import { nanoid } from 'nanoid'
import { db, schema, sqlite } from '../db/index.js'
import { eq, sql } from 'drizzle-orm'
import { randomArena, type Arena } from './arenas.js'
import { pickChallenge, type Challenge } from './challenges.js'
import { scoreRound, calculateElo, calculateTier } from './scoring.js'
import { fightEvents } from './events.js'
import { generateMockBotResponse } from './mock.js'
import { setCooldown } from './queue.js'

interface BotRecord {
  id: string
  name: string
  webhookUrl: string
  eloRating: number
  wins: number
  losses: number
  winStreak: number
  bestStreak: number
}

interface WebhookResponse {
  answer: string | null
  trashTalk?: string
  timeMs: number
  timedOut: boolean
  error: boolean
}

const MAX_ROUNDS = 10
const KO_THRESHOLD = 0
const MAX_RESPONSE_BYTES = 10 * 1024 // 10KB

// Track bots currently in a fight to prevent concurrent fights
const activeFighters = new Set<string>()

export function isInFight(botId: string): boolean {
  return activeFighters.has(botId)
}

function emit(fightId: string, type: string, data: Record<string, unknown>) {
  fightEvents.emit({
    fightId,
    type,
    data,
    timestamp: new Date().toISOString(),
  })
}

// SSRF protection: block internal/private URLs
function isAllowedWebhookUrl(url: string): boolean {
  try {
    const parsed = new URL(url)
    const hostname = parsed.hostname.toLowerCase()
    if (hostname === 'localhost' || hostname === '127.0.0.1' || hostname === '::1') return false
    if (hostname.startsWith('10.')) return false
    if (hostname.startsWith('192.168.')) return false
    if (hostname.startsWith('172.')) {
      const second = parseInt(hostname.split('.')[1])
      if (second >= 16 && second <= 31) return false
    }
    if (hostname === '169.254.169.254') return false
    if (hostname.endsWith('.local') || hostname.endsWith('.internal')) return false
    return true
  } catch {
    return false
  }
}

export { isAllowedWebhookUrl }

// Size-limited body reader to prevent OOM
async function readLimitedBody(res: Response, maxBytes: number): Promise<string> {
  const reader = res.body?.getReader()
  if (!reader) return ''
  const chunks: Uint8Array[] = []
  let totalBytes = 0
  try {
    while (true) {
      const { done, value } = await reader.read()
      if (done) break
      totalBytes += value.byteLength
      if (totalBytes > maxBytes) {
        reader.cancel()
        throw new Error(`Response body exceeds ${maxBytes} bytes`)
      }
      chunks.push(value)
    }
  } catch (err) {
    reader.cancel()
    throw err
  }
  const combined = new Uint8Array(totalBytes)
  let offset = 0
  for (const chunk of chunks) {
    combined.set(chunk, offset)
    offset += chunk.byteLength
  }
  return new TextDecoder().decode(combined)
}

async function callWebhook(
  url: string,
  challenge: Challenge,
  roundNumber: number,
  fightId: string,
  opponent: { name: string; wins: number; losses: number },
  arena: Arena,
): Promise<WebhookResponse> {
  const body = JSON.stringify({
    fight_id: fightId,
    round: roundNumber,
    type: challenge.type,
    challenge: challenge.prompt,
    constraints: {
      timeout_ms: challenge.timeout_ms,
      max_tokens: 500,
    },
    opponent,
    arena: arena.id,
    arena_modifier: arena.modifier,
  })

  const start = Date.now()
  console.log(`[webhook] POST ${url} round=${roundNumber} type=${challenge.type}`)

  // SSRF check
  if (!isAllowedWebhookUrl(url)) {
    console.log(`[webhook] ${url} BLOCKED (private/internal URL)`)
    return { answer: null, timeMs: 0, timedOut: false, error: true }
  }

  try {
    const controller = new AbortController()
    const timeout = setTimeout(() => controller.abort(), challenge.timeout_ms)

    const res = await fetch(url, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body,
      signal: controller.signal,
    })

    clearTimeout(timeout)
    const elapsed = Date.now() - start

    if (!res.ok) {
      console.log(`[webhook] ${url} returned ${res.status} in ${elapsed}ms`)
      return { answer: null, timeMs: elapsed, timedOut: false, error: true }
    }

    let text: string
    try {
      text = await readLimitedBody(res, MAX_RESPONSE_BYTES)
    } catch {
      console.log(`[webhook] ${url} response too large (>${MAX_RESPONSE_BYTES} bytes)`)
      return { answer: null, timeMs: elapsed, timedOut: false, error: true }
    }

    let data: { answer?: string; trash_talk?: string }
    try {
      data = JSON.parse(text)
    } catch {
      console.log(`[webhook] ${url} returned non-JSON in ${elapsed}ms: ${text.slice(0, 200)}`)
      return { answer: null, timeMs: elapsed, timedOut: false, error: true }
    }

    // Enforce size limits on fields
    const answer = data.answer ? data.answer.slice(0, 2000) : null
    const trashTalk = data.trash_talk ? data.trash_talk.slice(0, 200) : undefined

    console.log(`[webhook] ${url} OK in ${elapsed}ms answer=${(answer || '').slice(0, 80)}`)
    return {
      answer,
      trashTalk,
      timeMs: elapsed,
      timedOut: false,
      error: false,
    }
  } catch (err: unknown) {
    const elapsed = Date.now() - start
    const isAbort = err instanceof Error && err.name === 'AbortError'
    console.log(`[webhook] ${url} ${isAbort ? "TIMEOUT" : "ERROR"} in ${elapsed}ms: ${err instanceof Error ? err.message : err}`)
    return {
      answer: null,
      timeMs: elapsed,
      timedOut: isAbort,
      error: !isAbort,
    }
  }
}

export function isMockBot(webhookUrl: string): boolean {
  return webhookUrl.startsWith('http://mock.local')
}

async function getBotResponse(
  bot: BotRecord,
  challenge: Challenge,
  roundNumber: number,
  fightId: string,
  opponent: { name: string; wins: number; losses: number },
  arena: Arena,
): Promise<WebhookResponse> {
  if (isMockBot(bot.webhookUrl)) {
    console.log(`[fight] ${bot.name} is mock bot, generating response`)
    const mock = generateMockBotResponse(challenge, bot.name)
    return {
      answer: mock.answer || null,
      trashTalk: mock.trashTalk,
      timeMs: mock.timeMs,
      timedOut: mock.timedOut,
      error: mock.error,
    }
  }
  console.log(`[fight] ${bot.name} has real webhook: ${bot.webhookUrl}`)
  return callWebhook(bot.webhookUrl, challenge, roundNumber, fightId, opponent, arena)
}

async function loadBots(botAId: string, botBId: string): Promise<[BotRecord, BotRecord]> {
  const [botARows, botBRows] = await Promise.all([
    db.select().from(schema.bots).where(eq(schema.bots.id, botAId)).limit(1),
    db.select().from(schema.bots).where(eq(schema.bots.id, botBId)).limit(1),
  ])
  if (botARows.length === 0 || botBRows.length === 0) {
    throw new Error('One or both bots not found')
  }
  return [botARows[0] as BotRecord, botBRows[0] as BotRecord]
}

async function createFightRecord(botA: BotRecord, botB: BotRecord, arena: Arena): Promise<string> {
  const fightId = nanoid(12)
  const now = new Date().toISOString()
  await db.insert(schema.fights).values({
    id: fightId,
    botAId: botA.id,
    botBId: botB.id,
    arena: arena.id,
    status: 'live',
    startedAt: now,
    createdAt: now,
  })
  emit(fightId, 'fight_start', {
    botA: { id: botA.id, name: botA.name, elo: botA.eloRating },
    botB: { id: botB.id, name: botB.name, elo: botB.eloRating },
    arena: { id: arena.id, name: arena.name, description: arena.description, modifier: arena.modifier },
  })
  return fightId
}

// Track webhook errors per bot
async function trackWebhookResult(botId: string, webhookUrl: string, succeeded: boolean) {
  if (isMockBot(webhookUrl)) return
  if (succeeded) {
    await db.update(schema.bots).set({ consecutiveErrors: 0 }).where(eq(schema.bots.id, botId))
  } else {
    await db.update(schema.bots).set({
      consecutiveErrors: sql`${schema.bots.consecutiveErrors} + 1`,
      lastErrorAt: new Date().toISOString(),
    }).where(eq(schema.bots.id, botId))
    // Auto-deactivate after 5 consecutive errors
    const bot = await db.select({ consecutiveErrors: schema.bots.consecutiveErrors })
      .from(schema.bots).where(eq(schema.bots.id, botId)).limit(1)
    if (bot[0] && bot[0].consecutiveErrors >= 5) {
      await db.update(schema.bots).set({ isActive: false }).where(eq(schema.bots.id, botId))
      console.log(`[fight] bot ${botId} auto-deactivated after 5 consecutive webhook errors`)
    }
  }
}

async function executeFightRounds(fightId: string, botA: BotRecord, botB: BotRecord, arena: Arena): Promise<void> {
  let hpA = 200
  let hpB = 200
  let comboA = 0
  let comboB = 0
  let winnerId: string | null = null
  const usedTypes = new Set<string>()

  for (let round = 1; round <= MAX_ROUNDS; round++) {
    const challenge = pickChallenge(usedTypes, arena.modifier)
    usedTypes.add(challenge.type)

    emit(fightId, 'round_start', {
      round,
      challenge: { type: challenge.type, label: challenge.label, prompt: challenge.prompt },
    })

    // Call both bots simultaneously
    const [responseA, responseB] = await Promise.all([
      getBotResponse(botA, challenge, round, fightId, { name: botB.name, wins: botB.wins, losses: botB.losses }, arena),
      getBotResponse(botB, challenge, round, fightId, { name: botA.name, wins: botA.wins, losses: botA.losses }, arena),
    ])

    // Track webhook reliability for real bots
    await Promise.all([
      trackWebhookResult(botA.id, botA.webhookUrl, !responseA.error && !responseA.timedOut),
      trackWebhookResult(botB.id, botB.webhookUrl, !responseB.error && !responseB.timedOut),
    ])

    // Score the round
    const result = scoreRound(
      challenge,
      { id: botA.id, name: botA.name },
      { id: botB.id, name: botB.name },
      { answer: responseA.answer, timeMs: responseA.timeMs, timedOut: responseA.timedOut, error: responseA.error, trashTalk: responseA.trashTalk },
      { answer: responseB.answer, timeMs: responseB.timeMs, timedOut: responseB.timedOut, error: responseB.error, trashTalk: responseB.trashTalk },
      arena.modifier,
      comboA,
      comboB,
    )

    // Apply damage
    hpB = Math.max(KO_THRESHOLD, hpB - result.botADamage)
    hpA = Math.max(KO_THRESHOLD, hpA - result.botBDamage)

    // Update combos
    if (result.winnerId === botA.id) {
      comboA++
      comboB = 0
    } else if (result.winnerId === botB.id) {
      comboB++
      comboA = 0
    }

    // Save round
    await db.insert(schema.rounds).values({
      id: nanoid(12),
      fightId,
      roundNumber: round,
      challengeType: challenge.type,
      challengeData: JSON.stringify({ prompt: challenge.prompt, scoring: challenge.scoring }),
      botAResponse: responseA.answer,
      botATimeMs: responseA.timeMs,
      botAScore: result.botAScore,
      botBResponse: responseB.answer,
      botBTimeMs: responseB.timeMs,
      botBScore: result.botBScore,
      winnerId: result.winnerId,
      narration: result.narration,
      createdAt: new Date().toISOString(),
    })

    emit(fightId, 'round_end', {
      round,
      result: {
        ...result,
        botAResponse: responseA.answer?.slice(0, 200),
        botBResponse: responseB.answer?.slice(0, 200),
        botATimeMs: responseA.timeMs,
        botBTimeMs: responseB.timeMs,
        botATrashTalk: responseA.trashTalk,
        botBTrashTalk: responseB.trashTalk,
      },
      hp: { a: hpA, b: hpB },
      combo: { a: comboA, b: comboB },
    })

    // Update fight HP in DB
    await db.update(schema.fights).set({
      botAHp: hpA,
      botBHp: hpB,
      totalRounds: round,
    }).where(eq(schema.fights.id, fightId)).run()

    // Check for KO
    if (hpA <= KO_THRESHOLD || hpB <= KO_THRESHOLD) {
      winnerId = hpA <= KO_THRESHOLD ? botB.id : botA.id
      break
    }
  }

  // If no KO, winner is whoever has more HP
  if (!winnerId) {
    winnerId = hpA > hpB ? botA.id : hpB > hpA ? botB.id : null
  }

  const winnerName = winnerId === botA.id ? botA.name : winnerId === botB.id ? botB.name : 'nobody'
  const isPerfect = winnerId && (
    (winnerId === botA.id && hpA === 200) ||
    (winnerId === botB.id && hpB === 200)
  )

  // Finalize fight + update bot stats atomically
  const isMockFight = isMockBot(botA.webhookUrl) || isMockBot(botB.webhookUrl)
  const kFactor = isMockFight ? 12 : 32 // Dampened Elo for mock fights

  const finalize = sqlite.transaction(() => {
    // Mark fight finished
    db.update(schema.fights).set({
      status: 'finished',
      winnerId,
      endedAt: new Date().toISOString(),
    }).where(eq(schema.fights.id, fightId)).run()

    // Update bot stats
    if (winnerId) {
      const loserId = winnerId === botA.id ? botB.id : botA.id
      const winner = winnerId === botA.id ? botA : botB
      const loser = winnerId === botA.id ? botB : botA

      const { newWinnerElo, newLoserElo } = calculateElo(winner.eloRating, loser.eloRating, kFactor)
      const newWinStreak = winner.winStreak + 1
      const newBestStreak = Math.max(winner.bestStreak, newWinStreak)

      db.update(schema.bots).set({
        wins: sql`${schema.bots.wins} + 1`,
        eloRating: newWinnerElo,
        winStreak: newWinStreak,
        bestStreak: newBestStreak,
        tier: calculateTier(newWinnerElo, winner.wins + 1),
        lastFightAt: new Date().toISOString(),
      }).where(eq(schema.bots.id, winnerId)).run()

      db.update(schema.bots).set({
        losses: sql`${schema.bots.losses} + 1`,
        eloRating: newLoserElo,
        winStreak: 0,
        tier: calculateTier(newLoserElo, loser.wins),
        lastFightAt: new Date().toISOString(),
      }).where(eq(schema.bots.id, loserId)).run()
    } else {
      // Draw — update lastFightAt for both
      db.update(schema.bots).set({ lastFightAt: new Date().toISOString() }).where(eq(schema.bots.id, botA.id)).run()
      db.update(schema.bots).set({ lastFightAt: new Date().toISOString() }).where(eq(schema.bots.id, botB.id)).run()
    }
  })

  finalize()

  emit(fightId, 'fight_end', {
    winnerId,
    winnerName,
    isPerfect,
    finalHp: { a: hpA, b: hpB },
  })

  fightEvents.cleanup(fightId)
}

export async function runFight(botAId: string, botBId: string): Promise<string> {
  if (botAId === botBId) throw new Error('A bot cannot fight itself')
  if (activeFighters.has(botAId)) throw new Error(`Bot ${botAId} is already in a fight`)
  if (activeFighters.has(botBId)) throw new Error(`Bot ${botBId} is already in a fight`)

  activeFighters.add(botAId)
  activeFighters.add(botBId)

  try {
    const [botA, botB] = await loadBots(botAId, botBId)
    const arena = randomArena()
    const fightId = await createFightRecord(botA, botB, arena)
    await executeFightRounds(fightId, botA, botB, arena)
    return fightId
  } finally {
    activeFighters.delete(botAId)
    activeFighters.delete(botBId)
    setCooldown(botAId)
    setCooldown(botBId)
  }
}

/** Creates the fight record and returns the ID immediately. Rounds run in background. */
export async function runFightAsync(botAId: string, botBId: string): Promise<string> {
  if (botAId === botBId) throw new Error('A bot cannot fight itself')
  if (activeFighters.has(botAId)) throw new Error(`Bot ${botAId} is already in a fight`)
  if (activeFighters.has(botBId)) throw new Error(`Bot ${botBId} is already in a fight`)

  activeFighters.add(botAId)
  activeFighters.add(botBId)

  const [botA, botB] = await loadBots(botAId, botBId)
  const arena = randomArena()
  const fightId = await createFightRecord(botA, botB, arena)

  executeFightRounds(fightId, botA, botB, arena)
    .catch(err => {
      console.error(`[botfights] fight ${fightId} error:`, err)
      // Mark fight as cancelled so it doesn't stay 'live' forever
      db.update(schema.fights).set({
        status: 'cancelled',
        endedAt: new Date().toISOString(),
      }).where(eq(schema.fights.id, fightId)).run()
      fightEvents.cleanup(fightId)
    })
    .finally(() => {
      activeFighters.delete(botAId)
      activeFighters.delete(botBId)
      setCooldown(botAId)
      setCooldown(botBId)
    })

  return fightId
}

/** Clean up orphaned fights on startup */
export async function cleanupOrphanedFights(): Promise<number> {
  const tenMinutesAgo = new Date(Date.now() - 10 * 60 * 1000).toISOString()
  const result = await db.update(schema.fights)
    .set({ status: 'cancelled', endedAt: new Date().toISOString() })
    .where(sql`${schema.fights.status} = 'live' AND ${schema.fights.startedAt} < ${tenMinutesAgo}`)
  return 0 // drizzle doesn't return affected rows easily, but the cleanup runs
}