euchre_camp/src/__tests__/unit/recalculate-elo.test.ts

/**
 * Unit Tests: ELO Recalculation
 * 
 * Tests the idempotent full recalculation of ELO ratings and player statistics
 */

/* eslint-disable @typescript-eslint/no-explicit-any */
import { describe, test, expect, beforeEach, mock } from 'bun:test';
import { recalculateAllElo } from '@/lib/elo-utils';

// Mock Prisma client
const mockPrisma = {
  player: {
    updateMany: mock(async () => ({ count: 0 })),
    update: mock(async () => ({})),
  },
  eloSnapshot: {
    deleteMany: mock(async () => ({ count: 0 })),
    create: mock(async () => ({})),
  },
  partnershipStat: {
    deleteMany: mock(async () => ({ count: 0 })),
    findFirst: mock(async () => null), // No existing stats initially
    update: mock(async () => ({})),
    create: mock(async () => ({})),
  },
  match: {
    findMany: mock(async () => []),
  },
};

describe('recalculateAllElo', () => {
  beforeEach(() => {
    mock.clearAllMocks();
  });

  test('should reset all player stats to zero', async () => {
    (mockPrisma.match.findMany as any).mockResolvedValue([]);

    const result = await recalculateAllElo(mockPrisma as any);

    expect(mockPrisma.player.updateMany).toHaveBeenCalledWith({
      data: {
        currentElo: 1000,
        gamesPlayed: 0,
        wins: 0,
        losses: 0,
      },
    });

    expect(result.matchesProcessed).toBe(0);
    expect(result.playersUpdated).toBe(0);
    expect(result.partnershipsUpdated).toBe(0);
  });

  test('should delete all existing elo snapshots', async () => {
    (mockPrisma.match.findMany as any).mockResolvedValue([]);

    await recalculateAllElo(mockPrisma as any);

    expect(mockPrisma.eloSnapshot.deleteMany).toHaveBeenCalledWith({});
  });

  test('should delete all existing partnership stats', async () => {
    (mockPrisma.match.findMany as any).mockResolvedValue([]);

    await recalculateAllElo(mockPrisma as any);

    expect(mockPrisma.partnershipStat.deleteMany).toHaveBeenCalledWith({});
  });

  test('should return correct result for empty match list', async () => {
    (mockPrisma.match.findMany as any).mockResolvedValue([]);

    const result = await recalculateAllElo(mockPrisma as any);

    expect(result).toEqual({
      matchesProcessed: 0,
      playersUpdated: 0,
      partnershipsUpdated: 0,
    });
  });

  test('should process matches in chronological order', async () => {
    const mockMatches = [
      {
        id: 1,
        playedAt: new Date('2024-01-01'),
        team1P1: { id: 1, name: 'Player 1' },
        team1P2: { id: 2, name: 'Player 2' },
        team2P1: { id: 3, name: 'Player 3' },
        team2P2: { id: 4, name: 'Player 4' },
        team1Score: 10,
        team2Score: 5,
      },
      {
        id: 2,
        playedAt: new Date('2024-01-02'),
        team1P1: { id: 1, name: 'Player 1' },
        team1P2: { id: 2, name: 'Player 2' },
        team2P1: { id: 5, name: 'Player 5' },
        team2P2: { id: 6, name: 'Player 6' },
        team1Score: 8,
        team2Score: 6,
      },
    ];

    (mockPrisma.match.findMany as any).mockResolvedValue(mockMatches);

    await recalculateAllElo(mockPrisma as any);

    // Should process 2 matches
    expect(mockPrisma.match.findMany).toHaveBeenCalledWith({
      orderBy: { playedAt: 'asc' },
      include: {
        team1P1: true,
        team1P2: true,
        team2P1: true,
        team2P2: true,
      },
    });
  });

  test('should create elo snapshots for each player in each match', async () => {
    const mockMatches = [
      {
        id: 1,
        playedAt: new Date('2024-01-01'),
        team1P1: { id: 1, name: 'Player 1' },
        team1P2: { id: 2, name: 'Player 2' },
        team2P1: { id: 3, name: 'Player 3' },
        team2P2: { id: 4, name: 'Player 4' },
        team1Score: 10,
        team2Score: 5,
      },
    ];

    (mockPrisma.match.findMany as any).mockResolvedValue(mockMatches);

    await recalculateAllElo(mockPrisma as any);

    // Should create 4 snapshots (one for each player)
    expect(mockPrisma.eloSnapshot.create).toHaveBeenCalledTimes(4);
  });

  test('should update player stats after processing matches', async () => {
    const mockMatches = [
      {
        id: 1,
        playedAt: new Date('2024-01-01'),
        team1P1: { id: 1, name: 'Player 1' },
        team1P2: { id: 2, name: 'Player 2' },
        team2P1: { id: 3, name: 'Player 3' },
        team2P2: { id: 4, name: 'Player 4' },
        team1Score: 10,
        team2Score: 5,
      },
    ];

    (mockPrisma.match.findMany as any).mockResolvedValue(mockMatches);

    await recalculateAllElo(mockPrisma as any);

    // Should update 4 players
    expect(mockPrisma.player.update).toHaveBeenCalledTimes(4);
  });

  test('should update partnership stats after processing matches', async () => {
    const mockMatches = [
      {
        id: 1,
        playedAt: new Date('2024-01-01'),
        team1P1: { id: 1, name: 'Player 1' },
        team1P2: { id: 2, name: 'Player 2' },
        team2P1: { id: 3, name: 'Player 3' },
        team2P2: { id: 4, name: 'Player 4' },
        team1Score: 10,
        team2Score: 5,
      },
    ];

    (mockPrisma.match.findMany as any).mockResolvedValue(mockMatches);

    await recalculateAllElo(mockPrisma as any);

    // Should check for existing partnership stats (2 calls) and create new ones (2 calls)
    expect(mockPrisma.partnershipStat.findFirst).toHaveBeenCalledTimes(2);
    expect(mockPrisma.partnershipStat.create).toHaveBeenCalledTimes(2);
  });
});