/**
 * PearDock bridge collector (Phase 3 spike).
 *
 * Dials dock / agent peers and remaps their docker/container charts into
 * peardock.* — dials remote peers over public RPC (no PearDock source vendored).
 *
 * Enable: PEARDATA_PEARDOCK=1
 * Peers:  PEARDATA_PEARDOCK_PEERS=hex,hex  (or PEARDATA_PEARDOCK_PEERS_FILE)
 * Optional: PEARDATA_PEARDOCK_SEED, PEARDATA_PEARDOCK_POLL_MS
 *
 * Charts: peardock.containers, peardock.cpu.<id>, peardock.mem.<id>
 *         (sourced from remote docker.* charts when present)
 */
import fs from 'fs'
import { EventEmitter } from 'events'
import { PearDataConnection } from '../../../client/connection.js'
import { Methods } from '../../../shared/protocol.js'
import { registerChart } from '../../../shared/metrics.js'
import logger from '../../utils/logger.js'

const log = logger.child('peardock')

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

/**
 * @returns {string[]}
 */
export function parsePearDockPeers() {
  const raw = process.env.PEARDATA_PEARDOCK_PEERS || ''
  const fromEnv = raw
    .split(/[,\s]+/)
    .map((s) => s.trim().toLowerCase())
    .filter((s) => /^[0-9a-f]{64}$/.test(s))
  const file = process.env.PEARDATA_PEARDOCK_PEERS_FILE
  if (!file) return [...new Set(fromEnv)]
  try {
    const text = fs.readFileSync(file, 'utf8')
    const fromFile = text
      .split(/\r?\n/)
      .map((l) => l.replace(/#.*$/, '').trim().toLowerCase())
      .filter((s) => /^[0-9a-f]{64}$/.test(s))
    return [...new Set([...fromEnv, ...fromFile])]
  } catch {
    return [...new Set(fromEnv)]
  }
}

/**
 * Map remote docker/container chart id → peardock chart id.
 * @param {string} chartId
 * @returns {string|null}
 */
export function remapDockChart(chartId) {
  const id = String(chartId || '')
  if (id.startsWith('docker.')) return `peardock.${id.slice('docker.'.length)}`
  if (id.startsWith('container.')) return `peardock.${id.slice('container.'.length)}`
  if (id.startsWith('cgroup.docker.')) return `peardock.${id.slice('cgroup.docker.'.length)}`
  return null
}

/**
 * @param {any} metrics getAllMetrics-style payload
 * @returns {Array<{ chart: string, context: string, values: Record<string, number|null>, sourceChart: string }>}
 */
export function extractDockCharts(metrics) {
  const root = metrics?.body || metrics
  const charts = root?.charts || {}
  /** @type {Array<{ chart: string, context: string, values: Record<string, number|null>, sourceChart: string }>} */
  const out = []
  for (const [chartId, point] of Object.entries(charts)) {
    const mapped = remapDockChart(chartId)
    if (!mapped) continue
    const values = point?.dimensions || point?.values || {}
    /** @type {Record<string, number|null>} */
    const nums = {}
    for (const [k, v] of Object.entries(values)) {
      const n = typeof v === 'object' && v != null ? Number(v.value) : Number(v)
      nums[k] = Number.isFinite(n) ? n : null
    }
    const parts = mapped.split('.')
    const context = parts.length >= 2 ? `${parts[0]}.${parts[1]}` : mapped
    out.push({
      chart: mapped,
      context,
      values: nums,
      sourceChart: chartId,
    })
  }
  return out
}

function registerMappedChart(mappedId, context, values) {
  const dims = Object.keys(values).map((id) => ({
    id,
    name: id,
    algorithm: 'absolute',
  }))
  if (!dims.length) dims.push({ id: 'value', name: 'value', algorithm: 'absolute' })
  registerChart({
    id: mappedId,
    name: mappedId,
    context,
    title: mappedId,
    units: context.includes('mem') ? 'MiB' : context.includes('cpu') ? 'percentage' : 'count',
    family: 'peardock',
    chartType: 'line',
    priority: 8500,
    plugin: 'peardock',
    dimensions: dims,
  })
}

export class PearDockCollector extends EventEmitter {
  constructor(opts = {}) {
    super()
    this.pollMs = opts.pollMs || Number(process.env.PEARDATA_PEARDOCK_POLL_MS) || 5000
    this.adminSeed = opts.adminSeed || process.env.PEARDATA_PEARDOCK_SEED || null
    this.peerKeys = opts.peers || parsePearDockPeers()
    /** @type {Map<string, PearDataConnection|null>} */
    this.conns = new Map()
    this._timer = null
    this._busy = false
  }

  start() {
    if (this._timer) return
    registerChart({
      id: 'peardock.containers',
      name: 'peardock.containers',
      context: 'peardock.containers',
      title: 'PearDock bridged containers',
      units: 'containers',
      family: 'peardock',
      chartType: 'line',
      priority: 8490,
      plugin: 'peardock',
      dimensions: [
        { id: 'charts', name: 'charts', algorithm: 'absolute' },
        { id: 'peers', name: 'peers', algorithm: 'absolute' },
      ],
    })
    log.info('PearDock bridge started', { peers: this.peerKeys.length, pollMs: this.pollMs })
    this._tick()
    this._timer = setInterval(() => this._tick(), this.pollMs)
    if (typeof this._timer.unref === 'function') this._timer.unref()
  }

  stop() {
    if (this._timer) {
      clearInterval(this._timer)
      this._timer = null
    }
    for (const [pk, conn] of this.conns) {
      if (conn) conn.destroy().catch(() => {})
      this.conns.set(pk, null)
    }
  }

  async _ensure(pk) {
    let conn = this.conns.get(pk)
    if (conn?.connected) return conn
    try {
      if (conn) await conn.destroy().catch(() => {})
      conn = new PearDataConnection(pk, {
        adminSeed: this.adminSeed,
        timeoutMs: 20_000,
      })
      await conn.connect()
      this.conns.set(pk, conn)
      conn.on('disconnected', () => this.conns.set(pk, null))
      return conn
    } catch (err) {
      this.conns.set(pk, null)
      log.warn('PearDock dial failed', { peer: pk.slice(0, 12), error: err.message })
      return null
    }
  }

  async _tick() {
    if (this._busy) return
    this._busy = true
    try {
      const ts = Date.now()
      /** @type {Array<{ chart: string, context: string, ts: number, values: Record<string, number|null> }>} */
      const batch = []
      let peersUp = 0
      let chartCount = 0

      for (const pk of this.peerKeys) {
        const conn = await this._ensure(pk)
        if (!conn) continue
        try {
          const metrics = await conn.request(Methods.getAllMetrics, { format: 'json' })
          const mapped = extractDockCharts(metrics)
          peersUp++
          for (const row of mapped) {
            registerMappedChart(row.chart, row.context, row.values)
            batch.push({
              chart: row.chart,
              context: row.context,
              ts,
              values: row.values,
            })
            chartCount++
          }
        } catch (err) {
          log.warn('PearDock poll failed', { peer: pk.slice(0, 12), error: err.message })
          try {
            await conn.destroy()
          } catch {
            // ignore
          }
          this.conns.set(pk, null)
        }
      }

      batch.unshift({
        chart: 'peardock.containers',
        context: 'peardock.containers',
        ts,
        values: { charts: chartCount, peers: peersUp },
      })
      this.emit('samples', batch)
    } finally {
      this._busy = false
    }
  }
}

/** @type {PearDockCollector|null} */
let singleton = null

export function getPearDockCollector() {
  if (!singleton) singleton = new PearDockCollector()
  return singleton
}