apply_mutation_to_snapshot.py

from cssutils import parseStyle


def find_node_by_id(tree, search_id):
    recursive_priority = []
    for childNode in tree['childNodes']:
        if childNode['id'] == search_id:
            return childNode
        elif 'childNodes' in childNode:
            if childNode['id'] < search_id:
                # take advantage of depth first ordering
                recursive_priority.insert(0, childNode)
            else:
                recursive_priority.append(childNode)
    for childNode in recursive_priority:
        res = find_node_by_id(childNode, search_id)
        if res:
            return res


def apply_mutation(snapshot, mutation):
    for add in mutation['data']['adds']:
        parent = find_node_by_id(
            snapshot['data']['node'],
            add['parentId'],
        )
        if not parent:
            raise UnhandledMutation(
                f"could not find add parent {add['parentId']}"
            )
        if add['nextId'] is None:
            parent['childNodes'].append(add['node'])
            continue
        for i, child in enumerate(parent['childNodes']):
            if child['id'] == add['nextId']:
                parent['childNodes'] = \
                    parent['childNodes'][:i] + \
                    [add['node']] + \
                    parent['childNodes'][i:]
                break
        else:
            raise UnhandledMutation(
                f"could not find add nextId {add['nextId']}"
            )

    for attrNode in mutation['data']['attributes']:
        node = find_node_by_id(
            snapshot['data']['node'],
            attrNode['id'])
        if not node:
            raise UnhandledMutation(
                f"could not find node for attribute mutation {attrNode['id']}"
            )
        for attrKey in attrNode['attributes']:
            value = attrNode['attributes'][attrKey]
            if value is None:
                del node['attributes'][attrKey]
            elif isinstance(value, str):
                # update
                node['attributes'][attrKey] = value
            elif attrKey == 'style':
                # note: the parsing here modifies (normalises) other style
                # rules not included in the mutation. Hoping it's okay as
                # would be similar to how browser interprets the rules
                style_rule = parseStyle(
                    node['attributes'].get('style', ''),
                    validate=False,
                )
                for k, v in value.items():
                    if v is False:
                        style_rule.removeProperty(k)
                    elif isinstance(v, list):
                        style_rule.setProperty(k, v[0], v[1])
                    else:
                        if v is False or v is None or not v:
                            import pdb; pdb.set_trace();
                        style_rule[k] = v
                node['attributes'][attrKey] = style_rule.cssText.replace('\n', ' ')

    for text in mutation['data']['texts']:
        import pdb; pdb.set_trace();
        node = find_node_by_id(snapshot['data']['node'], text['id'])
        if not node:
            raise UnhandledMutation(
                f"could not find node for text mutation {attrNode['id']}"
            )
        node['textContent'] = text['value']

    for rem in mutation['data']['removes']:
        parent = find_node_by_id(
            snapshot['data']['node'],
            rem['parentId'])
        if not parent:
            raise UnhandledMutation(
                f"could not find remove parent {add['parentId']}"
            )
        for i, child in enumerate(parent['childNodes']):
            if child['id'] == rem['id']:
                parent['childNodes'] = \
                    parent['childNodes'][:i] + \
                    parent['childNodes'][i+1:]
                break
        else:
            raise UnhandledMutation(
                f"could not find remove by id {rem['id']}"
            )



class UnhandledMutation(Exception):
    pass