// Copyright 2019 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package rpmpack

import (
	"archive/tar"
	"fmt"
	"io"
	"io/ioutil"
	"path"

	"github.com/pkg/errors"
)

// FromTar reads a tar file and creates an rpm stuct.
func FromTar(inp io.Reader, md RPMMetaData) (*RPM, error) {

	r, err := NewRPM(md)
	if err != nil {
		return nil, errors.Wrap(err, "failed to create RPM structure")
	}
	t := tar.NewReader(inp)
	for {
		h, err := t.Next()
		if err == io.EOF {
			return r, nil
		} else if err != nil {
			return nil, errors.Wrap(err, "failed to read tar file")
		}
		var body []byte
		switch h.Typeflag {
		case tar.TypeDir:
			h.Mode |= 040000
		case tar.TypeSymlink:
			body = []byte(h.Linkname)
			h.Mode |= 0120000
		case tar.TypeReg:
			b, err := ioutil.ReadAll(t)
			if err != nil {
				return nil, errors.Wrapf(err, "failed to read file (%q)", h.Name)
			}
			body = b
		default:
			return nil, fmt.Errorf("unknown tar type: %d, (%q)", h.Typeflag, h.Name)
		}
		mtime := uint32(h.ModTime.Unix())

		r.AddFile(
			RPMFile{
				Name:  path.Join("/", h.Name),
				Body:  body,
				Mode:  uint(h.Mode),
				Owner: h.Uname,
				Group: h.Gname,
				MTime: mtime,
			})
	}
}