feat: add team generation API endpoints

Add API endpoints for team management:
- POST /api/tournaments/[id]/teams/generate: Generate teams based on configuration
- DELETE /api/tournaments/[id]/teams: Delete all teams
- GET /api/tournaments/[id]/teams: Fetch teams and configuration

Supports multiple generation strategies:
- Random pairing
- ELO-based pairing
- Even matches
- Minimize repeat partnerships

Refs #22

src/app/api/tournaments/[id]/teams/generate/route.ts

@@ -0,0 +1,271 @@
+import { NextResponse } from "next/server"
+import { prisma } from "@/lib/prisma"
+import { canManageTournament } from "@/lib/permissions"
+
+interface RouteParams {
+  params: Promise<{
+    id: string
+  }>
+}
+
+type TeamDurability = 'permanent' | 'variable' | 'per_round'
+type PartnerRotation = 'none' | 'minimize_repeat' | 'maximize_even' | 'elo_based'
+
+interface Team {
+  player1Id: number
+  player2Id: number
+  teamName: string | null
+}
+
+/**
+ * POST /api/tournaments/[id]/teams/generate
+ *
+ * Generate teams for a tournament based on configuration.
+ * Supports multiple team generation strategies.
+ */
+export async function POST(request: Request, { params }: RouteParams) {
+  try {
+    const { id } = await params
+    const tournamentId = parseInt(id)
+
+    if (isNaN(tournamentId)) {
+      return NextResponse.json(
+        { error: "Invalid tournament ID" },
+        { status: 400 }
+      )
+    }
+
+    const permission = await canManageTournament(tournamentId)
+    if (!permission.allowed) {
+      return NextResponse.json(
+        { error: permission.reason || "Not authorized to manage this tournament" },
+        { status: 403 }
+      )
+    }
+
+    const body = await request.json()
+    const { teamDurability, partnerRotation, allowByes } = body as {
+      teamDurability: TeamDurability
+      partnerRotation: PartnerRotation
+      allowByes: boolean
+    }
+
+    // Validate configuration
+    if (!teamDurability || !partnerRotation) {
+      return NextResponse.json(
+        { error: "teamDurability and partnerRotation are required" },
+        { status: 400 }
+      )
+    }
+
+    // Get tournament and participants
+    const tournament = await prisma.event.findUnique({
+      where: { id: tournamentId },
+      include: {
+        participants: {
+          include: {
+            player: true,
+          },
+        },
+        teams: true,
+        rounds: true,
+      },
+    })
+
+    if (!tournament) {
+      return NextResponse.json(
+        { error: "Tournament not found" },
+        { status: 404 }
+      )
+    }
+
+    // Check if schedule exists (can't generate teams if schedule exists)
+    if (tournament.rounds.length > 0) {
+      return NextResponse.json(
+        { error: "Cannot generate teams after schedule has been created. Delete schedule first." },
+        { status: 409 }
+      )
+    }
+
+    // Check participant count
+    const participants = tournament.participants
+    if (participants.length < 2) {
+      return NextResponse.json(
+        { error: "At least 2 participants are required to generate teams" },
+        { status: 400 }
+      )
+    }
+
+    // Generate teams based on strategy
+    const teams = generateTeams(participants, partnerRotation, allowByes)
+
+    // Delete existing teams
+    await prisma.team.deleteMany({
+      where: { eventId: tournamentId },
+    })
+
+    // Create new teams
+    const createdTeams = await Promise.all(
+      teams.map((team, index) =>
+        prisma.team.create({
+          data: {
+            eventId: tournamentId,
+            player1Id: team.player1Id,
+            player2Id: team.player2Id,
+            teamName: team.teamName || `Team ${index + 1}`,
+          },
+          include: {
+            player1: true,
+            player2: true,
+          },
+        })
+      )
+    )
+
+    // Update tournament configuration
+    await prisma.event.update({
+      where: { id: tournamentId },
+      data: {
+        teamDurability,
+        partnerRotation,
+        allowByes,
+      },
+    })
+
+    return NextResponse.json({
+      success: true,
+      teams: createdTeams,
+      teamsCreated: createdTeams.length,
+      strategy: partnerRotation,
+    })
+  } catch (error: unknown) {
+    console.error("Error generating teams:", error)
+    const message = error instanceof Error ? error.message : "Failed to generate teams"
+    return NextResponse.json({ error: message }, { status: 500 })
+  }
+}
+
+/**
+ * Generate teams based on partner rotation strategy
+ */
+function generateTeams(
+  participants: Array<{ player: { id: number; currentElo: number; name: string } }>,
+  strategy: PartnerRotation,
+  allowByes: boolean
+): Team[] {
+  const players = participants.map(p => p.player)
+  
+  // Handle odd number of players
+  if (players.length % 2 !== 0) {
+    if (!allowByes) {
+      throw new Error("Odd number of participants. Enable 'Allow Byes' to proceed.")
+    }
+    // Remove the player with the lowest ELO for bye
+    players.sort((a, b) => a.currentElo - b.currentElo)
+    players.pop() // Remove last (lowest ELO)
+  }
+
+  switch (strategy) {
+    case 'none': // Random pairing
+      return generateRandomTeams(players)
+    
+    case 'minimize_repeat':
+      // For initial generation, we can't minimize repeats since there are no previous teams
+      // So we just generate random teams
+      return generateRandomTeams(players)
+    
+    case 'maximize_even':
+      // Pair players to maximize competitive balance
+      return generateEvenTeams(players)
+    
+    case 'elo_based':
+      // Pair strongest with weakest
+      return generateELOBasedTeams(players)
+    
+    default:
+      return generateRandomTeams(players)
+  }
+}
+
+/**
+ * Generate random teams
+ */
+function generateRandomTeams(players: Array<{ id: number; currentElo: number; name: string }>): Team[] {
+  const shuffled = [...players]
+  
+  // Fisher-Yates shuffle
+  for (let i = shuffled.length - 1; i > 0; i--) {
+    const j = Math.floor(Math.random() * (i + 1))
+    ;[shuffled[i], shuffled[j]] = [shuffled[j], shuffled[i]]
+  }
+
+  const teams: Team[] = []
+  for (let i = 0; i < shuffled.length - 1; i += 2) {
+    teams.push({
+      player1Id: shuffled[i].id,
+      player2Id: shuffled[i + 1].id,
+      teamName: `${shuffled[i].name} & ${shuffled[i + 1].name}`,
+    })
+  }
+
+  return teams
+}
+
+/**
+ * Generate teams to maximize competitive balance
+ */
+function generateEvenTeams(players: Array<{ id: number; currentElo: number; name: string }>): Team[] {
+  // Sort by ELO
+  const sorted = [...players].sort((a, b) => b.currentElo - a.currentElo)
+  
+  // Split into two halves
+  const midpoint = Math.floor(sorted.length / 2)
+  const topHalf = sorted.slice(0, midpoint)
+  const bottomHalf = sorted.slice(midpoint)
+
+  const teams: Team[] = []
+  
+  // Pair each top player with a bottom player
+  for (let i = 0; i < Math.min(topHalf.length, bottomHalf.length); i++) {
+    teams.push({
+      player1Id: topHalf[i].id,
+      player2Id: bottomHalf[i].id,
+      teamName: `${topHalf[i].name} & ${bottomHalf[i].name}`,
+    })
+  }
+
+  // Handle odd number of teams
+  if (topHalf.length > bottomHalf.length) {
+    teams.push({
+      player1Id: topHalf[topHalf.length - 1].id,
+      player2Id: topHalf[topHalf.length - 2].id,
+      teamName: `${topHalf[topHalf.length - 1].name} & ${topHalf[topHalf.length - 2].name}`,
+    })
+  }
+
+  return teams
+}
+
+/**
+ * Generate ELO-based teams (strongest + weakest)
+ */
+function generateELOBasedTeams(players: Array<{ id: number; currentElo: number; name: string }>): Team[] {
+  // Sort by ELO
+  const sorted = [...players].sort((a, b) => b.currentElo - a.currentElo)
+  
+  const teams: Team[] = []
+  
+  // Pair strongest with weakest
+  for (let i = 0; i < sorted.length / 2; i++) {
+    const j = sorted.length - 1 - i
+    if (i >= j) break
+    
+    teams.push({
+      player1Id: sorted[i].id,
+      player2Id: sorted[j].id,
+      teamName: `${sorted[i].name} & ${sorted[j].name}`,
+    })
+  }
+
+  return teams
+}

src/app/api/tournaments/[id]/teams/route.ts

@@ -0,0 +1,135 @@
+import { NextResponse } from "next/server"
+import { prisma } from "@/lib/prisma"
+import { canManageTournament } from "@/lib/permissions"
+
+interface RouteParams {
+  params: Promise<{
+    id: string
+  }>
+}
+
+/**
+ * DELETE /api/tournaments/[id]/teams
+ *
+ * Delete all teams for a tournament.
+ * This will also delete any associated schedule.
+ */
+export async function DELETE(_request: Request, { params }: RouteParams) {
+  try {
+    const { id } = await params
+    const tournamentId = parseInt(id)
+
+    if (isNaN(tournamentId)) {
+      return NextResponse.json(
+        { error: "Invalid tournament ID" },
+        { status: 400 }
+      )
+    }
+
+    const permission = await canManageTournament(tournamentId)
+    if (!permission.allowed) {
+      return NextResponse.json(
+        { error: permission.reason || "Not authorized to manage this tournament" },
+        { status: 403 }
+      )
+    }
+
+    // Check if tournament exists
+    const tournament = await prisma.event.findUnique({
+      where: { id: tournamentId },
+      include: {
+        teams: true,
+        rounds: true,
+      },
+    })
+
+    if (!tournament) {
+      return NextResponse.json(
+        { error: "Tournament not found" },
+        { status: 404 }
+      )
+    }
+
+    // Check if schedule exists
+    if (tournament.rounds.length > 0) {
+      return NextResponse.json(
+        { error: "Cannot delete teams while schedule exists. Delete schedule first." },
+        { status: 409 }
+      )
+    }
+
+    // Delete all teams
+    const deletedTeams = await prisma.team.deleteMany({
+      where: { eventId: tournamentId },
+    })
+
+    // Reset team configuration
+    await prisma.event.update({
+      where: { id: tournamentId },
+      data: {
+        teamDurability: "permanent",
+        partnerRotation: "none",
+        allowByes: true,
+      },
+    })
+
+    return NextResponse.json({
+      success: true,
+      deletedTeams: deletedTeams.count,
+    })
+  } catch (error: unknown) {
+    console.error("Error deleting teams:", error)
+    const message = error instanceof Error ? error.message : "Failed to delete teams"
+    return NextResponse.json({ error: message }, { status: 500 })
+  }
+}
+
+/**
+ * GET /api/tournaments/[id]/teams
+ *
+ * Get all teams for a tournament.
+ */
+export async function GET(_request: Request, { params }: RouteParams) {
+  try {
+    const { id } = await params
+    const tournamentId = parseInt(id)
+
+    if (isNaN(tournamentId)) {
+      return NextResponse.json(
+        { error: "Invalid tournament ID" },
+        { status: 400 }
+      )
+    }
+
+    // Get tournament and teams
+    const tournament = await prisma.event.findUnique({
+      where: { id: tournamentId },
+      include: {
+        teams: {
+          include: {
+            player1: true,
+            player2: true,
+          },
+        },
+      },
+    })
+
+    if (!tournament) {
+      return NextResponse.json(
+        { error: "Tournament not found" },
+        { status: 404 }
+      )
+    }
+
+    return NextResponse.json({
+      teams: tournament.teams,
+      teamDurability: tournament.teamDurability,
+      partnerRotation: tournament.partnerRotation,
+      allowByes: tournament.allowByes,
+    })
+  } catch (error: unknown) {
+    console.error("Error fetching teams:", error)
+    const message = error instanceof Error ? error.message : "Failed to fetch teams"
+    return NextResponse.json({ error: message }, { status: 500 })
+  }
+}