package platform

import (
	"archive/tar"
	"archive/zip"
	"compress/gzip"
	"context"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strings"
)

func safeJoin(dest, name string) (string, error) {
	p := filepath.Join(dest, name)
	cleanDest := filepath.Clean(dest) + string(os.PathSeparator)
	if !strings.HasPrefix(filepath.Clean(p)+string(os.PathSeparator), cleanDest) {
		return "", fmt.Errorf("unsafe path %q escapes %q", name, dest)
	}
	return p, nil
}

func ExtractTarGz(ctx context.Context, archivePath, destDir string) error {
	f, err := os.Open(archivePath)
	if err != nil {
		return err
	}
	defer f.Close()
	gz, err := gzip.NewReader(f)
	if err != nil {
		return err
	}
	defer gz.Close()
	tr := tar.NewReader(gz)
	for {
		if err := ctx.Err(); err != nil {
			return err
		}
		h, err := tr.Next()
		if err == io.EOF {
			break
		}
		if err != nil {
			return err
		}
		target, err := safeJoin(destDir, h.Name)
		if err != nil {
			return err
		}
		switch h.Typeflag {
		case tar.TypeDir:
			if err := os.MkdirAll(target, os.FileMode(h.Mode)); err != nil {
				return err
			}
		case tar.TypeReg:
			if err := os.MkdirAll(filepath.Dir(target), 0o755); err != nil {
				return err
			}
			w, err := os.OpenFile(target, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, os.FileMode(h.Mode))
			if err != nil {
				return err
			}
			if _, err := io.Copy(w, tr); err != nil {
				w.Close()
				return err
			}
			w.Close()
		}
	}
	return nil
}

func ExtractZip(ctx context.Context, archivePath, destDir string) error {
	zr, err := zip.OpenReader(archivePath)
	if err != nil {
		return err
	}
	defer zr.Close()
	for _, zf := range zr.File {
		if err := ctx.Err(); err != nil {
			return err
		}
		target, err := safeJoin(destDir, zf.Name)
		if err != nil {
			return err
		}
		if zf.FileInfo().IsDir() {
			if err := os.MkdirAll(target, zf.Mode()); err != nil {
				return err
			}
			continue
		}
		if err := os.MkdirAll(filepath.Dir(target), 0o755); err != nil {
			return err
		}
		rc, err := zf.Open()
		if err != nil {
			return err
		}
		w, err := os.OpenFile(target, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, zf.Mode())
		if err != nil {
			rc.Close()
			return err
		}
		_, err = io.Copy(w, rc)
		rc.Close()
		w.Close()
		if err != nil {
			return err
		}
	}
	return nil
}