export interface PullRef {
  number: number
  title: string
  merged: boolean
  mergeCommitSha: string | null
}

export type ListPullsPage = (page: number) => Promise<PullRef[]>
export type ListPullCommits = (index: number) => Promise<string[]>

/**
 * 把未发布提交的 sha 对上已合并 PR。
 * 只认 Gitea 的 PR 提交列表 / squash 的 mergeCommitSha，不扫 commit message。
 */
export async function indexCommitsByPull(
  shas: readonly string[],
  listPulls: ListPullsPage,
  listCommits: ListPullCommits,
): Promise<Map<string, { number: number, title: string }>> {
  const needed = new Set(shas)
  const out = new Map<string, { number: number, title: string }>()
  if (needed.size === 0)
    return out

  for (let page = 1; page <= 20; page++) {
    const batch = await listPulls(page)
    if (batch.length === 0)
      break
    for (const pr of batch) {
      if (!pr.merged)
        continue
      const ref = { number: pr.number, title: pr.title }
      if (pr.mergeCommitSha && needed.has(pr.mergeCommitSha))
        out.set(pr.mergeCommitSha, ref)
      const commits = await listCommits(pr.number)
      for (const sha of commits) {
        if (needed.has(sha))
          out.set(sha, ref)
      }
      if (out.size === needed.size)
        return out
    }
    if (batch.length < 50)
      break
  }
  return out
}

export function attachPulls<T extends { sha: string }>(
  commits: T[],
  index: Map<string, { number: number, title: string }>,
): Array<T & { pr?: number, prTitle?: string }> {
  return commits.map((c) => {
    const hit = index.get(c.sha)
    return hit ? { ...c, pr: hit.number, prTitle: hit.title } : c
  })
}