botfights/server/src/engine/background.ts

import { db, schema } from '../db/index.js'
import { eq } from 'drizzle-orm'
import { runMockFight } from './mock.js'
import { logger } from '../lib/logger.js'
import {
  createTournament,
  joinTournament,
  startTournament,
  listTournaments,
  getPendingMatches,
  linkFightToMatch,
} from './tournaments.js'
import { runFightAsync } from './orchestrator.js'

// Background fight loop keeps mock bots fighting so the site always has fresh content.
// Configurable via env:
//   FIGHT_LOOP_ENABLED=true (default: true in production, false in dev)
//   FIGHT_LOOP_INTERVAL_MS=45000 (default: 45s between fights)
//   FIGHT_LOOP_QUIET_HOURS=2-8 (default: 2am-8am UTC, slower fights)

const isProduction = process.env.NODE_ENV === 'production'
const enabled = process.env.FIGHT_LOOP_ENABLED
  ? process.env.FIGHT_LOOP_ENABLED === 'true'
  : isProduction
const intervalMs = Number(process.env.FIGHT_LOOP_INTERVAL_MS) || 45_000
const quietStart = Number(process.env.FIGHT_LOOP_QUIET_START) || 2
const quietEnd = Number(process.env.FIGHT_LOOP_QUIET_END) || 8

let running = false

export function startBackgroundFights() {
  if (!enabled) {
    logger.info('background', 'fight loop disabled (set FIGHT_LOOP_ENABLED=true to enable)')
    return
  }

  if (running) return
  running = true
  logger.info('background', `fight loop started — interval ${intervalMs}ms, quiet hours ${quietStart}-${quietEnd} UTC`)

  loop().catch(err => {
    logger.error('background', 'fight loop crashed', err)
    running = false
  })
}

export function stopBackgroundFights() {
  running = false
}

// Track last tournament check times
let lastDailyCheck = 0
let lastWeeklyCheck = 0

/** Check if we should create a "Lightning Round" daily 8-bot tournament */
async function checkDailyTournament() {
  const now = Date.now()
  if (now - lastDailyCheck < 60 * 60 * 1000) return // Check at most hourly
  lastDailyCheck = now

  const hour = new Date().getUTCHours()
  if (hour !== 12) return // Noon UTC daily

  // Don't create if there's already an open/active tournament today
  const active = listTournaments('open').concat(listTournaments('active'))
  const today = new Date().toISOString().slice(0, 10)
  const existsToday = active.some(t => t.createdAt.startsWith(today))
  if (existsToday) return

  try {
    const id = createTournament('Lightning Round', 'single_elim', 8, 0)
    await fillTournamentWithMockBots(id, 8)
    startTournament(id)
    await runTournamentMatches(id)
    logger.info('background', `daily Lightning Round tournament created: ${id}`)
  } catch (err) {
    logger.error('background', 'failed to create daily tournament', err)
  }
}

/** Check if we should create "The Halvening" weekly 32-bot tournament */
async function checkWeeklyTournament() {
  const now = Date.now()
  if (now - lastWeeklyCheck < 60 * 60 * 1000) return
  lastWeeklyCheck = now

  const d = new Date()
  if (d.getUTCDay() !== 6 || d.getUTCHours() !== 20) return // Saturday 20:00 UTC

  const active = listTournaments('open').concat(listTournaments('active'))
  const today = new Date().toISOString().slice(0, 10)
  const existsToday = active.some(t => t.createdAt.startsWith(today) && t.size === 32)
  if (existsToday) return

  try {
    const id = createTournament('The Halvening', 'single_elim', 32, 0)
    await fillTournamentWithMockBots(id, 32)
    startTournament(id)
    await runTournamentMatches(id)
    logger.info('background', `weekly The Halvening tournament created: ${id}`)
  } catch (err) {
    logger.error('background', 'failed to create weekly tournament', err)
  }
}

/** Fill remaining tournament slots with random mock bots */
async function fillTournamentWithMockBots(tournamentId: string, size: number) {
  const mockBots = await db.select({ id: schema.bots.id })
    .from(schema.bots)
    .where(eq(schema.bots.botType, 'mock'))
    .all()

  const shuffled = mockBots.sort(() => Math.random() - 0.5)
  const toAdd = Math.min(size, shuffled.length)
  for (let i = 0; i < toAdd; i++) {
    try {
      joinTournament(tournamentId, shuffled[i].id)
    } catch { /* already joined or full */ }
  }
}

/** Run all pending matches in a tournament */
async function runTournamentMatches(tournamentId: string) {
  const pending = getPendingMatches(tournamentId)
  for (const match of pending) {
    if (!match.botAId || !match.botBId) continue
    try {
      const fightId = await runFightAsync(match.botAId, match.botBId, 'free')
      linkFightToMatch(match.id, fightId)
    } catch (err) {
      logger.error('background', `tournament match failed: ${match.id}`, err)
    }
    await sleep(2000)
  }
}

async function loop() {
  // Small delay on startup to let everything settle
  await sleep(5_000)

  while (running) {
    try {
      await runOneBackgroundFight()
    } catch (err) {
      logger.error('background', 'fight error', err)
    }

    // Check for scheduled tournaments
    try {
      await checkDailyTournament()
      await checkWeeklyTournament()
    } catch (err) {
      logger.error('background', 'tournament check error', err)
    }

    // During quiet hours, fights run 4x slower
    const hour = new Date().getUTCHours()
    const isQuiet = quietStart < quietEnd
      ? hour >= quietStart && hour < quietEnd
      : hour >= quietStart || hour < quietEnd
    const delay = isQuiet ? intervalMs * 4 : intervalMs

    // Add jitter (±25%) so fights don't feel robotic
    const jitter = delay * (0.75 + Math.random() * 0.5)
    await sleep(jitter)
  }

  logger.info('background', 'fight loop stopped')
}

async function runOneBackgroundFight() {
  // Pick two mock bots with ELO-weighted matchmaking
  const allBots = await db.select({
    id: schema.bots.id,
    webhookUrl: schema.bots.webhookUrl,
    eloRating: schema.bots.eloRating,
    name: schema.bots.name,
  }).from(schema.bots)

  const mockBots = allBots.filter(b => b.webhookUrl.startsWith('http://mock.local'))
  if (mockBots.length < 2) return

  // Mixed matchmaking: 70% close ELO, 30% wild card
  const isWild = Math.random() < 0.3
  const botA = mockBots[Math.floor(Math.random() * mockBots.length)]
  const others = mockBots.filter(b => b.id !== botA.id)

  let botB: typeof botA
  if (isWild) {
    botB = others[Math.floor(Math.random() * others.length)]
  } else {
    others.sort((a, b) => {
      const diffA = Math.abs(a.eloRating - botA.eloRating) + Math.random() * 150
      const diffB = Math.abs(b.eloRating - botA.eloRating) + Math.random() * 150
      return diffA - diffB
    })
    botB = others[0]
  }

  const fightId = await runMockFight(botA.id, botB.id)
  logger.info('background', `${botA.name} vs ${botB.name} => fight ${fightId}`)
}

function sleep(ms: number): Promise<void> {
  return new Promise(resolve => setTimeout(resolve, ms))
}