1// Copyright 2012 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package present
6
7import (
8	"fmt"
9	"log"
10	"net/url"
11	"strings"
12)
13
14func init() {
15	Register("link", parseLink)
16}
17
18type Link struct {
19	URL   *url.URL
20	Label string
21}
22
23func (l Link) TemplateName() string { return "link" }
24
25func parseLink(ctx *Context, fileName string, lineno int, text string) (Elem, error) {
26	args := strings.Fields(text)
27	if len(args) < 2 {
28		return nil, fmt.Errorf("link element must have at least 2 arguments")
29	}
30	url, err := url.Parse(args[1])
31	if err != nil {
32		return nil, err
33	}
34	label := ""
35	if len(args) > 2 {
36		label = strings.Join(args[2:], " ")
37	} else {
38		scheme := url.Scheme + "://"
39		if url.Scheme == "mailto" {
40			scheme = "mailto:"
41		}
42		label = strings.Replace(url.String(), scheme, "", 1)
43	}
44	return Link{url, label}, nil
45}
46
47func renderLink(href, text string) string {
48	text = font(text)
49	if text == "" {
50		text = href
51	}
52	// Open links in new window only when their url is absolute.
53	target := "_blank"
54	if u, err := url.Parse(href); err != nil {
55		log.Println("renderLink parsing url:", err)
56	} else if !u.IsAbs() || u.Scheme == "javascript" {
57		target = "_self"
58	}
59
60	return fmt.Sprintf(`<a href="%s" target="%s">%s</a>`, href, target, text)
61}
62
63// parseInlineLink parses an inline link at the start of s, and returns
64// a rendered HTML link and the total length of the raw inline link.
65// If no inline link is present, it returns all zeroes.
66func parseInlineLink(s string) (link string, length int) {
67	if !strings.HasPrefix(s, "[[") {
68		return
69	}
70	end := strings.Index(s, "]]")
71	if end == -1 {
72		return
73	}
74	urlEnd := strings.Index(s, "]")
75	rawURL := s[2:urlEnd]
76	const badURLChars = `<>"{}|\^[] ` + "`" // per RFC2396 section 2.4.3
77	if strings.ContainsAny(rawURL, badURLChars) {
78		return
79	}
80	if urlEnd == end {
81		simpleUrl := ""
82		url, err := url.Parse(rawURL)
83		if err == nil {
84			// If the URL is http://foo.com, drop the http://
85			// In other words, render [[http://golang.org]] as:
86			//   <a href="http://golang.org">golang.org</a>
87			if strings.HasPrefix(rawURL, url.Scheme+"://") {
88				simpleUrl = strings.TrimPrefix(rawURL, url.Scheme+"://")
89			} else if strings.HasPrefix(rawURL, url.Scheme+":") {
90				simpleUrl = strings.TrimPrefix(rawURL, url.Scheme+":")
91			}
92		}
93		return renderLink(rawURL, simpleUrl), end + 2
94	}
95	if s[urlEnd:urlEnd+2] != "][" {
96		return
97	}
98	text := s[urlEnd+2 : end]
99	return renderLink(rawURL, text), end + 2
100}
101