"""Read imported metadata even when Grocy's sanitizer removes the pre tag."""
import json
from html import escape
from lxml import html


def read_metadata(description):
    try:
        text = html.fromstring(description or '<p></p>').text_content()
    except (html.etree.ParserError, ValueError):
        return {}
    for index, character in enumerate(text):
        if character == '{':
            try:
                value, _ = json.JSONDecoder().raw_decode(text[index:])
                if isinstance(value, dict) and 'Ocado product ID' in value:
                    return value
            except ValueError:
                pass
    return {}


def replace_metadata(description, metadata):
    tree = html.fragment_fromstring(description, create_parent='div')
    for node in tree.iter():
        for attr in ('text', 'tail'):
            text = getattr(node, attr) or ''
            for index, character in enumerate(text):
                if character != '{':
                    continue
                try:
                    old, end = json.JSONDecoder().raw_decode(text[index:])
                except ValueError:
                    continue
                if isinstance(old, dict) and 'Ocado product ID' in old:
                    setattr(node, attr, text[:index] + json.dumps(metadata, ensure_ascii=False, indent=2) + text[index + end:])
                    return escape(tree.text or '') + ''.join(html.tostring(child, encoding='unicode') for child in tree)
    raise ValueError('Cannot safely locate imported metadata in description')