brackt/app/models/__tests__/llws-20-bracket.test.ts

/**
 * LLWS 20-Team Double-Elimination Bracket Tests
 *
 * Verifies the llws_20 template against the official 2026 LLBWS bracket
 * (Williamsport, Aug 19–30). The PDF numbers its games 1–38; those numbers appear
 * throughout as `G<n>` so the routing can be checked against the printed bracket.
 *
 * The critical property under test is the double-elimination loser routing: a loss in
 * the winners bracket drops a team into the elimination bracket at a specific slot,
 * while a loss in the elimination bracket is final.
 */

import { describe, it, expect, vi } from "vitest";
import {
  LLWS_20,
  getScoringRoundType,
  llwsMatchNumber,
  llwsSideAndLocal,
} from "~/lib/bracket-templates";
import {
  doesLoserAdvance,
  generateBracketFromTemplate,
  resolveLLWSAdvancement,
} from "../playoff-match";
import {
  calculateBracketPoints,
  calculateAveragedPoints,
  type ScoringRules,
} from "../scoring-rules";
import {
  GAME_TO_MATCH,
  EXPECTED_SLOTS,
  gameNumberFor,
  required,
  destinationGame,
} from "~/test/fixtures/llws-bracket";

// generateBracketFromTemplate's only DB touch for llws_20 is the bulk insert, so a
// minimal stub is enough to capture the generated rows.
const insertedRows: Record<string, unknown>[] = [];
vi.mock("~/database/context", () => ({
  database: () => ({
    insert: () => ({
      values: (rows: Record<string, unknown>[]) => ({
        returning: async () => {
          insertedRows.push(...rows);
          return rows;
        },
      }),
    }),
  }),
}));

const DEFAULT_SCORING: ScoringRules = {
  pointsFor1st: 100,
  pointsFor2nd: 70,
  pointsFor3rd: 50,
  pointsFor4th: 40,
  pointsFor5th: 25,
  pointsFor6th: 20,
  pointsFor7th: 15,
  pointsFor8th: 10,
};

describe("LLWS 20 Bracket Template", () => {
  describe("Template structure", () => {
    it("has correct identity and size", () => {
      expect(LLWS_20.id).toBe("llws_20");
      expect(LLWS_20.totalTeams).toBe(20);
      expect(LLWS_20.scoringStartsAtRound).toBe("Winners Final");
    });

    it("has 12 rounds totalling 38 matches", () => {
      expect(LLWS_20.rounds).toHaveLength(12);
      const total = LLWS_20.rounds.reduce((sum, r) => sum + r.matchCount, 0);
      expect(total).toBe(38);
    });

    it("has the expected match count per round", () => {
      const counts = Object.fromEntries(
        LLWS_20.rounds.map((r) => [r.name, r.matchCount])
      );
      expect(counts).toEqual({
        "Opening Round": 8,
        "Winners Round 2": 4,
        "Elimination Round 1": 4,
        "Winners Semifinals": 4,
        "Elimination Round 2": 4,
        "Elimination Round 3": 4,
        "Winners Final": 2,
        "Elimination Round 4": 2,
        "Elimination Final": 2,
        "Bracket Championship": 2,
        "Consolation Third Place": 1,
        "World Championship": 1,
      });
    });

    it("marks exactly the point-awarding rounds as scoring", () => {
      const scoring = LLWS_20.rounds.filter((r) => r.isScoring).map((r) => r.name);
      expect(scoring).toEqual([
        "Winners Final",
        "Elimination Round 4",
        "Elimination Final",
        "Bracket Championship",
        "Consolation Third Place",
        "World Championship",
      ]);
    });

    it("lists rounds in chronological order", () => {
      // Elimination Round 1 (Aug 22) is played before Winners Semifinals (Aug 23).
      const names = LLWS_20.rounds.map((r) => r.name);
      expect(names.indexOf("Elimination Round 1")).toBeLessThan(
        names.indexOf("Winners Semifinals")
      );
      expect(names.indexOf("Winners Final")).toBeLessThan(
        names.indexOf("Elimination Final")
      );
    });

    it("gives elimination-bracket winners a floor matching their real worst case", () => {
      const byName = (n: string) => LLWS_20.rounds.find((r) => r.name === n);
      // Winning Elim R3 only guarantees 7th (a loss in Elim R4 is the 7–8 tier),
      // so the engine's default floor of 5 would overstate it.
      expect(byName("Elimination Round 3")?.nonScoringWinnerFloor).toBe(7);
      // Reaching the Winners Final guarantees 5th at worst.
      expect(byName("Winners Semifinals")?.nonScoringWinnerFloor).toBe(5);
      // Nothing is guaranteed earlier than that.
      expect(byName("Opening Round")?.nonScoringWinnerFloor).toBeNull();
      expect(byName("Winners Round 2")?.nonScoringWinnerFloor).toBeNull();
      expect(byName("Elimination Round 1")?.nonScoringWinnerFloor).toBeNull();
      expect(byName("Elimination Round 2")?.nonScoringWinnerFloor).toBeNull();
    });

    it("has 20 participant labels", () => {
      expect(LLWS_20.participantLabels).toHaveLength(20);
    });

    it("splits display into U.S., International and Championship phases", () => {
      expect(LLWS_20.phases?.map((p) => p.name)).toEqual([
        "United States",
        "International",
        "Championship",
      ]);
    });

    it("assigns every match to exactly one phase group", () => {
      const claimed = new Map<string, number>();
      for (const phase of LLWS_20.phases ?? []) {
        for (const group of phase.groups ?? []) {
          for (const [round, numbers] of Object.entries(group.roundMatchNumbers)) {
            for (const n of numbers) {
              const key = `${round}#${n}`;
              claimed.set(key, (claimed.get(key) ?? 0) + 1);
            }
          }
        }
      }
      // Every per-side match claimed exactly once (36 games; the 2 finals live in
      // the Championship phase's plain round list, not in a group).
      expect(claimed.size).toBe(36);
      expect([...claimed.values()].every((c) => c === 1)).toBe(true);
    });
  });

  describe("Bracket generation", () => {
    const PARTICIPANTS = Array.from({ length: 20 }, (_, i) => `team-${i}`);

    async function generate() {
      insertedRows.length = 0;
      await generateBracketFromTemplate("event-1", "llws_20", PARTICIPANTS);
      return insertedRows.map((r) => ({
        round: r.round as string,
        matchNumber: r.matchNumber as number,
        participant1Id: (r.participant1Id ?? null) as string | null,
        participant2Id: (r.participant2Id ?? null) as string | null,
        isScoring: r.isScoring as boolean,
      }));
    }

    it("creates all 38 matches", async () => {
      const rows = await generate();
      expect(rows).toHaveLength(38);
    });

    it("creates the right number of matches per round", async () => {
      const rows = await generate();
      for (const round of LLWS_20.rounds) {
        expect(
          rows.filter((r) => r.round === round.name),
          `${round.name} match count`
        ).toHaveLength(round.matchCount);
      }
    });

    it("numbers matches 1..n within each round", async () => {
      const rows = await generate();
      for (const round of LLWS_20.rounds) {
        const numbers = rows
          .filter((r) => r.round === round.name)
          .map((r) => r.matchNumber)
          .toSorted((a, b) => a - b);
        expect(numbers).toEqual(
          Array.from({ length: round.matchCount }, (_, i) => i + 1)
        );
      }
    });

    it("seeds the Opening Round two teams at a time, U.S. then International", async () => {
      const rows = await generate();
      const opening = rows
        .filter((r) => r.round === "Opening Round")
        .toSorted((a, b) => a.matchNumber - b.matchNumber);
      // U.S. slots 0–7 fill matches 1–4; International slots 10–17 fill matches 5–8.
      expect(opening.map((m) => [m.participant1Id, m.participant2Id])).toEqual([
        ["team-0", "team-1"],
        ["team-2", "team-3"],
        ["team-4", "team-5"],
        ["team-6", "team-7"],
        ["team-10", "team-11"],
        ["team-12", "team-13"],
        ["team-14", "team-15"],
        ["team-16", "team-17"],
      ]);
    });

    it("seats the four bye teams in Winners Round 2 awaiting an opponent", async () => {
      const rows = await generate();
      const wr2 = rows
        .filter((r) => r.round === "Winners Round 2")
        .toSorted((a, b) => a.matchNumber - b.matchNumber);
      expect(wr2.map((m) => [m.participant1Id, m.participant2Id])).toEqual([
        ["team-8", null],
        ["team-9", null],
        ["team-18", null],
        ["team-19", null],
      ]);
    });

    it("uses each participant exactly once and leaves every other slot empty", async () => {
      const rows = await generate();
      const seeded = rows
        .flatMap((r) => [r.participant1Id, r.participant2Id])
        .filter((id): id is string => id !== null);
      expect(seeded).toHaveLength(20);
      expect(new Set(seeded).size).toBe(20);
      expect(new Set(seeded)).toEqual(new Set(PARTICIPANTS));
    });

    it("stamps isScoring from the template", async () => {
      const rows = await generate();
      for (const round of LLWS_20.rounds) {
        for (const row of rows.filter((r) => r.round === round.name)) {
          expect(row.isScoring, `${round.name} #${row.matchNumber}`).toBe(round.isScoring);
        }
      }
    });

    it("rejects a participant count other than 20", async () => {
      await expect(
        generateBracketFromTemplate("event-1", "llws_20", PARTICIPANTS.slice(0, 19))
      ).rejects.toThrow(/requires 20 participants/);
    });
  });

  describe("Side / match-number mapping", () => {
    it("round-trips every match number through side-local form", () => {
      for (const round of LLWS_20.rounds) {
        if (round.matchCount === 1) continue; // shared finals have no side
        for (let n = 1; n <= round.matchCount; n++) {
          const { side, localMatch } = llwsSideAndLocal(round.name, n);
          expect(llwsMatchNumber(round.name, side, localMatch)).toBe(n);
        }
      }
    });

    it("puts U.S. matches in the low half and International in the high half", () => {
      expect(llwsSideAndLocal("Opening Round", 4).side).toBe(0);
      expect(llwsSideAndLocal("Opening Round", 5).side).toBe(1);
      expect(llwsSideAndLocal("Winners Semifinals", 2).side).toBe(0);
      expect(llwsSideAndLocal("Winners Semifinals", 3).side).toBe(1);
      expect(llwsSideAndLocal("Winners Final", 1).side).toBe(0);
      expect(llwsSideAndLocal("Winners Final", 2).side).toBe(1);
    });
  });

  describe("Advancement matches the official bracket", () => {
    /**
     * Replay the whole tournament through resolveLLWSAdvancement and record which
     * feed label ends up in each slot, then compare against the printed bracket.
     */
    const actualSlots: Record<number, [string | null, string | null]> = {};
    for (const game of Object.keys(EXPECTED_SLOTS)) {
      actualSlots[Number(game)] = [null, null];
    }

    for (const [gameStr, { round, matchNumber }] of Object.entries(GAME_TO_MATCH)) {
      const game = Number(gameStr);
      const { winner, loser } = resolveLLWSAdvancement(round, matchNumber);
      for (const [dest, label] of [
        [winner, `W${game}`],
        [loser, `L${game}`],
      ] as const) {
        if (!dest) continue;
        const targetGame = gameNumberFor(dest.round, dest.matchNumber);
        const slotIndex = dest.slot === "participant1Id" ? 0 : 1;
        actualSlots[targetGame][slotIndex] = label;
      }
    }

    it.each(Object.keys(EXPECTED_SLOTS).map(Number).toSorted((a, b) => a - b))(
      "Game %i has the printed participants",
      (game) => {
        expect(actualSlots[game]).toEqual(EXPECTED_SLOTS[game]);
      }
    );

    it("fills every slot in the bracket exactly once", () => {
      // 38 games × 2 slots = 76. 20 are seeded directly (16 opening teams + 4 byes),
      // leaving 56 to be filled by advancement.
      const filled = Object.values(actualSlots)
        .flat()
        .filter((s) => s !== null).length;
      expect(filled).toBe(56);
    });
  });

  describe("Double-elimination loser routing", () => {
    it("routes every winners-bracket loser into the elimination bracket", () => {
      const winnersRounds = [
        "Opening Round",
        "Winners Round 2",
        "Winners Semifinals",
        "Winners Final",
      ];
      for (const roundName of winnersRounds) {
        const round = LLWS_20.rounds.find((r) => r.name === roundName);
        if (!round) throw new Error(`missing round ${roundName}`);
        for (let n = 1; n <= round.matchCount; n++) {
          const { loser } = resolveLLWSAdvancement(roundName, n);
          expect(loser, `${roundName} #${n} loser should advance`).not.toBeNull();
          expect(loser?.round.startsWith("Elimination")).toBe(true);
        }
      }
    });

    it("eliminates every elimination-bracket loser", () => {
      const elimRounds = [
        "Elimination Round 1",
        "Elimination Round 2",
        "Elimination Round 3",
        "Elimination Round 4",
        "Elimination Final",
      ];
      for (const roundName of elimRounds) {
        const round = LLWS_20.rounds.find((r) => r.name === roundName);
        if (!round) throw new Error(`missing round ${roundName}`);
        for (let n = 1; n <= round.matchCount; n++) {
          const { loser } = resolveLLWSAdvancement(roundName, n);
          expect(loser, `${roundName} #${n} loser should be out`).toBeNull();
        }
      }
    });

    it("keeps the winners-bracket final loser alive via the Elimination Final", () => {
      // G30 (U.S. Winners Final) loser → G34, not out. This is the defining
      // double-elimination behavior: a first loss never eliminates.
      const { winner, loser } = resolveLLWSAdvancement("Winners Final", 1);
      expect(destinationGame(loser)).toBe(34);
      expect(destinationGame(winner)).toBe(36);
    });

    it("sends the side-championship loser to the consolation game, not out", () => {
      // No "if necessary" rematch: the winners-bracket champion that loses G36 is
      // done in the bracket, but still plays G37 for 3rd/4th.
      const us = resolveLLWSAdvancement("Bracket Championship", 1);
      expect(destinationGame(us.winner)).toBe(38);
      expect(destinationGame(us.loser)).toBe(37);
      expect(required(us.winner).slot).toBe("participant1Id");
      expect(required(us.loser).slot).toBe("participant1Id");

      const intl = resolveLLWSAdvancement("Bracket Championship", 2);
      expect(required(intl.winner).slot).toBe("participant2Id");
      expect(required(intl.loser).slot).toBe("participant2Id");
    });

    it("flags winners-bracket losers as advancing so they are not marked eliminated", () => {
      // doesLoserAdvance is what stops the scoring engine writing a 0-point
      // elimination (and announcing a knockout) for a team that is still alive.
      // Winners Final and Bracket Championship are scoring rounds and are covered
      // by loserIsPartial instead, so they are deliberately not listed here.
      for (const round of ["Opening Round", "Winners Round 2", "Winners Semifinals"]) {
        expect(doesLoserAdvance(round, 1, "llws_20"), round).toBe(true);
      }
      for (const round of [
        "Elimination Round 1",
        "Elimination Round 2",
        "Elimination Round 3",
        "Elimination Round 4",
        "Elimination Final",
      ]) {
        expect(doesLoserAdvance(round, 1, "llws_20"), round).toBe(false);
      }
    });

    it("does not apply LLWS loser routing to other templates", () => {
      expect(doesLoserAdvance("Opening Round", 1, "ncaa_68")).toBe(false);
      expect(doesLoserAdvance("Winners Semifinals", 1, "")).toBe(false);
    });

    it("advances nobody out of the two final games", () => {
      for (const round of ["Consolation Third Place", "World Championship"]) {
        expect(resolveLLWSAdvancement(round, 1)).toEqual({ winner: null, loser: null });
      }
    });

    it("never crosses a team between the U.S. and International sides", () => {
      for (const round of LLWS_20.rounds) {
        if (round.name === "Bracket Championship") continue; // the crossover point
        if (round.matchCount === 1) continue;
        for (let n = 1; n <= round.matchCount; n++) {
          const { side } = llwsSideAndLocal(round.name, n);
          const { winner, loser } = resolveLLWSAdvancement(round.name, n);
          for (const dest of [winner, loser]) {
            if (!dest) continue;
            const destRound = LLWS_20.rounds.find((r) => r.name === dest.round);
            if (!destRound || destRound.matchCount === 1) continue;
            expect(llwsSideAndLocal(dest.round, dest.matchNumber).side).toBe(side);
          }
        }
      }
    });
  });

  describe("Placement tiers", () => {
    it("classifies scoring rounds correctly", () => {
      expect(getScoringRoundType("Elimination Round 4", LLWS_20)).toBe("quarterfinals");
      expect(getScoringRoundType("Elimination Final", LLWS_20)).toBe("quarterfinals");
      expect(getScoringRoundType("Bracket Championship", LLWS_20)).toBe("semifinals");
      expect(getScoringRoundType("World Championship", LLWS_20)).toBe("finals");
      // Nobody is eliminated in the Winners Final — the loser drops to the
      // elimination bracket — so it has no placement tier.
      expect(getScoringRoundType("Winners Final", LLWS_20)).toBeNull();
    });

    it("pays 3rd and 4th distinctly (there is a real consolation game)", () => {
      expect(calculateBracketPoints(3, DEFAULT_SCORING, "llws_20")).toBe(50);
      expect(calculateBracketPoints(4, DEFAULT_SCORING, "llws_20")).toBe(40);
    });

    it("splits 5–8 into two two-team tiers", () => {
      const upper = calculateAveragedPoints([5, 6], DEFAULT_SCORING); // (25+20)/2
      const lower = calculateAveragedPoints([7, 8], DEFAULT_SCORING); // (15+10)/2
      expect(calculateBracketPoints(5, DEFAULT_SCORING, "llws_20")).toBe(upper);
      expect(calculateBracketPoints(6, DEFAULT_SCORING, "llws_20")).toBe(upper);
      expect(calculateBracketPoints(7, DEFAULT_SCORING, "llws_20")).toBe(lower);
      expect(calculateBracketPoints(8, DEFAULT_SCORING, "llws_20")).toBe(lower);
      // Surviving Elimination Round 4 is worth more than losing it.
      expect(upper).toBeGreaterThan(lower);
    });

    it("awards nothing below 8th", () => {
      // The 12 teams knocked out in Elimination Rounds 1–3 finish 9th–20th.
      expect(calculateBracketPoints(9, DEFAULT_SCORING, "llws_20")).toBe(0);
      expect(calculateBracketPoints(0, DEFAULT_SCORING, "llws_20")).toBe(0);
    });

    it("has exactly 8 teams alive when the first scoring elimination game is played", () => {
      // Elimination Round 4 is the 7th–8th tier, so the field must be 8 at that point:
      // per side the Winners Final winner, the Winners Final loser, and the two
      // Elimination Round 3 winners.
      const eliminatedBeforeElimR4 =
        (LLWS_20.rounds.find((r) => r.name === "Elimination Round 1")?.matchCount ?? 0) +
        (LLWS_20.rounds.find((r) => r.name === "Elimination Round 2")?.matchCount ?? 0) +
        (LLWS_20.rounds.find((r) => r.name === "Elimination Round 3")?.matchCount ?? 0);
      expect(eliminatedBeforeElimR4).toBe(12);
      expect(LLWS_20.totalTeams - eliminatedBeforeElimR4).toBe(8);
    });
  });
});