package main

import (
	"bufio"
	"flag"
	"fmt"
	"log"
	"os"
	"regexp"
)

func fileExists(file string) bool {
	_, err := os.Stat(file)
	if err == nil {
		return true
	}
	if os.IsNotExist(err) {
		return false
	}
	return false
}

func fileOpen(file string, canCreate bool) (*os.File, bool) {
	if fileExists(file) {
		f, e := os.OpenFile(file, os.O_RDWR, 0666)
		if nil != e {
			return nil, false
		}
		return f, true
	} else if canCreate {
		f, e := os.OpenFile(file, os.O_RDWR|os.O_CREATE, 0666)
		if nil != e {
			return nil, false
		}
		return f, true
	} else {
		return nil, false
	}
}

func fileWrite(file *os.File, txt []string) {
	for i := 0; i < len(txt); i++ {
		file.WriteString(txt[i])
	}
	file.Sync()
}

func fileClose(file *os.File) {
	file.Close()
}

func insertSpace2Line(line string) string {
	reg1 := regexp.MustCompile("([A-Za-z0-9?)/,*])([\u4e00-\u9fa5])")
	reg2 := regexp.MustCompile("([\u4e00-\u9fa5])([A-Za-z0-9?(/,*])")
	line = reg2.ReplaceAllString(reg1.ReplaceAllString(line, "$1 $2"), "$1 $2")
	return line
}

func SpacePipeline(file *os.File) []string {
	var txt []string
	file.Seek(0, os.SEEK_SET)
	reader := bufio.NewReader(file)
	for {
		line, e := reader.ReadString('\n')
		if nil != e {
			break
		}
		line = insertSpace2Line(line)
		txt = append(txt, line)
	}
	return txt
}

func usage() {
	fmt.Println("SpaceMarkdown")
	fmt.Println("version 0.1.0")
	flag.PrintDefaults()
}

func main() {
	var ifile, ofile string
	var ifd, ofd *os.File
	var ret bool

	flag.StringVar(&ifile, "i", "", "Input markdown file")
	flag.StringVar(&ofile, "o", "", "Output markdown file")

	flag.Usage = usage
	flag.Parse()

	if "" == ifile || "" == ofile {
		usage()
		return
	}
	ifd, ret = fileOpen(ifile, false)
	if !ret {
		log.Println("Can not open " + ifile)
	}
	ofd, ret = fileOpen(ofile, true)
	if !ret {
		log.Println("Can not open " + ofile)
	}

	fileWrite(ofd, SpacePipeline(ifd))
	fileClose(ifd)
	fileClose(ofd)
}