const {init, extnameCheck, runExtnames} = require('./minify')
const path = require('path')
const fs = require('fs')

const analysisUrl = url => {
  if (!url){
    throw '无效路径'
  } else if (path.isAbsolute(url)) {
    return url
  } else {
    return path.join(__dirname, url)
  }
}

const analysisArgs = args => {
  const config = {
    input: analysisUrl(args.shift()),
    width: 0,
    height: 0,
    quality: 75,
    format: undefined
  }

  if (args.length >= 5 || (
        args.length &&
        isNaN(Number(args[args.length - 1])) && 
        !extnameCheck(args[args.length - 1]))
      ) {
    config.output = analysisUrl(args.pop())
  } else {
    config.output = config.input
  }

  switch(args.length) {
    case 0:
      break;
    case 1:
      if (extnameCheck(args[0])) {
        config.format = args[0]
      } else {
        config.quality = args[0]
      }
      break;
    case 2:
      if (extnameCheck(args[1])) {
        config.format = args[1]
        config.quality = args[0]
      } else {
        config.width = args[0]
        config.height = args[1]
      }
      break;
    case 4:
      config.format = extnameCheck(args[3]) && args[3]
    default:
      if (extnameCheck(args[2])) {
        config.format = args[2]
        config.width = args[0]
        config.height = args[1]
      } else {
        config.quality = args[0]
        config.width = args[1]
        config.height = args[2]
      }
  }

  if (config.format) {
    let extIndex = config.output.lastIndexOf('.')
    let extNameLen = config.output.length - extIndex - 1
    let maxLen = Math.max(runExtnames.map(s => s.length))
    if (!~extIndex || extNameLen > maxLen) {
      config.output += '.' + config.format
    } else {
      config.output = config.output.substring(0, extIndex) + '.' + config.format
    }
  }

  return config
}

const main = async () => {
  const config = analysisArgs(process.argv.slice(2))

  if (!fs.existsSync(config.input)) {
    throw config.input + ' No such file or directory'
  }

  const gm = await init({fileUri: config.input})

  if (config.width && config.height) {
    gm.zoom({width: config.width, height: config.height})
  }
  if (config.quality) {
    gm.quality(config.quality)
  }
  
  gm.write(config.output, err => {
    if (err) {
      console.error(err)
    } else {
      console.log('成功转换，存储路径为', config.output)
    }
  })
}

main();