/**
 * Token-scoped discovery for onboarding. Given just a base URL + PAT (no repo
 * chosen yet), enumerate the owners and repositories the token can reach, so the
 * connect screen can offer them as dropdowns instead of free-text. These
 * endpoints are user-scoped, not repo-scoped, so they don't belong on the
 * repo-bound `GiteaClient` — this is a standalone call with the same injected
 * `fetch` seam (real fetch in main, stub in tests).
 */
import { GiteaApiError } from './types.js'
import type { FetchLike } from './types.js'

/** What onboarding needs to render the owner + repo pickers. */
export interface DiscoveredRepos {
  /** The token's own login (its default owner). */
  user: string
  /** Owners with at least one accessible repo — the user first, then the rest, sorted. */
  owners: string[]
  /** Repo names per owner, sorted. Keys match `owners`. */
  reposByOwner: Record<string, string[]>
}

interface RawRepo {
  name: string
  owner?: { login?: string } | null
}

const PAGE_LIMIT = 50

async function getJson(url: string, token: string, fetchImpl: FetchLike): Promise<unknown> {
  const res = await fetchImpl(url, { headers: { Authorization: `token ${token}`, Accept: 'application/json' } })
  if (!res.ok) {
    const body = await res.text().catch(() => '')
    throw new GiteaApiError(res.status, `GET ${url} failed (${res.status})`, body)
  }
  return res.json()
}

/**
 * Enumerate the owners + repos a token can reach. Hits `/user` (to learn the
 * token's own login and prove the token works) and paginates `/user/repos`
 * (every repo the token can access across personal + org namespaces).
 */
export async function discoverRepos(conn: { baseUrl: string; token: string }, fetchImpl: FetchLike): Promise<DiscoveredRepos> {
  const apiBase = `${conn.baseUrl.replace(/\/+$/, '')}/api/v1`

  const me = (await getJson(`${apiBase}/user`, conn.token, fetchImpl)) as { login?: string }
  const user = me.login ?? ''

  const repos: RawRepo[] = []
  for (let page = 1; ; page++) {
    const batch = (await getJson(`${apiBase}/user/repos?page=${page}&limit=${PAGE_LIMIT}`, conn.token, fetchImpl)) as RawRepo[]
    repos.push(...batch)
    if (batch.length < PAGE_LIMIT) break
  }

  const reposByOwner: Record<string, string[]> = {}
  for (const r of repos) {
    const owner = r.owner?.login
    if (!owner || !r.name) continue
    ;(reposByOwner[owner] ??= []).push(r.name)
  }
  for (const owner of Object.keys(reposByOwner)) {
    reposByOwner[owner] = [...new Set(reposByOwner[owner])].sort((a, b) => a.localeCompare(b))
  }

  // owners sorted alphabetically, but the token's own login always leads.
  const owners = Object.keys(reposByOwner).sort((a, b) => {
    if (a === user) return -1
    if (b === user) return 1
    return a.localeCompare(b)
  })

  return { user, owners, reposByOwner }
}