//<pre style="font-family:Courier New;">
// gsh - Go lang based Shell
// (c) 2020 ITS more Co., Ltd.
// 2020-0807 created by SatoxITS (sato@its-more.jp)
//
// Reference: https://golang.org/pkg/
//
package main // gsh main

import (
	"bufio"
	"strings"
	"strconv"
	"fmt"
	"os"
	"time"
	"syscall"
	"go/types"
	"go/token"
)

var VERSION = "gsh/0.0.2 (2020-0807b)"
var LINESIZE = (8*1024)
var PATHSEP = ":" // should be ";" in Windows
var PROMPT = "> "

func env(argv []string) {
	env := os.Environ()
	for _, v := range env {
		fmt.Printf("%v\n",v)
	}
}
func which(path string, show bool) (xfullpath string, itis bool){
	pathenv, found := os.LookupEnv("PATH")
	if found {
		dirv := strings.Split(pathenv,PATHSEP)
		for _, dir := range dirv {
			fullpath := dir + "/" + path
			fi, err := os.Stat(fullpath)
			if err != nil {
				fullpath = dir + "/" + path + ".go"
				fi, err = os.Stat(fullpath)
			}
			if err == nil {
				fm := fi.Mode()
				if fm.IsRegular() {
					if show {
						fmt.Printf("%s\n",fullpath)
					}
					return fullpath, true
				}
			}
		}
	}
	return "", false
}
func eval(argv []string, nlend bool){
	var ai = 1
	pfmt := "%s"
	if argv[ai][0:1] == "%" {
		pfmt = argv[ai]
		ai = 2
	}
	if len(argv) <= ai {
		return
	}
	gocode := strings.Join(argv[ai:]," ");
	fset := token.NewFileSet()
	rval, _ := types.Eval(fset,nil,token.NoPos,gocode)
	fmt.Printf(pfmt,rval.Value)
	if nlend { fmt.Printf("\n") }
}
func getval(name string) (found bool, val int) {
	/* should expand the name here */
	if name == "gsh.pid" {
		return true, os.Getpid()
	}else
	if name == "gsh.ppid" {
		return true, os.Getppid()
	}
	return false, 0
}
func echo(argv []string, nlend bool){
	for ai := 1; ai < len(argv); ai++ {
		if 1 < ai {
			fmt.Printf(" ");
		}
		arg := argv[ai]
		found, val := getval(arg)
		if found {
			fmt.Printf("%d",val)
		}else{
			fmt.Printf("%s",arg)
		}
	}
	if nlend {
		fmt.Printf("\n");
	}
}
func resfile() string {
	return "gsh.tmp"
}
//var resF *File
func resmap() {
	//_ , err := os.OpenFile(resfile(), os.O_RDWR|os.O_CREATE, os.ModeAppend)
		// https://developpaper.com/solution-to-golang-bad-file-descriptor-problem/
	_ , err := os.OpenFile(resfile(), os.O_RDWR|os.O_CREATE, 0)
	if err != nil {
		fmt.Printf("refF could not open: %s\n",err)
	}else{
		fmt.Printf("refF opened\n")
	}
}
func excommand(gshPA syscall.ProcAttr, exec bool, argv []string) (ret int) {
	fullpath, itis := which(argv[0],false)
	if itis == false {
		return -1
	}
	if 0 < strings.Index(fullpath,".go") {
		nargv := argv // []string{}
		gofullpath, itis := which("go",false)
		if itis == false {
			fmt.Printf("-- Go not found\n")
			return -1
		}
		nargv = []string{ gofullpath, "run", fullpath }
		fmt.Printf("-- %s {%s %s %s}\n",gofullpath,nargv[0],nargv[1],nargv[2])
		if exec {
			syscall.Exec(gofullpath,nargv,os.Environ())
		}else{
			pid, _ := syscall.ForkExec(gofullpath,nargv,&gshPA)
			syscall.Wait4(pid,nil,0,nil);
		}
	}else{
		if exec {
			syscall.Exec(fullpath,argv,os.Environ())
		}else{
			pid, _ := syscall.ForkExec(fullpath,argv,&gshPA)
			//fmt.Printf("[%d]\n",pid); // '&' to be background
			syscall.Wait4(pid,nil,0,nil);
		}
	}
	return 0
}
func sleep(gshPA syscall.ProcAttr, argv []string) {
	if len(argv) < 2 {
		fmt.Printf("Sleep 100ms, 100us, 100ns, ...\n")
		return
	}
	duration := argv[1];
	d, err := time.ParseDuration(duration)
	if err != nil {
		d, err = time.ParseDuration(duration+"s")
		if err != nil {
			fmt.Printf("duration ? %s (%s)\n",duration,err)
			return
		}
	}
	fmt.Printf("Sleep %v ns\n",duration)
	time.Sleep(d)
	if 0 < len(argv[2:]) {
		gshellv(gshPA, argv[2:])
	}
}
func repeat(gshPA syscall.ProcAttr, argv []string) {
	if len(argv) < 2 {
		return
	}
	for ri,_ := strconv.Atoi(argv[1]); 0 < ri; ri-- {
		if 0 < len(argv[2:]) {
			gshellv(gshPA, argv[2:])
		}
	}
}
func gshellv(gshPA syscall.ProcAttr, argv []string) (fin bool) {
	if len(argv) <= 0 {
		return false
	}
	cmd := argv[0]
	if cmd == "-i" || cmd == "-o" || cmd == "-a" || cmd == "-s" {
		if len(argv) < 2 {
			return false
		}
		fdix := 0;
		mode := os.O_RDONLY;
		if cmd == "-i" {
		}
		if cmd == "-o" {
			fdix = 1;
			mode = os.O_RDWR | os.O_CREATE;
		}
		if cmd == "-a" {
			fdix = 1;
			mode = os.O_RDWR | os.O_CREATE | os.O_APPEND;
		}
		if cmd == "-s" {
			// bi-directional, source/sync, maybe socket
		}
		f, err := os.OpenFile(argv[1], mode, 0600)
		if err != nil {
			fmt.Printf("%s\n",err)
			return false
		}
		savfd := gshPA.Files[fdix]
		gshPA.Files[fdix] = f.Fd()
		fmt.Printf("-- Opened [%d] %s\n",f.Fd(),argv[1])
		gshellv(gshPA, argv[2:])
		gshPA.Files[fdix] = savfd
		return false
	}
	if cmd == "call" {
		excommand(gshPA, false,argv[1:])
		return false
	}
	if cmd == "echo" {
		echo(argv,true)
		return false
	}
	if cmd == "env" {
		env(argv)
		return false
	}
	if cmd == "eval" {
		eval(argv,true)
		return false
	}
	if cmd == "exec" {
		excommand(gshPA, true,argv[1:])
		return false // should exit
	}
	if cmd == "exit" || cmd == "quit" {
		// write Result code EXIT to 3>
		return true
	}
	if cmd == "nop" {
		return false
	}
	if cmd == "-ver" {
		fmt.Printf("%s\n",VERSION);
		return false
	}
	if cmd == "repeat" { // repeat cond command
		repeat(gshPA,argv)
		return false
	}
	if cmd == "set" { // set name ...
		return false;
	}
	if cmd == "sleep" {
		sleep(gshPA,argv)
		return false;
	}
	if cmd == "which" {
		which(argv[1],true);
		return false
	}
	excommand(gshPA, false,argv)
	return false
}
func gshelll(gshPA syscall.ProcAttr, gline string) (rfin bool) {
	argv := strings.Split(string(gline)," ")
	fin := gshellv(gshPA,argv)
	return fin
}
func tgshelll(gshPA syscall.ProcAttr, gline string) (xfin bool) {
	start := time.Now()
	fin := gshelll(gshPA,gline)
	end := time.Now()
	elps := end.Sub(start);
	fmt.Printf("--(%d.%09ds)\n",elps/1000000000,elps%1000000000)
	return fin
}
func main() {
	gshPA := syscall.ProcAttr {
		"",
		os.Environ(),
		[]uintptr{os.Stdin.Fd(),os.Stdout.Fd(),os.Stderr.Fd()},
		nil,
	}
	resmap()
	for hix := 0; ; hix++ {
		fmt.Printf("%d",hix)
		fmt.Print(PROMPT)
		reader := bufio.NewReaderSize(os.Stdin,LINESIZE);
		gline, _, _ := reader.ReadLine()

		fin := tgshelll(gshPA,string(gline))
		if fin {
			break;
		}
	}
}
//---END--- (^-^)/</pre>