const fs = require('fs')
const path = require('path')
const util = require('util')
const { CommandDispatcher, builder: { LiteralArgumentBuilder: { literal }, RequiredArgumentBuilder: { argument } }, arguments: { StringArgumentType: { greedyString } }, exceptions: { CommandSyntaxException } } = require('brigadier-commands')
const CommandSource = require('../util/command/command_source')
const TextMessage = require('../util/command/text_message')
const colorCodeStringify = require('../util/chat/stringify/color_code')

function inject (bot) {
  bot.commands = {
    dispatcher: new CommandDispatcher(),
    add,
    execute,
    info,
    isCommand,
    loadFromDir,
    isValid
  }

  bot.on('message', ({ sender, plain }) => {
    if (!plain.startsWith(bot.prefix)) return

    function sendFeedback (message) {
      bot.tellraw(message, '@a')
    }
    bot.commands.execute(plain.substring(bot.prefix.length), new CommandSource({ bot, player: sender, sendFeedback }))
  })

  function add (command) {
    if (command.register) {
      command.register(bot.commands.dispatcher)
      return
    }

    if (isValid(command)) {
      bot.console.warn(`Command '${command.aliases[0]}' is using the legacy command system!`)

      const _execute = (c, args) => {
        try {
          const player = c.source.player
          command.execute(bot, command.aliases[0], { UUID: player?.uuid, name: player?.username }, args)
        } catch (error) {
          bot.core.run('minecraft:tellraw @a ' + JSON.stringify({ text: error.toString(), color: 'red' }))
        }
      }

      const requirement = source => source.permissionLevel >= command.permLevel

      const node = bot.commands.dispatcher.register(
        literal(command.aliases[0])
          .executes(c => { _execute(c, []); return 0 })
          .requires(requirement)
          .then(
            argument('args', greedyString())
              .executes(c => { _execute(c, c.getArgument('args').split(' ')); return 0 })
          )
      )
      for (let i = 1; i < command.aliases.length; i++) {
        bot.commands.dispatcher.register(
          literal(command.aliases[i])
          .executes(context => { _execute([]); return 0 })
          .requires(requirement)
          .redirect(node)
        )
      }

      // add metadata for help command
      node.description = command.description
      node.permissionLevel = command.permLevel

      return
    }

    throw new Error('Invalid command', 'invalid_command')
  }

  function loadFromDir (dirpath) {
    fs.readdirSync(dirpath).forEach(filename => {
      const filepath = path.resolve(dirpath, filename)
      if (!filepath.endsWith('js') || !fs.statSync(filepath).isFile()) return
      try {
        bot.commands.add(require(filepath))
      } catch (error) {
        bot.console.error('Error loading command ' + filepath + ': ' + util.inspect(error))
      }
    })
  }

  function info (command) {
    const info = bot.commands.commands[command] ?? command
    if (isValid(info)) { return info }
  }

  function isCommand (command) { return true }

  function execute (command, source) {
    try {
      bot.commands.dispatcher.execute(command, source)
    } catch (error) {
      if (error instanceof CommandSyntaxException) {
        const text = (error._message instanceof TextMessage) ? error._message.text : error._message.getString()
        source.sendError(text)
        const context = getContext(error)
        if (context) source.sendError(context)

        return
      }

      source.sendError({ translate: 'command.failed', hoverEvent: { action: 'show_text', contents: error.stack } })
    }
  }

  function getContext (error) {
    const _cursor = error.cursor
    const input = error.input

    if (input == null || _cursor < 0) {
      return null
    }

    const text = [{ text: '', color: 'gray', clickEvent: { action: 'suggest_command', value: bot.prefix + input } }]

    const cursor = Math.min(input.length, _cursor)

    if (cursor > CommandSyntaxException.CONTEXT_AMOUNT) {
      text.push('...')
    }

    text.push(
      input.substring(Math.max(0, cursor - CommandSyntaxException.CONTEXT_AMOUNT), cursor),
      { text: input.substring(cursor), color: 'red', underline: true },
      { translate: 'command.context.here', color: 'red', italic: true }
    )

    return text
  }
}

function isValid (command) {
  return command != null &&
  typeof command.execute === 'function' &&
  typeof command.name === 'string' &&
  typeof command.description === 'string' &&
  Array.isArray(command.usages) &&
  Array.isArray(command.aliases) &&
  typeof command.enabled === 'boolean' &&
  command.aliases.length > 0 &&
  typeof command.permLevel === 'number'
}

module.exports = inject