import { EventEmitter } from 'node:events'
import WebSocket, { RawData } from 'ws'

import type { TapeTrade } from '../../core/types.js'

interface HyperliquidTrade {
  side: 'A' | 'B'
  px: string
  sz: string
  time: number
  tid: number
}

interface HyperliquidMessage {
  channel?: string
  data?: HyperliquidTrade[] | {
    method?: string
    subscription?: {
      type?: string
      coin?: string
    }
  }
}

const HYPERLIQUID_URL = 'wss://api.hyperliquid.xyz/ws'

export class HyperliquidTradeStreamer extends EventEmitter {
  readonly name = 'hyperliquid'

  private socket?: WebSocket
  private reconnectTimer?: NodeJS.Timeout
  private stopped = false

  start(): void {
    this.stopped = false
    const socket = new WebSocket(HYPERLIQUID_URL)
    this.socket = socket

    socket.on('open', () => {
      socket.send(
        JSON.stringify({
          method: 'subscribe',
          subscription: {
            type: 'trades',
            coin: 'BTC'
          }
        })
      )
    })

    socket.on('message', (payload: RawData) => {
      try {
        const message = JSON.parse(payload.toString()) as HyperliquidMessage

        if (message.channel === 'subscriptionResponse') {
          this.emit('discover', { stream: 'perp', count: 1, symbols: ['BTC'] })
          this.emit('ready', { stream: 'perp', symbolCount: 1, url: HYPERLIQUID_URL })
          return
        }

        if (message.channel !== 'trades' || !Array.isArray(message.data)) {
          return
        }

        for (const update of message.data) {
          const price = Number(update.px)
          const size = Number(update.sz)
          const timestamp = Number(update.time)

          if (!Number.isFinite(price) || !Number.isFinite(size) || !Number.isFinite(timestamp) || price <= 0 || size <= 0) {
            continue
          }

          const trade: TapeTrade = {
            exchange: 'HYPERLIQUID',
            exchangeClass: 'dex',
            instrumentType: 'perp',
            symbol: 'BTC',
            timestamp,
            price,
            size,
            notionalUsd: price * size,
            side: update.side === 'B' ? 'buy' : 'sell',
            tradeId: String(update.tid),
            raw: update
          }

          this.emit('trade', trade)
        }
      } catch (error) {
        this.emit('error', error)
      }
    })

    socket.on('error', (error: Error) => this.emit('error', error))
    socket.on('close', () => this.handleClose())
  }

  stop(): void {
    this.stopped = true

    if (this.reconnectTimer) {
      clearTimeout(this.reconnectTimer)
      this.reconnectTimer = undefined
    }

    this.socket?.close()
    this.socket = undefined
  }

  private handleClose(): void {
    this.socket = undefined

    if (this.stopped) {
      return
    }

    this.reconnectTimer = setTimeout(() => this.start(), 3_000)
    this.emit('warn', 'Reconnecting perp stream in 3s')
  }
}