/** Qwen Edit / PE-I2I prompt helpers. Start still = <image1>; Hero is never a slot. */

export const QWEN21_EDIT_KEEP =
  'Keep the identity, face, body, pose, and likeness of the person in <image1>.\nDo not invent a different person.'

export const QWEN21_EDIT_KEEP_CHANGE =
  `${QWEN21_EDIT_KEEP}\nApply only this change:`

const EDIT_VERB =
  /\b(?:change|replace|put|swap|keep|remove|add|edit|make|turn|convert|transform|modify|update|set|apply|wear|place|swap|switch)\b/i

const DESCRIBE_LEAD =
  /^(?:the image is\b|this is a photograph of\b|a vertical photorealistic\b|a photorealistic\b|this (?:image|photo|picture) (?:shows|depicts|features)\b|the (?:photo|picture) (?:shows|depicts|features)\b)/i

/** Fixed identity stanza + the user's raw edit instruction. Always includes <image1>. */
export function buildQwen21EditKeepStanza(rawInstruction) {
  const raw = String(rawInstruction || '').trim()
  if (!raw) return QWEN21_EDIT_KEEP.trim()
  return `${QWEN21_EDIT_KEEP_CHANGE} ${raw}`.trim()
}

/** Enhance off / refusal: ensure the sample prompt is the keep stanza, never PE-only. */
export function ensureQwen21EditPrompt(prompt) {
  const text = String(prompt || '').trim()
  if (!text) return text
  if (/Keep the identity, face, body, pose, and likeness of the person in <image1>/i.test(text)) return text
  return buildQwen21EditKeepStanza(text)
}

/** PE rewrite looks like a T2I observer caption, not an edit directive. */
export function isQwen21PeEditDescribe(rewritten) {
  const text = String(rewritten || '').trim()
  if (!text) return true
  if (DESCRIBE_LEAD.test(text)) return true
  if (!EDIT_VERB.test(text)) return true
  return false
}

function retagNaturalImageRefs(text) {
  return String(text || '')
    .replace(/\bthe woman in the (?:input )?(?:photo|picture|image)\b/gi, 'the person in <image1>')
    .replace(/\bthe (?:person|man|subject) in the (?:input )?(?:photo|picture|image)\b/gi, 'the person in <image1>')
    .replace(/\bin the (?:input )?(?:photo|picture|image)\b/gi, 'in <image1>')
    .replace(/\bthe (?:input )?(?:photo|picture|image)\b/gi, '<image1>')
}

/**
 * After PE-I2I: never let the PE chunk be the entire prompt.
 * Always lead with the keep/<image1> stanza + raw instruction; append PE only when it is an edit directive.
 */
export function stitchQwen21PeEditPrompt(rawInstruction, rewritten) {
  const stanza = buildQwen21EditKeepStanza(rawInstruction)
  let pe = retagNaturalImageRefs(String(rewritten || '').trim()).trim()
  if (!pe) return { prompt: stanza, skippedAsDescribe: false }
  if (isQwen21PeEditDescribe(pe)) {
    return { prompt: stanza, skippedAsDescribe: true }
  }
  // No <image1> in the PE chunk is fine — stanza already has the tag; keep PE as extra detail.
  return { prompt: `${stanza}\n\n${pe}`.trim(), skippedAsDescribe: false }
}