Improve/Fix wrapping of plain text messages on preview and reply (#6974, #8391, #8378, #8289)

In short, we always wrap, but we detect patches/diffs in the text and make them unwrappable.

5 files changed, 91 insertions, 15 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4bc3cca6d..8145d677a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -33,7 +33,7 @@
 - Add option to purge deleted mails older than 30, 60 or 90 days (#5493)
 - Add ability to mark multiple messages as not deleted at once (#5133)
 - Add possibility to disable line-wrapping of sent mail body (#5101)
-- Improve auto-wrapping of plain text messages on preview and reply, don't wrap non-format=flowed content (#6974)
+- Improve/Fix wrapping of plain text messages on preview and reply (#6974, #8391, #8378, #8289)
 - Improve searching by sender/recipient headers, support Reply-To and Followup-To (#6582)
 - Add option to control links handling behavior on html to text conversion (#6485)
 - Add 'loginform_content' plugin hook (#8273, #6569)
diff --git a/program/actions/mail/index.php b/program/actions/mail/index.php
index 76f1c5da2..428329449 100644
--- a/program/actions/mail/index.php
+++ b/program/actions/mail/index.php
@@ -1066,7 +1066,6 @@ class rcmail_action_mail_index extends rcmail_action
     {
         $options = [
             'flowed'   => $flowed,
-            'wrap'     => $flowed,
             'replacer' => 'rcmail_string_replacer',
             'delsp'    => $delsp
         ];
diff --git a/program/lib/Roundcube/rcube_text2html.php b/program/lib/Roundcube/rcube_text2html.php
index 7d751b6f1..86cfc1405 100644
--- a/program/lib/Roundcube/rcube_text2html.php
+++ b/program/lib/Roundcube/rcube_text2html.php
@@ -56,7 +56,10 @@ class rcube_text2html
     ];
 
     /** @var bool Internal state */
-    protected $_converted = false;
+    protected $converted = false;
+
+    /** @var bool Internal no-wrap mode state */
+    protected $nowrap = false;
 
 
     /**
@@ -96,7 +99,7 @@ class rcube_text2html
             $this->text = $source;
         }
 
-        $this->_converted = false;
+        $this->converted = false;
     }
 
     /**
@@ -106,8 +109,8 @@ class rcube_text2html
      */
     function get_html()
     {
-        if (!$this->_converted) {
-            $this->_convert();
+        if (!$this->converted) {
+            $this->convert();
         }
 
         return $this->html;
@@ -122,13 +125,13 @@ class rcube_text2html
     }
 
     /**
-     * Workhorse function that does actual conversion (calls _converter() method).
+     * Workhorse function that does actual conversion (calls converter() method).
      */
-    protected function _convert()
+    protected function convert()
     {
         // Convert TXT to HTML
-        $this->html       = $this->_converter($this->text);
-        $this->_converted = true;
+        $this->html      = $this->converter($this->text);
+        $this->converted = true;
     }
 
     /**
@@ -138,7 +141,7 @@ class rcube_text2html
      *
      * @return string HTML content
      */
-    protected function _converter($text)
+    protected function converter($text)
     {
         // make links and email-addresses clickable
         $attribs  = ['link_attribs' => ['rel' => 'noreferrer', 'target' => '_blank']];
@@ -167,7 +170,7 @@ class rcube_text2html
             if ($first == '>' && preg_match('/^(>+ {0,1})+/', $text[$n], $regs)) {
                 $q        = substr_count($regs[0], '>');
                 $text[$n] = substr($text[$n], strlen($regs[0]));
-                $text[$n] = $this->_convert_line($text[$n]);
+                $text[$n] = $this->convert_line($text[$n]);
                 $_length  = strlen(str_replace(' ', '', $text[$n]));
 
                 if ($q > $quote_level) {
@@ -199,7 +202,7 @@ class rcube_text2html
                 }
             }
             else {
-                $text[$n] = $this->_convert_line($text[$n]);
+                $text[$n] = $this->convert_line($text[$n]);
                 $q        = 0;
                 $_length  = strlen(str_replace(' ', '', $text[$n]));
 
@@ -260,7 +263,7 @@ class rcube_text2html
      *
      * @return string Converted text
      */
-    protected function _convert_line($text)
+    protected function convert_line($text)
     {
         static $table;
 
@@ -273,16 +276,39 @@ class rcube_text2html
             $table["\t"] = '    ';
         }
 
+        // empty line?
+        if ($text === '') {
+            return $text;
+        }
+
         // skip signature separator
         if ($text == '-- ') {
             return '--' . $this->config['space'];
         }
 
+        if ($this->nowrap) {
+            if (!in_array($text[0], [' ', '-', '+', '@'])) {
+                $this->nowrap = false;
+            }
+        }
+        else {
+            // Detect start of a unified diff
+            // TODO: Support normal diffs
+            // TODO: Support diff header and comment
+            if (
+                ($text[0] === '-' && preg_match('/^--- \S+/', $text))
+                || ($text[0] === '+' && preg_match('/^\+\+\+ \S+/', $text))
+                || ($text[0] === '@' && preg_match('/^@@ [0-9 ,+-]+ @@/', $text))
+            ) {
+                $this->nowrap = true;
+            }
+        }
+
         // replace HTML special and whitespace characters
         $text = strtr($text, $table);
 
         $nbsp      = $this->config['space'];
-        $wrappable = $this->config['flowed'] || $this->config['wrap'];
+        $wrappable = !$this->nowrap && ($this->config['flowed'] || $this->config['wrap']);
 
         // make the line wrappable
         if ($wrappable) {
diff --git a/skins/elastic/styles/styles.less b/skins/elastic/styles/styles.less
index 827df9dfc..b6932edbd 100644
--- a/skins/elastic/styles/styles.less
+++ b/skins/elastic/styles/styles.less
@@ -405,6 +405,18 @@ body.task-error-login #layout {
         font-family: monospace;
         font-size: 13px;
     }
+
+    // This is needed for proper display of quoted plain text
+    blockquote {
+        display: inline-block;
+        min-width: 100%;
+
+        & + br {
+            // compensate the spacing "removed" by the inline-block style above
+            display: block;
+            margin-top: 1em;
+        }
+    }
 }
 
 #compose-attachments {
diff --git a/tests/Framework/Text2Html.php b/tests/Framework/Text2Html.php
index 619e7d03a..c035350b8 100644
--- a/tests/Framework/Text2Html.php
+++ b/tests/Framework/Text2Html.php
@@ -157,4 +157,43 @@ class Framework_Text2Html extends PHPUnit\Framework\TestCase
 
         $this->assertEquals($expected, $html);
     }
+
+    /**
+     * Test patches/diffs handling
+     */
+    function test_text2html_patches_handling()
+    {
+        $input = "Start\n"
+            . "diff --git a/test.txt b/test.txt\n"
+            . "index 7642f44b9..6ce0170aa 100644\n"
+            . "--- a/test.txt\n"
+            . "+++ b/test.txt\n"
+            . "@@ -1982,7 +1982,7 @@ class test\n"
+            . " test1\n"
+            . " test2\n"
+            . " test3\n"
+            . "-test4\n"
+            . "+test5\n"
+            . " \n"
+            . "End";
+
+        $expected = "<div class=\"pre\">Start<br>\n"
+            . "diff --git a/test.txt b/test.txt<br>\n"
+            . "index 7642f44b9..6ce0170aa 100644<br>\n"
+            . "<span style=\"white-space:nowrap\">---_a/test.txt</span><br>\n"
+            . "<span style=\"white-space:nowrap\">+++_b/test.txt</span><br>\n"
+            . "<span style=\"white-space:nowrap\">@@_-1982,7_+1982,7_@@_class_test</span><br>\n"
+            . "<span style=\"white-space:nowrap\">_test1</span><br>\n"
+            . "<span style=\"white-space:nowrap\">_test2</span><br>\n"
+            . "<span style=\"white-space:nowrap\">_test3</span><br>\n"
+            . "<span style=\"white-space:nowrap\">-test4</span><br>\n"
+            . "<span style=\"white-space:nowrap\">+test5</span><br>\n"
+            . "<span style=\"white-space:nowrap\">_</span><br>\n"
+            . "End</div>";
+
+        $t2h = new rcube_text2html($input, false, ['space' => '_']);
+        $html = $t2h->get_html();
+
+        $this->assertEquals($expected, $html);
+    }
 }