const { literal, argument, greedyString, SimpleCommandExceptionType } = require('brigadier-commands')
const TextMessage = require('../util/command/text_message')
const fs = require('fs')
const path = require('path')
const zlib = require('zlib')
const stream = require('stream/promises')

const LOG_QUERY_ALREADY_RUNNING_ERROR = new SimpleCommandExceptionType(new TextMessage('Another log query is already running!'))

module.exports = {
  running: false,
  stream: null,

  create () {
    return Object.create(this)
  },

  register (dispatcher) {
    const node = dispatcher.register(
      literal('logquery')
        .then(
          literal('count')
            .then(
              argument('string', greedyString())
                .executes(c => this.countCommand(c))
            )
        )
        .then(
          literal('abort')
            .executes(c => this.abortCommand(c))
        )
    )

    node.description = 'Searches for text in log files'
    node.permissionLevel = 0
  },

  cleanup () {
    this.abort()
  },

  async countCommand (context) {
    const source = context.source
    const bot = source.bot
    const string = context.getArgument('string')

    source.sendFeedback([{ text: 'Searching for instances of ', ...bot.styles.primary }, { text: string, ...bot.styles.secondary }, ' in logs...'], false)

    let count = 0
    const ran = await this.queryLogs(source, line => line.includes(string) && count++)

    if (ran) source.sendFeedback([{ text: 'Found ', ...bot.styles.primary }, { text: count + '', ...bot.styles.secondary }, ' instances of ', { text: string, ...bot.styles.secondary }], true)
  },
 
  abortCommand (context) {
    const source = context.source
    const bot = source.bot

    this.abort()

    source.sendFeedback({ text: 'Stopped the running log query', ...bot.styles.primary })
  },

  abort () {
    this.running = false
    this.stream?.close()
    this.stream = null
  },

  async queryLogs (source, handler) {
    if (this.running) throw LOG_QUERY_ALREADY_RUNNING_ERROR.create()

    const bot = source.bot
    const logsDir = bot.paths.logs

    this.running = true

    const filenames = await fs.promises.readdir(logsDir)
    for (let i = 0; i < filenames.length; i++) {
      const filename = filenames[i]

      const readStream = fs.createReadStream(path.join(logsDir, filename))
      this.stream = readStream

      if (filename.endsWith('.gz')) {
        const gunzip = zlib.createGunzip()
        readStream.pipe(gunzip)
        this.stream = gunzip
      }

      let queue = ''
      this.stream.on('data', chunk => {
       queue += chunk // * This should convert it to a string

        const lastNewlineIdx = queue.lastIndexOf('\n')
        const lines = queue.substring(0, lastNewlineIdx)
        queue = queue.substring(lastNewlineIdx + 1)

        for (const line of lines.split('\n')) handler(line)
      })

      try {
        await stream.finished(this.stream)
      } catch {
      }

      if (!this.running) return false // if this was aborted
    }

    this.running = false
    this.stream = null
    return true
  }
}