/**
 * MongoDB TCP probe (+ optional serverStatus HTTP sidecar).
 * Enable: PEARDATA_MONGODB=1
 * URL: PEARDATA_MONGODB_URL=127.0.0.1:27017
 */
import net from 'net'
import { CollectorPlugin } from './plugin.js'
import { registerChart } from '../../../shared/metrics.js'

export function isMongodbEnabled() {
  const v = process.env.PEARDATA_MONGODB
  return v === '1' || v === 'on' || v === 'true'
}

function endpoint() {
  const raw = process.env.PEARDATA_MONGODB_URL || '127.0.0.1:27017'
  const u = raw.replace(/^mongodb:\/\//, '')
  const [host, port] = u.split(':')
  return { host: host || '127.0.0.1', port: Number(port) || 27017 }
}

function probeTcp(host, port, timeoutMs = 1500) {
  return new Promise((resolve) => {
    const start = Date.now()
    const sock = net.connect({ host, port }, () => {
      const ms = Date.now() - start
      sock.end()
      resolve({ up: 1, latency_ms: ms })
    })
    sock.setTimeout(timeoutMs)
    sock.on('timeout', () => {
      sock.destroy()
      resolve({ up: 0, latency_ms: timeoutMs })
    })
    sock.on('error', () => resolve({ up: 0, latency_ms: timeoutMs }))
  })
}

export class MongodbCollector extends CollectorPlugin {
  constructor() {
    super({ name: 'mongodb' })
  }

  isEnabled() {
    return isMongodbEnabled()
  }

  async collect() {
    const ts = Date.now()
    const { host, port } = endpoint()
    const probe = await probeTcp(host, port)
    registerChart({
      id: 'mongodb.up',
      name: 'mongodb.up',
      context: 'mongodb.up',
      title: 'MongoDB up',
      units: 'boolean',
      family: 'mongodb',
      chartType: 'line',
      priority: 8700,
      plugin: 'mongodb',
      dimensions: [
        { id: 'up', name: 'up', algorithm: 'absolute' },
        { id: 'latency_ms', name: 'latency_ms', algorithm: 'absolute' },
      ],
    })
    /** @type {Array<{ chart: string, context: string, ts: number, values: object }>} */
    const batch = [
      { chart: 'mongodb.up', context: 'mongodb.up', ts, values: probe },
    ]
    const statsUrl = process.env.PEARDATA_MONGODB_STATS_URL
    if (statsUrl) {
      try {
        const res = await fetch(statsUrl, { signal: AbortSignal.timeout(2000) })
        const text = await res.text()
        /** @type {Record<string, number>} */
        const vals = {}
        for (const line of text.split('\n')) {
          const [k, v] = line.split(/[=\s]+/)
          if (k && v != null && Number.isFinite(Number(v))) vals[k] = Number(v)
        }
        registerChart({
          id: 'mongodb.stats',
          name: 'mongodb.stats',
          context: 'mongodb.stats',
          title: 'MongoDB stats',
          units: 'value',
          family: 'mongodb',
          chartType: 'line',
          priority: 8710,
          plugin: 'mongodb',
          dimensions: Object.keys(vals).map((id) => ({
            id,
            name: id,
            algorithm: 'absolute',
          })),
        })
        batch.push({ chart: 'mongodb.stats', context: 'mongodb.stats', ts, values: vals })
      } catch {
        // ignore
      }
    }
    return batch
  }
}

let singleton = null
export function getMongodbCollector() {
  if (!singleton) singleton = new MongodbCollector()
  return singleton
}