package generate

import (
	"bufio"
	"fmt"
	"math/rand"
	"os"
	"time"

	"github.com/spf13/cobra"
)

var Cmd = &cobra.Command{
	Use:   "generate",
	Short: "生成随机文件",
	Long:  "生成指定大小的随机文件",
	Run: func(this *cobra.Command, args []string) {
		sum, _ := this.Flags().GetInt("sum")
		num, _ := this.Flags().GetInt("num")
		cap, _ := this.Flags().GetInt("cap")
		if len(args) != 1 {
			this.Help()
			return
		}
		if num <= 0 {
			fmt.Println("num不合法，不应该小于1！")
			os.Exit(2)
		}
		if sum < 0 {
			fmt.Println("sum不合法，不应该小于0！")
			os.Exit(2)
		}
		if cap <= 0 {
			fmt.Println("cap不合法，不应该小于1！")
			os.Exit(2)
		}
		err := FillWithRandom(args[0], num, cap, sum, func(pect float64) {
			fmt.Printf("文件已处理：%f%%\r", pect)
		})
		if err != nil {
			fmt.Println("err:" + err.Error())
		}
		fmt.Println("文件已处理：100.0000000%")
		time.Sleep(time.Millisecond * 10)
	},
}

func init() {
	Cmd.Flags().IntP("sum", "s", 3, "随机的种子组数")
	Cmd.Flags().IntP("num", "n", 1024, "生成的文件大小")
	Cmd.Flags().IntP("cap", "c", 1048576, "bufcap大小")
	Cmd.MarkFlagRequired("num")
}

// FillWithRandom 随机写filesize大小的文件，每次buf大小为bufcap，随机bufnum个字符
func FillWithRandom(filepath string, filesize int, bufcap int, bufnum int, shell func(float64)) error {
	var buf [][]byte
	var buftmp []byte
	rand.Seed(time.Now().Unix())
	if bufnum <= 0 {
		bufnum = 1
	}
	if bufcap > filesize {
		bufcap = filesize
	}
	myfile, err := os.Create(filepath)
	if err != nil {
		return err
	}
	defer myfile.Close()
	writer := bufio.NewWriter(myfile)
	for i := 0; i < bufnum; i++ {
		buftmp = []byte{}
		for j := 0; j < bufcap; j++ {
			buftmp = append(buftmp, byte(rand.Intn(256)))
		}
		buf = append(buf, buftmp)
	}
	sum := 0
	for {
		if filesize-sum < bufcap {
			writer.Write(buf[rand.Intn(bufnum)][0 : filesize-sum])
			sum += filesize - sum
		} else {
			writer.Write(buf[rand.Intn(bufnum)])
			sum += bufcap
		}
		go shell(float64(sum) / float64(filesize) * 100)
		if sum >= filesize {
			break
		}
	}
	writer.Flush()
	return nil
}