package main

import (
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	"os"
	"os/exec"
	"regexp"
	"strconv"
	"strings"
)

const version = "V0.1.3"

var (
	tmpDir  string
	numeric = regexp.MustCompile(`^[0-9]+$`)
)

func main() {
	if os.Geteuid() != 0 {
		fmt.Fprintf(os.Stderr, "Run this program as root, for example: sudo %s\n", os.Args[0])
		os.Exit(1)
	}

	if _, err := exec.LookPath("whiptail"); err != nil {
		fmt.Fprintln(os.Stderr, "whiptail is required. Install it with: apt install whiptail")
		os.Exit(1)
	}

	var err error
	tmpDir, err = os.MkdirTemp("", "proxmox-toolkit-*")
	if err != nil {
		fmt.Fprintf(os.Stderr, "Could not create temporary directory: %v\n", err)
		os.Exit(1)
	}
	defer os.RemoveAll(tmpDir)

	mainMenu()
}

// whiptail runs a dialog and captures its selected value through file
// descriptor 3. The dialog itself uses the terminal.
func whiptail(args ...string) string {
	readEnd, writeEnd, err := os.Pipe()
	if err != nil {
		return ""
	}
	defer readEnd.Close()

	args = append([]string{"--output-fd", "3"}, args...)
	cmd := exec.Command("whiptail", args...)
	cmd.Stdin = os.Stdin
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	cmd.ExtraFiles = []*os.File{writeEnd}

	err = cmd.Run()
	_ = writeEnd.Close()

	var result bytes.Buffer
	_, _ = result.ReadFrom(readEnd)
	if err != nil {
		return ""
	}
	return strings.TrimSpace(result.String())
}

func menu(title, prompt string, height, width, menuHeight int, items ...string) string {
	args := []string{
		"--title", title,
		"--menu", prompt,
		strconv.Itoa(height),
		strconv.Itoa(width),
		strconv.Itoa(menuHeight),
	}
	args = append(args, items...)
	return whiptail(args...)
}

func message(title, text string) {
	whiptail("--title", title, "--msgbox", text, "8", "70")
}

func confirmAction(text string) bool {
	readEnd, writeEnd, err := os.Pipe()
	if err != nil {
		return false
	}
	defer readEnd.Close()

	cmd := exec.Command(
		"whiptail",
		"--title", "Confirm",
		"--yesno", text,
		"10", "70",
	)
	cmd.Stdin = os.Stdin
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	cmd.ExtraFiles = []*os.File{writeEnd}

	err = cmd.Run()
	_ = writeEnd.Close()
	return err == nil
}

func inputValue(title, prompt string) (string, bool) {
	readEnd, writeEnd, err := os.Pipe()
	if err != nil {
		return "", false
	}
	defer readEnd.Close()

	cmd := exec.Command(
		"whiptail",
		"--output-fd", "3",
		"--title", title,
		"--inputbox", prompt,
		"9", "72",
	)
	cmd.Stdin = os.Stdin
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	cmd.ExtraFiles = []*os.File{writeEnd}

	err = cmd.Run()
	_ = writeEnd.Close()

	var result bytes.Buffer
	_, _ = result.ReadFrom(readEnd)
	if err != nil {
		return "", false
	}
	return strings.TrimSpace(result.String()), true
}

func requireCommand(name string) bool {
	if _, err := exec.LookPath(name); err != nil {
		message(
			"Command unavailable",
			fmt.Sprintf("The command '%s' is not installed or not available on this node.", name),
		)
		return false
	}
	return true
}

func askID(prompt string) (string, bool) {
	value, ok := inputValue("Enter ID", prompt)
	if !ok {
		return "", false
	}
	if !numeric.MatchString(value) {
		message("Invalid ID", "Enter a numeric VM or container ID.")
		return "", false
	}
	return value, true
}

func terminalSize(name string, fallback int) int {
	out, err := exec.Command("tput", name).Output()
	if err != nil {
		return fallback
	}

	value, err := strconv.Atoi(strings.TrimSpace(string(out)))
	if err != nil || value <= 0 {
		return fallback
	}
	return value
}

func showOutput(title string, name string, args ...string) {
	outputPath := tmpDir + "/output.txt"

	output, err := os.Create(outputPath)
	if err != nil {
		message("Error", "Could not create a temporary output file.")
		return
	}

	cmd := exec.Command(name, args...)
	cmd.Stdout = output
	cmd.Stderr = output
	runErr := cmd.Run()
	_ = output.Close()

	status := 0
	if runErr != nil {
		status = 1
		var exitErr *exec.ExitError
		if errors.As(runErr, &exitErr) {
			status = exitErr.ExitCode()
		}
	}

	data, _ := os.ReadFile(outputPath)
	if len(data) == 0 {
		data = []byte(fmt.Sprintf(
			"Command completed with exit status %d; no output.\n",
			status,
		))
	} else if status != 0 {
		data = append(data, []byte(fmt.Sprintf(
			"\nCommand exited with status %d.\n",
			status,
		))...)
	}

	if err := os.WriteFile(outputPath, data, 0600); err != nil {
		message("Error", "Could not write command output to the temporary file.")
		return
	}

	// Leave room around the dialog and use fallback dimensions if tput fails.
	height := terminalSize("lines", 24) - 4
	width := terminalSize("cols", 80) - 4

	// Keep dimensions within whiptail's practical limits.
	if height < 12 {
		height = 12
	}
	if width < 50 {
		width = 50
	}

	whiptail(
		"--title", title,
		"--textbox", outputPath,
		strconv.Itoa(height),
		strconv.Itoa(width),
	)
}

func showMemory(title, id string) {
	output, err := exec.Command("qm", "config", id).CombinedOutput()
	if err != nil {
		status := 1
		var exitErr *exec.ExitError
		if errors.As(err, &exitErr) {
			status = exitErr.ExitCode()
		}
		text := string(output)
		if text != "" {
			text += "\n"
		}
		text += fmt.Sprintf("Command exited with status %d.\n", status)
		showText(title, text)
		return
	}

	var matches []string
	for _, line := range strings.Split(string(output), "\n") {
		if strings.HasPrefix(line, "memory:") {
			matches = append(matches, line)
		}
	}
	if len(matches) == 0 {
		matches = []string{"No memory setting found."}
	}

	showText(title, strings.Join(matches, "\n")+"\n")
}

func showText(title, text string) {
	outputPath := tmpDir + "/output.txt"
	if err := os.WriteFile(outputPath, []byte(text), 0600); err != nil {
		message("Error", "Could not write command output to the temporary file.")
		return
	}

	height := terminalSize("lines", 24) - 4
	width := terminalSize("cols", 80) - 4
	if height < 12 {
		height = 12
	}
	if width < 50 {
		width = 50
	}

	whiptail(
		"--title", title,
		"--textbox", outputPath,
		strconv.Itoa(height),
		strconv.Itoa(width),
	)
}

func showResourceNames(title, resourceType string) {
	output, err := exec.Command(
		"pvesh", "get", "/cluster/resources", "--output-format", "json",
	).CombinedOutput()
	if err != nil {
		text := string(output)
		if text == "" {
			text = err.Error()
		}
		showText(title, text)
		return
	}

	var resources []struct {
		Type string `json:"type"`
		Name string `json:"name"`
	}
	if err := json.Unmarshal(output, &resources); err != nil {
		showText(title, "Could not parse pvesh output:\n"+err.Error())
		return
	}

	var names []string
	for _, resource := range resources {
		if resource.Type == resourceType {
			names = append(names, resource.Name)
		}
	}

	if len(names) == 0 {
		showText(title, "No matching resources found.\n")
		return
	}

	showText(title, strings.Join(names, "\n")+"\n")
}

func vmMenu() {
	for {
		choice := menu(
			"Virtual Machines (QEMU)",
			"Choose an action:",
			18, 72, 10,
			"list", "List VMs (qm list)",
			"names", "List VM names",
			"config", "Show VM configuration",
			"memory", "Show VM memory setting",
			"unlock", "Unlock a VM",
			"back", "Back",
		)

		switch choice {
		case "list":
			if requireCommand("qm") {
				showOutput("VM list", "qm", "list")
			}
		case "names":
			if requireCommand("pvesh") {
				showResourceNames("VM names", "qemu")
			}
		case "config", "memory", "unlock":
			if !requireCommand("qm") {
				continue
			}

			id, ok := askID("Enter the VMID:")
			if !ok {
				continue
			}

			switch choice {
			case "config":
				showOutput("VM "+id+" configuration", "qm", "config", id)
			case "memory":
				showMemory("VM "+id+" memory", id)
			case "unlock":
				if confirmAction(
					"Unlock VM " + id + "?\n\n" +
						"Only do this if you have confirmed that no task is still running for this VM.",
				) {
					showOutput("Unlock VM "+id, "qm", "unlock", id)
				}
			}
		case "back", "":
			return
		}
	}
}

func containerMenu() {
	for {
		choice := menu(
			"Containers (LXC)",
			"Choose an action:",
			16, 72, 8,
			"list", "List containers (pct list)",
			"names", "List container names",
			"config", "Show container configuration",
			"unlock", "Unlock a container",
			"back", "Back",
		)

		switch choice {
		case "list":
			if requireCommand("pct") {
				showOutput("Container list", "pct", "list")
			}
		case "names":
			if requireCommand("pvesh") {
				showResourceNames("Container names", "lxc")
			}
		case "config", "unlock":
			if !requireCommand("pct") {
				continue
			}

			id, ok := askID("Enter the container ID:")
			if !ok {
				continue
			}

			if choice == "config" {
				showOutput("Container "+id+" configuration", "pct", "config", id)
			} else if confirmAction(
				"Unlock container " + id + "?\n\n" +
					"Only do this if you have confirmed that no task is still running for this container.",
			) {
				showOutput("Unlock container "+id, "pct", "unlock", id)
			}
		case "back", "":
			return
		}
	}
}

func backupMenu() {
	if !requireCommand("vzdump") {
		return
	}

	id, ok := askID("Enter the VM or container ID to back up:")
	if !ok {
		return
	}

	if confirmAction(
		"Start a backup for ID " + id + " using vzdump defaults?\n\n" +
			"Review your node's backup configuration and storage capacity first.",
	) {
		showOutput("Backup ID "+id, "vzdump", id)
	}
}

func restoreMenu() {
	choice := menu(
		"Restore",
		"Choose what to restore:",
		12, 72, 4,
		"vm", "Restore a QEMU VM (qmrestore)",
		"ct", "Restore a container (pct restore)",
		"back", "Back",
	)
	if choice != "vm" && choice != "ct" {
		return
	}

	id, ok := askID("Enter the new VMID or container ID:")
	if !ok {
		return
	}

	archive, ok := inputValue(
		"Backup archive",
		"Enter the full path to the vzdump archive:",
	)
	if !ok {
		return
	}

	info, err := os.Stat(archive)
	if archive == "" || err != nil || !info.Mode().IsRegular() {
		message("Archive not found", "That file does not exist or is not a regular file.")
		return
	}

	if !confirmAction(
		"Restore '" + archive + "' as ID " + id + "?\n\n" +
			"Restoring can create or overwrite resources. Confirm the target ID and archive carefully.",
	) {
		return
	}

	if choice == "vm" {
		if requireCommand("qmrestore") {
			showOutput("Restore VM "+id, "qmrestore", archive, id)
		}
	} else if requireCommand("pct") {
		showOutput("Restore container "+id, "pct", "restore", id, archive)
	}
}

func storageMenu() {
	for {
		choice := menu(
			"Storage / LVM",
			"Choose a read-only report:",
			14, 72, 6,
			"pvs", "Physical volumes (pvs)",
			"vgs", "Volume groups (vgs)",
			"lvs", "Logical volumes (lvs)",
			"back", "Back",
		)

		switch choice {
		case "pvs":
			if requireCommand("pvs") {
				showOutput("Physical volumes", "pvs")
			}
		case "vgs":
			if requireCommand("vgs") {
				showOutput("Volume groups", "vgs")
			}
		case "lvs":
			if requireCommand("lvs") {
				showOutput("Logical volumes", "lvs")
			}
		case "back", "":
			return
		}
	}
}

func mainMenu() {
	for {
		choice := menu(
			"Proxmox VE Toolkit "+version,
			"Select a task:",
			21, 76, 13,
			"vms", "Virtual machines (QEMU)",
			"containers", "Containers (LXC)",
			"backup", "Back up a VM or container (vzdump)",
			"restore", "Restore a VM or container",
			"cluster", "Cluster status (pvecm status)",
			"version", "Proxmox version (pveversion -v)",
			"storage", "Storage / LVM reports",
			"perf", "Host performance test (pveperf)",
			"subscription", "Subscription status",
			"dab", "Debian Appliance Builder help",
			"quit", "Exit",
		)

		switch choice {
		case "vms":
			vmMenu()
		case "containers":
			containerMenu()
		case "backup":
			backupMenu()
		case "restore":
			restoreMenu()
		case "cluster":
			if requireCommand("pvecm") {
				showOutput("Cluster status", "pvecm", "status")
			}
		case "version":
			if requireCommand("pveversion") {
				showOutput("Proxmox VE version", "pveversion", "-v")
			}
		case "storage":
			storageMenu()
		case "perf":
			if requireCommand("pveperf") &&
				confirmAction("Run pveperf?\n\nThis can cause temporary disk activity.") {
				showOutput("Host performance", "pveperf")
			}
		case "subscription":
			if requireCommand("pvesubscription") {
				showOutput("Subscription status", "pvesubscription", "get")
			}
		case "dab":
			if requireCommand("dab") {
				showOutput("Debian Appliance Builder help", "dab", "help")
			}
		case "quit", "":
			return
		}
	}
}