package main

import (
	"flag"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strings"

	"github.com/kevinburke/ssh_config"
	"github.com/moby/sys/mountinfo"
)

var eFlag = flag.Bool("e", false, "open mountpoint in your editor")

func main() {
	flag.Parse()
	args := flag.Args()

	if len(args) == 0 {
		fmt.Fprintln(os.Stderr, "No hostname specified.")
		os.Exit(2)
	}

	hostname := ssh_config.Get(args[0], "HostName")
	user := ssh_config.Get(args[0], "User")
	port := ssh_config.Get(args[0], "Port")
	ifile := ssh_config.Get(args[0], "IdentityFile")

	if len(hostname) == 0 || len(user) == 0 || len(ifile) == 0 {
		fmt.Fprintln(os.Stderr, "Hostname not found in ~/.ssh/config")
		os.Exit(3)
	}
	if len(port) == 0 {
		port = "22"
	}

	mount, err := verify_mount_dir(hostname)
	if err != nil {
		fmt.Fprintln(os.Stderr, "verify_mount_dir() failed:", err)
		os.Exit(4)
	}

	fmt.Println("Hostname:	", hostname)
	fmt.Println("User:		", user)
	fmt.Println("Port:		", port)
	fmt.Println("Ifile:		", ifile)
	fmt.Println("Mount:		", mount)
	fmt.Println("---")

	chkmount, chkmount_err := mountinfo.Mounted(mount)
	if chkmount_err != nil {
		fmt.Fprintf(os.Stderr, "mountinfo.Mounted() failed with %s\n", chkmount_err)
		os.Exit(5)
	}
	if !chkmount {
		if err := mount_sshfs(hostname, user, ifile, port, mount); err != nil {
			fmt.Fprintln(os.Stderr, "mount_sshfs() failed:", err)
			os.Exit(6)
		}
	} else {
		fmt.Println("!!! Already mounted")
	}
	run_editor(mount)
}

func run_editor(mount string) {
	if *eFlag {
		cmd := exec.Command("subl", mount)
		cmd.Stdout = os.Stdout
		cmd.Stderr = os.Stderr
		err := cmd.Run()
		if err != nil {
			fmt.Fprintln(os.Stderr, "run_editor() failed with", err)
		}
	}
}

func verify_mount_dir(hostname string) (string, error) {
	homedir, err := os.UserHomeDir()
	if err != nil {
		return "", fmt.Errorf("resolve home dir: %w", err)
	}
	base := filepath.Join(homedir, "Servers")
	mount := filepath.Clean(filepath.Join(base, hostname))
	if !strings.HasPrefix(mount, base+string(os.PathSeparator)) {
		return "", fmt.Errorf("hostname %q escapes mount base %q", hostname, base)
	}
	if err := os.MkdirAll(mount, 0700); err != nil {
		return "", fmt.Errorf("create mount dir %q: %w", mount, err)
	}
	return mount, nil
}

func mount_sshfs(hostname string, user string, ifile string, port string, mount string) error {
	cmd := exec.Command("sshfs", "-p", port,
		"-o", "IdentityFile="+ifile,
		"-o", "idmap=user",
		"-o", "cache=yes",
		"-o", "kernel_cache",
		"-o", "attr_timeout=60",
		"-o", "entry_timeout=60",
		"-o", "negative_timeout=20",
		"-o", "Ciphers=aes128-gcm@openssh.com",
		"-o", "Compression=no",
		"-o", "reconnect",
		"-o", "ServerAliveInterval=15",
		"-o", "ServerAliveCountMax=3",
		user+"@"+hostname+":/", mount)
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	return cmd.Run()
}