import fs from 'fs'
import path from 'path'
import { Tail } from 'tail'
import express from 'express'

import type { Config } from './Config'

import { fixMinecraftUsername } from './lib/util'

export type LogLine = {
  username: string
  message: string
} | null

type Callback = (data: LogLine) => void

class MinecraftHandler {
  config: Config

  app: express.Application
  tail: Tail

  constructor(config: Config) {
    this.config = config
  }

  private parseLogLine (data: string): LogLine {
    const ignored = new RegExp(this.config.REGEX_IGNORED_CHAT)

    if (ignored.test(data) || data.includes('Rcon connection')) {
      if (this.config.DEBUG) console.log('[DEBUG] Line ignored')
      return null
    }

    if (this.config.DEBUG) console.log('[DEBUG] Received ' + data)

    const logLineDataRegex = new RegExp(
      `${(this.config.REGEX_SERVER_PREFIX || "\\[Server thread/INFO\\]:")} (.*)`
    )

    // get the part after the log prefix, so all the actual data is here
    const logLineData = data.match(logLineDataRegex)

    if (!logLineDataRegex.test(data) || !logLineData) {
      if (this.config.DEBUG) {
        console.log('[DEBUG] Regex could not match the string:')
        console.log('Received: "' + data + '", Regex matches lines that start with: "' + this.config.REGEX_SERVER_PREFIX + '"')
      }
      return null
    }

    const logLine = logLineData[1]

    // the username used for server messages
    const serverUsername = `${this.config.SERVER_NAME} - Server`

    if (logLine.startsWith('<')) {
      if (this.config.DEBUG){
        console.log('[DEBUG] A player sent a chat message')
      }

      const re = new RegExp(this.config.REGEX_MATCH_CHAT_MC)
      const matches = logLine.match(re)

      if (!matches) {
        console.log('[ERROR] Could not parse message: ' + logLine)
        return null
      }

      const username = fixMinecraftUsername(matches[1])
      const message = matches[2]
      if (this.config.DEBUG) {
        console.log('[DEBUG] Username: ' + matches[1])
        console.log('[DEBUG] Text: ' + matches[2])
      }
      return { username, message }
    } else if (
      this.config.SHOW_PLAYER_CONN_STAT && (
        logLine.includes('left the game') ||
        logLine.includes('joined the game')
      )
    ) {
      // handle disconnection etc.
      if (this.config.DEBUG){
        console.log(`[DEBUG] A player's connection status changed`)
      }

      return { username: serverUsername, message: logLine }
    } else if (this.config.SHOW_SERVER_STATUS && (logLine.includes('Starting minecraft server'))) {
        if (this.config.DEBUG) {
          console.log('[DEBUG] Server has started')
        }
        return { username: serverUsername, message: 'Server is online' }
    } else if (this.config.SHOW_SERVER_STATUS && (logLine.includes('Stopping the server'))) {
        if (this.config.DEBUG) {
          console.log('[DEBUG] Server has stopped')
        }
        return { username: serverUsername, message: 'Server is offline' }
    } else if (this.config.SHOW_PLAYER_ADVANCEMENT && logLine.includes('made the advancement')) {
      // handle advancements
      if (this.config.DEBUG){
        console.log('[DEBUG] A player has made an advancement')
      }
      return { username: `${this.config.SERVER_NAME} - Server`, message: logLine }
    } else if (this.config.SHOW_PLAYER_ME && logLine.startsWith('* ')) {
      // /me commands have the bolded name and the action they did
      const usernameMatch = data.match(/: \* ([a-zA-Z0-9_]{1,16}) (.*)/)
      if (usernameMatch) {
        const username = usernameMatch[1]
        const rest = usernameMatch[2]
        return { username: serverUsername, message: `**${username}** ${rest}` }
      }
    } else if (this.config.SHOW_PLAYER_DEATH) {
      const deathMessageRegex = new RegExp(this.config.REGEX_DEATH_MESSAGE ?? '^[\\w_]+ died')
      const deathMessageMatch = logLine.match(deathMessageRegex)

      if (deathMessageMatch) {
        if (this.config.DEBUG) {
          console.log(`[DEBUG] A player died. Matched on "${deathMessageMatch[1]}"`)
        }
        return { username: serverUsername, message: logLine }
      }
    }

    return null
  }

  private initWebServer (callback: Callback) {
    // init the webserver
    this.app = express()

    this.app.use((request, _response, next) => {
      request.rawBody = ''
      request.setEncoding('utf8')

      request.on('data', (chunk: string) => {
        request.rawBody += chunk
      })

      request.on('end', function () {
        next()
      })
    })

    this.app.post(this.config.WEBHOOK, (req, res) => {
      if (req.rawBody) {
        const logLine = this.parseLogLine(req.rawBody)
        callback(logLine)
      }
      res.json({ received: true })
    })

    const port: number = Number(process.env.PORT) || this.config.PORT

    this.app.listen(port, () => {
      console.log('[INFO] Bot listening on *:' + port)

      if (!this.config.IS_LOCAL_FILE && this.config.SHOW_INIT_MESSAGE) {
        // in case someone inputs the actual path and url in the config here...
        let mcPath: string = this.config.PATH_TO_MINECRAFT_SERVER_INSTALL || 'PATH_TO_MINECRAFT_SERVER_INSTALL'
        const url: string = this.config.YOUR_URL || 'YOUR_URL'

        const defaultPath = mcPath === 'PATH_TO_MINECRAFT_SERVER_INSTALL'
        const defaultUrl = url === 'YOUR_URL'

        console.log('[INFO] Please enter the following command on your server running the Minecraft server:')
        if (defaultPath) {
          console.log('       Replace "PATH_TO_MINECRAFT_SERVER_INSTALL" with the path to your Minecraft server install' + (defaultUrl ? ' and "YOUR_URL" with the URL/IP of the server running Shulker.' : ''))
        } else {
          if (defaultUrl) console.log('       Replace "YOUR_URL" with the URL/IP of the server running Shulker')
        }

        mcPath = (defaultPath ? '/' : '') + path.join(mcPath, '/logs/latest.log')

        let grepMatch = ': <'
        if (this.config.SHOW_PLAYER_DEATH || this.config.SHOW_PLAYER_ME || this.config.SHOW_PLAYER_ADVANCEMENT || this.config.SHOW_PLAYER_CONN_STAT) {
          grepMatch = this.config.REGEX_SERVER_PREFIX
        }
        console.log(`  \`tail -F ${mcPath} | grep --line-buffered "${grepMatch}" | while read x ; do echo -ne $x | curl -X POST -d @- http://${url}:${port}${this.config.WEBHOOK} ; done\``)
        if (grepMatch !== ': <') {
          console.log('       Please note that the above command can send a lot of requests to the server. Disable the non-text messages (such as "SHOW_PLAYER_CONN_STAT") to reduce this if necessary.')
        }
      }
    })
  }

  private initTail (callback: Callback) {
    if (fs.existsSync(this.config.LOCAL_FILE_PATH)) {
      console.log(`[INFO] Using configuration for local log file at "${this.config.LOCAL_FILE_PATH}"`)
      this.tail = new Tail(this.config.LOCAL_FILE_PATH, {useWatchFile: this.config.FS_WATCH_FILE ?? true})
    } else {
      throw new Error(`[ERROR] Local log file not found at "${this.config.LOCAL_FILE_PATH}"`)
    }
    this.tail.on('line', (data: string) => {
      // Parse the line to see if we care about it
      let logLine = this.parseLogLine(data)
      if (data) {
        callback(logLine)
      }
    })
    this.tail.on('error', (error: any) => {
      console.log('[ERROR] Error tailing log file: ' + error)
    })
  }

  public init (callback: Callback) {
    if (this.config.IS_LOCAL_FILE) {
      this.initTail(callback)
    } else {
      this.initWebServer(callback)
    }
  }
}

export default MinecraftHandler