function extraPictureNumbers(extraRefs: number | number[]) {
  if (Array.isArray(extraRefs)) {
    return [...new Set(extraRefs.map(Number).filter(n => n >= 2 && n <= 5))].sort((a, b) => a - b)
  }
  const extras = Math.max(0, Math.min(4, extraRefs))
  return Array.from({ length: extras }, (_, i) => i + 2)
}

export function identityBoilerplate(extraRefs: number | number[] = 0) {
  const extras = extraPictureNumbers(extraRefs)
  const secondary = extras.length === 0
    ? ''
    : extras.length === 1
      ? ` <Picture ${extras[0]}> is a secondary reference angle for profile details.`
      : ` ${extras.map(n => `<Picture ${n}>`).join(' and ')} are secondary reference angles for profile features only.`
  return `<Picture 1> is the exact facial identity, hairstyle, body proportions and clothing of the main character. Preserve this identity with high fidelity even when the subject temporarily leaves the frame and returns.${secondary}`
}

export function looksLikeIdentityPrompt(text: string) {
  return /primary identity anchor|exact facial identity/i.test(String(text || ''))
}

export function buildIdentityPrompt(actionPrompt: string, extraRefs: number | number[] = 0) {
  const action = String(actionPrompt || '').trim()
  if (looksLikeIdentityPrompt(action)) return action
  const boilerplate = identityBoilerplate(extraRefs)
  return action ? `${boilerplate}\n\n${action}` : boilerplate
}

export const IDENTITY_ACTION_TEMPLATE = `[SHOT CONFIGURATION]
- Shot Type: Medium close-up, 50mm lens, eye-level
- Camera Movement: Slow tracking dolly-in following the subject
- Lighting: Warm golden-hour rim lighting with soft directional fill from screen left
- Environment/Scenery: Dense pine forest, soft ambient ground mist

[SUBJECT DIRECTION & ACTION]
The subject from <Picture 1> walks slowly through the path, glancing toward camera-left in awe. She turns slightly, speaking softly: "Look at the way the light hits the trees."

[AUDIO CUES]
Ambient forest breeze, soft footsteps on twigs, warm cinematic background strings.`