import type { BackendContext } from '@jaspers-ai/sdk'

// The ClinicalTrials.gov API v2 client: builds a search query and fetches JSON with a time limit.

export const HOST = 'clinicaltrials.gov'
export const BASE = `https://${HOST}/api/v2`

export interface SearchArgs {
  condition?: string
  intervention?: string
  sponsor?: string
  term?: string
  phases?: string[]
  statuses?: string[]
  startFrom?: string
  startTo?: string
  primaryCompletionFrom?: string
  primaryCompletionTo?: string
  sort?: string
  pageSize: number
  pageToken?: string
}

/** The query string for /studies from the search arguments. */
export function searchQuery(args: SearchArgs): URLSearchParams {
  const query = new URLSearchParams({ format: 'json', countTotal: 'true', pageSize: String(args.pageSize) })
  query.set('fields', SEARCH_FIELDS.join(','))
  if (args.condition) query.set('query.cond', args.condition)
  if (args.intervention) query.set('query.intr', args.intervention)
  if (args.sponsor) query.set('query.spons', args.sponsor)
  if (args.term) query.set('query.term', args.term)
  if (args.statuses?.length) query.set('filter.overallStatus', args.statuses.join(','))
  const advanced: string[] = []
  if (args.phases?.length) advanced.push(`AREA[Phase](${args.phases.join(' OR ')})`)
  if (args.startFrom || args.startTo)
    advanced.push(`AREA[StartDate]RANGE[${args.startFrom ?? 'MIN'}, ${args.startTo ?? 'MAX'}]`)
  if (args.primaryCompletionFrom || args.primaryCompletionTo)
    advanced.push(
      `AREA[PrimaryCompletionDate]RANGE[${args.primaryCompletionFrom ?? 'MIN'}, ${args.primaryCompletionTo ?? 'MAX'}]`,
    )
  if (advanced.length) query.set('filter.advanced', advanced.join(' AND '))
  // The API sorts a date field newest first when no direction is given; a bare field here means ascending.
  if (args.sort) query.set('sort', args.sort.includes(':') || args.sort.startsWith('@') ? args.sort : `${args.sort}:asc`)
  if (args.pageToken) query.set('pageToken', args.pageToken)
  return query
}

/** The modules a search row reads, so a page of results stays small. */
const SEARCH_FIELDS = [
  'protocolSection.identificationModule',
  'protocolSection.statusModule',
  'protocolSection.sponsorCollaboratorsModule',
  'protocolSection.conditionsModule',
  'protocolSection.designModule',
  'protocolSection.armsInterventionsModule',
  'hasResults',
]

/** GET a path under the API, aborted after a few seconds; throws with the status and the body's first line. */
export async function getJson(ctx: BackendContext, path: string, query?: URLSearchParams): Promise<unknown> {
  const url = `${BASE}${path}${query ? `?${query}` : ''}`
  const controller = new AbortController()
  const timer = setTimeout(() => controller.abort(), 4500)
  try {
    const response = await ctx.fetch(url, { signal: controller.signal, headers: { Accept: 'application/json' } })
    if (!response.ok) {
      const body = (await response.text()).split('\n')[0] ?? ''
      throw new Error(`ClinicalTrials.gov answered ${response.status}: ${body.slice(0, 200)}`)
    }
    return await response.json()
  } catch (error) {
    if (controller.signal.aborted) throw new Error('ClinicalTrials.gov did not answer within 4.5 seconds; try a smaller pageSize.')
    throw error
  } finally {
    clearTimeout(timer)
  }
}