From c1a6908801b47f4a48e1b8391854d71842098edb Mon Sep 17 00:00:00 2001
From: Ted Unangst <tedu@tedunangst.com>
Date: Sun, 6 Oct 2019 15:14:18 -0400
Subject: [PATCH] better markdown linebreaks (and add the file, doh)

---
 markitzero.go      | 101 +++++++++++++++++++++++++++++++++++++++++++++
 markitzero_test.go |  36 ++++++++++++++--
 2 files changed, 133 insertions(+), 4 deletions(-)
 create mode 100644 markitzero.go

diff --git a/markitzero.go b/markitzero.go
new file mode 100644
index 0000000..ade5089
--- /dev/null
+++ b/markitzero.go
@@ -0,0 +1,101 @@
+//
+// Copyright (c) 2019 Ted Unangst <tedu@tedunangst.com>
+//
+// Permission to use, copy, modify, and distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+package main
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+
+	"golang.org/x/net/html"
+)
+
+
+var re_bolder = regexp.MustCompile(`(^|\W)\*\*([\w\s,.!?':_-]+)\*\*($|\W)`)
+var re_italicer = regexp.MustCompile(`(^|\W)\*([\w\s,.!?':_-]+)\*($|\W)`)
+var re_bigcoder = regexp.MustCompile("```\n?((?s:.*?))\n?```\n?")
+var re_coder = regexp.MustCompile("`([^`]*)`")
+var re_quoter = regexp.MustCompile(`(?m:^&gt; (.*)\n?)`)
+
+func markitzero(s string) string {
+	// prepare the string
+	s = strings.TrimSpace(s)
+	s = strings.Replace(s, "\r", "", -1)
+	s = html.EscapeString(s)
+	s = strings.Replace(s, "&#39;", "'", -1) // dammit go
+
+	// save away the code blocks so we don't mess them up further
+	var bigcodes, lilcodes []string
+	s = re_bigcoder.ReplaceAllStringFunc(s, func(code string) string {
+		bigcodes = append(bigcodes, code)
+		return "``````"
+	})
+	s = re_coder.ReplaceAllStringFunc(s, func(code string) string {
+		lilcodes = append(lilcodes, code)
+		return "`x`"
+	})
+
+	// mark it zero
+	s = re_bolder.ReplaceAllString(s, "$1<b>$2</b>$3")
+	s = re_italicer.ReplaceAllString(s, "$1<i>$2</i>$3")
+	s = re_quoter.ReplaceAllString(s, "<blockquote>$1</blockquote><p>")
+	s = re_link.ReplaceAllStringFunc(s, linkreplacer)
+
+	// now restore the code blocks
+	s = re_coder.ReplaceAllStringFunc(s, func(s string) string {
+		code := lilcodes[0]
+		lilcodes = lilcodes[1:]
+		return code
+	})
+	s = re_bigcoder.ReplaceAllStringFunc(s, func(s string) string {
+		code := bigcodes[0]
+		bigcodes = bigcodes[1:]
+		return code
+	})
+	s = re_bigcoder.ReplaceAllString(s, "<pre><code>$1</code></pre><p>")
+	s = re_coder.ReplaceAllString(s, "<code>$1</code>")
+
+	// some final fixups
+	s = strings.Replace(s, "\n", "<br>", -1)
+	s = strings.Replace(s, "<br><blockquote>", "<blockquote>", -1)
+	s = strings.Replace(s, "<br><pre>", "<pre>", -1)
+	s = strings.Replace(s, "<p><br>", "<p>", -1)
+	return s
+}
+
+func linkreplacer(url string) string {
+	if url[0] == '@' {
+		return url
+	}
+	addparen := false
+	adddot := false
+	if strings.HasSuffix(url, ")") && strings.IndexByte(url, '(') == -1 {
+		url = url[:len(url)-1]
+		addparen = true
+	}
+	if strings.HasSuffix(url, ".") {
+		url = url[:len(url)-1]
+		adddot = true
+	}
+	url = fmt.Sprintf(`<a class="mention u-url" href="%s">%s</a>`, url, url)
+	if adddot {
+		url += "."
+	}
+	if addparen {
+		url += ")"
+	}
+	return url
+}
diff --git a/markitzero_test.go b/markitzero_test.go
index a26b234..e6874bd 100644
--- a/markitzero_test.go
+++ b/markitzero_test.go
@@ -4,12 +4,40 @@ import (
 	"testing"
 )
 
-func TestMarkitzero(t *testing.T) {
-	input := `link to https://example.com/ with **bold** text`
-	output := `link to <a class="mention u-url" href="https://example.com/">https://example.com/</a> with <b>bold</b> text`
-
+func onetest(t *testing.T, input, output string) {
 	result := markitzero(input)
 	if result != output {
 		t.Errorf("\nexpected:\n%s\noutput:\n%s", output, result)
 	}
 }
+
+func basictest(t *testing.T) {
+	input := `link to https://example.com/ with **bold** text`
+	output := `link to <a class="mention u-url" href="https://example.com/">https://example.com/</a> with <b>bold</b> text`
+	onetest(t, input, output)
+}
+
+func linebreak1(t *testing.T) {
+	input := "hello\n> a quote\na comment"
+	output := "hello<blockquote>a quote</blockquote><p>a comment"
+	onetest(t, input, output)
+}
+
+func linebreak2(t *testing.T) {
+	input := "hello\n\n> a quote\n\na comment"
+	output := "hello<br><blockquote>a quote</blockquote><p>a comment"
+	onetest(t, input, output)
+}
+
+func linebreak3(t *testing.T) {
+	input := "hello\n\n```\nfunc(s string)\n```\n\ndoes it go?"
+	output := "hello<br><pre><code>func(s string)</code></pre><p>does it go?"
+	onetest(t, input, output)
+}
+
+func TestMarkitzero(t *testing.T) {
+	basictest(t)
+	linebreak1(t)
+	linebreak2(t)
+	linebreak3(t)
+}