package common

import (
	"bytes"
	"encoding/json"
	"io"
	"os"
	"path/filepath"
	"strings"

	"github.com/sirupsen/logrus"
	"github.com/spf13/cast"
)

func FormatJson(data string) (string, error) {
	var out bytes.Buffer
	err := json.Indent(&out, []byte(data), "", "    ")
	return out.String(), err
}

func SubStr(str string, start int, length int) (result string) {
	s := []rune(str)
	total := len(s)
	if total == 0 {
		return
	}
	// 允许从尾部开始计算
	if start < 0 {
		start = total + start
		if start < 0 {
			return
		}
	}
	if start > total {
		return
	}
	// 到末尾
	if length < 0 {
		length = total
	}

	end := start + length
	if end > total {
		result = string(s[start:])
	} else {
		result = string(s[start:end])
	}

	return
}

// 是否升级
func IsUpgrade(newVersion, oldVersion string) bool {
	nvArr := strings.SplitN(newVersion, ".", 3)
	if len(nvArr) != 3 {
		logrus.Error("new version format err")
		return false
	}

	ovArr := strings.SplitN(oldVersion, ".", 3)
	if len(ovArr) != 3 {
		logrus.Error("old version format err")
		return false
	}

	nvNum := cast.ToInt(nvArr[0])*100 + cast.ToInt(nvArr[1])*10 + cast.ToInt(nvArr[2])
	ovNum := cast.ToInt(ovArr[0])*100 + cast.ToInt(ovArr[1])*10 + cast.ToInt(ovArr[2])

	if nvNum > ovNum {
		return true
	}
	return false
}

func Copy(src, dst string) (len int64, err error) {

	dstWriter, err := os.Create(dst)
	if err != nil {
		logrus.Error(err)
		return
	}
	srcReader, err := os.Open(src)
	if err != nil {
		logrus.Error(err)
		return
	}
	// Copy()函数其实是调用了
	// io包中私有函数copyBuffer() 默认缓冲区是32K
	// 与Copy()函数功能一致的是CopyBuffer()可以设置缓冲区
	len, err = io.Copy(dstWriter, srcReader)
	if err != nil {
		logrus.Error(err)
		return
	}
	return
}

func DeleteFile(filePath string) error {
	return os.Remove(filePath)
}

func RemoveContents(dir string) error {
	d, err := os.Open(dir)
	if err != nil {
		return err
	}
	defer d.Close()
	names, err := d.Readdirnames(-1)
	if err != nil {
		return err
	}
	for _, name := range names {
		err = os.RemoveAll(filepath.Join(dir, name))
		if err != nil {
			return err
		}
	}
	return nil
}