/**
 * Created by IntelliJ IDEA.
 * User: Ar.M
 * Date: 2020-05-10
 * Time: 22:10
 */
package main

import (
	"bytes"
	"context"
	"flag"
	"fmt"
	"github.com/dustin/go-humanize"
	"google.golang.org/grpc"
	"io"
	"log"
	"os"
	"strings"
	transportpb "yunlian-file-transfer-demo/proto"
)

var (
	fn       *string
	ip       *string
	port     *int
	savePath *string
)

func init() {
	fn = flag.String("fn", "", "文件名称")
	ip = flag.String("ip", "127.0.0.1", "服务端 IP 地址")
	port = flag.Int("port", 10086, "服务端端口号")
	savePath = flag.String("savepath", "./", "存储路径")

	flag.Usage = func() {
		fmt.Println("yunlian-file-transfer-demo version: 0.0.1")
		flag.PrintDefaults()
	}
}

func main() {
	flag.Parse()

	if len(*fn) < 1 {
		flag.Usage()
		return
	}

	requestedFile := *fn
	serverIp := fmt.Sprintf("%s:%d", *ip, *port)

	cc, err := grpc.Dial(serverIp, grpc.WithInsecure())
	if err != nil {
		log.Fatalf("监听服务端异常 : %v\n", err)
	}
	defer cc.Close()

	c := transportpb.NewFileServiceClient(cc)

	if err := download(requestedFile, c); err != nil {
		log.Fatalf("下载异常 %s : %v\n", requestedFile, err)
	}
	fmt.Printf("\n%s 下载成功\n", requestedFile)
}

func writeFile(fileName string, content []byte) {
	if len(content) != 0 {
		fp, err := os.OpenFile(fileName, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0755)
		if err != nil {
			log.Fatalf("文件打开异常: %s\n", err)
		}
		defer fp.Close()
		_, err = fp.Write(content)
		if err != nil {
			log.Fatalf("文件保存异常: %s\n", err)
		}
	}
}

func getFileStat(fileName string) int64 {
	fileinfo, err := os.Stat(fileName)
	if err != nil {
		if os.IsNotExist(err) {
			return int64(0)
		}
		log.Fatalf("获取文件元数据失败: %s\n", err)
	}
	return fileinfo.Size()
}

func download(fileName string, client transportpb.FileServiceClient) error {
	fileRange := getFileStat(fileName)
	req := &transportpb.FileRequest{
		FileName:  fileName,
		FileRange: fileRange,
	}

	stream, err := client.Download(context.Background(), req)
	if err != nil {
		return err
	}

	var recvSize int64
	var buffer bytes.Buffer

	recvSize = fileRange
	for {
		res, err := stream.Recv()
		if err == io.EOF {
			break
		}
		if err != nil {
			buffer.Reset()
			return err
		}

		block := res.GetBlock()
		fileSize := res.GetFileSize()
		blockSize := len(block)
		recvSize += int64(blockSize)

		writeFile(fileName, block)

		// fmt.Printf("\r%s", strings.Repeat(" ", 30))
		fmt.Printf("\r文件%s: %s / %s 已下载%s", fileName, humanize.IBytes(uint64(recvSize)), humanize.IBytes(uint64(fileSize)), strings.Repeat(" ", 60))
	}
	return nil
}