botfights/server/src/engine/challenges.ts

import { TEMPLATES, type ChallengeTemplate, type PromptEntry, type PromptTheme, type PromptDifficulty } from './challenge-data.js'
import { EXTRA_PROMPTS } from './challenges-extra.js'
import { BITCOIN_PROMPTS } from './challenges-bitcoin.js'
import { pick } from '../lib/utils.js'

export interface Challenge {
  type: string
  label: string
  prompt: string
  answers?: string[]
  choices?: string[]
  timeout_ms: number
  scoring: 'factual' | 'creative'
  baseDamage: number
  displayPrompt?: string
}

export type { ChallengeTemplate, PromptEntry, PromptTheme, PromptDifficulty }


// Merge extra prompts into templates
for (const t of TEMPLATES) {
  const extras = EXTRA_PROMPTS[t.type]
  if (extras) t.prompts.push(...extras)
  const btc = BITCOIN_PROMPTS[t.type]
  if (btc) t.prompts.push(...btc)
}

// ═══════════════════════════════════════════════
// Challenge selection + generation
// ═══════════════════════════════════════════════

function shuffleArray<T>(arr: T[]): T[] {
  const s = [...arr]
  for (let i = s.length - 1; i > 0; i--) {
    const j = Math.floor(Math.random() * (i + 1))
    ;[s[i], s[j]] = [s[j], s[i]]
  }
  return s
}

// Target theme distribution: 30% bitcoin, 20% conspiracy, 20% pc_culture, 30% bot_coding
const THEME_WEIGHTS: Record<PromptTheme, number> = {
  bitcoin: 0.3,
  conspiracy: 0.2,
  pc_culture: 0.2,
  bot_coding: 0.3,
}

function pickTheme(): PromptTheme | undefined {
  const roll = Math.random()
  let cumulative = 0
  for (const [theme, weight] of Object.entries(THEME_WEIGHTS)) {
    cumulative += weight
    if (roll < cumulative) return theme as PromptTheme
  }
  return undefined
}

/** Map round number to target difficulty: Round 1-2 easy, 3-4 medium, 5+ hard */
export function roundToDifficulty(round: number): PromptDifficulty {
  if (round <= 2) return 'easy'
  if (round <= 4) return 'medium'
  return 'hard'
}

export function pickChallenge(usedTypes: Set<string>, _arenaModifier: string | null, themeBias?: PromptTheme, roundNumber?: number): Challenge {
  let available = TEMPLATES.filter(t => !usedTypes.has(t.type))
  if (available.length === 0) available = TEMPLATES

  // Bias toward factual challenges (70% factual, 30% creative)
  const factual = available.filter(t => t.scoring === 'factual')
  const creative = available.filter(t => t.scoring === 'creative')

  let pool: ChallengeTemplate[]
  if (factual.length > 0 && creative.length > 0) {
    pool = Math.random() < 0.7 ? factual : creative
  } else {
    pool = available
  }

  const template = pick(pool)
  const targetTheme = themeBias || pickTheme()
  const targetDifficulty = roundNumber ? roundToDifficulty(roundNumber) : undefined
  return templateToChallenge(template, targetTheme, targetDifficulty)
}

/** Ranked challenge: no multiple choice, only harder creative/open-ended prompts */
export function pickRankedChallenge(usedTypes: Set<string>): Challenge {
  let available = TEMPLATES.filter(t => !usedTypes.has(t.type))
  if (available.length === 0) available = TEMPLATES

  // Filter to creative-only (open-ended, harder) — no factual multiple choice
  const creative = available.filter(t => t.scoring === 'creative')
  const pool = creative.length > 0 ? creative : available

  const template = pick(pool)

  // Pick a prompt that has no choices array (open-ended)
  const openPrompts = template.prompts.filter(p => !p.choices)
  const prompts = openPrompts.length > 0 ? openPrompts : template.prompts
  const entry = pick(prompts)

  return {
    type: template.type,
    label: template.label,
    prompt: entry.prompt,
    answers: entry.answers,
    choices: undefined, // Never multiple choice in ranked
    timeout_ms: template.timeout_ms,
    scoring: template.scoring,
    baseDamage: template.baseDamage,
  }
}

function templateToChallenge(template: ChallengeTemplate, targetTheme?: PromptTheme, targetDifficulty?: PromptDifficulty): Challenge {
  // Prefer prompts matching target theme if any are tagged
  let prompts = template.prompts
  if (targetTheme) {
    const themed = prompts.filter(p => p.theme === targetTheme)
    if (themed.length > 0) prompts = themed
  }
  // Prefer prompts matching target difficulty if any are tagged
  if (targetDifficulty) {
    const byDifficulty = prompts.filter(p => p.difficulty === targetDifficulty)
    if (byDifficulty.length > 0) prompts = byDifficulty
  }
  const entry = pick(prompts)

  // Determine choices
  let choices: string[] | undefined
  if (entry.choices) {
    choices = shuffleArray(entry.choices)
  } else if (entry.answers?.length === 1 && ['true', 'false'].includes(entry.answers[0].toLowerCase())) {
    // Auto-generate True/False choices for boolean questions
    choices = shuffleArray(['True', 'False'])
  }

  return {
    type: template.type,
    label: template.label,
    prompt: entry.prompt,
    answers: entry.answers,
    choices,
    timeout_ms: template.timeout_ms,
    scoring: template.scoring,
    baseDamage: template.baseDamage,
  }
}

export function getAllChallengeTypes(): string[] {
  return TEMPLATES.map(t => t.type)
}

export function getAnswerPool(type: string): string[] {
  const template = TEMPLATES.find(t => t.type === type)
  if (!template) return []
  return template.prompts
    .flatMap(p => p.answers || [])
    .filter((v, i, arr) => arr.indexOf(v) === i)
}