import { defineSource } from '@jaspers-ai/sdk'
import { z } from 'zod'


// The Bureau of Labor Statistics. Its public API v2 answers without a key; registering raises the
// daily limit and is not needed to read a series. Inflation and the labour market, from the office
// that measures them.

const HOST = 'api.bls.gov'

/** The series worth knowing by name, so a request can say "CPI" rather than CUUR0000SA0. */
const KNOWN: Record<string, string> = {
  cpi: 'CUUR0000SA0',
  'cpi-core': 'CUUR0000SA0L1E',
  unemployment: 'LNS14000000',
  payrolls: 'CES0000000001',
  'average-hourly-earnings': 'CES0500000003',
  'labor-force-participation': 'LNS11300000',
  ppi: 'WPUFD4',
  'job-openings': 'JTS000000000000000JOL',
}

interface Answer {
  status: string
  message?: string[]
  Results?: { series: { seriesID: string; data: { year: string; period: string; periodName: string; value: string }[] }[] }
}

export const series = defineSource({
  description: `One BLS series over time, monthly. series is a BLS id like CUUR0000SA0, or one of these names: ${Object.keys(KNOWN).join(', ')}. Values come back oldest first, ready to chart.`,
  hosts: [HOST],
  input: z.object({
    series: z.string().default('cpi'),
    startYear: z.number().int().optional(),
    endYear: z.number().int().optional(),
  }),
  async run({ series: wanted, startYear, endYear }, ctx) {
    const id = KNOWN[wanted.trim().toLowerCase()] ?? wanted.trim().toUpperCase()
    // BLS refuses one year without the other, so naming either fills in the rest.
    const query = new URLSearchParams()
    if (startYear || endYear) {
      const thisYear = new Date().getFullYear()
      query.set('startyear', String(startYear ?? (endYear ?? thisYear) - 10))
      query.set('endyear', String(endYear ?? thisYear))
    }
    const url = `https://${HOST}/publicAPI/v2/timeseries/data/${encodeURIComponent(id)}${query.size ? `?${query.toString()}` : ''}`
    const response = await ctx.fetch(url)
    if (!response.ok) throw new Error(`BLS answered ${response.status}.`)
    const body = (await response.json()) as Answer
    if (body.status !== 'REQUEST_SUCCEEDED') throw new Error(body.message?.join(' ') || `BLS refused: ${body.status}.`)
    const found = body.Results?.series?.[0]
    if (!found || found.data.length === 0) throw new Error(`BLS has no data for ${id}. Check the series id.`)
    const rows = found.data
      // M13 is the annual average, which does not belong on a monthly line.
      .filter((one) => one.period !== 'M13')
      .map((one) => ({
        series: found.seriesID,
        date: `${one.year}-${one.period.replace('M', '')}-01`,
        year: Number(one.year),
        period: one.periodName,
        value: Number(one.value),
      }))
      .filter((one) => Number.isFinite(one.value))
      .sort((a, b) => a.date.localeCompare(b.date))
    return { series: found.seriesID, rows }
  },
})