From 6806cff2d5f8c57c7ca422691c2b4f01d88d4424 Mon Sep 17 00:00:00 2001
From: Matt Westcott <matt@west.co.tt>
Date: Mon, 4 Dec 2017 02:03:05 +0000
Subject: [PATCH] Add skeleton DraftailRichTextArea, with provision for
 converting from dbHTML to contentstate

---
 .../rich_text/converters/contentstate.py      |  12 +
 .../converters/contentstate_models.py         |  88 +++++++
 .../converters/html_to_contentstate.py        | 238 ++++++++++++++++++
 wagtail/admin/rich_text/editors/draftail.py   |  37 +++
 4 files changed, 375 insertions(+)
 create mode 100644 wagtail/admin/rich_text/converters/contentstate.py
 create mode 100644 wagtail/admin/rich_text/converters/contentstate_models.py
 create mode 100644 wagtail/admin/rich_text/converters/html_to_contentstate.py
 create mode 100644 wagtail/admin/rich_text/editors/draftail.py

diff --git a/wagtail/admin/rich_text/converters/contentstate.py b/wagtail/admin/rich_text/converters/contentstate.py
new file mode 100644
index 000000000..fb9c040d9
--- /dev/null
+++ b/wagtail/admin/rich_text/converters/contentstate.py
@@ -0,0 +1,12 @@
+from wagtail.admin.rich_text.converters.html_to_contentstate import HtmlToContentStateHandler
+
+
+class ContentstateConverter():
+    def __init__(self, features=None):
+        self.features = features
+        self.html_to_contentstate_handler = HtmlToContentStateHandler(features)
+
+    def from_database_format(self, html):
+        self.html_to_contentstate_handler.reset()
+        self.html_to_contentstate_handler.feed(html)
+        return self.html_to_contentstate_handler.contentstate.as_json(indent=4, separators=(',', ': '))
diff --git a/wagtail/admin/rich_text/converters/contentstate_models.py b/wagtail/admin/rich_text/converters/contentstate_models.py
new file mode 100644
index 000000000..68425819a
--- /dev/null
+++ b/wagtail/admin/rich_text/converters/contentstate_models.py
@@ -0,0 +1,88 @@
+import json
+import random
+import string
+
+
+class Block(object):
+    def __init__(self, typ, depth=0):
+        self.type = typ
+        self.depth = depth
+        self.text = ""
+        self.key = ''.join(random.choice(string.ascii_lowercase + string.digits) for _ in range(5))
+        self.inline_style_ranges = []
+        self.entity_ranges = []
+
+    def as_dict(self):
+        return {
+            'key': self.key,
+            'type': self.type,
+            'depth': self.depth,
+            'text': self.text,
+            'inlineStyleRanges': [isr.as_dict() for isr in self.inline_style_ranges],
+            'entityRanges': [er.as_dict() for er in self.entity_ranges],
+        }
+
+
+class InlineStyleRange(object):
+    def __init__(self, style):
+        self.style = style
+        self.offset = None
+        self.length = None
+
+    def as_dict(self):
+        return {
+            'offset': self.offset,
+            'length': self.length,
+            'style': self.style,
+        }
+
+
+class Entity(object):
+    def __init__(self, entity_type, mutability, data):
+        self.entity_type = entity_type
+        self.mutability = mutability
+        self.data = data
+
+    def as_dict(self):
+        return {
+            'mutability': self.mutability,
+            'type': self.entity_type,
+            'data': self.data,
+        }
+
+
+class EntityRange(object):
+    def __init__(self, key):
+        self.key = key
+        self.offset = None
+        self.length = None
+
+    def as_dict(self):
+        return {
+            'key': self.key,
+            'offset': self.offset,
+            'length': self.length,
+        }
+
+
+class ContentState(object):
+    """Pythonic representation of a draft.js contentState structure"""
+    def __init__(self):
+        self.blocks = []
+        self.entity_count = 0
+        self.entity_map = {}
+
+    def add_entity(self, entity):
+        key = self.entity_count
+        self.entity_map[key] = entity
+        self.entity_count += 1
+        return key
+
+    def as_dict(self):
+        return {
+            'blocks': [block.as_dict() for block in self.blocks],
+            'entityMap': {key: entity.as_dict() for (key, entity) in self.entity_map.items()},
+        }
+
+    def as_json(self, **kwargs):
+        return json.dumps(self.as_dict(), **kwargs)
diff --git a/wagtail/admin/rich_text/converters/html_to_contentstate.py b/wagtail/admin/rich_text/converters/html_to_contentstate.py
new file mode 100644
index 000000000..a2b9bfee3
--- /dev/null
+++ b/wagtail/admin/rich_text/converters/html_to_contentstate.py
@@ -0,0 +1,238 @@
+from html.parser import HTMLParser
+
+from wagtail.admin.rich_text.converters.contentstate_models import (
+    Block, ContentState, Entity, EntityRange, InlineStyleRange
+)
+
+
+class HandlerState(object):
+    def __init__(self):
+        self.current_block = None
+        self.current_inline_styles = []
+        self.current_entity_ranges = []
+        self.depth = 0
+        self.list_item_type = None
+        self.pushed_states = []
+
+    def push(self):
+        self.pushed_states.append({
+            'current_block': self.current_block,
+            'current_inline_styles': self.current_inline_styles,
+            'current_entity_ranges': self.current_entity_ranges,
+            'depth': self.depth,
+            'list_item_type': self.list_item_type
+        })
+
+    def pop(self):
+        last_state = self.pushed_states.pop()
+        self.current_block = last_state['current_block']
+        self.current_inline_styles = last_state['current_inline_styles']
+        self.current_entity_ranges = last_state['current_entity_ranges']
+        self.depth = last_state['depth']
+        self.list_item_type = last_state['list_item_type']
+
+
+class ListElementHandler(object):
+    """ Handler for <ul> / <ol> tags """
+    def __init__(self, list_item_type):
+        self.list_item_type = list_item_type
+
+    def handle_starttag(self, name, attrs, state, contentstate):
+        state.push()
+
+        if state.list_item_type is None:
+            # this is not nested in another list => depth remains unchanged
+            pass
+        else:
+            # start the next nesting level
+            state.depth += 1
+
+        state.list_item_type = self.list_item_type
+
+    def handle_endtag(self, name, state, contentstate):
+        state.pop()
+
+
+class BlockElementHandler(object):
+    def __init__(self, block_type):
+        self.block_type = block_type
+
+    def create_block(self, name, attrs, state, contentstate):
+        assert state.current_block is None, "%s element found nested inside another block" % name
+        return Block(self.block_type, depth=state.depth)
+
+    def handle_starttag(self, name, attrs, state, contentstate):
+        block = self.create_block(name, dict(attrs), state, contentstate)
+        contentstate.blocks.append(block)
+        state.current_block = block
+
+    def handle_endtag(self, name, state, contentState):
+        assert not state.current_inline_styles, "End of block reached without closing inline style elements"
+        assert not state.current_entity_ranges, "End of block reached without closing entity elements"
+        state.current_block = None
+
+
+class ListItemElementHandler(BlockElementHandler):
+    """ Handler for <li> tag """
+
+    def __init__(self):
+        pass  # skip setting self.block_type
+
+    def create_block(self, name, attrs, state, contentstate):
+        assert state.list_item_type is not None, "%s element found outside of an enclosing list element" % name
+        return Block(state.list_item_type, depth=state.depth)
+
+
+class InlineStyleElementHandler(object):
+    def __init__(self, style):
+        self.style = style
+
+    def handle_starttag(self, name, attrs, state, contentstate):
+        assert state.current_block is not None, "%s element found at the top level" % name
+        inline_style_range = InlineStyleRange(self.style)
+        inline_style_range.offset = len(state.current_block.text)
+        state.current_block.inline_style_ranges.append(inline_style_range)
+        state.current_inline_styles.append(inline_style_range)
+
+    def handle_endtag(self, name, state, contentstate):
+        inline_style_range = state.current_inline_styles.pop()
+        assert inline_style_range.style == self.style
+        inline_style_range.length = len(state.current_block.text) - inline_style_range.offset
+
+
+class LinkElementHandler(object):
+    def __init__(self, entity_type):
+        self.entity_type = entity_type
+
+    def handle_starttag(self, name, attrs, state, contentstate):
+        assert state.current_block is not None, "%s element found at the top level" % name
+        attrs = dict(attrs)
+
+        entity = Entity(self.entity_type, 'MUTABLE', {'url': attrs['href']})
+        key = contentstate.add_entity(entity)
+
+        entity_range = EntityRange(key)
+        entity_range.offset = len(state.current_block.text)
+        state.current_block.entity_ranges.append(entity_range)
+        state.current_entity_ranges.append(entity_range)
+
+    def handle_endtag(self, name, state, contentstate):
+        entity_range = state.current_entity_ranges.pop()
+        entity_range.length = len(state.current_block.text) - entity_range.offset
+
+
+class AtomicBlockEntityElementHandler(object):
+    """
+    Handler for elements like <img> that exist as a single immutable item at the block level
+    """
+    def handle_starttag(self, name, attrs, state, contentstate):
+        assert state.current_block is None, "%s element found nested inside another block" % name
+
+        entity = self.create_entity(name, dict(attrs), state, contentstate)
+        key = contentstate.add_entity(entity)
+
+        block = Block('atomic', depth=state.depth)
+        contentstate.blocks.append(block)
+        block.text = ' '
+        entity_range = EntityRange(key)
+        entity_range.offset = 0
+        entity_range.length = 1
+        block.entity_ranges.append(entity_range)
+
+    def handle_endtag(self, name, state, contentstate):
+        pass
+
+
+class ImageElementHandler(AtomicBlockEntityElementHandler):
+    def create_entity(self, name, attrs, state, contentstate):
+        return Entity('IMAGE', 'IMMUTABLE', {'altText': attrs.get('alt'), 'src': attrs['src']})
+
+
+ELEMENT_HANDLERS_BY_FEATURE = {
+    'ol': {
+        'ol': ListElementHandler('ordered-list-item'),
+        'li': ListItemElementHandler(),
+    },
+    'ul': {
+        'ul': ListElementHandler('unordered-list-item'),
+        'li': ListItemElementHandler(),
+    },
+    'h1': {
+        'h1': BlockElementHandler('header-one'),
+    },
+    'h2': {
+        'h2': BlockElementHandler('header-two'),
+    },
+    'h3': {
+        'h3': BlockElementHandler('header-three'),
+    },
+    'h4': {
+        'h4': BlockElementHandler('header-four'),
+    },
+    'h5': {
+        'h5': BlockElementHandler('header-five'),
+    },
+    'h6': {
+        'h6': BlockElementHandler('header-six'),
+    },
+    'italic': {
+        'i': InlineStyleElementHandler('ITALIC'),
+        'em': InlineStyleElementHandler('ITALIC'),
+    },
+    'bold': {
+        'b': InlineStyleElementHandler('BOLD'),
+        'strong': InlineStyleElementHandler('BOLD'),
+    },
+    'link': {
+        'a': LinkElementHandler('LINK'),
+    },
+    # 'img': ImageElementHandler(),
+}
+
+
+class HtmlToContentStateHandler(HTMLParser):
+    def __init__(self, features=None):
+        self.element_handlers = {
+            'p': BlockElementHandler('unstyled'),
+        }
+        if features is not None:
+            for feature in features:
+                try:
+                    feature_element_handlers = ELEMENT_HANDLERS_BY_FEATURE[feature]
+                except KeyError:
+                    continue
+                self.element_handlers.update(feature_element_handlers)
+
+        super().__init__()
+
+    def reset(self):
+        self.state = HandlerState()
+        self.contentstate = ContentState()
+        super().reset()
+
+    def add_block(self, block):
+        self.contentstate.blocks.append(block)
+        self.current_block = block
+
+    def handle_starttag(self, name, attrs):
+        try:
+            element_handler = self.element_handlers[name]
+        except KeyError:
+            return  # ignore unrecognised elements
+
+        element_handler.handle_starttag(name, attrs, self.state, self.contentstate)
+
+    def handle_endtag(self, name):
+        try:
+            element_handler = self.element_handlers[name]
+        except KeyError:
+            return  # ignore unrecognised elements
+
+        element_handler.handle_endtag(name, self.state, self.contentstate)
+
+    def handle_data(self, content):
+        if self.state.current_block is None:
+            assert not content.strip(), "Bare text content found at the top level: %r" % content
+
+        else:
+            self.state.current_block.text += content
diff --git a/wagtail/admin/rich_text/editors/draftail.py b/wagtail/admin/rich_text/editors/draftail.py
new file mode 100644
index 000000000..a65bdd7a0
--- /dev/null
+++ b/wagtail/admin/rich_text/editors/draftail.py
@@ -0,0 +1,37 @@
+from django.forms import widgets
+
+from wagtail.admin.edit_handlers import RichTextFieldPanel
+from wagtail.admin.rich_text.converters.contentstate import ContentstateConverter
+from wagtail.core.rich_text import features
+
+
+class DraftailRichTextArea(widgets.Textarea):
+    # this class's constructor accepts a 'features' kwarg
+    accepts_features = True
+
+    def get_panel(self):
+        return RichTextFieldPanel
+
+    def __init__(self, *args, **kwargs):
+        self.options = kwargs.pop('options', None)
+
+        self.features = kwargs.pop('features', None)
+        if self.features is None:
+            self.features = features.get_default_features()
+
+        self.converter = ContentstateConverter(self.features)
+
+        super().__init__(*args, **kwargs)
+
+    def render(self, name, value, attrs=None):
+        if value is None:
+            translated_value = None
+        else:
+            translated_value = self.converter.from_database_format(value)
+        return super().render(name, translated_value, attrs)
+
+    def value_from_datadict(self, data, files, name):
+        original_value = super().value_from_datadict(data, files, name)
+        if original_value is None:
+            return None
+        return self.converter.to_database_format(original_value)