonRaces: vi.fn(),
}));

// ─── Fixtures ─────────────────────────────────────────────────────────────────

const DRIVERS = ["d1", "d2", "d3", "d4", "d5"].map((id) => ({ id }));

const PROB_KEYS = [
  "probFirst", "probSecond", "probThird", "probFourth",
  "probFifth", "probSixth", "probSeventh", "probEighth",
] as const;

function makeSeasonResult(participantId: string, currentPoints: string) {
  return { participant: { id: participantId }, currentPoints };
}

function makeEv(participantId: string, sourceOdds: number | null) {
  return { participantId, sourceOdds };
}

function mockDb(drivers: { id: string }[] = DRIVERS) {
  return {
    query: {
      seasonParticipants: {
        findMany: vi.fn().mockResolvedValue(drivers),
      },
    },
  };
}

/** Set the race counts the simulator reads from the calendar. */
async function setRaceCounts(completed: number, remaining: number) {
  const { countSeasonRaces } = await import("~/models/season-races");
  (countSeasonRaces as unknown as MockInstance).mockResolvedValue({
    completed,
    remaining,
    total: completed + remaining,
  });
}

async function setStandings(results: ReturnType<typeof makeSeasonResult>[]) {
  const { getSeasonResults } = await import("~/models/participant-season-result");
  (getSeasonResults as unknown as MockInstance).mockResolvedValue(results);
}

async function setOdds(evs: ReturnType<typeof makeEv>[]) {
  const { getAllParticipantEVsForSeason } = await import("~/models/participant-expected-value");
  (getAllParticipantEVsForSeason as unknown as MockInstance).mockResolvedValue(evs);
}

async function useDrivers(drivers: { id: string }[]) {
  const { database } = await import("~/database/context");
  (database as unknown as MockInstance).mockReturnValue(mockDb(drivers));
}

// ─── Setup ────────────────────────────────────────────────────────────────────

beforeEach(async () => {
  const { database } = await import("~/database/context");
  (database as unknown as MockInstance).mockReturnValue(mockDb());
  await setStandings([]);
  await setOdds([]);
  await setRaceCounts(0, 0);
});

// ─── Tests ────────────────────────────────────────────────────────────────────

describe("AutoRacingSimulator", () => {
  it("throws when no participants are found", async () => {
    await useDrivers([]);
    await expect(
      new AutoRacingSimulator(F1_RACE_POINTS, "f1").simulate("s1")
    ).rejects.toThrow(/No participants found/);
  });

  describe("pre-season path (no races run, none remaining)", () => {
    beforeEach(async () => {
      await setRaceCounts(0, 0);
      // Heavy favourite: d1 at −500, all others at +1000
      await setOdds([
        makeEv("d1", -500),
        makeEv("d2", 1000),
        makeEv("d3", 1000),
        makeEv("d4", 1000),
        makeEv("d5", 1000),
      ]);
    });

    it("returns one result per driver", async () => {
      const results = await new AutoRacingSimulator(F1_RACE_POINTS, "f1").simulate("s1");
      expect(results).toHaveLength(5);
    });

    it("normalizes each position column to sum to 1.0", async () => {
      const results = await new AutoRacingSimulator(F1_RACE_POINTS, "f1").simulate("s1");
      for (const key of PROB_KEYS) {
        const sum = results.reduce((s, r) => s + r.probabilities[key], 0);
        expect(sum, `${key} column sum`).toBeCloseTo(1.0, 6);
      }
    });

    it("heavy favourite ranks first more often than long shots", async () => {
      const results = await new AutoRacingSimulator(F1_RACE_POINTS, "f1").simulate("s1");
      const favourite = results.find((r) => r.participantId === "d1");
      const longShot = results.find((r) => r.participantId === "d2");
      expect(favourite).toBeDefined();
      expect(longShot).toBeDefined();
      if (!favourite || !longShot) return;
      expect(favourite.probabilities.probFirst).toBeGreaterThan(longShot.probabilities.probFirst);
    });

    it("drivers without odds get equal fallback probability", async () => {
      await setOdds([]);
      const results = await new AutoRacingSimulator(F1_RACE_POINTS, "f1").simulate("s1");
      // With equal weights all 5 drivers should finish 1st roughly equally
      for (const r of results) {
        expect(r.probabilities.probFirst).toBeGreaterThan(0.1);
        expect(r.probabilities.probFirst).toBeLessThan(0.3);
      }
    });

    it("floors an unpriced driver at the bottom of the priced market", async () => {
      // d5 has no odds at all; d2–d4 are +1000 long shots. Before power devig
      // an unpriced driver was handed 1/N, which rated them above the field.
      await setOdds([
        makeEv("d1", -500),
        makeEv("d2", 1000),
        makeEv("d3", 1000),
        makeEv("d4", 1000),
      ]);
      const results = await new AutoRacingSimulator(F1_RACE_POINTS, "f1").simulate("s1");
      const unpriced = results.find((r) => r.participantId === "d5");
      const longShot = results.find((r) => r.participantId === "d2");
      expect(unpriced).toBeDefined();
      expect(longShot).toBeDefined();
      if (!unpriced || !longShot) return;
      expect(unpriced.probabilities.probFirst).toBeLessThanOrEqual(
        longShot.probabilities.probFirst + 0.02
      );
    });
  });

  describe("season complete (races run, none remaining)", () => {
    it("returns the final standings order deterministically", async () => {
      await setRaceCounts(17, 0);
      // getSeasonResults returns rows already sorted by championship position.
      await setStandings([
        makeSeasonResult("d3", "601"),
        makeSeasonResult("d1", "480"),
        makeSeasonResult("d5", "446"),
        makeSeasonResult("d2", "420"),
        makeSeasonResult("d4", "398"),
      ]);
      // Futures odds disagree entirely — they must be ignored once it is over.
      await setOdds([makeEv("d1", -10000), makeEv("d3", 20000)]);

      const results = await new AutoRacingSimulator(F1_RACE_POINTS, "f1").simulate("s1");
      const byId = new Map(results.map((r) => [r.participantId, r.probabilities]));

      expect(byId.get("d3")?.probFirst).toBe(1);
      expect(byId.get("d1")?.probFirst).toBe(0);
      expect(byId.get("d1")?.probSecond).toBe(1);
      expect(byId.get("d5")?.probThird).toBe(1);
      expect(byId.get("d2")?.probFourth).toBe(1);
      expect(byId.get("d4")?.probFifth).toBe(1);
    });

    it("warns and falls back to odds when there are no standings rows", async () => {
      const warnSpy = vi.spyOn(console, "warn").mockImplementation(() => {});
      await setRaceCounts(17, 0);
      await setStandings([]);
      await setOdds([makeEv("d1", -500), makeEv("d2", 1000)]);

      const results = await new AutoRacingSimulator(F1_RACE_POINTS, "f1").simulate("s1");

      expect(warnSpy).toHaveBeenCalledWith(
        expect.stringContaining("no races left but no standings rows")
      );
      // Still produces a usable distribution rather than all zeroes.
      const total = results.reduce((s, r) => s + r.probabilities.probFirst, 0);
      expect(total).toBeCloseTo(1.0, 6);
      warnSpy.mockRestore();
    });
  });

  describe("no race calendar", () => {
    it("warns when the season has championship points but no events", async () => {
      const warnSpy = vi.spyOn(console, "warn").mockImplementation(() => {});
      await setRaceCounts(0, 0);
      await setStandings([makeSeasonResult("d1", "400"), makeSeasonResult("d2", "300")]);

      await new AutoRacingSimulator(F1_RACE_POINTS, "f1").simulate("s1");

      expect(warnSpy).toHaveBeenCalledWith(
        expect.stringContaining("championship points but no race calendar")
      );
      warnSpy.mockRestore();
    });

    it("stays quiet for a genuine pre-season with no points yet", async () => {
      const warnSpy = vi.spyOn(console, "warn").mockImplementation(() => {});
      await setRaceCounts(0, 0);
      await setStandings([]);

      await new AutoRacingSimulator(F1_RACE_POINTS, "f1").simulate("s1");

      expect(warnSpy).not.toHaveBeenCalled();
      warnSpy.mockRestore();
    });
  });

  describe("in-season path (races remaining)", () => {
    beforeEach(async () => {
      await setRaceCounts(10, 5);
    });

    it("normalizes each position column to sum to 1.0", async () => {
      await setStandings(DRIVERS.map((d, i) => makeSeasonResult(d.id, String((5 - i) * 50))));
      const results = await new AutoRacingSimulator(F1_RACE_POINTS, "f1").simulate("s1");
      for (const key of PROB_KEYS) {
        const sum = results.reduce((s, r) => s + r.probabilities[key], 0);
        expect(sum, `${key} column sum`).toBeCloseTo(1.0, 6);
      }
    });

    it("standings leader ranks higher than a driver far behind when standings dominate", async () => {
      // 20/25 races done → seasonProgress = 0.8 → standings weighted 80%
      await setRaceCounts(20, 5);
      // d1 leads with 400 pts; d2 is a distant 2nd with 50 pts
      await setStandings([
        makeSeasonResult("d1", "400"),
        makeSeasonResult("d2", "50"),
        makeSeasonResult("d3", "40"),
        makeSeasonResult("d4", "30"),
        makeSeasonResult("d5", "20"),
      ]);
      // Futures odds heavily favour d2 (pretend markets disagree)
      await setOdds([
        makeEv("d1", 5000),  // very long shot per futures
        makeEv("d2", -500),  // heavy favourite per futures
      ]);

      const results = await new AutoRacingSimulator(F1_RACE_POINTS, "f1").simulate("s1");
      const leader = results.find((r) => r.participantId === "d1");
      const distant = results.find((r) => r.participantId === "d2");
      expect(leader).toBeDefined();
      expect(distant).toBeDefined();
      if (!leader || !distant) return;
      // Standings signal should dominate: d1's massive points lead wins out
      expect(leader.probabilities.probFirst).toBeGreaterThan(distant.probabilities.probFirst);
    });

    it("falls back to odds for all drivers when no standings data exists", async () => {
      // totalCurrentPoints = 0 → standings signal disabled, odds take over
      await setOdds([makeEv("d1", -500), makeEv("d2", 1000)]);
      const results = await new AutoRacingSimulator(F1_RACE_POINTS, "f1").simulate("s1");
      const fav = results.find((r) => r.participantId === "d1");
      const longShot = results.find((r) => r.participantId === "d2");
      expect(fav).toBeDefined();
      expect(longShot).toBeDefined();
      if (!fav || !longShot) return;
      // Without standings, odds-favoured driver should still rank higher
      expect(fav.probabilities.probFirst).toBeGreaterThan(longShot.probabilities.probFirst);
    });

    it("a driver with 0 points mid-season is not penalized beyond their odds weight", async () => {
      // Early season → standings gap is small
      await setRaceCounts(2, 20);
      // d1-d4 have a modest lead; d5 is absent (0 pts, new entry)
      await setStandings([
        makeSeasonResult("d1", "10"),
        makeSeasonResult("d2", "8"),
        makeSeasonResult("d3", "6"),
        makeSeasonResult("d4", "4"),
        // d5 intentionally absent → falls back to odds weight
      ]);
      await setOdds([makeEv("d5", -500)]); // strong odds favourite despite 0 pts

      const results = await new AutoRacingSimulator(F1_RACE_POINTS, "f1").simulate("s1");
      // d5 should win championships at a non-trivial rate given their strong odds weight
      const d5 = results.find((r) => r.participantId === "d5");
      expect(d5).toBeDefined();
      if (!d5) return;
      expect(d5.probabilities.probFirst).toBeGreaterThan(0.1);
    });

    it("emits a warning when participants are missing from standings", async () => {
      const warnSpy = vi.spyOn(console, "warn").mockImplementation(() => {});
      // Only 3 of 5 drivers have standings rows
      await setStandings([
        makeSeasonResult("d1", "100"),
        makeSeasonResult("d2", "80"),
        makeSeasonResult("d3", "60"),
      ]);
      await new AutoRacingSimulator(F1_RACE_POINTS, "f1").simulate("s1");
      expect(warnSpy).toHaveBeenCalledWith(
        expect.stringContaining("2 participant(s) missing from standings")
      );
      warnSpy.mockRestore();
    });
  });

  describe("IndyCar regression: near-clinched championship leader", () => {
    // The reported bug. A 121-point lead with 2 races left is arithmetically
    // unassailable (max 100 available, and the leader banks at least 10), but
    // the simulator skipped `schedule_event` rows, saw zero remaining races,
    // took the pre-season branch and echoed stale futures odds at ~55%.
    const POINTS = [
      601, 480, 446, 420, 398, 372, 350, 331, 315, 300, 288, 270, 255, 240,
      228, 215, 200, 188, 175, 160, 148, 135, 120, 105, 90, 70, 55,
    ];
    const ODDS = [
      -300, 450, 700, 1200, 1800, 2500, 4000, 5000, 6000, 8000, 10000, 12000,
      15000, 20000, 25000, 30000, 40000, 50000, 50000, 50000, 50000, 50000,
      50000, 50000, 50000, 50000, 50000,
    ];
    const FIELD = POINTS.map((_, i) => ({ id: `driver${i}` }));

    beforeEach(async () => {
      await useDrivers(FIELD);
      await setStandings(FIELD.map((d, i) => makeSeasonResult(d.id, String(POINTS[i]))));
      await setOdds(FIELD.map((d, i) => makeEv(d.id, ODDS[i])));
    });

    it("gives the leader ~100% with 2 of 17 races left", async () => {
      await setRaceCounts(15, 2);
      const results = await new AutoRacingSimulator(INDYCAR_RACE_POINTS, "indycar").simulate("s1", {
        iterations: 2000,
      });
      const leader = results.find((r) => r.participantId === "driver0");
      expect(leader).toBeDefined();
      if (!leader) return;
      expect(leader.probabilities.probFirst).toBeGreaterThan(0.99);
    });

    it("without a calendar it can only echo the stale odds — the shape of the bug", async () => {
      const warnSpy = vi.spyOn(console, "warn").mockImplementation(() => {});
      await setRaceCounts(0, 0);
      const results = await new AutoRacingSimulator(INDYCAR_RACE_POINTS, "indycar").simulate("s1", {
        iterations: 2000,
      });
      const leader = results.find((r) => r.participantId === "driver0");
      expect(leader).toBeDefined();
      if (!leader) return;
      // Nowhere near the truth, which is exactly why the no-calendar warning
      // above exists. Power devig keeps the -300 favourite well clear of the
      // 55% that proportional devig produced, but odds alone cannot see a
      // 121-point lead.
      expect(leader.probabilities.probFirst).toBeLessThan(0.9);
      expect(warnSpy).toHaveBeenCalledWith(
        expect.stringContaining("championship points but no race calendar")
      );
      warnSpy.mockRestore();
    });

    it("still gives the leader a commanding lead with 5 races left", async () => {
      await setRaceCounts(12, 5);
      const results = await new AutoRacingSimulator(INDYCAR_RACE_POINTS, "indycar").simulate("s1", {
        iterations: 2000,
      });
      const leader = results.find((r) => r.participantId === "driver0");
      expect(leader).toBeDefined();
      if (!leader) return;
      expect(leader.probabilities.probFirst).toBeGreaterThan(0.9);
    });
  });
});

describe("race points tables", () => {
  it("IndyCar pays 50 for a win and scores down to P26", () => {
    expect(INDYCAR_RACE_POINTS[1]).toBe(50);
    expect(INDYCAR_RACE_POINTS[2]).toBe(40);
    expect(INDYCAR_RACE_POINTS[25]).toBe(5);
    expect(INDYCAR_RACE_POINTS[26]).toBe(5);
    expect(INDYCAR_RACE_POINTS[27]).toBeUndefined();
  });

  it("F1 pays 25 for a win and scores down to P10", () => {
    expect(F1_RACE_POINTS[1]).toBe(25);
    expect(F1_RACE_POINTS[10]).toBe(1);
    expect(F1_RACE_POINTS[11]).toBeUndefined();
  });

  it("both tables decrease monotonically so the points loop never truncates early", () => {
    for (const table of [F1_RACE_POINTS, INDYCAR_RACE_POINTS]) {
      const positions = Object.keys(table).map(Number).toSorted((a, b) => a - b);
      // Contiguous from P1, no gaps — the award loop breaks at the first 0.
      positions.forEach((pos, i) => expect(pos).toBe(i + 1));
      for (let i = 1; i < positions.length; i++) {
        expect(table[positions[i]]).toBeLessThanOrEqual(table[positions[i - 1]]);
      }
    }
  });
});