// package utils provides shared utility functions.
package utils

import (
	"archive/zip"
	"crypto/sha1"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strings"
)

// SHA1File computes the SHA-1 hex digest of the file at path.
func SHA1File(path string) (string, error) {
	f, err := os.Open(path)
	if err != nil {
		return "", fmt.Errorf("opening %s: %w", path, err)
	}
	defer f.Close()

	h := sha1.New()
	if _, err := io.Copy(h, f); err != nil {
		return "", fmt.Errorf("hashing %s: %w", path, err)
	}
	return fmt.Sprintf("%x", h.Sum(nil)), nil
}

// SHA1Bytes returns the SHA-1 hex digest of data.
func SHA1Bytes(data []byte) string {
	return fmt.Sprintf("%x", sha1.Sum(data))
}

// Unzip extracts a zip archive into dest, preserving the directory structure.
func Unzip(src, dest string) error {
	r, err := zip.OpenReader(src)
	if err != nil {
		return fmt.Errorf("opening zip %s: %w", src, err)
	}
	defer r.Close()

	for _, f := range r.File {
		target := filepath.Join(dest, f.Name)

		// Prevent zip-slip.
		if !strings.HasPrefix(target, filepath.Clean(dest)+string(os.PathSeparator)) {
			return fmt.Errorf("illegal zip path: %s", f.Name)
		}

		if f.FileInfo().IsDir() {
			if err := os.MkdirAll(target, f.Mode()); err != nil {
				return fmt.Errorf("creating directory %s: %w", target, err)
			}
			continue
		}

		if err := os.MkdirAll(filepath.Dir(target), 0o755); err != nil {
			return fmt.Errorf("creating parent for %s: %w", target, err)
		}

		out, err := os.OpenFile(target, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, f.Mode())
		if err != nil {
			return fmt.Errorf("creating file %s: %w", target, err)
		}

		rc, err := f.Open()
		if err != nil {
			out.Close()
			return fmt.Errorf("reading zip entry %s: %w", f.Name, err)
		}

		if _, err := io.Copy(out, rc); err != nil {
			rc.Close()
			out.Close()
			return fmt.Errorf("extracting %s: %w", f.Name, err)
		}
		rc.Close()
		out.Close()
	}
	return nil
}