1// Tomljson reads TOML and converts to JSON.
2//
3// Usage:
4//   cat file.toml | tomljson > file.json
5//   tomljson file1.toml > file.json
6package main
7
8import (
9	"encoding/json"
10	"flag"
11	"fmt"
12	"io"
13	"os"
14
15	"github.com/pelletier/go-toml"
16)
17
18func main() {
19	flag.Usage = func() {
20		fmt.Fprintln(os.Stderr, "tomljson can be used in two ways:")
21		fmt.Fprintln(os.Stderr, "Writing to STDIN and reading from STDOUT:")
22		fmt.Fprintln(os.Stderr, "  cat file.toml | tomljson > file.json")
23		fmt.Fprintln(os.Stderr, "")
24		fmt.Fprintln(os.Stderr, "Reading from a file name:")
25		fmt.Fprintln(os.Stderr, "  tomljson file.toml")
26	}
27	flag.Parse()
28	os.Exit(processMain(flag.Args(), os.Stdin, os.Stdout, os.Stderr))
29}
30
31func processMain(files []string, defaultInput io.Reader, output io.Writer, errorOutput io.Writer) int {
32	// read from stdin and print to stdout
33	inputReader := defaultInput
34
35	if len(files) > 0 {
36		var err error
37		inputReader, err = os.Open(files[0])
38		if err != nil {
39			printError(err, errorOutput)
40			return -1
41		}
42	}
43	s, err := reader(inputReader)
44	if err != nil {
45		printError(err, errorOutput)
46		return -1
47	}
48	io.WriteString(output, s+"\n")
49	return 0
50}
51
52func printError(err error, output io.Writer) {
53	io.WriteString(output, err.Error()+"\n")
54}
55
56func reader(r io.Reader) (string, error) {
57	tree, err := toml.LoadReader(r)
58	if err != nil {
59		return "", err
60	}
61	return mapToJSON(tree)
62}
63
64func mapToJSON(tree *toml.Tree) (string, error) {
65	treeMap := tree.ToMap()
66	bytes, err := json.MarshalIndent(treeMap, "", "  ")
67	if err != nil {
68		return "", err
69	}
70	return string(bytes[:]), nil
71}
72