package agent

import (
	"errors"
	"os"
	"os/exec"
	"runtime"
	"strconv"
	"strings"
	"sync"

	"golang.org/x/sys/unix"
)

// termsBySID are the running terminals by their session, so the panel can
// ask where one of them is.
var termsBySID sync.Map // sid -> *PTY

// Cwd is the folder the terminal is in now: that of the program in front
// (the shell, or what it runs), else of the shell itself.
func (p *PTY) Cwd() (string, error) {
	pid := 0
	if g, err := unix.IoctlGetInt(int(p.f.Fd()), unix.TIOCGPGRP); err == nil && g > 0 {
		pid = g
	}
	if pid > 0 {
		if d, err := procCwd(pid); err == nil {
			return d, nil
		}
	}
	return procCwd(p.cmd.Process.Pid)
}

// procCwd is a process's working folder: /proc on Linux, lsof elsewhere.
func procCwd(pid int) (string, error) {
	if runtime.GOOS == "linux" {
		return os.Readlink("/proc/" + strconv.Itoa(pid) + "/cwd")
	}
	out, err := exec.Command("lsof", "-a", "-p", strconv.Itoa(pid), "-d", "cwd", "-Fn").Output()
	if err != nil {
		return "", err
	}
	for _, l := range strings.Split(string(out), "\n") {
		if strings.HasPrefix(l, "n/") {
			return l[1:], nil
		}
	}
	return "", errors.New("папка терминала не найдена")
}

// termCwd answers the panel: where the terminal of session sid is now.
func termCwd(sid string) (any, error) {
	v, ok := termsBySID.Load(sid)
	if !ok {
		return nil, errors.New("терминал не найден")
	}
	d, err := v.(*PTY).Cwd()
	if err != nil {
		return nil, err
	}
	return map[string]string{"path": d}, nil
}