feat: add investment and redemption functionality for hedge funds

- Implemented POST endpoint for investing in hedge funds, allowing users to invest a specified amount and receive shares based on the fund's NAV.
- Implemented POST endpoint for redeeming shares in hedge funds, enabling users to redeem shares for cash based on the current NAV.
- Created InvestPanel component for user interactions, including investing and redeeming shares, displaying current NAV, user balance, and holdings summary.

prisma/schema.prisma

@@ -26,6 +26,7 @@ model User {
   passwordResets PasswordReset[]
   managedFunds   FundManager[]
   fund           HedgeFund?
+  fundInvestments FundInvestment[]
 }
 
 model HedgeFund {
@@ -34,13 +35,30 @@ model HedgeFund {
   slug              String        @unique  // lowercase, URL-safe
   userId            String        @unique  // shadow User account that holds positions/trades/balance
   user              User          @relation(fields: [userId], references: [id])
+  sharesOutstanding Float         @default(0)  // total fund shares currently in circulation
   createdAt         DateTime      @default(now())
 
   managers    FundManager[]
+  investments FundInvestment[]
 
   @@index([slug])
 }
 
+model FundInvestment {
+  id            String    @id @default(cuid())
+  fundId        String
+  fund          HedgeFund @relation(fields: [fundId], references: [id], onDelete: Cascade)
+  userId        String
+  user          User      @relation(fields: [userId], references: [id], onDelete: Cascade)
+  shares        Float     // fund shares held by this investor
+  avgNavAtBuy   Float     // NAV per share at time of purchase (for display only)
+  createdAt     DateTime  @default(now())
+  updatedAt     DateTime  @updatedAt
+
+  @@unique([fundId, userId])
+  @@index([userId])
+}
+
 model FundManager {
   id      String    @id @default(cuid())
   fundId  String

src/app/api/funds/[slug]/invest/route.ts

@@ -0,0 +1,89 @@
+import { NextRequest, NextResponse } from 'next/server'
+import { getServerSession } from 'next-auth'
+import { authOptions } from '@/lib/auth'
+import { prisma } from '@/lib/prisma'
+import { calcFundNav } from '@/lib/pricing'
+
+export async function POST(req: NextRequest, { params }: { params: { slug: string } }) {
+  const session = await getServerSession(authOptions)
+  if (!session) return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
+
+  const slug = decodeURIComponent(params.slug).toLowerCase()
+  const body = await req.json()
+  const amount = Number(body.amount)
+
+  if (!amount || amount < 1) {
+    return NextResponse.json({ error: 'Minimum investment is $1' }, { status: 400 })
+  }
+
+  const fund = await prisma.hedgeFund.findUnique({
+    where: { slug },
+    include: {
+      user: {
+        select: {
+          balance: true,
+          positions: {
+            where: { shares: { gt: 0 } },
+            select: { shares: true, avgBuyPrice: true, positionType: true, hashtag: { select: { currentPrice: true } } },
+          },
+        },
+      },
+    },
+  })
+
+  if (!fund) return NextResponse.json({ error: 'Fund not found' }, { status: 404 })
+
+  // Verify investor is not the fund's own shadow user
+  const investor = await prisma.user.findUnique({ where: { id: session.user.id }, select: { balance: true, isFund: true } })
+  if (!investor || investor.isFund) {
+    return NextResponse.json({ error: 'Invalid account' }, { status: 403 })
+  }
+  if (investor.balance < amount) {
+    return NextResponse.json({ error: 'Insufficient balance' }, { status: 400 })
+  }
+
+  const portfolioValue = fund.user.positions.reduce((sum, p) => {
+    const val = p.positionType === 'LONG'
+      ? p.shares * p.hashtag.currentPrice
+      : p.avgBuyPrice * p.shares - (p.hashtag.currentPrice - p.avgBuyPrice) * p.shares
+    return sum + val
+  }, 0)
+  const totalValue = fund.user.balance + portfolioValue
+  const nav = calcFundNav(totalValue, fund.sharesOutstanding)
+  const sharesToMint = amount / nav
+
+  // Weighted average NAV at buy for display
+  const existingInvestment = await prisma.fundInvestment.findUnique({
+    where: { fundId_userId: { fundId: fund.id, userId: session.user.id } },
+    select: { shares: true, avgNavAtBuy: true },
+  })
+
+  let newAvgNav: number
+  if (existingInvestment) {
+    const totalShares = existingInvestment.shares + sharesToMint
+    newAvgNav = (existingInvestment.avgNavAtBuy * existingInvestment.shares + nav * sharesToMint) / totalShares
+  } else {
+    newAvgNav = nav
+  }
+
+  const [updatedInvestor] = await prisma.$transaction([
+    // Deduct from investor (returns updated user with new balance)
+    prisma.user.update({ where: { id: session.user.id }, data: { balance: { decrement: amount } } }),
+    // Add to fund's cash
+    prisma.user.update({ where: { id: fund.userId }, data: { balance: { increment: amount } } }),
+    // Upsert FundInvestment record
+    prisma.fundInvestment.upsert({
+      where: { fundId_userId: { fundId: fund.id, userId: session.user.id } },
+      create: { fundId: fund.id, userId: session.user.id, shares: sharesToMint, avgNavAtBuy: newAvgNav },
+      update: { shares: { increment: sharesToMint }, avgNavAtBuy: newAvgNav },
+    }),
+    // Increment fund shares outstanding
+    prisma.hedgeFund.update({ where: { id: fund.id }, data: { sharesOutstanding: { increment: sharesToMint } } }),
+  ])
+
+  return NextResponse.json({
+    shares: sharesToMint,
+    nav,
+    newBalance: updatedInvestor.balance,
+  })
+}

src/app/api/funds/[slug]/redeem/route.ts

@@ -0,0 +1,84 @@
+import { NextRequest, NextResponse } from 'next/server'
+import { getServerSession } from 'next-auth'
+import { authOptions } from '@/lib/auth'
+import { prisma } from '@/lib/prisma'
+import { calcFundNav } from '@/lib/pricing'
+
+export async function POST(req: NextRequest, { params }: { params: { slug: string } }) {
+  const session = await getServerSession(authOptions)
+  if (!session) return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
+
+  const slug = decodeURIComponent(params.slug).toLowerCase()
+  const body = await req.json()
+  const sharesToRedeem = Number(body.shares)
+
+  if (!sharesToRedeem || sharesToRedeem <= 0) {
+    return NextResponse.json({ error: 'Invalid share amount' }, { status: 400 })
+  }
+
+  const fund = await prisma.hedgeFund.findUnique({
+    where: { slug },
+    include: {
+      user: {
+        select: {
+          balance: true,
+          positions: {
+            where: { shares: { gt: 0 } },
+            select: { shares: true, avgBuyPrice: true, positionType: true, hashtag: { select: { currentPrice: true } } },
+          },
+        },
+      },
+    },
+  })
+
+  if (!fund) return NextResponse.json({ error: 'Fund not found' }, { status: 404 })
+
+  const investment = await prisma.fundInvestment.findUnique({
+    where: { fundId_userId: { fundId: fund.id, userId: session.user.id } },
+    select: { shares: true },
+  })
+
+  if (!investment || investment.shares < sharesToRedeem) {
+    return NextResponse.json({ error: 'Insufficient fund shares' }, { status: 400 })
+  }
+
+  const portfolioValue = fund.user.positions.reduce((sum, p) => {
+    const val = p.positionType === 'LONG'
+      ? p.shares * p.hashtag.currentPrice
+      : p.avgBuyPrice * p.shares - (p.hashtag.currentPrice - p.avgBuyPrice) * p.shares
+    return sum + val
+  }, 0)
+  const totalValue = fund.user.balance + portfolioValue
+  const nav = calcFundNav(totalValue, fund.sharesOutstanding)
+  const payout = sharesToRedeem * nav
+
+  if (fund.user.balance < payout) {
+    return NextResponse.json({ error: 'Fund has insufficient cash to redeem. Try a smaller amount.' }, { status: 400 })
+  }
+
+  const remainingShares = investment.shares - sharesToRedeem
+
+  const [updatedInvestor] = await prisma.$transaction([
+    // Return cash to investor
+    prisma.user.update({ where: { id: session.user.id }, data: { balance: { increment: payout } } }),
+    // Deduct from fund's cash
+    prisma.user.update({ where: { id: fund.userId }, data: { balance: { decrement: payout } } }),
+    // Update or delete FundInvestment
+    ...(remainingShares > 0
+      ? [prisma.fundInvestment.update({
+          where: { fundId_userId: { fundId: fund.id, userId: session.user.id } },
+          data: { shares: remainingShares },
+        })]
+      : [prisma.fundInvestment.delete({
+          where: { fundId_userId: { fundId: fund.id, userId: session.user.id } },
+        })]),
+    // Decrement fund shares outstanding
+    prisma.hedgeFund.update({ where: { id: fund.id }, data: { sharesOutstanding: { decrement: sharesToRedeem } } }),
+  ])
+
+  return NextResponse.json({
+    payout,
+    nav,
+    newBalance: updatedInvestor.balance,
+  })
+}

src/app/fund/[slug]/InvestPanel.tsx

@@ -0,0 +1,194 @@
+'use client'
+
+import { useState } from 'react'
+import { useRouter } from 'next/navigation'
+import { formatCurrency } from '@/lib/utils'
+
+interface Props {
+  fundSlug: string
+  nav: number
+  userBalance: number
+  userShares: number
+  userAvgNav: number
+}
+
+export default function InvestPanel({ fundSlug, nav, userBalance, userShares, userAvgNav }: Props) {
+  const router = useRouter()
+  const [tab, setTab] = useState<'invest' | 'redeem'>('invest')
+  const [amount, setAmount] = useState('')
+  const [shares, setShares] = useState('')
+  const [loading, setLoading] = useState(false)
+  const [error, setError] = useState('')
+  const [success, setSuccess] = useState('')
+
+  const amountNum = parseFloat(amount) || 0
+  const sharesNum = parseFloat(shares) || 0
+  const previewShares = nav > 0 ? amountNum / nav : 0
+  const previewPayout = sharesNum * nav
+
+  async function handleInvest(e: React.FormEvent) {
+    e.preventDefault()
+    setError('')
+    setSuccess('')
+    if (amountNum < 1) { setError('Minimum $1'); return }
+    setLoading(true)
+    try {
+      const res = await fetch(`/api/funds/${fundSlug}/invest`, {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({ amount: amountNum }),
+      })
+      const data = await res.json()
+      if (!res.ok) { setError(data.error ?? 'Failed'); return }
+      setSuccess(`Invested! You received ${data.shares.toFixed(4)} shares at NAV ${formatCurrency(data.nav)}.`)
+      setAmount('')
+      router.refresh()
+    } finally {
+      setLoading(false)
+    }
+  }
+
+  async function handleRedeem(e: React.FormEvent) {
+    e.preventDefault()
+    setError('')
+    setSuccess('')
+    if (sharesNum <= 0) { setError('Enter shares to redeem'); return }
+    setLoading(true)
+    try {
+      const res = await fetch(`/api/funds/${fundSlug}/redeem`, {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({ shares: sharesNum }),
+      })
+      const data = await res.json()
+      if (!res.ok) { setError(data.error ?? 'Failed'); return }
+      setSuccess(`Redeemed ${sharesNum.toFixed(4)} shares for ${formatCurrency(data.payout)}.`)
+      setShares('')
+      router.refresh()
+    } finally {
+      setLoading(false)
+    }
+  }
+
+  return (
+    <div className="bg-surface-card border border-surface-border rounded-xl overflow-hidden">
+      {/* Tab bar */}
+      <div className="flex border-b border-surface-border">
+        {(['invest', 'redeem'] as const).map((t) => (
+          <button
+            key={t}
+            onClick={() => { setTab(t); setError(''); setSuccess('') }}
+            className={`flex-1 py-3 text-sm font-medium capitalize transition-colors ${
+              tab === t
+                ? 'text-indigo-300 border-b-2 border-indigo-400 bg-indigo-500/5'
+                : 'text-slate-400 hover:text-slate-200'
+            }`}
+          >
+            {t}
+          </button>
+        ))}
+      </div>
+
+      <div className="p-5 space-y-4">
+        {/* NAV info */}
+        <div className="flex items-center justify-between text-sm">
+          <span className="text-slate-400">Current NAV / share</span>
+          <span className="font-semibold">{formatCurrency(nav)}</span>
+        </div>
+
+        {/* Holdings summary */}
+        {userShares > 0 && (
+          <div className="bg-indigo-500/5 border border-indigo-500/20 rounded-lg px-4 py-3 text-sm space-y-1">
+            <div className="flex justify-between">
+              <span className="text-slate-400">Your shares</span>
+              <span className="font-medium">{userShares.toFixed(4)}</span>
+            </div>
+            <div className="flex justify-between">
+              <span className="text-slate-400">Current value</span>
+              <span className="font-medium">{formatCurrency(userShares * nav)}</span>
+            </div>
+            <div className="flex justify-between">
+              <span className="text-slate-400">Avg buy NAV</span>
+              <span className="font-medium">{formatCurrency(userAvgNav)}</span>
+            </div>
+          </div>
+        )}
+
+        {tab === 'invest' ? (
+          <form onSubmit={handleInvest} className="space-y-3">
+            <div>
+              <label className="text-xs text-slate-400 mb-1 block">Amount to invest</label>
+              <div className="relative">
+                <span className="absolute left-3 top-1/2 -translate-y-1/2 text-slate-400">$</span>
+                <input
+                  type="number"
+                  min="1"
+                  step="0.01"
+                  value={amount}
+                  onChange={(e) => setAmount(e.target.value)}
+                  placeholder="0.00"
+                  className="w-full bg-surface border border-surface-border rounded-lg pl-7 pr-3 py-2.5 text-sm focus:outline-none focus:border-indigo-500"
+                />
+              </div>
+              <p className="text-xs text-slate-500 mt-1">
+                Balance: {formatCurrency(userBalance)}
+              </p>
+            </div>
+            {amountNum >= 1 && (
+              <p className="text-xs text-slate-400">
+                You&apos;ll receive ≈ <span className="text-white font-medium">{previewShares.toFixed(4)} shares</span>
+              </p>
+            )}
+            <button
+              type="submit"
+              disabled={loading || amountNum < 1}
+              className="w-full py-2.5 rounded-lg bg-indigo-600 hover:bg-indigo-500 disabled:opacity-50 disabled:cursor-not-allowed text-sm font-medium transition-colors"
+            >
+              {loading ? 'Investing…' : 'Invest'}
+            </button>
+          </form>
+        ) : (
+          <form onSubmit={handleRedeem} className="space-y-3">
+            <div>
+              <label className="text-xs text-slate-400 mb-1 block">Shares to redeem</label>
+              <input
+                type="number"
+                min="0"
+                step="0.0001"
+                max={userShares}
+                value={shares}
+                onChange={(e) => setShares(e.target.value)}
+                placeholder="0.0000"
+                className="w-full bg-surface border border-surface-border rounded-lg px-3 py-2.5 text-sm focus:outline-none focus:border-indigo-500"
+              />
+              {userShares > 0 && (
+                <button
+                  type="button"
+                  onClick={() => setShares(String(userShares))}
+                  className="text-xs text-indigo-400 hover:text-indigo-300 mt-1"
+                >
+                  Max ({userShares.toFixed(4)})
+                </button>
+              )}
+            </div>
+            {sharesNum > 0 && (
+              <p className="text-xs text-slate-400">
+                You&apos;ll receive ≈ <span className="text-white font-medium">{formatCurrency(previewPayout)}</span>
+              </p>
+            )}
+            <button
+              type="submit"
+              disabled={loading || sharesNum <= 0 || sharesNum > userShares}
+              className="w-full py-2.5 rounded-lg bg-emerald-700 hover:bg-emerald-600 disabled:opacity-50 disabled:cursor-not-allowed text-sm font-medium transition-colors"
+            >
+              {loading ? 'Redeeming…' : 'Redeem'}
+            </button>
+          </form>
+        )}
+
+        {error && <p className="text-red-400 text-sm">{error}</p>}
+        {success && <p className="text-emerald-400 text-sm">{success}</p>}
+      </div>
+    </div>
+  )
+}

src/app/fund/[slug]/page.tsx

@@ -6,6 +6,8 @@ import { formatCurrency, formatPnl, pnlColor } from '@/lib/utils'
 import { formatDistanceToNow } from 'date-fns'
 import Link from 'next/link'
 import { Building2, TrendingUp, TrendingDown } from 'lucide-react'
+import { calcFundNav } from '@/lib/pricing'
+import InvestPanel from './InvestPanel'
 
 export const dynamic = 'force-dynamic'
 
@@ -34,11 +36,23 @@ export default async function FundPage({ params }: { params: { slug: string } })
         include: { user: { select: { id: true, username: true, displayUsername: true } } },
         orderBy: { addedAt: 'asc' },
       },
+      _count: { select: { investments: true } },
     },
   })
 
   if (!fund) notFound()
 
+  // Fetch current user's balance and investment in this fund
+  const [currentUser, userInvestment] = session
+    ? await Promise.all([
+        prisma.user.findUnique({ where: { id: session.user.id }, select: { balance: true, isFund: true } }),
+        prisma.fundInvestment.findUnique({
+          where: { fundId_userId: { fundId: fund.id, userId: session.user.id } },
+          select: { shares: true, avgNavAtBuy: true },
+        }),
+      ])
+    : [null, null]
+
   const isManager = session
     ? fund.managers.some((m) => m.userId === session.user.id)
     : false
@@ -58,6 +72,8 @@ export default async function FundPage({ params }: { params: { slug: string } })
   }, 0)
 
   const totalValue = fund.user.balance + portfolioValue
+  const nav = calcFundNav(totalValue, fund.sharesOutstanding)
+  const canInvest = !!session && !!currentUser && !currentUser.isFund
 
   return (
     <div className="max-w-4xl mx-auto space-y-8">
@@ -82,12 +98,14 @@ export default async function FundPage({ params }: { params: { slug: string } })
       </div>
 
       {/* Stats */}
-      <div className="grid grid-cols-2 sm:grid-cols-4 gap-4">
+      <div className="grid grid-cols-2 sm:grid-cols-3 lg:grid-cols-6 gap-4">
         {[
           { label: 'Cash', value: formatCurrency(fund.user.balance) },
           { label: 'Invested', value: formatCurrency(portfolioValue) },
           { label: 'Unrealized P&L', value: formatPnl(unrealizedPnl), colorClass: pnlColor(unrealizedPnl) },
-          { label: 'Managers', value: String(fund.managers.length) },
+          { label: 'NAV / Share', value: formatCurrency(nav) },
+          { label: 'Shares Out.', value: fund.sharesOutstanding.toFixed(2) },
+          { label: 'Investors', value: String(fund._count.investments) },
         ].map(({ label, value, colorClass }) => (
           <div key={label} className="bg-surface-card border border-surface-border rounded-xl p-4">
             <p className="text-xs text-slate-500 mb-1">{label}</p>
@@ -127,6 +145,22 @@ export default async function FundPage({ params }: { params: { slug: string } })
         </div>
       )}
 
+      {/* Invest / Redeem panel */}
+      {canInvest && (
+        <div>
+          <h2 className="font-semibold mb-3 flex items-center gap-2 text-sm text-slate-400 uppercase tracking-wider">
+            Invest in this Fund
+          </h2>
+          <InvestPanel
+            fundSlug={fund.slug}
+            nav={nav}
+            userBalance={currentUser!.balance}
+            userShares={userInvestment?.shares ?? 0}
+            userAvgNav={userInvestment?.avgNavAtBuy ?? 0}
+          />
+        </div>
+      )}
+
       {/* Open positions */}
       {positions.length > 0 && (
         <div className="bg-surface-card border border-surface-border rounded-xl overflow-hidden">

src/lib/pricing.ts

@@ -39,6 +39,12 @@ export function getBalanceTier(balance: number): BalanceTier {
   return                           { level: 1, pointsPerDay: 1, nextThreshold: 10_000 }
 }
 
+/** Calculate NAV (net asset value) per fund share. Returns 1.00 if no shares outstanding. */
+export function calcFundNav(totalValue: number, sharesOutstanding: number): number {
+  if (sharesOutstanding <= 0) return 1.00
+  return totalValue / sharesOutstanding
+}
+
 /**
  * Calculate the cost/proceeds and realized P&L for a trade.
  *

src/middleware.ts

@@ -11,5 +11,6 @@ export const config = {
     '/api/user/:path*',
     '/api/admin/:path*',
     '/api/lottery/:path*',
+    '/api/funds/:path*',
   ],
 }