// GET /api/status?sigs=<signature>[,<signature>…]&until=<lastValidBlockHeight>: pending, confirmed,
// failed or expired for each (expired: the blockhash ran out before it landed, so it never will).

import { blockHeight, txStatuses, type Ctx } from '../../server/card.ts'
import { ConfigError, configFailure, contextFor, gate, type CardEnv } from '../../server/env.ts'
import { allowInMemory, clientIp, failure, json } from '../../server/http.ts'

// Near expiry every pending poll needs the block height; one reading serves this isolate for two
// seconds (a height two seconds old only delays "expired" by as much). Only the finished value is
// shared, never the pending read: Workers cancel a request's work when its client leaves, which
// would leave every other request waiting on that read hanging.
const HEIGHT_TTL_MS = 2000
let height: { at: number; value: number } | null = null

const sharedHeight = (ctx: Ctx) => async (): Promise<number> => {
  if (height && Date.now() - height.at < HEIGHT_TTL_MS) return height.value
  const value = await blockHeight(ctx)
  height = { at: Date.now(), value }
  return value
}

export const onRequestGet: PagesFunction<CardEnv> = async ({ request, env }) => {
  const params = new URL(request.url).searchParams
  if ([...params.keys()].some((k) => k !== 'sigs' && k !== 'until')) return json({ error: 'Expected ?sigs=&until=.', code: 'bad-request' }, 400)
  // The app polls every 2 s per purchase (30 a minute); phone carriers put many people behind one IP.
  const refused = await gate(request, env, 'status', 240, 'memory')
  if (refused) return refused
  try {
    // Statuses never depend on the pause flags, so polls skip reading them.
    const ctx = await contextFor(env, { flags: false })
    // The history search is the costly call; a buyer needs about one per purchase, so a client
    // gets 20 a minute (beyond that, "pending" until the next minute).
    const mayDeepSearch = () => allowInMemory('status-deep', clientIp(request), 20, env.RATE_SALT)
    return json(await txStatuses(ctx, params.get('sigs'), params.get('until'), sharedHeight(ctx), mayDeepSearch))
  } catch (err) {
    return err instanceof ConfigError ? configFailure(err) : failure(err, 'status')
  }
}