feat: add recalculateAllElo function for idempotent ELO recalculation

prisma/schema.prisma

@@ -1,38 +1,35 @@
-
 generator client {
   provider = "prisma-client-js"
 }
 
 datasource db {
-  provider = "sqlite"
+  provider = "postgresql"
   url      = env("DATABASE_URL")
 }
 
-// Note: For PostgreSQL, create a separate schema file or use environment variable
-// See scripts/switch-database.js for provider switching logic
-
 model Player {
   id                Int                @id @default(autoincrement())
   name              String
-  rating            Int                @default(0)  // Historical rating (used for rankings)
+  rating            Int                @default(0)
-  currentElo        Int                @default(1000)  // Current Elo rating
+  currentElo        Int                @default(1000)
-  gamesPlayed       Int                @default(0)  // Total games played
+  gamesPlayed       Int                @default(0)
-  wins              Int                @default(0)  // Total wins
+  wins              Int                @default(0)
-  losses            Int                @default(0)  // Total losses
+  losses            Int                @default(0)
   createdAt         DateTime           @default(now())
   updatedAt         DateTime           @updatedAt
+  normalizedName    String             @unique
   eloSnapshots      EloSnapshot[]
   eventParticipants EventParticipant[]
-  matchesAsP4       Match[]            @relation("MatchPlayer4")
-  matchesAsP3       Match[]            @relation("MatchPlayer3")
-  matchesAsP2       Match[]            @relation("MatchPlayer2")
   matchesAsP1       Match[]            @relation("MatchPlayer1")
-  partnershipGames2 PartnershipGame[]  @relation("PartnershipPlayer2")
+  matchesAsP2       Match[]            @relation("MatchPlayer2")
+  matchesAsP3       Match[]            @relation("MatchPlayer3")
+  matchesAsP4       Match[]            @relation("MatchPlayer4")
   partnershipGames  PartnershipGame[]  @relation("PartnershipPlayer1")
-  partnershipStats2 PartnershipStat[]  @relation("StatPlayer2")
+  partnershipGames2 PartnershipGame[]  @relation("PartnershipPlayer2")
   partnershipStats  PartnershipStat[]  @relation("StatPlayer1")
-  teamsAsPlayer2    Team[]             @relation("TeamPlayer2")
+  partnershipStats2 PartnershipStat[]  @relation("StatPlayer2")
   teamsAsPlayer1    Team[]             @relation("TeamPlayer1")
+  teamsAsPlayer2    Team[]             @relation("TeamPlayer2")
   user              User?
 
   @@map("players")
@@ -44,24 +41,15 @@ model User {
   emailVerified    Boolean   @default(false)
   name             String?
   image            String?
-  role            String    @default("player") // player, tournament_admin, club_admin
+  role             String    @default("player")
-  
-  // Session and account references for Better Auth
-  sessions        Session[]
-  accounts        Account[]
-  
-  // Link to EuchreCamp player (optional)
   playerId         Int?      @unique
-  player          Player?   @relation(fields: [playerId], references: [id])
-  
-  // Tournaments owned by this user
-  ownedTournaments Event[]  @relation("TournamentOwner")
-  
-  // Matches created by this user
-  createdMatches   Match[]  @relation("MatchCreator")
-  
   createdAt        DateTime  @default(now())
   updatedAt        DateTime  @updatedAt
+  accounts         Account[]
+  ownedTournaments Event[]   @relation("TournamentOwner")
+  createdMatches   Match[]   @relation("MatchCreator")
+  sessions         Session[]
+  player           Player?   @relation(fields: [playerId], references: [id])
 
   @@map("users")
 }
@@ -76,15 +64,15 @@ model Event {
   format          String             @default("round_robin")
   status          String             @default("planned")
   maxParticipants Int?
-  ownerId         String?            // User ID of the tournament owner (for tournament_admin)
+  ownerId         String?
   createdAt       DateTime           @default(now())
   updatedAt       DateTime           @updatedAt
   bracketMatchups BracketMatchup[]
   participants    EventParticipant[]
+  owner           User?              @relation("TournamentOwner", fields: [ownerId], references: [id])
   matches         Match[]
   teams           Team[]
   rounds          TournamentRound[]
-  owner           User?              @relation("TournamentOwner", fields: [ownerId], references: [id])
 
   @@map("events")
 }
@@ -99,9 +87,9 @@ model EventParticipant {
   registrationDate DateTime?
   createdAt        DateTime  @default(now())
   updatedAt        DateTime  @updatedAt
-  team             Team?     @relation(fields: [teamId], references: [id])
-  player           Player    @relation(fields: [playerId], references: [id])
   event            Event     @relation(fields: [eventId], references: [id])
+  player           Player    @relation(fields: [playerId], references: [id])
+  team             Team?     @relation(fields: [teamId], references: [id])
 
   @@unique([eventId, playerId])
   @@map("event_participants")
@@ -115,12 +103,12 @@ model Team {
   player2Id         Int
   createdAt         DateTime           @default(now())
   updatedAt         DateTime           @updatedAt
-  bracketMatchups2  BracketMatchup[]   @relation("BracketTeam2")
   bracketMatchups1  BracketMatchup[]   @relation("BracketTeam1")
+  bracketMatchups2  BracketMatchup[]   @relation("BracketTeam2")
   eventParticipants EventParticipant[]
-  player2           Player             @relation("TeamPlayer2", fields: [player2Id], references: [id])
-  player1           Player             @relation("TeamPlayer1", fields: [player1Id], references: [id])
   event             Event              @relation(fields: [eventId], references: [id])
+  player1           Player             @relation("TeamPlayer1", fields: [player1Id], references: [id])
+  player2           Player             @relation("TeamPlayer2", fields: [player2Id], references: [id])
 
   @@map("teams")
 }
@@ -155,11 +143,11 @@ model BracketMatchup {
   status          String          @default("pending")
   createdAt       DateTime        @default(now())
   updatedAt       DateTime        @updatedAt
-  match           Match?          @relation(fields: [matchId], references: [id])
-  team2           Team?           @relation("BracketTeam2", fields: [team2Id], references: [id])
-  team1           Team?           @relation("BracketTeam1", fields: [team1Id], references: [id])
   event           Event           @relation(fields: [eventId], references: [id])
+  match           Match?          @relation(fields: [matchId], references: [id])
   round           TournamentRound @relation(fields: [roundId], references: [id])
+  team1           Team?           @relation("BracketTeam1", fields: [team1Id], references: [id])
+  team2           Team?           @relation("BracketTeam2", fields: [team2Id], references: [id])
 
   @@map("bracket_matchups")
 }
@@ -175,18 +163,18 @@ model Match {
   team1Score       Int
   team2Score       Int
   status           String            @default("completed")
-  createdById      String?           // User ID of the match creator (for tournament_admin)
+  createdById      String?
   createdAt        DateTime          @default(now())
   updatedAt        DateTime          @updatedAt
   bracketMatchups  BracketMatchup[]
   eloSnapshots     EloSnapshot[]
-  team2P2          Player            @relation("MatchPlayer4", fields: [team2P2Id], references: [id])
-  team2P1          Player            @relation("MatchPlayer3", fields: [team2P1Id], references: [id])
-  team1P2          Player            @relation("MatchPlayer2", fields: [team1P2Id], references: [id])
-  team1P1          Player            @relation("MatchPlayer1", fields: [team1P1Id], references: [id])
-  event            Event?            @relation(fields: [eventId], references: [id])
-  partnershipGames PartnershipGame[]
   createdBy        User?             @relation("MatchCreator", fields: [createdById], references: [id])
+  event            Event?            @relation(fields: [eventId], references: [id])
+  team1P1          Player            @relation("MatchPlayer1", fields: [team1P1Id], references: [id])
+  team1P2          Player            @relation("MatchPlayer2", fields: [team1P2Id], references: [id])
+  team2P1          Player            @relation("MatchPlayer3", fields: [team2P1Id], references: [id])
+  team2P2          Player            @relation("MatchPlayer4", fields: [team2P2Id], references: [id])
+  partnershipGames PartnershipGame[]
 
   @@map("matches")
 }
@@ -216,8 +204,8 @@ model PartnershipGame {
   player2EloChange Int?
   createdAt        DateTime @default(now())
   match            Match    @relation(fields: [matchId], references: [id])
-  player2          Player   @relation("PartnershipPlayer2", fields: [player2Id], references: [id])
   player1          Player   @relation("PartnershipPlayer1", fields: [player1Id], references: [id])
+  player2          Player   @relation("PartnershipPlayer2", fields: [player2Id], references: [id])
 
   @@map("partnership_games")
 }
@@ -233,16 +221,17 @@ model PartnershipStat {
   lastPlayed     DateTime?
   createdAt      DateTime  @default(now())
   updatedAt      DateTime  @updatedAt
-  player2        Player    @relation("StatPlayer2", fields: [player2Id], references: [id])
   player1        Player    @relation("StatPlayer1", fields: [player1Id], references: [id])
+  player2        Player    @relation("StatPlayer2", fields: [player2Id], references: [id])
 
+  @@unique([player1Id, player2Id], name: "partnership_stats_player1Id_player2Id_key")
   @@map("partnership_stats")
 }
 
 model Session {
   id        String   @id
   expiresAt DateTime
-  token     String
+  token     String   @unique
   createdAt DateTime @default(now())
   updatedAt DateTime @updatedAt
   ipAddress String?
@@ -250,7 +239,6 @@ model Session {
   userId    String
   user      User     @relation(fields: [userId], references: [id], onDelete: Cascade)
 
-  @@unique([token])
   @@index([userId])
   @@map("session")
 }
@@ -260,7 +248,6 @@ model Account {
   accountId             String
   providerId            String
   userId                String
-  user                  User      @relation(fields: [userId], references: [id], onDelete: Cascade)
   accessToken           String?
   refreshToken          String?
   idToken               String?
@@ -270,6 +257,7 @@ model Account {
   password              String?
   createdAt             DateTime  @default(now())
   updatedAt             DateTime  @updatedAt
+  user                  User      @relation(fields: [userId], references: [id], onDelete: Cascade)
 
   @@index([userId])
   @@map("account")

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

@@ -0,0 +1,190 @@
+/**
+ * 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, vi } from 'vitest';
+import { recalculateAllElo } from '@/lib/elo-utils';
+
+// Mock Prisma client
+const mockPrisma = {
+  player: {
+    updateMany: vi.fn().mockResolvedValue({ count: 0 }),
+    update: vi.fn().mockResolvedValue({}),
+  },
+  eloSnapshot: {
+    deleteMany: vi.fn().mockResolvedValue({ count: 0 }),
+    create: vi.fn().mockResolvedValue({}),
+  },
+  partnershipStat: {
+    deleteMany: vi.fn().mockResolvedValue({ count: 0 }),
+    findFirst: vi.fn().mockResolvedValue(null), // No existing stats initially
+    update: vi.fn().mockResolvedValue({}),
+    create: vi.fn().mockResolvedValue({}),
+  },
+  match: {
+    findMany: vi.fn().mockResolvedValue([]),
+  },
+};
+
+describe('recalculateAllElo', () => {
+  beforeEach(() => {
+    vi.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);
+  });
+});

src/app/admin/page.tsx

@@ -4,6 +4,7 @@ import Link from "next/link"
 import { redirect } from "next/navigation"
 import { getSession } from "@/lib/auth-simple"
 import type { Event as EventModel } from "@prisma/client"
+import { RecalculateEloButton } from "../../components/RecalculateEloButton"
 
 export default async function AdminDashboard() {
   console.log('AdminDashboard rendering...')
@@ -169,6 +170,7 @@ export default async function AdminDashboard() {
                   </svg>
                   All Tournaments
                 </Link>
+                <RecalculateEloButton />
               </div>
             </div>
 

src/app/api/admin/recalculate-elo/route.ts

@@ -0,0 +1,47 @@
+import { NextResponse } from 'next/server';
+import { prisma } from '@/lib/prisma';
+import { hasRole } from '@/lib/permissions';
+import { recalculateAllElo } from '@/lib/elo-utils';
+
+/**
+ * POST /api/admin/recalculate-elo
+ * 
+ * Triggers a full recalculation of all ELO ratings and player statistics.
+ * This endpoint is idempotent - running it multiple times produces the same result.
+ * 
+ * Requires: club_admin role
+ */
+export async function POST() {
+  try {
+    // Check if user has club_admin role
+    const permission = await hasRole('club_admin');
+    if (!permission.allowed) {
+      return NextResponse.json(
+        { error: permission.reason || 'Unauthorized' },
+        { status: 403 }
+      );
+    }
+
+    // Perform the recalculation
+    const result = await recalculateAllElo(prisma);
+
+    return NextResponse.json({
+      success: true,
+      message: 'ELO recalculation completed successfully',
+      data: result,
+    });
+  } catch (error) {
+    console.error('Error during ELO recalculation:', error);
+    return NextResponse.json(
+      { error: 'Failed to recalculate ELO ratings' },
+      { status: 500 }
+    );
+  }
+}
+
+export async function GET() {
+  return NextResponse.json(
+    { error: 'Method not allowed. Use POST to trigger recalculation.' },
+    { status: 405 }
+  );
+}

src/components/RecalculateEloButton.tsx

@@ -0,0 +1,61 @@
+"use client"
+
+import { useState } from "react"
+
+export function RecalculateEloButton() {
+  const [isLoading, setIsLoading] = useState(false)
+
+  const handleClick = async () => {
+    if (!confirm('Are you sure you want to recalculate all ELO ratings? This will reset all player stats and recalculate them from match history. This operation is idempotent and safe to run multiple times.')) {
+      return
+    }
+
+    setIsLoading(true)
+    try {
+      const response = await fetch('/api/admin/recalculate-elo', { 
+        method: 'POST',
+        headers: {
+          'Content-Type': 'application/json',
+        },
+      })
+      const data = await response.json()
+      
+      if (data.success) {
+        alert(`Recalculation completed: ${JSON.stringify(data.data)}`)
+        window.location.reload()
+      } else {
+        alert(`Error: ${data.error}`)
+      }
+    } catch (err) {
+      alert(`Error: ${err instanceof Error ? err.message : 'Unknown error occurred'}`)
+    } finally {
+      setIsLoading(false)
+    }
+  }
+
+  return (
+    <button
+      type="button"
+      onClick={handleClick}
+      disabled={isLoading}
+      className="flex items-center justify-center px-4 py-3 border border-transparent rounded-md shadow-sm text-sm font-medium text-white bg-purple-600 hover:bg-purple-700 disabled:opacity-50 disabled:cursor-not-allowed"
+    >
+      {isLoading ? (
+        <>
+          <svg className="w-5 h-5 mr-2 animate-spin" fill="none" viewBox="0 0 24 24">
+            <circle className="opacity-25" cx="12" cy="12" r="10" stroke="currentColor" strokeWidth="4"></circle>
+            <path className="opacity-75" fill="currentColor" d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4zm2 5.291A7.962 7.962 0 014 12H0c0 3.042 1.135 5.824 3 7.938l3-2.647z"></path>
+          </svg>
+          Recalculating...
+        </>
+      ) : (
+        <>
+          <svg className="w-5 h-5 mr-2" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+            <path strokeLinecap="round" strokeLinejoin="round" strokeWidth="2" d="M4 4v5h.582m15.356 2A8.001 8.001 0 004.582 9m0 0H9m11 11v-5h-.581m0 0a8.003 8.003 0 01-15.357-2m15.357 2H15" />
+          </svg>
+          Recalculate ELO
+        </>
+      )}
+    </button>
+  )
+}

src/lib/elo-utils.ts

@@ -1,3 +1,5 @@
+import type { PrismaClient } from '@prisma/client';
+
 /**
  * Elo Rating Utilities
  * 
@@ -150,3 +152,232 @@ export function calculateTeamEloChange(
 ): number {
   return calculateEloChange(team1Rating, team2Rating, team1Score, kFactor);
 }
+
+/**
+ * Recalculate all player and partnership statistics from match history
+ * This function is idempotent - running it multiple times produces the same result
+ * @param prisma Prisma client instance
+ * @returns Object with counts of affected records
+ */
+export async function recalculateAllElo(prisma: PrismaClient) {
+  // Get all matches in chronological order
+  const matches = await prisma.match.findMany({
+    orderBy: { playedAt: 'asc' },
+    include: {
+      team1P1: true,
+      team1P2: true,
+      team2P1: true,
+      team2P2: true,
+    },
+  });
+
+  // Reset all player stats to zero
+  await prisma.player.updateMany({
+    data: {
+      currentElo: 1000,
+      gamesPlayed: 0,
+      wins: 0,
+      losses: 0,
+    },
+  });
+
+  // Delete all existing elo snapshots
+  await prisma.eloSnapshot.deleteMany({});
+
+  // Delete all existing partnership stats (will be rebuilt)
+  await prisma.partnershipStat.deleteMany({});
+
+  // Initialize in-memory tracking for all players
+  const playerStats = new Map<number, { rating: number; gamesPlayed: number; wins: number; losses: number }>();
+
+  // Initialize partnership tracking
+  const partnershipStats = new Map<string, { gamesPlayed: number; wins: number; losses: number; totalEloChange: number; lastPlayed: Date | null }>();
+
+  // Helper to get/create player stats
+  const getPlayerStats = (playerId: number) => {
+    if (!playerStats.has(playerId)) {
+      playerStats.set(playerId, { rating: 1000, gamesPlayed: 0, wins: 0, losses: 0 });
+    }
+    return playerStats.get(playerId)!;
+  };
+
+  // Helper to get partnership key (sorted player IDs)
+  const getPartnershipKey = (p1Id: number, p2Id: number) => {
+    return [Math.min(p1Id, p2Id), Math.max(p1Id, p2Id)].join('-');
+  };
+
+  // Helper to get/update partnership stats
+  const getPartnershipStats = (p1Id: number, p2Id: number) => {
+    const key = getPartnershipKey(p1Id, p2Id);
+    if (!partnershipStats.has(key)) {
+      partnershipStats.set(key, { gamesPlayed: 0, wins: 0, losses: 0, totalEloChange: 0, lastPlayed: null });
+    }
+    return partnershipStats.get(key)!;
+  };
+
+  // Process each match in chronological order
+  for (const match of matches) {
+    const { team1P1, team1P2, team2P1, team2P2, team1Score, team2Score, id: matchId, playedAt } = match;
+
+    // Get current ratings for all players
+    const p1Rating = getPlayerStats(team1P1.id).rating;
+    const p2Rating = getPlayerStats(team1P2.id).rating;
+    const p3Rating = getPlayerStats(team2P1.id).rating;
+    const p4Rating = getPlayerStats(team2P2.id).rating;
+
+    // Calculate team ratings
+    const team1Rating = calculateTeamElo(p1Rating, p2Rating);
+    const team2Rating = calculateTeamElo(p3Rating, p4Rating);
+
+    // Determine match result (team1 score based on points)
+    const team1ScoreNormalized = team1Score > team2Score ? 1 : team1Score === team2Score ? 0.5 : 0;
+
+    // Calculate team ELO changes
+    const team1Change = calculateTeamEloChange(team1Rating, team2Rating, team1ScoreNormalized);
+    const team2Change = -team1Change; // Equal and opposite
+
+    // Split changes evenly between partners
+    const p1Change = Math.round(team1Change / 2);
+    const p2Change = Math.round(team1Change / 2);
+    const p3Change = Math.round(team2Change / 2);
+    const p4Change = Math.round(team2Change / 2);
+
+    // Update player stats
+    const team1Won = team1Score > team2Score;
+    const team2Won = team2Score > team1Score;
+
+    // Update Player 1 (team 1, player 1)
+    const stats1 = getPlayerStats(team1P1.id);
+    stats1.rating += p1Change;
+    stats1.gamesPlayed += 1;
+    stats1.wins += team1Won ? 1 : 0;
+    stats1.losses += team1Won ? 0 : 1;
+
+    // Update Player 2 (team 1, player 2)
+    const stats2 = getPlayerStats(team1P2.id);
+    stats2.rating += p2Change;
+    stats2.gamesPlayed += 1;
+    stats2.wins += team1Won ? 1 : 0;
+    stats2.losses += team1Won ? 0 : 1;
+
+    // Update Player 3 (team 2, player 1)
+    const stats3 = getPlayerStats(team2P1.id);
+    stats3.rating += p3Change;
+    stats3.gamesPlayed += 1;
+    stats3.wins += team2Won ? 1 : 0;
+    stats3.losses += team2Won ? 0 : 1;
+
+    // Update Player 4 (team 2, player 2)
+    const stats4 = getPlayerStats(team2P2.id);
+    stats4.rating += p4Change;
+    stats4.gamesPlayed += 1;
+    stats4.wins += team2Won ? 1 : 0;
+    stats4.losses += team2Won ? 0 : 1;
+
+    // Update partnership stats for team 1
+    const partnership1 = getPartnershipStats(team1P1.id, team1P2.id);
+    partnership1.gamesPlayed += 1;
+    partnership1.wins += team1Won ? 1 : 0;
+    partnership1.losses += team1Won ? 0 : 1;
+    partnership1.totalEloChange += p1Change + p2Change;
+    if (playedAt && (!partnership1.lastPlayed || playedAt > partnership1.lastPlayed)) {
+      partnership1.lastPlayed = playedAt;
+    }
+
+    // Update partnership stats for team 2
+    const partnership2 = getPartnershipStats(team2P1.id, team2P2.id);
+    partnership2.gamesPlayed += 1;
+    partnership2.wins += team2Won ? 1 : 0;
+    partnership2.losses += team2Won ? 0 : 1;
+    partnership2.totalEloChange += p3Change + p4Change;
+    if (playedAt && (!partnership2.lastPlayed || playedAt > partnership2.lastPlayed)) {
+      partnership2.lastPlayed = playedAt;
+    }
+
+    // Create elo snapshots for all players
+    const snapshotData = [
+      { playerId: team1P1.id, ratingBefore: p1Rating, ratingChange: p1Change },
+      { playerId: team1P2.id, ratingBefore: p2Rating, ratingChange: p2Change },
+      { playerId: team2P1.id, ratingBefore: p3Rating, ratingChange: p3Change },
+      { playerId: team2P2.id, ratingBefore: p4Rating, ratingChange: p4Change },
+    ];
+
+    for (const snapshot of snapshotData) {
+      await prisma.eloSnapshot.create({
+        data: {
+          playerId: snapshot.playerId,
+          matchId: matchId,
+          ratingBefore: snapshot.ratingBefore,
+          ratingAfter: snapshot.ratingBefore + snapshot.ratingChange,
+          ratingChange: snapshot.ratingChange,
+        },
+      });
+    }
+  }
+
+  // Write all updated player stats to database
+  const playerUpdatePromises = Array.from(playerStats.entries()).map(
+    async ([playerId, stats]) =>
+      await prisma.player.update({
+        where: { id: playerId },
+        data: {
+          currentElo: stats.rating,
+          gamesPlayed: stats.gamesPlayed,
+          wins: stats.wins,
+          losses: stats.losses,
+        },
+      })
+  );
+
+  await Promise.all(playerUpdatePromises);
+
+  // Write all partnership stats to database
+  const partnershipUpdatePromises = Array.from(partnershipStats.entries()).map(async ([key, stats]) => {
+    const [player1Id, player2Id] = key.split('-').map(Number);
+    
+    // Check if the partnership stat already exists
+    const existingStat = await prisma.partnershipStat.findFirst({
+      where: {
+        player1Id,
+        player2Id,
+      },
+    });
+
+    if (existingStat) {
+      // Update existing record
+      return await prisma.partnershipStat.update({
+        where: {
+          id: existingStat.id,
+        },
+        data: {
+          gamesPlayed: stats.gamesPlayed,
+          wins: stats.wins,
+          losses: stats.losses,
+          totalEloChange: stats.totalEloChange,
+          lastPlayed: stats.lastPlayed,
+        },
+      });
+    } else {
+      // Create new record
+      return await prisma.partnershipStat.create({
+        data: {
+          player1Id,
+          player2Id,
+          gamesPlayed: stats.gamesPlayed,
+          wins: stats.wins,
+          losses: stats.losses,
+          totalEloChange: stats.totalEloChange,
+          lastPlayed: stats.lastPlayed,
+        },
+      });
+    }
+  });
+
+  await Promise.all(partnershipUpdatePromises);
+
+  return {
+    matchesProcessed: matches.length,
+    playersUpdated: playerStats.size,
+    partnershipsUpdated: partnershipStats.size,
+  };
+}

src/lib/permissions.ts

@@ -215,3 +215,17 @@ export async function getManageableTournaments() {
     orderBy: { createdAt: 'desc' }
   });
 }
+
+/**
+ * Check if the user can edit user profiles (only club_admin)
+ */
+export async function canEditUserProfiles(): Promise<PermissionCheck> {
+  return hasRole('club_admin');
+}
+
+/**
+ * Check if the user can recalculate ELO ratings (only club_admin)
+ */
+export async function canRecalculateElo(): Promise<PermissionCheck> {
+  return hasRole('club_admin');
+}