botfights/server/src/engine/betting.ts

// BOTFIGHTS Betting Engine
// Cashu ecash escrow with Lightning deposit/withdraw
// All amounts in satoshis

import { nanoid } from 'nanoid'
import { calculateOdds, calculatePayout, validateBet } from './odds.js'

// --- Cashu Token Interface ---
// Cashu tokens are base64-encoded ecash tokens from a Cashu mint
// See: https://github.com/cashubtc/nuts

export interface CashuToken {
  token: string      // base64-encoded Cashu token
  amount: number     // total sats in token
  mint: string       // mint URL
}

export interface BetPlacement {
  id: string
  fightId: string
  bettorPubkey: string
  botId: string
  amountSats: number
  oddsAtPlacement: number
  potentialPayout: number
  cashuToken: string
}

export interface BetSettlement {
  betId: string
  won: boolean
  payoutSats: number
  payoutToken: string | null
}

// --- Escrow State ---
// In-memory escrow for active fights. Persisted to DB on settlement.
const escrow = new Map<string, {
  fightId: string
  bets: BetPlacement[]
  totalPool: number
  lockedAt: string
}>()

/**
 * Place a bet on a fight outcome.
 * Validates the bet, verifies the Cashu token, and locks it in escrow.
 */
export async function placeBet(
  fightId: string,
  bettorPubkey: string,
  botId: string,
  amountSats: number,
  cashuToken: string,
  eloA: number,
  eloB: number,
  botAId: string,
): Promise<BetPlacement> {
  // Validate bet amount
  const validation = validateBet(amountSats)
  if (!validation.valid) {
    throw new Error(validation.error)
  }

  // Verify Cashu token (in production, this would call the mint's /verify endpoint)
  const tokenValid = await verifyCashuToken(cashuToken, amountSats)
  if (!tokenValid) {
    throw new Error('Invalid or insufficient Cashu token.')
  }

  // Calculate odds at time of placement
  const odds = calculateOdds(eloA, eloB)
  const isOnBotA = botId === botAId
  const payoutMultiplier = isOnBotA ? odds.botAPayoutMultiplier : odds.botBPayoutMultiplier
  const potentialPayout = calculatePayout(amountSats, payoutMultiplier)

  const bet: BetPlacement = {
    id: nanoid(12),
    fightId,
    bettorPubkey,
    botId,
    amountSats,
    oddsAtPlacement: payoutMultiplier,
    potentialPayout,
    cashuToken,
  }

  // Add to escrow
  if (!escrow.has(fightId)) {
    escrow.set(fightId, {
      fightId,
      bets: [],
      totalPool: 0,
      lockedAt: new Date().toISOString(),
    })
  }
  const pool = escrow.get(fightId)!
  pool.bets.push(bet)
  pool.totalPool += amountSats

  return bet
}

/**
 * Lock all bets for a fight (no more bets accepted after fight starts).
 */
export function lockBets(fightId: string): void {
  const pool = escrow.get(fightId)
  if (pool) {
    pool.lockedAt = new Date().toISOString()
  }
}

/**
 * Settle all bets for a completed fight.
 * Winners get their payout as new Cashu tokens.
 * Losers forfeit their tokens.
 */
export async function settleBets(
  fightId: string,
  winnerId: string | null,
): Promise<BetSettlement[]> {
  const pool = escrow.get(fightId)
  if (!pool || pool.bets.length === 0) return []

  const settlements: BetSettlement[] = []

  for (const bet of pool.bets) {
    // Draw: refund all bets
    if (!winnerId) {
      const refundToken = await mintCashuToken(bet.amountSats)
      settlements.push({
        betId: bet.id,
        won: false,
        payoutSats: bet.amountSats,
        payoutToken: refundToken,
      })
      continue
    }

    const won = bet.botId === winnerId
    if (won) {
      // Winner: mint payout token
      const payoutToken = await mintCashuToken(bet.potentialPayout)
      settlements.push({
        betId: bet.id,
        won: true,
        payoutSats: bet.potentialPayout,
        payoutToken,
      })
    } else {
      // Loser: no payout
      settlements.push({
        betId: bet.id,
        won: false,
        payoutSats: 0,
        payoutToken: null,
      })
    }
  }

  // Clean up escrow
  escrow.delete(fightId)

  return settlements
}

/**
 * Get all active bets for a fight.
 */
export function getFightBets(fightId: string): BetPlacement[] {
  return escrow.get(fightId)?.bets ?? []
}

/**
 * Get escrow pool info for a fight.
 */
export function getPoolInfo(fightId: string): {
  totalPool: number
  betCount: number
  botAPool: number
  botBPool: number
} | null {
  const pool = escrow.get(fightId)
  if (!pool) return null

  // We don't track which is A/B here, caller provides that context
  return {
    totalPool: pool.totalPool,
    betCount: pool.bets.length,
    botAPool: 0, // Caller should aggregate from bets
    botBPool: 0,
  }
}

// --- Cashu Integration Stubs ---
// These would connect to a real Cashu mint in production.
// For now they validate format and simulate minting.

const MINT_URL = process.env.CASHU_MINT_URL || 'https://mint.botfights.example.com'

/**
 * Verify a Cashu token is valid and has sufficient amount.
 * In production: POST to mint's /verify endpoint.
 */
async function verifyCashuToken(token: string, expectedAmount: number): Promise<boolean> {
  if (!token || token.length < 10) return false

  // Production: decode token, check mint URL, verify with mint
  // For now, accept any non-empty token with valid base64-ish format
  try {
    // Cashu tokens start with 'cashuA' (v1) or 'cashuB' (v2)
    if (token.startsWith('cashuA') || token.startsWith('cashuB')) {
      return true
    }
    // Also accept for development/testing
    if (process.env.NODE_ENV !== 'production') {
      return true
    }
    return false
  } catch {
    return false
  }
}

/**
 * Mint new Cashu tokens for a payout amount.
 * In production: POST to mint's /mint endpoint.
 */
async function mintCashuToken(amountSats: number): Promise<string> {
  // Production: request tokens from mint
  // Returns a base64-encoded Cashu token
  return `cashuA_payout_${amountSats}_${nanoid(8)}`
}

// --- Lightning Integration ---
// For depositing sats to get Cashu tokens, and withdrawing Cashu to Lightning

export interface LightningInvoice {
  bolt11: string
  amountSats: number
  hash: string
  expiresAt: string
}

/**
 * Create a Lightning invoice for depositing sats.
 * User pays this invoice, receives Cashu tokens in return.
 * In production: calls Lightning node (LND/CLN/LDK) to create invoice.
 */
export async function createDepositInvoice(
  amountSats: number,
  pubkey: string,
): Promise<LightningInvoice> {
  // Production: call LN node to create invoice
  // On payment confirmation, mint Cashu tokens and credit to user
  return {
    bolt11: `lnbc${amountSats}n1_deposit_${nanoid(8)}`,
    amountSats,
    hash: nanoid(32),
    expiresAt: new Date(Date.now() + 15 * 60 * 1000).toISOString(),
  }
}

/**
 * Withdraw Cashu tokens to a Lightning address.
 * Burns the Cashu tokens, pays the Lightning invoice.
 * In production: verify token, burn with mint, pay invoice via LN node.
 */
export async function withdrawToLightning(
  cashuToken: string,
  bolt11Invoice: string,
): Promise<{ success: boolean; preimage?: string; error?: string }> {
  // Production: verify token amount >= invoice amount, burn token, pay invoice
  if (!cashuToken || !bolt11Invoice) {
    return { success: false, error: 'Missing token or invoice.' }
  }

  // Simulate successful payment
  return {
    success: true,
    preimage: nanoid(32),
  }
}

// --- Bet Verification ---
// Cryptographic proof that bets were settled fairly

export interface BetProof {
  betId: string
  fightId: string
  winnerId: string | null
  betOnBotId: string
  amountSats: number
  oddsAtPlacement: number
  won: boolean
  payoutSats: number
  timestamp: string
}

/**
 * Generate a verifiable proof of bet settlement.
 * In production, this could be signed with a server key or
 * published to a Nostr relay for public verification.
 */
export function generateBetProof(
  bet: BetPlacement,
  settlement: BetSettlement,
  winnerId: string | null,
): BetProof {
  return {
    betId: bet.id,
    fightId: bet.fightId,
    winnerId,
    betOnBotId: bet.botId,
    amountSats: bet.amountSats,
    oddsAtPlacement: bet.oddsAtPlacement,
    won: settlement.won,
    payoutSats: settlement.payoutSats,
    timestamp: new Date().toISOString(),
  }
}