package main

import (
	"bytes"
	"encoding/base64"
	"io"
	"io/ioutil"
	"log"
	"os"
	"path/filepath"
	"strings"
)

//作者 bambuo
//时间 2021/7/19 19:42
//版本 1.0

func readKeyFile(srcFile string) string {
	in, err := os.OpenFile(srcFile, os.O_RDONLY, os.ModePerm)
	if err != nil {
		return ""
	}
	data, err := ioutil.ReadAll(in)
	if err != nil {
		return ""
	}
	decode, err := base64.StdEncoding.DecodeString(string(data))
	if err != nil {
		return ""
	}
	return string(decode)
}

func mergeFiles(srcDir, savePath, keyFile string) {

	join := filepath.Join(srcDir, keyFile)
	key := readKeyFile(join)

	out, err := os.OpenFile(savePath, os.O_CREATE|os.O_WRONLY|os.O_APPEND, os.ModePerm)
	if err != nil {
		return
	}
	log.Println(key, out)
	infos, err := ioutil.ReadDir(srcDir)
	if err != nil {
		return
	}
	var tsFiles []string
	for _, v := range infos {
		switch filepath.Ext(v.Name()) {
		case ".ts":
			tsFiles = append(tsFiles, filepath.Join(srcDir, v.Name()))
		}
	}

	//排序
	for i := 0; i < len(tsFiles); i++ {
		for j := i + 1; j < len(tsFiles); j++ {
			switch {
			case len(tsFiles[i]) > len(tsFiles[j]):
				tsFiles[i], tsFiles[j] = tsFiles[j], tsFiles[i]
			case len(tsFiles[i]) == len(tsFiles[j]):
				switch strings.Compare(tsFiles[i], tsFiles[j]) {
				case 1:
					tsFiles[i], tsFiles[j] = tsFiles[j], tsFiles[i]
				}
			}
		}
	}

	itr(tsFiles, func(s string) error {
		in, err := os.Open(s)
		if err != nil {
			return err
		}
		defer in.Close()
		data, err := ioutil.ReadAll(in)
		if err != nil {
			return err
		}
		decrypt, err := AESCBCDecrypt(data, []byte(key))
		if err != nil {
			return err
		}

		size, err := io.Copy(out, bytes.NewReader(decrypt))
		if err != nil {
			return err
		}
		log.Println("合并了", size, "字节")
		return nil
	})
	out.Close()
}

func itr(list []string, callback func(string) error) {
	for _, v := range list {
		if nil != callback {
			if err := callback(v); nil != err {
				log.Println(err)
				return
			}
		}
	}
}