1// Copyright 2019 Unknwon
2//
3// Licensed under the Apache License, Version 2.0 (the "License"): you may
4// not use this file except in compliance with the License. You may obtain
5// a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
11// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
12// License for the specific language governing permissions and limitations
13// under the License.
14
15package ini
16
17import (
18	"bytes"
19	"fmt"
20	"io"
21	"io/ioutil"
22	"os"
23)
24
25var (
26	_ dataSource = (*sourceFile)(nil)
27	_ dataSource = (*sourceData)(nil)
28	_ dataSource = (*sourceReadCloser)(nil)
29)
30
31// dataSource is an interface that returns object which can be read and closed.
32type dataSource interface {
33	ReadCloser() (io.ReadCloser, error)
34}
35
36// sourceFile represents an object that contains content on the local file system.
37type sourceFile struct {
38	name string
39}
40
41func (s sourceFile) ReadCloser() (_ io.ReadCloser, err error) {
42	return os.Open(s.name)
43}
44
45// sourceData represents an object that contains content in memory.
46type sourceData struct {
47	data []byte
48}
49
50func (s *sourceData) ReadCloser() (io.ReadCloser, error) {
51	return ioutil.NopCloser(bytes.NewReader(s.data)), nil
52}
53
54// sourceReadCloser represents an input stream with Close method.
55type sourceReadCloser struct {
56	reader io.ReadCloser
57}
58
59func (s *sourceReadCloser) ReadCloser() (io.ReadCloser, error) {
60	return s.reader, nil
61}
62
63func parseDataSource(source interface{}) (dataSource, error) {
64	switch s := source.(type) {
65	case string:
66		return sourceFile{s}, nil
67	case []byte:
68		return &sourceData{s}, nil
69	case io.ReadCloser:
70		return &sourceReadCloser{s}, nil
71	case io.Reader:
72		return &sourceReadCloser{ioutil.NopCloser(s)}, nil
73	default:
74		return nil, fmt.Errorf("error parsing data source: unknown type %q", s)
75	}
76}
77