msgviewer: open http links from messages

Parse http links from a message and display them as completions in the
:open-link command.

Add the following binds to the [view] section in your binds.conf:
<C-l> = :open-link <space>

Parsing can be disabled in aerc.conf by setting parse-http-links to
false in the viewer section.

Thanks to Moritz for the help with the regular expression.

Signed-off-by: Koni Marti <koni.marti@gmail.com>
Reviewed-by: Moritz Poldrack <git@moritz.sh>
Acked-by: Robin Jarry <robin@jarry.cc>

lib/parse/hyperlinks.go

@@ -0,0 +1,44 @@
+package parse
+
+import (
+	"bufio"
+	"bytes"
+	"io"
+	"regexp"
+	"strings"
+)
+
+var submatch = `(https?:\/\/[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,10}\b(?:[-a-zA-Z0-9()@:%_\+.~#?&\/=]*))`
+var httpRe = regexp.MustCompile("\"" + submatch + "\"" + "|" + "\\(" + submatch + "\\)" + "|" + "<" + submatch + ">" + "|" + submatch)
+
+// HttpLinks searches a reader for a http link and returns a copy of the
+// reader and a slice with links.
+func HttpLinks(r io.Reader) (io.Reader, []string) {
+	var buf bytes.Buffer
+	tr := io.TeeReader(r, &buf)
+
+	scanner := bufio.NewScanner(tr)
+	linkMap := make(map[string]struct{})
+	for scanner.Scan() {
+		line := scanner.Text()
+		if !strings.Contains(line, "http") {
+			continue
+		}
+		for _, word := range strings.Fields(line) {
+			if links := httpRe.FindStringSubmatch(word); len(links) > 0 {
+				for _, l := range links[1:] {
+					if l != "" {
+						linkMap[strings.TrimSpace(l)] = struct{}{}
+					}
+				}
+			}
+		}
+	}
+
+	results := []string{}
+	for link, _ := range linkMap {
+		results = append(results, link)
+	}
+
+	return &buf, results
+}

lib/parse/hyperlinks_test.go

@@ -0,0 +1,99 @@
+package parse_test
+
+import (
+	"io/ioutil"
+	"strings"
+	"testing"
+
+	"git.sr.ht/~rjarry/aerc/lib/parse"
+)
+
+func TestHyperlinks(t *testing.T) {
+	tests := []struct {
+		text  string
+		links []string
+	}{
+		{
+			text:  "http://aerc-mail.org",
+			links: []string{"http://aerc-mail.org"},
+		},
+		{
+			text:  "https://aerc-mail.org",
+			links: []string{"https://aerc-mail.org"},
+		},
+		{
+			text:  "text https://aerc-mail.org more text",
+			links: []string{"https://aerc-mail.org"},
+		},
+		{
+			text:  "text (https://aerc-mail.org) more text",
+			links: []string{"https://aerc-mail.org"},
+		},
+		{
+			text:  "text \"https://aerc-mail.org\" more text",
+			links: []string{"https://aerc-mail.org"},
+		},
+		{
+			text:  "text <https://aerc-mail.org> more text",
+			links: []string{"https://aerc-mail.org"},
+		},
+		{
+			text:  "<a href=\"https://aerc-mail.org\">",
+			links: []string{"https://aerc-mail.org"},
+		},
+		{
+			text:  "text https://aerc-mail.org more text https://aerc-mail.org more text",
+			links: []string{"https://aerc-mail.org"},
+		},
+		{
+			text:  "text https://aerc-mail.org more text http://git.sr.ht/~rjarry/aerc more text",
+			links: []string{"https://aerc-mail.org", "http://git.sr.ht/~rjarry/aerc"},
+		},
+		{
+			text:  "text http://www.ietf.org/rfc/rfc2396.txt more text",
+			links: []string{"http://www.ietf.org/rfc/rfc2396.txt"},
+		},
+		{
+			text:  "text <http://example.com:8042/over/there?name=ferret#nose> more text",
+			links: []string{"http://example.com:8042/over/there?name=ferret#nose"},
+		},
+		{
+			text:  "text http://cnn.example.com&story=breaking_news@10.0.0.1/top_story.htm more text",
+			links: []string{"http://cnn.example.com&story=breaking_news@10.0.0.1/top_story.htm"},
+		},
+		{
+			text:  "text https://www.ics.uci.edu/pub/ietf/uri/#Related more text",
+			links: []string{"https://www.ics.uci.edu/pub/ietf/uri/#Related"},
+		},
+		{
+			text:  "text https://www.example.com/index.php?id_sezione=360&sid=3a5ebc944f41daa6f849f730f1 more text",
+			links: []string{"https://www.example.com/index.php?id_sezione=360&sid=3a5ebc944f41daa6f849f730f1"},
+		},
+	}
+
+	for _, test := range tests {
+
+		// make sure reader is exact copy of input reader
+		reader, links := parse.HttpLinks(strings.NewReader(test.text))
+		if data, err := ioutil.ReadAll(reader); err != nil {
+			t.Errorf("could not read text: %v", err)
+		} else if string(data) != test.text {
+			t.Errorf("did not copy input reader correctly")
+		}
+
+		// check correct parsed links
+		if len(links) != len(test.links) {
+			t.Errorf("different number of links: got %d but expected %d", len(links), len(test.links))
+		}
+		linkMap := make(map[string]struct{})
+		for _, got := range links {
+			linkMap[got] = struct{}{}
+		}
+		for _, expected := range test.links {
+			if _, ok := linkMap[expected]; !ok {
+				t.Errorf("link not parsed: %s", expected)
+			}
+		}
+
+	}
+}