Process plain text TABs, refactoring

app/src/main/java/eu/faircode/email/HtmlHelper.java

@@ -71,6 +71,7 @@ public class HtmlHelper {
     private static final int PREVIEW_SIZE = 500; // characters
 
     private static final float MIN_LUMINANCE = 0.5f;
+    private static final int TAB_SIZE = 2;
     private static final int MAX_AUTO_LINK = 250;
     private static final int TRACKING_PIXEL_SURFACE = 25; // pixels
 
@@ -266,31 +267,68 @@ public class HtmlHelper {
 
         // Pre formatted text
         for (Element pre : document.select("pre")) {
-            Element div = document.createElement("font");
-            div.attr("face", "monospace");
-
+            int level = 0;
+            StringBuilder sb = new StringBuilder();
             String[] lines = pre.wholeText().split("\\r?\\n");
             for (String line : lines) {
+                // Opening quotes
+                int tlevel = 0;
+                while (line.startsWith(">")) {
+                    tlevel++;
+                    if (tlevel > level)
+                        sb.append("<blockquote>");
+
+                    line = line.substring(1); // >
+
+                    if (line.startsWith(" "))
+                        line = line.substring(1);
+                }
+
+                // Closing quotes
+                for (int i = 0; i < level - tlevel; i++)
+                    sb.append("</blockquote>");
+                level = tlevel;
+
+                // Tabs characters
+                StringBuilder l = new StringBuilder();
+                for (int j = 0; j < line.length(); j++) {
+                    char kar = line.charAt(j);
+                    if (kar == '\t') {
+                        l.append(' ');
+                        while (l.length() % TAB_SIZE != 0)
+                            l.append(' ');
+                    } else
+                        l.append(kar);
+                }
+                line = l.toString();
+
+                // Html characters
                 line = Html.escapeHtml(line);
 
-                StringBuilder sb = new StringBuilder();
+                // Space characters
                 int len = line.length();
                 for (int j = 0; j < len; j++) {
                     char kar = line.charAt(j);
-                    if (kar == ' ' &&
-                            j + 1 < len && line.charAt(j + 1) == ' ')
-                        sb.append("&nbsp;");
-                    else
+                    if (kar == ' ') {
+                        // Prevent trimming start
+                        // Keep one space for word wrapping
+                        if (j == 0 || (j + 1 < len && line.charAt(j + 1) == ' '))
+                            sb.append("&nbsp;");
+                        else
+                            sb.append(' ');
+                    } else
                         sb.append(kar);
                 }
 
-                Element span = document.createElement("span");
-                span.html(sb.toString());
-                div.appendChild(span);
-                div.appendElement("br");
+                sb.append("<br>");
             }
 
-            pre.replaceWith(div);
+            // Closing quotes
+            for (int i = 0; i < level; i++)
+                sb.append("</blockquote>");
+
+            pre.tagName("tt"); // monospace
+            pre.html(sb.toString());
         }
 
         // Code

app/src/main/java/eu/faircode/email/MessageHelper.java

@@ -23,7 +23,6 @@ import android.content.Context;
 import android.content.SharedPreferences;
 import android.net.MailTo;
 import android.net.Uri;
-import android.text.Html;
 import android.text.TextUtils;
 
 import androidx.preference.PreferenceManager;
@@ -1041,60 +1040,8 @@ public class MessageHelper {
                 warnings.add(Helper.formatThrowable(ex, false));
             }
 
-            // Prevent Jsoup throwing an exception
-            if (part == plain) {
-                StringBuilder sb = new StringBuilder();
-                sb.append("<span>");
-
-                int level = 0;
-                String[] lines = result.split("\\r?\\n");
-                for (String line : lines) {
-                    // Opening quotes
-                    int tlevel = 0;
-                    while (line.startsWith(">")) {
-                        tlevel++;
-                        if (tlevel > level)
-                            sb.append("<blockquote>");
-
-                        line = line.substring(1); // >
-
-                        if (line.startsWith(" "))
-                            line = line.substring(1);
-                    }
-
-                    // Closing quotes
-                    for (int i = 0; i < level - tlevel; i++)
-                        sb.append("</blockquote>");
-                    level = tlevel;
-
-                    // Show as-is
-                    line = Html.escapeHtml(line);
-
-                    // Non breaking spaces
-                    boolean start = true;
-                    int len = line.length();
-                    for (int j = 0; j < len; j++) {
-                        char kar = line.charAt(j);
-                        if (kar == ' ' &&
-                                (start || j + 1 < len && line.charAt(j + 1) == ' '))
-                            sb.append("&nbsp;");
-                        else {
-                            start = false;
-                            sb.append(kar);
-                        }
-                    }
-
-                    sb.append("<br>");
-                }
-
-                // Closing quotes
-                for (int i = 0; i < level; i++)
-                    sb.append("</blockquote>");
-
-                sb.append("</span>");
-
-                result = sb.toString();
-            }
+            if (part == plain)
+                result = "<pre>" + result + "</pre>";
 
             return result;
         }