[syntax_highlight] Simplify plugin code

Fix deprecations warnings in config

9 files changed, 429 insertions, 583 deletions

diff --git a/syntax_highlight/README.md b/syntax_highlight/README.md
deleted file mode 100644
index 29f16cf..0000000
--- a/syntax_highlight/README.md
+++ /dev/null
@@ -1,123 +0,0 @@
-# Syntax Highlighting Plugin for Gajim
-
-[Gajim](https://gajim.org) Plugin that highlights source code blocks in the chat window.
-
-## Installation
-
-The recommended way of installing this plugin is to use Gajim's Plugin Installer.
-
-For more information and instruction on how to install plugins manually, please
-refer to the [Gajim Plugin Wiki site](https://dev.gajim.org/gajim/gajim-plugins/wikis/home#how-to-install-plugins).
-
-
-## Usage
-
-This plugin uses markdown-style syntax to identify which parts of a message
-should be formatted as code in the chat window.
-
-```
-Inline source code will be highlighted when placed in between `two single
-back-ticks`.
-```
-
-The language used to highlight the syntax of inline code is selected as the
-default language in the plugin settings.
-
-
-Multi-line code blocks are started by three back-ticks followed by a newline.
-Optionally, a language can be specified directly after the opening back-ticks and
-before the line break:
-````
-```language
-Note, that the last line of a code block may only contain the closing back-ticks,
-i.e. there must be a newline here.
-```
-````
-
-In case no language is specified with the opening tag or the specified language
-could not be identified, the default language configured in the settings is
-used.
-
-You can test it by copying and sending the following text to one of your
-contacts:
-````
-```python
-def test():
-    print("Hello, world!")
-```
-````
-(**Note:** your contact will not receive highlighted text unless she is also
-using the plugin.)
-
-
-## Relation to XEP-0393 - 'Message Styling'
-
-https://xmpp.org/extensions/xep-0393.html#pre-block
-
-In [XEP-0393](https://xmpp.org/extensions/xep-0393.html),
-the back-tick based syntax is defined as markup for preformatted
-text blocks, respectively inline preformatted text.
-Formatting of such text blocks with mono-spaced fonts is recommended by the XEP.
-
-By using the same syntax as defined in XEP-0393 XMPP clients with only XEP-0393
-support but without syntax highlighting can at least present their users blocks
-of preformatted text.
-
-Since text in between the back-tick markers is not further formatted by this
-plugin, it can be considered "preformatted".
-Hence, this plugin is compatible to the formatting options defined by XEP-0393,
-[section 5.1.2, "Preformatted Text"](https://xmpp.org/extensions/xep-0393.html#pre-block)
-and [section 5.2.5, "Preformatted Span"](https://xmpp.org/extensions/xep-0393.html#mono).
-
-Nevertheless, syntax highlighting for source code is not part of XEP but
-rather a non-standard extension introduced with this plugin.
-
-
-## Configuration
-
-The configuration can be found via 'Gajim' > 'Plugins', then select the
-'Source Code Syntax Highlight' Plugin and click the gears symbol.
-The configuration options let you specify many details how code is formatted,
-including default language, style, font settings, background color and formatting
-of the code markers.
-
-In the configuration window, the current settings are displayed in an
-interactive preview panel. This allows you to directly check how code would
-look like in the message
-window.
-
-## Report Bugs and Feature Requests
-
-For bug reports, please report them to the [Gajim Plugin Issue tracker](https://dev.gajim.org/gajim/gajim-plugins/issues/new?issue[FlorianMuenchbach]=&issue[description]=Gajim%20Version%3A%20%0APlugin%20Version%3A%0AOperating%20System%3A&issue[title]=[syntax_highlight]).
-
-Please make sure that the issue you create contains `[syntax_highlight]` in the
-title and information such as Gajim version, Plugin version, Operating system,
-etc.
-
-## Debug
-
-The plugin adds its own logger. It can be used to set a specific debug level
-for this plugin and/or filter log messages.
-
-Run
-```
-gajim --loglevel gajim.p.syntax_highlight=DEBUG
-```
-in a terminal to display the debug messages.
-
-
-## Known Issues / ToDo
-
- * ~~Gajim crashes when correcting a message containing highlighted code.~~
-   (fixed in version 1.1.0)
-
-
-## Credits
-
-Since I had no experience in writing Plugins for Gajim, I used the
-[Latex Plugin](https://dev.gajim.org/gajim/gajim-plugins/wikis/LatexPlugin)
-written by Yves Fischer and Yann Leboulanger as an example and copied a big
-portion of initial code. Therefore, credits go to the authors of the Latex
-Plugin for providing an example.
-
-The syntax highlighting itself is done by [pygments](http://pygments.org/).
diff --git a/syntax_highlight/chat_syntax_highlighter.py b/syntax_highlight/chat_syntax_highlighter.py
index c18cc18..338dd62 100644
--- a/syntax_highlight/chat_syntax_highlighter.py
+++ b/syntax_highlight/chat_syntax_highlighter.py
@@ -8,12 +8,22 @@ from syntax_highlight.gtkformatter import GTKFormatter
 from syntax_highlight.types import MatchType
 from syntax_highlight.types import LineBreakOptions
 from syntax_highlight.types import CodeMarkerOptions
+from syntax_highlight.types import PLUGIN_INTERNAL_NONE_LEXER_ID
 
 log = logging.getLogger('gajim.p.syntax_highlight')
 
 
 class ChatSyntaxHighlighter:
-    def hide_code_markup(self, buf, start, end):
+    def __init__(self, plugin_config, highlighter_config, textview):
+        self.textview = textview
+        self._plugin_config = plugin_config
+        self._highlighter_config = highlighter_config
+
+    def update_config(self, plugin_config):
+        self._plugin_config = plugin_config
+
+    @staticmethod
+    def _hide_code_markup(buf, start, end):
         tag = buf.get_tag_table().lookup('hide_code_markup')
         if tag is None:
             tag = Gtk.TextTag.new('hide_code_markup')
@@ -22,17 +32,16 @@ class ChatSyntaxHighlighter:
 
         buf.apply_tag_by_name('hide_code_markup', start, end)
 
-    def check_line_break(self, is_multiline):
-        line_break = self.config.get_line_break_action()
-
+    def _check_line_break(self, is_multiline):
+        line_break = self._plugin_config['line_break'].value
         return (line_break == LineBreakOptions.ALWAYS) \
             or (is_multiline and line_break == LineBreakOptions.MULTILINE)
 
-    def format_code(self, buf, s_tag, s_code, e_tag, e_code, language):
-        style = self.config.get_style_name()
-        if self.config.get_code_marker_setting() == CodeMarkerOptions.HIDE:
-            self.hide_code_markup(buf, s_tag, s_code)
-            self.hide_code_markup(buf, e_code, e_tag)
+    def _format_code(self, buf, s_tag, s_code, e_tag, e_code, language):
+        style = self._plugin_config['style']
+        if self._plugin_config['code_marker'] == CodeMarkerOptions.HIDE:
+            self._hide_code_markup(buf, s_tag, s_code)
+            self._hide_code_markup(buf, e_code, e_tag)
         else:
             comment_tag = GTKFormatter.create_tag_for_token(
                 pygments.token.Comment,
@@ -49,24 +58,25 @@ class ChatSyntaxHighlighter:
         lexer = None
 
         if language is None:
-            lexer = self.config.get_default_lexer()
+            lexer = self._highlighter_config.get_default_lexer()
             log.info('No Language specified. '
                      'Falling back to default lexer: %s.',
-                     self.config.get_default_lexer_name())
+                     self._highlighter_config.get_default_lexer_name())
         else:
             log.debug('Using lexer for %s.', str(language))
-            lexer = self.config.get_lexer_with_fallback(language)
+            lexer = self._highlighter_config.get_lexer_with_fallback(language)
 
         if lexer is None:
             iterator = buf.get_iter_at_mark(start_mark)
             buf.insert(iterator, '\n')
-        elif not self.config.is_internal_none_lexer(lexer):
+        elif lexer != PLUGIN_INTERNAL_NONE_LEXER_ID:
             tokens = pygments.lex(code, lexer)
 
             formatter = GTKFormatter(style=style, start_mark=start_mark)
             pygments.format(tokens, formatter, buf)
 
-    def find_multiline_matches(self, text):
+    @staticmethod
+    def _find_multiline_matches(text):
         start = None
         matches = []
         # Less strict, allow prefixed whitespaces:
@@ -84,7 +94,8 @@ class ChatSyntaxHighlighter:
                 continue
         return matches
 
-    def find_inline_matches(self, text):
+    @staticmethod
+    def _find_inline_matches(text):
         """
         Inline code is highlighted if the start marker is precedded by a start
         of line, a whitespace character or either of the other span markers
@@ -95,18 +106,19 @@ class ChatSyntaxHighlighter:
                 re.finditer(r'(?:^|\s|\*|~|_)(`((?!`).+?)`)(?:\s|\*|~|_|$)',
                             text)]
 
-    def merge_match_groups(self, real_text, inline_matches, multiline_matches):
+    @staticmethod
+    def _merge_match_groups(real_text, inline_matches, multiline_matches):
         it_inline = iter(inline_matches)
         it_multi = iter(multiline_matches)
         length = len(real_text)
 
         # Just to get cleaner code below...
-        def get_next(iterator):
+        def _get_next(iterator):
             return next(iterator, (length, length, ''))
 
         # In order to simplify the process, we use the 'length' here.
-        cur_inline = get_next(it_inline)
-        cur_multi = get_next(it_multi)
+        cur_inline = _get_next(it_inline)
+        cur_multi = _get_next(it_multi)
 
         pos = 0
 
@@ -142,18 +154,18 @@ class ChatSyntaxHighlighter:
             # Also, forward the other one, if regions overlap or we took over...
             if selected[2] == MatchType.INLINE:
                 if cur_multi[0] < cur_inline[1]:
-                    cur_multi = get_next(it_multi)
-                cur_inline = get_next(it_inline)
+                    cur_multi = _get_next(it_multi)
+                cur_inline = _get_next(it_inline)
             elif selected[2] == MatchType.MULTILINE:
                 if cur_inline[0] < cur_multi[1]:
-                    cur_inline = get_next(it_inline)
-                cur_multi = get_next(it_multi)
+                    cur_inline = _get_next(it_inline)
+                cur_multi = _get_next(it_multi)
 
         return parts
 
     def process_text(self, real_text, other_tags, _graphics, iter_,
-            _additional):
-        def fix_newline(char, marker_len_no_newline, force=False):
+                     _additional):
+        def _fix_newline(char, marker_len_no_newline, force=False):
             fixed = (marker_len_no_newline, '')
             if char == '\n':
                 fixed = (marker_len_no_newline + 1, '')
@@ -164,8 +176,8 @@ class ChatSyntaxHighlighter:
         buf = self.textview.tv.get_buffer()
 
         # First, try to find inline or multiline code snippets
-        inline_matches = self.find_inline_matches(real_text)
-        multiline_matches = self.find_multiline_matches(real_text)
+        inline_matches = self._find_inline_matches(real_text)
+        multiline_matches = self._find_multiline_matches(real_text)
 
         if not inline_matches and not multiline_matches:
             log.debug('Stopping early, since there is no code block in it...')
@@ -177,10 +189,10 @@ class ChatSyntaxHighlighter:
         start_mark = buf.create_mark('SHP_start', iterator, True)
         end_mark = buf.create_mark('SHP_end', iterator, False)
 
-        insert_newline_for_multiline = self.check_line_break(True)
-        insert_newline_for_inline = self.check_line_break(False)
+        insert_newline_for_multiline = self._check_line_break(True)
+        insert_newline_for_inline = self._check_line_break(False)
 
-        split_text = self.merge_match_groups(
+        split_text = self._merge_match_groups(
             real_text, inline_matches, multiline_matches)
 
         buf.begin_user_action()
@@ -204,20 +216,20 @@ class ChatSyntaxHighlighter:
                     language_len = 0 if language is None else len(language)
 
                     # We account the language word width for the front marker
-                    front = fix_newline(
+                    front = _fix_newline(
                         text_to_insert[0],
                         3 + language_len,
                         insert_newline_for_multiline)
-                    back = fix_newline(
+                    back = _fix_newline(
                         text_to_insert[-1],
                         3,
                         insert_newline_for_multiline and not end_of_message)
                 else:
-                    front = fix_newline(
+                    front = _fix_newline(
                         text_to_insert[0],
                         1,
                         insert_newline_for_inline)
-                    back = fix_newline(
+                    back = _fix_newline(
                         text_to_insert[-1],
                         1,
                         insert_newline_for_inline and not end_of_message)
@@ -226,8 +238,9 @@ class ChatSyntaxHighlighter:
                 text_to_insert = ''.join([front[1], text_to_insert, back[1]])
 
                 # Insertion invalidates iterator, let's use our start mark...
-                self.insert_and_format_code(buf, text_to_insert, language,
-                        marker_widths, start_mark, end_mark, other_tags)
+                self._insert_and_format_code(
+                    buf, text_to_insert, language, marker_widths, start_mark,
+                    end_mark, other_tags)
 
             iterator = buf.get_iter_at_mark(end_mark)
             # The current end of the buffer's contents is the start for the
@@ -244,14 +257,13 @@ class ChatSyntaxHighlighter:
         # print_special_text method is resetting the plugin_modified variable...
         self.textview.plugin_modified = True
 
-    def insert_and_format_code(self, buf, insert_text, language, marker,
-            start_mark, end_mark, other_tags=None):
+    def _insert_and_format_code(self, buf, insert_text, language, marker,
+                                start_mark, end_mark, other_tags=None):
 
         start_iter = buf.get_iter_at_mark(start_mark)
 
         if other_tags:
-            buf.insert_with_tags_by_name(start_iter, insert_text,
-                    *other_tags)
+            buf.insert_with_tags_by_name(start_iter, insert_text, *other_tags)
         else:
             buf.insert(start_iter, insert_text)
 
@@ -264,20 +276,16 @@ class ChatSyntaxHighlighter:
 
         log.debug('full text between tags: %s.', tag_start.get_text(tag_end))
 
-        self.format_code(buf, tag_start, s_code, tag_end, e_code, language)
+        self._format_code(buf, tag_start, s_code, tag_end, e_code, language)
 
         self.textview.plugin_modified = True
 
         # Set general code block format
         tag = Gtk.TextTag.new()
-        if self.config.is_bgcolor_override_enabled():
-            tag.set_property('background', self.config.get_bgcolor())
-            tag.set_property('paragraph-background', self.config.get_bgcolor())
-        tag.set_property('font', self.config.get_font())
+        bg_color = self._plugin_config['bgcolor']
+        if self._plugin_config['bgcolor_override']:
+            tag.set_property('background', bg_color)
+            tag.set_property('paragraph-background', bg_color)
+        tag.set_property('font', self._plugin_config['font'])
         buf.get_tag_table().add(tag)
         buf.apply_tag(tag, tag_start, tag_end)
-
-    def __init__(self, config, textview):
-        self.last_end_mark = None
-        self.config = config
-        self.textview = textview
diff --git a/syntax_highlight/config_dialog.py b/syntax_highlight/config_dialog.py
new file mode 100644
index 0000000..0cfc95e
--- /dev/null
+++ b/syntax_highlight/config_dialog.py
@@ -0,0 +1,206 @@
+import logging
+import re
+import math
+from pathlib import Path
+import pygments
+
+from gi.repository import Gtk
+from gi.repository import Gdk
+from gi.repository.Pango import FontDescription
+from gi.repository.Pango import Style
+from gi.repository.Pango import SCALE
+
+from gajim.common import app
+
+from gajim.plugins.plugins_i18n import _
+from gajim.plugins.helpers import get_builder
+
+from syntax_highlight.gtkformatter import GTKFormatter
+from syntax_highlight.types import LineBreakOptions
+from syntax_highlight.types import CodeMarkerOptions
+from syntax_highlight.types import PLUGIN_INTERNAL_NONE_LEXER_ID
+
+log = logging.getLogger('gajim.p.syntax_highlight')
+
+PLUGIN_INTERNAL_NONE_LEXER = ('None (monospace only)',
+                              PLUGIN_INTERNAL_NONE_LEXER_ID)
+
+
+class SyntaxHighlighterPluginConfig(Gtk.ApplicationWindow):
+    def __init__(self, plugin, transient):
+        Gtk.ApplicationWindow.__init__(self)
+        self.set_application(app.app)
+        self.set_show_menubar(False)
+        self.set_title(_('Syntax Highlighter Configuration'))
+        self.set_transient_for(transient)
+        self.set_default_size(400, 500)
+        self.set_type_hint(Gdk.WindowTypeHint.DIALOG)
+        self.set_modal(True)
+        self.set_destroy_with_parent(True)
+
+        ui_path = Path(__file__).parent
+        self._ui = get_builder(ui_path.resolve() / 'config_dialog.ui')
+        self.add(self._ui.main_box)
+        self.show_all()
+
+        self._ui.preview_textview.get_buffer().connect(
+            'insert-text', self._on_preview_text_inserted)
+        self._ui.connect_signals(self)
+
+        self._lexer_liststore = Gtk.ListStore(str)
+        self._ui.default_lexer_combobox.set_model(self._lexer_liststore)
+
+        self._style_liststore = Gtk.ListStore(str)
+        self._ui.style_combobox.set_model(self._style_liststore)
+
+        self._plugin = plugin
+        self._lexers = plugin.highlighter_config.get_lexer_list()
+        self._styles = plugin.highlighter_config.get_styles_list()
+
+        self._provider = None
+        self._add_css_provider()
+
+        self._initialize()
+
+    def _initialize(self):
+        default_lexer = self._plugin.highlighter_config.get_default_lexer_name()
+
+        for i, lexer in enumerate(self._lexers):
+            self._lexer_liststore.append([lexer[0]])
+            if lexer[1] == default_lexer:
+                self._ui.default_lexer_combobox.set_active(i)
+
+        for i, style in enumerate(self._styles):
+            self._style_liststore.append([style])
+            if style == self._plugin.config['style']:
+                self._ui.style_combobox.set_active(i)
+
+        self._ui.line_break_combobox.set_active(
+            self._plugin.config['line_break'].value)
+        self._ui.code_marker_combobox.set_active(
+            self._plugin.config['code_marker'])
+        self._ui.font_button.set_font(self._plugin.config['font'])
+
+        bg_override_enabled = self._plugin.config['bgcolor_override']
+        self._ui.bg_color_checkbutton.set_active(bg_override_enabled)
+        self._ui.bg_color_colorbutton.set_sensitive(bg_override_enabled)
+        color = Gdk.RGBA()
+        if color.parse(self._plugin.config['bgcolor']):
+            self._ui.bg_color_colorbutton.set_rgba(color)
+        self._update_preview()
+
+    def _lexer_changed(self, widget):
+        self._plugin.highlighter_config.set_default_lexer(
+            self._lexers[widget.get_active()][1])
+        self._update_preview()
+
+    def _line_break_changed(self, widget):
+        self._plugin.config['line_break'] = LineBreakOptions(
+            widget.get_active())
+        self._update_preview()
+
+    def _code_marker_changed(self, widget):
+        self._plugin.config['code_marker'] = CodeMarkerOptions(
+            widget.get_active())
+
+    def _bg_color_enabled(self, widget):
+        override_color = widget.get_active()
+        self._plugin.config['bgcolor_override'] = override_color
+        self._ui.bg_color_colorbutton.set_sensitive(override_color)
+        self._update_preview()
+
+    def _bg_color_changed(self, widget):
+        color = widget.get_rgba()
+        self._plugin.config['bgcolor'] = color.to_string()
+        self._update_preview()
+
+    def _style_changed(self, widget):
+        style = self._styles[widget.get_active()]
+        if style is not None and style != '':
+            self._plugin.config['style'] = style
+        self._update_preview()
+
+    def _font_changed(self, widget):
+        font = widget.get_font()
+        if font is not None and font != '':
+            self._plugin.config['font'] = font
+        self._update_preview()
+
+    def _update_preview(self):
+        self._format_preview_text()
+
+    def _on_preview_text_inserted(self, _buf, _iterator, text, length, *_args):
+        if (length == 1 and re.match(r'\s', text)) or length > 1:
+            self._format_preview_text()
+
+    def _add_css_provider(self):
+        self._context = self._ui.preview_textview.get_style_context()
+        self._provider = Gtk.CssProvider()
+        self._context.add_provider(
+            self._provider, Gtk.STYLE_PROVIDER_PRIORITY_USER)
+        self._context.add_class('syntax-preview')
+
+    def _format_preview_text(self):
+        buf = self._ui.preview_textview.get_buffer()
+        start_iter = buf.get_start_iter()
+        start_mark = buf.create_mark(None, start_iter, True)
+        buf.remove_all_tags(start_iter, buf.get_end_iter())
+
+        formatter = GTKFormatter(
+            style=self._plugin.config['style'], start_mark=start_mark)
+
+        code = start_iter.get_text(buf.get_end_iter())
+        lexer = self._plugin.highlighter_config.get_default_lexer()
+        if lexer != PLUGIN_INTERNAL_NONE_LEXER_ID:
+            tokens = pygments.lex(code, lexer)
+            pygments.format(tokens, formatter, buf)
+
+        buf.delete_mark(start_mark)
+        css = self._get_css()
+        self._provider.load_from_data(bytes(css.encode()))
+
+    def _get_css(self):
+        # Build CSS from Pango.FontDescription
+        description = FontDescription.from_string(self._plugin.config['font'])
+        size = description.get_size() / SCALE
+        style = self._get_string_from_pango_style(description.get_style())
+        weight = self._pango_to_css_weight(int(description.get_weight()))
+        family = description.get_family()
+        font = '%spt %s' % (size, family)
+
+        if self._plugin.config['bgcolor_override']:
+            color = self._plugin.config['bgcolor']
+        else:
+            color = '@theme_base_color'
+
+        css = '''
+        .syntax-preview {
+            font: %s;
+            font-weight: %s;
+            font-style: %s;
+        }
+        .syntax-preview > text {
+            background-color: %s;
+        }
+        ''' % (font, weight, style, color)
+        return css
+
+    @staticmethod
+    def _pango_to_css_weight(number):
+        # Pango allows for weight values between 100 and 1000
+        # CSS allows only full hundred numbers like 100, 200 ..
+        number = int(number)
+        if number < 100:
+            return 100
+        if number > 900:
+            return 900
+        return int(math.ceil(number / 100.0)) * 100
+
+    @staticmethod
+    def _get_string_from_pango_style(style: Style) -> str:
+        if style == Style.NORMAL:
+            return 'normal'
+        if style == Style.ITALIC:
+            return 'italic'
+        # Style.OBLIQUE:
+        return 'oblique'
diff --git a/syntax_highlight/config_dialog.ui b/syntax_highlight/config_dialog.ui
index 64328d3..09a2764 100644
--- a/syntax_highlight/config_dialog.ui
+++ b/syntax_highlight/config_dialog.ui
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<!-- Generated with glade 3.22.1 -->
+<!-- Generated with glade 3.36.0 -->
 <interface>
-  <requires lib="gtk+" version="3.20"/>
+  <requires lib="gtk+" version="3.22"/>
   <object class="GtkTextBuffer"/>
   <object class="GtkListStore" id="code_marker_selection">
     <columns>
@@ -309,7 +309,4 @@
       </packing>
     </child>
   </object>
-  <object class="GtkTextBuffer" id="textbuffer1">
-    <property name="text">Plug-in decription should be displayed here. This text will be erased during PluginsWindow initialization.</property>
-  </object>
 </interface>
diff --git a/syntax_highlight/gtkformatter.py b/syntax_highlight/gtkformatter.py
index d7347f0..823f1ad 100644
--- a/syntax_highlight/gtkformatter.py
+++ b/syntax_highlight/gtkformatter.py
@@ -67,7 +67,7 @@ class GTKFormatter(Formatter):
 
     def format(self, tokensource, outfile):
         if not isinstance(outfile, Gtk.TextBuffer) or outfile is None:
-            log.warn("Did not get a buffer to format...")
+            log.warning('Did not get a buffer to format...')
             return
         buf = outfile
 
diff --git a/syntax_highlight/highlighter_config.py b/syntax_highlight/highlighter_config.py
new file mode 100644
index 0000000..061ccee
--- /dev/null
+++ b/syntax_highlight/highlighter_config.py
@@ -0,0 +1,97 @@
+import logging
+
+from pygments.lexers import get_lexer_by_name
+from pygments.lexers import get_all_lexers
+from pygments.styles import get_all_styles
+from pygments.util import ClassNotFound
+
+from syntax_highlight.types import PLUGIN_INTERNAL_NONE_LEXER_ID
+
+log = logging.getLogger('gajim.p.syntax_highlight')
+PLUGIN_INTERNAL_NONE_LEXER = ('None (monospace only)',
+                              PLUGIN_INTERNAL_NONE_LEXER_ID)
+
+
+class HighlighterConfig:
+    def __init__(self, plugin_config):
+        self._plugin_config = plugin_config
+
+        self._lexer_list = self._create_lexer_list()
+        self._style_list = []
+        for style in get_all_styles():
+            self._style_list.append(style)
+        self._style_list.sort()
+
+        self._default_lexer = None
+        self.set_default_lexer(self._plugin_config['default_lexer'])
+
+    @staticmethod
+    def _create_lexer_list():
+        # The list we create here contains the plain text name and the lexer's
+        # id string
+        lexers = []
+
+        # Iteration over get_all_lexers() seems to be broken somehow
+        # Workaround
+        all_lexers = get_all_lexers()
+        for lexer in all_lexers:
+            # We don't want to add lexers that we cant identify by name later
+            if lexer[1] is not None and lexer[1]:
+                lexers.append((lexer[0], lexer[1][0]))
+        lexers.sort()
+
+        # Insert our internal 'none' type at top of the list
+        lexers.insert(0, PLUGIN_INTERNAL_NONE_LEXER)
+        return lexers
+
+    @staticmethod
+    def get_lexer_by_name(name):
+        lexer = None
+        try:
+            lexer = get_lexer_by_name(name)
+        except ClassNotFound:
+            pass
+        return lexer
+
+    def get_lexer_with_fallback(self, language):
+        lexer = self.get_lexer_by_name(language)
+        if lexer is None:
+            log.info('Falling back to default lexer for %s.',
+                     self.get_default_lexer_name())
+            lexer = self._default_lexer[1]
+        return lexer
+
+    def set_default_lexer(self, name):
+        if name != PLUGIN_INTERNAL_NONE_LEXER_ID:
+            lexer = get_lexer_by_name(name)
+
+            if lexer is None and self._default_lexer is None:
+                log.error('Failed to get default lexer by name.'
+                          'Falling back to simply using the first lexer '
+                          'in the list.')
+                lexer = self._lexer_list[0]
+                name = lexer[0]
+                self._default_lexer = (name, lexer)
+            if lexer is None and self._default_lexer is not None:
+                log.info('Failed to get default lexer by name, keeping '
+                         'previous setting (lexer = %s).',
+                         self._default_lexer[0])
+                name = self._default_lexer[0]
+            else:
+                self._default_lexer = (name, lexer)
+        else:
+            self._default_lexer = PLUGIN_INTERNAL_NONE_LEXER
+
+        self._plugin_config['default_lexer'] = name
+
+    def get_default_lexer(self):
+        return self._default_lexer[1]
+
+    def get_default_lexer_name(self):
+        return self._default_lexer[0]
+
+    def get_lexer_list(self):
+        return self._lexer_list
+
+    def get_styles_list(self):
+        return self._style_list
diff --git a/syntax_highlight/plugin_config.py b/syntax_highlight/plugin_config.py
deleted file mode 100644
index ebed683..0000000
--- a/syntax_highlight/plugin_config.py
+++ /dev/null
@@ -1,168 +0,0 @@
-import logging
-
-from gi.repository import Gdk
-
-from pygments.lexers import get_lexer_by_name
-from pygments.lexers import get_all_lexers
-from pygments.styles import get_all_styles
-from pygments.util import ClassNotFound
-
-from syntax_highlight.types import LineBreakOptions
-from syntax_highlight.types import CodeMarkerOptions
-from syntax_highlight.types import PLUGIN_INTERNAL_NONE_LEXER_ID
-
-log = logging.getLogger('gajim.p.syntax_highlight')
-
-
-class SyntaxHighlighterConfig:
-    PLUGIN_INTERNAL_NONE_LEXER = ('None (monospace only)',
-                                  PLUGIN_INTERNAL_NONE_LEXER_ID)
-
-    def _create_lexer_list(self):
-        # The list we create here contains the plain text name and the lexer's
-        # id string
-        lexers = []
-
-        # Iteration over get_all_lexers() seems to be broken somehow
-        # Workaround
-        all_lexers = get_all_lexers()
-        for lexer in all_lexers:
-            # We don't want to add lexers that we cant identify by name later
-            if lexer[1] is not None and lexer[1]:
-                lexers.append((lexer[0], lexer[1][0]))
-        lexers.sort()
-
-        # Insert our internal 'none' type at top of the list
-        lexers.insert(0, self.PLUGIN_INTERNAL_NONE_LEXER)
-        return lexers
-
-    def is_internal_none_lexer(self, lexer):
-        return lexer == PLUGIN_INTERNAL_NONE_LEXER_ID
-
-    def get_internal_none_lexer(self):
-        return self.PLUGIN_INTERNAL_NONE_LEXER
-
-    def get_lexer_by_name(self, name):
-        lexer = None
-        try:
-            lexer = get_lexer_by_name(name)
-        except ClassNotFound:
-            pass
-        return lexer
-
-    def get_lexer_with_fallback(self, language):
-        lexer = self.get_lexer_by_name(language)
-        if lexer is None:
-            log.info('Falling back to default lexer for %s.',
-                     self.get_default_lexer_name())
-            lexer = self.default_lexer[1]
-        return lexer
-
-    def set_font(self, font):
-        if font is not None and font != '':
-            self.config['font'] = font
-
-    def set_style(self, style):
-        if style is not None and style != '':
-            self.config['style'] = style
-
-    def set_line_break_action(self, option):
-        if isinstance(option, int):
-            option = LineBreakOptions(option)
-        self.config['line_break'] = option
-
-    def set_default_lexer(self, name):
-        if not self.is_internal_none_lexer(name):
-            lexer = get_lexer_by_name(name)
-
-            if lexer is None and self.default_lexer is None:
-                log.error('Failed to get default lexer by name.'
-                          'Falling back to simply using the first lexer '
-                          'in the list.')
-                lexer = self.lexer_list[0]
-                name = lexer[0]
-                self.default_lexer = (name, lexer)
-            if lexer is None and self.default_lexer is not None:
-                log.info('Failed to get default lexer by name, keeping '
-                         'previous setting (lexer = %s).',
-                         self.default_lexer[0])
-                name = self.default_lexer[0]
-            else:
-                self.default_lexer = (name, lexer)
-        else:
-            self.default_lexer = self.PLUGIN_INTERNAL_NONE_LEXER
-
-        self.config['default_lexer'] = name
-
-    def set_bgcolor_override_enabled(self, state):
-        self.config['bgcolor_override'] = state
-
-    def set_bgcolor(self, color):
-        if isinstance(color, Gdk.RGBA):
-            color = color.to_string()
-        self.config['bgcolor'] = color
-
-    def set_code_marker_setting(self, option):
-        if isinstance(option, int):
-            option = CodeMarkerOptions(option)
-        self.config['code_marker'] = option
-
-    def set_pygments_path(self, path):
-        self.config['pygments_path'] = path
-
-    def get_default_lexer(self):
-        return self.default_lexer[1]
-
-    def get_default_lexer_name(self):
-        return self.default_lexer[0]
-
-    def get_lexer_list(self):
-        return self.lexer_list
-
-    def get_line_break_action(self):
-        # Return int only
-        if isinstance(self.config['line_break'], int):
-            # In case of legacy settings, convert.
-            action = self.config['line_break']
-            self.set_line_break_action(action)
-        else:
-            action = self.config['line_break'].value
-
-        return action
-
-    def get_pygments_path(self):
-        return self.config['pygments_path']
-
-    def get_font(self):
-        return self.config['font']
-
-    def get_style_name(self):
-        return self.config['style']
-
-    def is_bgcolor_override_enabled(self):
-        return self.config['bgcolor_override']
-
-    def get_bgcolor(self):
-        return self.config['bgcolor']
-
-    def get_code_marker_setting(self):
-        return self.config['code_marker']
-
-    def get_styles_list(self):
-        return self.style_list
-
-    def init_pygments(self):
-        """
-        Initialize all config variables that depend directly on pygments being
-        available.
-        """
-        self.lexer_list = self._create_lexer_list()
-        self.style_list = [s for s in get_all_styles()]
-        self.style_list.sort()
-        self.set_default_lexer(self.config['default_lexer'])
-
-    def __init__(self, config):
-        self.lexer_list = []
-        self.style_list = []
-        self.config = config
-        self.default_lexer = None
diff --git a/syntax_highlight/plugin_config_dialog.py b/syntax_highlight/plugin_config_dialog.py
deleted file mode 100644
index c33e2b1..0000000
--- a/syntax_highlight/plugin_config_dialog.py
+++ /dev/null
@@ -1,151 +0,0 @@
-import re
-import pygments
-
-from gi.repository import Gtk
-from gi.repository import Gdk
-from gi.repository.Pango import FontDescription
-
-from gajim.plugins.gui import GajimPluginConfigDialog
-from gajim.plugins.helpers import get_builder
-
-from syntax_highlight.gtkformatter import GTKFormatter
-from syntax_highlight.types import LineBreakOptions
-from syntax_highlight.types import CodeMarkerOptions
-
-
-class SyntaxHighlighterPluginConfiguration(GajimPluginConfigDialog):
-    def init(self):
-        path = self.plugin.local_file_path('config_dialog.ui')
-        self._ui = get_builder(path)
-        box = self.get_content_area()
-        box.pack_start(self._ui.main_box, True, True, 0)
-
-        self._ui.set_translation_domain('gajim_plugins')
-
-        self.liststore = Gtk.ListStore(str)
-        self._ui.default_lexer_combobox.set_model(self.liststore)
-
-        self.style_liststore = Gtk.ListStore(str)
-        self._ui.style_combobox.set_model(self.style_liststore)
-
-        self._ui.preview_textview.get_buffer().connect(
-            'insert-text', self._on_preview_text_inserted)
-
-        self._ui.connect_signals(self)
-
-        self.default_lexer_id = 0
-        self.style_id = 0
-
-    def set_config(self, config):
-        self.config = config
-        self.lexers = self.config.get_lexer_list()
-        self.styles = self.config.get_styles_list()
-        default_lexer = self.config.get_default_lexer_name()
-        default_style = self.config.get_style_name()
-
-        for i, lexer in enumerate(self.lexers):
-            self.liststore.append([lexer[0]])
-            if lexer[1] == default_lexer:
-                self.default_lexer_id = i
-
-        for i, style in enumerate(self.styles):
-            self.style_liststore.append([style])
-            if style == default_style:
-                self.style_id = i
-        self._update_preview()
-
-    def _lexer_changed(self, _widget):
-        new = self._ui.default_lexer_combobox.get_active()
-        if new != self.default_lexer_id:
-            self.default_lexer_id = new
-            self.config.set_default_lexer(self.lexers[self.default_lexer_id][1])
-            self._update_preview()
-
-    def _line_break_changed(self, _widget):
-        new = LineBreakOptions(self._ui.line_break_combobox.get_active())
-        if new != self.config.get_line_break_action():
-            self.config.set_line_break_action(new)
-            self._update_preview()
-
-    def _code_marker_changed(self, _widget):
-        new = CodeMarkerOptions(self._ui.code_marker_combobox.get_active())
-        if new != self.config.get_code_marker_setting():
-            self.config.set_code_marker_setting(new)
-
-    def _bg_color_enabled(self, _widget):
-        new = self._ui.bg_color_checkbutton.get_active()
-        if new != self.config.is_bgcolor_override_enabled():
-            bg_override_enabled = new
-            self.config.set_bgcolor_override_enabled(bg_override_enabled)
-            self._ui.bg_color_colorbutton.set_sensitive(bg_override_enabled)
-            self._update_preview()
-
-    def _bg_color_changed(self, _widget):
-        new = self._ui.bg_color_colorbutton.get_rgba()
-        if new != self.config.get_bgcolor():
-            self.config.set_bgcolor(new)
-            self._update_preview()
-
-    def _style_changed(self, _widget):
-        new = self._ui.style_combobox.get_active()
-        if new != self.style_id:
-            self.style_id = new
-            self.config.set_style(self.styles[self.style_id])
-            self._update_preview()
-
-    def _font_changed(self, _widget):
-        new = self._ui.font_button.get_font()
-        if new != self.config.get_font():
-            self.config.set_font(new)
-            self._update_preview()
-
-    def _update_preview(self):
-        self._format_preview_text()
-
-    def _on_preview_text_inserted(self, _buf, _iterator, text, length, *_args):
-        if (length == 1 and re.match(r'\s', text)) or length > 1:
-            self._format_preview_text()
-
-    def _format_preview_text(self):
-        buf = self._ui.preview_textview.get_buffer()
-        start_iter = buf.get_start_iter()
-        start_mark = buf.create_mark(None, start_iter, True)
-        buf.remove_all_tags(start_iter, buf.get_end_iter())
-
-        formatter = GTKFormatter(
-            style=self.config.get_style_name(), start_mark=start_mark)
-
-        code = start_iter.get_text(buf.get_end_iter())
-        lexer = self.config.get_default_lexer()
-        if not self.config.is_internal_none_lexer(lexer):
-            tokens = pygments.lex(code, lexer)
-            pygments.format(tokens, formatter, buf)
-
-        buf.delete_mark(start_mark)
-
-        self._ui.preview_textview.override_font(
-            FontDescription.from_string(self.config.get_font()))
-
-        color = Gdk.RGBA()
-        if color.parse(self.config.get_bgcolor()):
-            self._ui.preview_textview.override_background_color(
-                Gtk.StateFlags.NORMAL, color)
-
-    def on_run(self):
-        self._ui.default_lexer_combobox.set_active(self.default_lexer_id)
-        self._ui.line_break_combobox.set_active(
-            self.config.get_line_break_action())
-        self._ui.code_marker_combobox.set_active(
-            self.config.get_code_marker_setting())
-        self._ui.style_combobox.set_active(self.style_id)
-
-        self._ui.font_button.set_font(self.config.get_font())
-
-        bg_override_enabled = self.config.is_bgcolor_override_enabled()
-        self._ui.bg_color_checkbutton.set_active(bg_override_enabled)
-
-        self._ui.bg_color_colorbutton.set_sensitive(bg_override_enabled)
-
-        color = Gdk.RGBA()
-        if color.parse(self.config.get_bgcolor()):
-            self._ui.bg_color_colorbutton.set_rgba(color)
diff --git a/syntax_highlight/syntax_highlight.py b/syntax_highlight/syntax_highlight.py
index c041d02..00190c8 100644
--- a/syntax_highlight/syntax_highlight.py
+++ b/syntax_highlight/syntax_highlight.py
@@ -1,111 +1,91 @@
 import logging
-import sys
+from functools import partial
 
 from gajim.plugins import GajimPlugin
+from gajim.plugins.plugins_i18n import _
 
 from syntax_highlight.types import LineBreakOptions
 from syntax_highlight.types import CodeMarkerOptions
 from syntax_highlight.types import PLUGIN_INTERNAL_NONE_LEXER_ID
-if sys.version_info >= (3, 4):
-    from importlib.util import find_spec as find_module
-else:
-    from importlib import find_loader as find_module
-
-PYGMENTS_MISSING = 'You are missing Python-Pygments.'
 
 log = logging.getLogger('gajim.p.syntax_highlight')
 
-
-def try_loading_pygments():
-    success = find_module('pygments') is not None
-    if success:
-        try:
-            from syntax_highlight.chat_syntax_highlighter import \
-                ChatSyntaxHighlighter
-            from syntax_highlight.plugin_config_dialog import \
-                SyntaxHighlighterPluginConfiguration
-            from syntax_highlight.plugin_config import SyntaxHighlighterConfig
-            global SyntaxHighlighterPluginConfiguration
-            global ChatSyntaxHighlighter
-            global SyntaxHighlighterConfig
-            success = True
-            log.debug("pygments loaded.")
-        except Exception as exception:
-            log.error("Import Error: %s.", exception)
-            success = False
-
-    return success
+HAS_PYGMENTS = False
+try:
+    from syntax_highlight.chat_syntax_highlighter import ChatSyntaxHighlighter
+    from syntax_highlight.config_dialog import SyntaxHighlighterPluginConfig
+    from syntax_highlight.highlighter_config import HighlighterConfig
+    HAS_PYGMENTS = True
+except Exception as exception:
+    log.error('Could not load pygments: %s', exception)
 
 
 class SyntaxHighlighterPlugin(GajimPlugin):
-    def on_connect_with_chat_control(self, chat_control):
-        account = chat_control.contact.account.name
-        jid = chat_control.contact.jid
-        if account not in self.ccontrol:
-            self.ccontrol[account] = {}
-        self.ccontrol[account][jid] = ChatSyntaxHighlighter(
-            self.conf, chat_control.conv_textview)
-
-    def on_disconnect_from_chat_control(self, chat_control):
-        account = chat_control.contact.account.name
-        jid = chat_control.contact.jid
-        del self.ccontrol[account][jid]
-
-    def on_print_real_text(self, text_view, real_text, other_tags, graphics,
-            iterator, additional):
-        account = text_view.account
-        for jid in self.ccontrol[account]:
-            if self.ccontrol[account][jid].textview != text_view:
-                continue
-            self.ccontrol[account][jid].process_text(
-                real_text, other_tags, graphics, iterator, additional)
-            return
-
-    def try_init(self):
-        """
-        Separating this part of the initialization from the init() method
-        allows repeating this step again, without reloading the plugin,
-        i.e. restarting Gajim for instance.
-        Doing so allows resolving the dependency issues without restart :)
-        """
-        pygments_loaded = try_loading_pygments()
-        if not pygments_loaded:
-            return False
-
-        self.activatable = True
-        self.available_text = None
-        self.config_dialog = SyntaxHighlighterPluginConfiguration(self)
-
-        self.conf = SyntaxHighlighterConfig(self.config)
-        # The following initialization requires pygments to be available.
-        self.conf.init_pygments()
-
-        self.config_dialog = SyntaxHighlighterPluginConfiguration(self)
-        self.config_dialog.set_config(self.conf)
-
-        self.gui_extension_points = {
-            'chat_control_base': (
-                self.on_connect_with_chat_control,
-                self.on_disconnect_from_chat_control),
-            'print_real_text': (self.on_print_real_text, None), }
-        return True
-
     def init(self):
-        self.ccontrol = {}
+        self.description = _(
+            'Source code syntax highlighting in the chat window.\n\n'
+            'Markdown-style syntax is supported, i.e. text inbetween '
+            '`single backticks` is rendered as inline code.\n'
+            '```language\n'
+            'selection is possible in multi-line code snippets inbetween '
+            'triple-backticks\n'
+            'Note the newlines in this case…\n'
+            '```\n\n'
+            'Changed settings will take effect after re-opening the message '
+            'tab/window.')
 
         self.config_default_values = {
             'default_lexer': (PLUGIN_INTERNAL_NONE_LEXER_ID, ''),
             'line_break': (LineBreakOptions.MULTILINE, ''),
             'style': ('default', ''),
             'font': ('Monospace 10', ''),
-            'bgcolor': ('#ccc', ''),
+            'bgcolor': ('rgb(200, 200, 200)', ''),
             'bgcolor_override': (True, ''),
             'code_marker': (CodeMarkerOptions.AS_COMMENT, ''),
-            'pygments_path': (None, ''), }
+        }
 
-        is_initialized = self.try_init()
+        self.gui_extension_points = {
+            'chat_control_base': (
+                self._connect_chat_control,
+                self._disconnect_chat_control),
+            'print_real_text': (self._on_print_real_text, None)
+        }
 
-        if not is_initialized:
+        if not HAS_PYGMENTS:
             self.activatable = False
-            self.available_text = PYGMENTS_MISSING
+            self.available_text = _('You are missing python-pygments.')
             self.config_dialog = None
+
+        self._migrate_settings()
+        self._highlighters = {}
+        self.config_dialog = partial(SyntaxHighlighterPluginConfig, self)
+        self.highlighter_config = HighlighterConfig(self.config)
+
+    def _migrate_settings(self):
+        line_break = self.config['line_break']
+        if isinstance(line_break, int):
+            self.config['line_break'] = LineBreakOptions(line_break)
+
+    def _connect_chat_control(self, chat_control):
+        highlighter = ChatSyntaxHighlighter(
+            self.config, self.highlighter_config, chat_control.conv_textview)
+        self._highlighters[chat_control.control_id] = highlighter
+
+    def _disconnect_chat_control(self, chat_control):
+        highlighter = self._highlighters.get(chat_control.control_id)
+        if highlighter is not None:
+            del highlighter
+            self._highlighters.pop(chat_control.control_id, None)
+
+    def _on_print_real_text(self, text_view, real_text, other_tags, graphics,
+                            iterator, additional):
+        for highlighter in self._highlighters.values():
+            if highlighter.textview != text_view:
+                continue
+            highlighter.process_text(
+                real_text, other_tags, graphics, iterator, additional)
+            return
+
+    def update_highlighters(self):
+        for highlighter in self._highlighters.values():
+            highlighter.update_config(self.config)