export interface ParsedShot {
  n: number
  prompt: string
  role: 'initial' | 'extension'
}

function parseMarkedBlocks(text: string, marker: RegExp): ParsedShot[] {
  const src = String(text || '').replace(/\r\n/g, '\n')
  const markers: { n: number; start: number; end: number }[] = []
  for (const match of src.matchAll(marker)) {
    markers.push({
      n: Number(match[1]),
      start: match.index || 0,
      end: (match.index || 0) + match[0].length
    })
  }
  const blocks: { n: number; prompt: string }[] = []
  if (!markers.length) {
    const prompt = src.trim()
    return prompt ? [{ n: 1, prompt, role: 'initial' }] : []
  }
  const preamble = src.slice(0, markers[0].start).trim()
  if (preamble) blocks.push({ n: 1, prompt: preamble })
  for (let i = 0; i < markers.length; i++) {
    const from = markers[i].end
    const to = i + 1 < markers.length ? markers[i + 1].start : src.length
    const prompt = src.slice(from, to).trim()
    if (prompt) blocks.push({ n: markers[i].n, prompt })
  }
  const byN = new Map<number, string>()
  for (const block of blocks) {
    const prev = byN.get(block.n)
    byN.set(block.n, prev ? `${prev}\n${block.prompt}` : block.prompt)
  }
  return [...byN.entries()]
    .sort((a, b) => a[0] - b[0])
    .map(([n, prompt], index) => ({
      n,
      prompt,
      role: index === 0 ? 'initial' : 'extension'
    }))
}

export function parseShotScript(text: string): ParsedShot[] {
  return parseMarkedBlocks(text, /^[ \t]*shot\s+(\d+)\b/gim)
}

export function parseImageBatchScript(text: string): ParsedShot[] {
  return parseMarkedBlocks(text, /^[ \t]*(?:shot|image|prompt)\s+(\d+)\b/gim)
}