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

export const QWEN21_EDIT_KEEP =
  'Keep the identity, face, body, and pose of the person in <image1>.'

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

/** User omitted <image1> — prepend the keep-identity instruction once. */
export function ensureQwen21EditPrompt(prompt) {
  const text = String(prompt || '').trim()
  if (!text) return text
  if (/<image1>/i.test(text)) return text
  return `${QWEN21_EDIT_KEEP_CHANGE} ${text}`.trim()
}

/**
 * After PE-I2I: official PE told N=1 not to use tags, so rewrites often say
 * "the photo" / "the image" with zero <image1>. Qwen Edit only binds Start still
 * when the text contains the tag — force it onto every Edit rewrite.
 */
export function stitchQwen21PeEditPrompt(rewritten) {
  let text = String(rewritten || '').trim()
  if (!text) return text
  // Prefer the tag over natural substitutes (do not invent <image2>).
  text = 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>')
  if (/<image1>/i.test(text)) return text
  return `${QWEN21_EDIT_KEEP} ${text}`.trim()
}