/**
 * Export formatters (JSON / Prometheus / shell) for /api/v1|v2|v3/allmetrics.
 */
import os from 'os'
import { getStore } from '../services/store.js'
import { CHART_BY_ID } from '../../shared/metrics.js'
import { APP_NAME, APP_VERSION } from '../../shared/protocol.js'

/**
 * @param {'json'|'prometheus'|'shell'} format
 */
export function formatAllMetrics(format = 'json') {
  const latest = getStore().latestValues()
  if (format === 'prometheus') return { contentType: 'text/plain; version=0.0.4', body: toPrometheus(latest) }
  if (format === 'shell') return { contentType: 'text/plain', body: toShell(latest) }
  return {
    contentType: 'application/json',
    body: {
      hostname: os.hostname(),
      app: APP_NAME,
      version: APP_VERSION,
      charts: Object.fromEntries(
        Object.entries(latest).map(([chart, point]) => [
          chart,
          {
            name: chart,
            context: CHART_BY_ID.get(chart)?.context || chart,
            last_updated: Math.floor(point.ts / 1000),
            dimensions: point.values,
          },
        ])
      ),
    },
  }
}

/**
 * @param {Record<string, { ts: number, values: Record<string, number|null> }>} latest
 */
function toPrometheus(latest) {
  const lines = [`# HELP peardata_info PearData agent info`, `# TYPE peardata_info gauge`]
  lines.push(`peardata_info{version="${APP_VERSION}",hostname="${os.hostname()}"} 1`)
  for (const [chart, point] of Object.entries(latest)) {
    const metric = chart.replace(/\./g, '_')
    for (const [dim, val] of Object.entries(point.values)) {
      if (val == null || Number.isNaN(val)) continue
      lines.push(`${metric}{dimension="${dim}"} ${val}`)
    }
  }
  return lines.join('\n') + '\n'
}

/**
 * @param {Record<string, { ts: number, values: Record<string, number|null> }>} latest
 */
function toShell(latest) {
  const lines = []
  for (const [chart, point] of Object.entries(latest)) {
    for (const [dim, val] of Object.entries(point.values)) {
      if (val == null || Number.isNaN(val)) continue
      lines.push(`PEARDATA_${chart.replace(/\./g, '_').toUpperCase()}_${dim.toUpperCase()}="${val}"`)
    }
  }
  return lines.join('\n') + '\n'
}