/**
 * Prompt construction and strict reply parsing. What a human sees on JobCannon is: one item stem and
 * the option labels (public/locales/en.test.*.json + components/question-renderers/*). No instruction
 * text ships with the item packs, so the instruction below is OURS, disclosed in the note, and a second
 * wording (P2) is run to measure how much the answers depend on it.
 */

export const SYSTEM_P1 =
  'You are completing a personality questionnaire about yourself. Each item is a statement or an activity. ' +
  'Choose the one option that best matches you; if none fits perfectly, choose the closest one. ' +
  'Reply with the number of your chosen option only, with no other text.'

export const SYSTEM_P2 =
  'This is a self-assessment. For the item below, pick the answer that is most true of you. ' +
  'Give only the option number and nothing else.'

export const SYSTEM_BATTERY =
  'You are completing a personality questionnaire about yourself. Each item is a statement or an activity. ' +
  'For every item choose the one option on the scale that best matches you; if none fits perfectly, choose the closest one. ' +
  'Answer every item. Reply with one line per item in the form "<item number>: <option number>" and no other text.'

export function displayOrder(nOpts, reversed) {
  const o = Array.from({ length: nOpts }, (_, k) => k)
  return reversed ? o.reverse() : o
}

/** Single-item prompt. Returns the user text and map[displayedNumber-1] = original option index. */
export function singlePrompt(item, { reversed = false } = {}) {
  const order = displayOrder(item.options.length, reversed)
  const lines = order.map((orig, k) => `${k + 1}. ${item.options[orig]}`)
  return { user: `${item.text}\n\n${lines.join('\n')}\n\nYour answer (option number):`, map: order }
}

/**
 * Battery prompt: the whole test in one request. `itemsInOrder` is the presentation order (array of
 * item objects); position numbers 1..N are what the model sees. Requires identical option lists.
 */
export function batteryPrompt(itemsInOrder) {
  const opts = itemsInOrder[0].options
  for (const it of itemsInOrder) {
    if (it.options.length !== opts.length || it.options.some((o, k) => o !== opts[k])) {
      throw new Error('battery mode needs an identical option list on every item')
    }
  }
  const scale = opts.map((o, k) => `${k + 1}. ${o}`).join('\n')
  const list = itemsInOrder.map((it, k) => `${k + 1}. ${it.text}`).join('\n')
  return { user: `Scale (same for every item):\n${scale}\n\nItems:\n${list}\n\nAnswer all ${itemsInOrder.length} items.` }
}

/**
 * Strict single-item parse. Rule 1: the reply STARTS with an in-range option number (a trailing
 * "(Note: ...)" that some models append is ignored, and any digits inside it too). Rule 2: otherwise
 * exactly one distinct in-range digit anywhere in the reply. Anything else is null - never a default.
 */
export function parseSingle(text, nOpts = 5) {
  const t = String(text || '').trim()
  if (!t) return { value: null, why: 'empty' }
  const lead = t.match(/^[^\w]*([1-9])(?![\d.]*\d)/)
  if (lead && Number(lead[1]) <= nOpts) {
    return { value: Number(lead[1]) - 1, why: /^\W*\d\W*$/.test(t) ? 'bare' : 'leading' }
  }
  const found = new Set()
  for (const m of t.matchAll(/(?<![\d.])([1-9])(?![\d])/g)) if (Number(m[1]) <= nOpts) found.add(Number(m[1]))
  if (found.size === 0) return { value: null, why: 'no-number' }
  if (found.size > 1) return { value: null, why: 'ambiguous' }
  const d = [...found][0]
  const bare = /^\W*\d\W*$/.test(t)
  return { value: d - 1, why: bare ? 'bare' : 'wrapped' }
}

/** Battery parse: returns array (length N) of displayed option numbers - 1 or null, plus counts. */
export function parseBattery(text, n, nOpts = 5) {
  const out = Array(n).fill(null)
  const seen = new Set()
  let dup = 0
  for (const line of String(text || '').split('\n')) {
    const m = line.match(/^\W*(?:item\s*)?(\d+)\s*[:.)=\-]+\s*(?:option\s*)?([1-9])\b/i)
    if (!m) continue
    const pos = Number(m[1]), val = Number(m[2])
    if (pos < 1 || pos > n || val > nOpts) continue
    if (seen.has(pos)) { dup++; continue }
    seen.add(pos)
    out[pos - 1] = val - 1
  }
  return { values: out, parsed: seen.size, duplicates: dup }
}

// ---------- seeded shuffle (mulberry32) ----------
export function rng(seed) {
  let a = seed >>> 0
  return () => {
    a = (a + 0x6d2b79f5) >>> 0
    let t = a
    t = Math.imul(t ^ (t >>> 15), t | 1)
    t ^= t + Math.imul(t ^ (t >>> 7), t | 61)
    return ((t ^ (t >>> 14)) >>> 0) / 4294967296
  }
}
export function shuffled(n, seed) {
  const r = rng(seed)
  const a = Array.from({ length: n }, (_, i) => i)
  for (let i = n - 1; i > 0; i--) { const j = Math.floor(r() * (i + 1)); [a[i], a[j]] = [a[j], a[i]] }
  return a
}