/**
 * RabbitMQ management API collector.
 * Enable: PEARDATA_RABBITMQ=1
 * URL: PEARDATA_RABBITMQ_URL=http://guest:guest@127.0.0.1:15672
 */
import { CollectorPlugin } from './plugin.js'
import { registerChart } from '../../../shared/metrics.js'

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

function baseUrl() {
  return (process.env.PEARDATA_RABBITMQ_URL || 'http://guest:guest@127.0.0.1:15672').replace(
    /\/$/,
    ''
  )
}

export class RabbitmqCollector extends CollectorPlugin {
  constructor() {
    super({ name: 'rabbitmq' })
    this._prev = null
    this._prevTs = 0
  }

  isEnabled() {
    return isRabbitmqEnabled()
  }

  async collect() {
    const ts = Date.now()
    const overview = await fetchJson(`${baseUrl()}/api/overview`)
    if (!overview) {
      registerChart({
        id: 'rabbitmq.up',
        name: 'rabbitmq.up',
        context: 'rabbitmq.up',
        title: 'RabbitMQ up',
        units: 'boolean',
        family: 'rabbitmq',
        chartType: 'line',
        priority: 8600,
        plugin: 'rabbitmq',
        dimensions: [{ id: 'up', name: 'up', algorithm: 'absolute' }],
      })
      return [{ chart: 'rabbitmq.up', context: 'rabbitmq.up', ts, values: { up: 0 } }]
    }
    const q = overview.queue_totals || {}
    const m = overview.message_stats || {}
    const dt = this._prevTs ? (ts - this._prevTs) / 1000 : 0
    const prev = this._prev
    const rate = (key) => {
      const cur = m[key] || 0
      if (!prev || dt <= 0) return 0
      return Math.max(0, (cur - (prev[key] || 0)) / dt)
    }
    registerChart({
      id: 'rabbitmq.up',
      name: 'rabbitmq.up',
      context: 'rabbitmq.up',
      title: 'RabbitMQ up',
      units: 'boolean',
      family: 'rabbitmq',
      chartType: 'line',
      priority: 8600,
      plugin: 'rabbitmq',
      dimensions: [{ id: 'up', name: 'up', algorithm: 'absolute' }],
    })
    registerChart({
      id: 'rabbitmq.queues',
      name: 'rabbitmq.queues',
      context: 'rabbitmq.queues',
      title: 'RabbitMQ queue messages',
      units: 'messages',
      family: 'rabbitmq',
      chartType: 'line',
      priority: 8610,
      plugin: 'rabbitmq',
      dimensions: [
        { id: 'ready', name: 'ready', algorithm: 'absolute' },
        { id: 'unacked', name: 'unacked', algorithm: 'absolute' },
        { id: 'total', name: 'total', algorithm: 'absolute' },
      ],
    })
    registerChart({
      id: 'rabbitmq.rates',
      name: 'rabbitmq.rates',
      context: 'rabbitmq.rates',
      title: 'RabbitMQ message rates',
      units: 'messages/s',
      family: 'rabbitmq',
      chartType: 'line',
      priority: 8620,
      plugin: 'rabbitmq',
      dimensions: [
        { id: 'publish', name: 'publish', algorithm: 'incremental' },
        { id: 'deliver', name: 'deliver', algorithm: 'incremental' },
        { id: 'ack', name: 'ack', algorithm: 'incremental' },
      ],
    })
    this._prev = { publish: m.publish || 0, deliver: m.deliver_get || 0, ack: m.ack || 0 }
    this._prevTs = ts
    return [
      { chart: 'rabbitmq.up', context: 'rabbitmq.up', ts, values: { up: 1 } },
      {
        chart: 'rabbitmq.queues',
        context: 'rabbitmq.queues',
        ts,
        values: {
          ready: q.messages_ready || 0,
          unacked: q.messages_unacknowledged || 0,
          total: q.messages || 0,
        },
      },
      {
        chart: 'rabbitmq.rates',
        context: 'rabbitmq.rates',
        ts,
        values: {
          publish: rate('publish'),
          deliver: rate('deliver_get'),
          ack: rate('ack'),
        },
      },
    ]
  }
}

async function fetchJson(url) {
  try {
    const res = await fetch(url, { signal: AbortSignal.timeout(2000) })
    if (!res.ok) return null
    return await res.json()
  } catch {
    return null
  }
}

let singleton = null
export function getRabbitmqCollector() {
  if (!singleton) singleton = new RabbitmqCollector()
  return singleton
}