type DocResponse = { code: number, msg: string, data: string }

const TTL_MS = 60 * 60 * 1000

const cache = new Map<string, { value: string, expiresAt: number }>()
const inFlight = new Map<string, Promise<string>>()

export default defineEventHandler(async (event) => {
  const { key } = getQuery(event) as { key?: string }

  if (!key) {
    throw createError({ statusCode: 400, statusMessage: 'Missing key' })
  }

  const now = Date.now()
  const hit = cache.get(key)
  if (hit && hit.expiresAt > now) {
    return { code: 0, msg: '', data: hit.value }
  }

  const existing = inFlight.get(key)
  if (existing) {
    return { code: 0, msg: '', data: await existing }
  }

  const p = (async () => {
    const runtimeConfig = useRuntimeConfig()
    const baseURL = runtimeConfig.serverApiBase as string | undefined
    if (!baseURL) {
      throw createError({ statusCode: 500, statusMessage: 'Missing serverApiBase' })
    }

    const res = await $fetch<DocResponse>('/base/doc/get', {
      baseURL,
      params: { key },
    })

    if (!res || res.code !== 0) {
      throw createError({ statusCode: 500, statusMessage: res?.msg || 'Request failed' })
    }

    const html = res.data || ''
    cache.set(key, { value: html, expiresAt: Date.now() + TTL_MS })
    return html
  })()

  inFlight.set(key, p)

  try {
    return { code: 0, msg: '', data: await p }
  }
  finally {
    inFlight.delete(key)
  }
})