import re

from docutils.core import publish_parts
from docutils.parsers.rst.roles import register_canonical_role

from pysite.rst.roles import icon_role, page_role, url_for_role

RST_TEMPLATE = """.. contents::

{0}"""

CONTENTS_REGEX = re.compile(r"""<div class=\"contents topic\" id=\"contents\">(.*?)</div>""", re.DOTALL)
HREF_REGEX = re.compile(r"""<a class=\"reference internal\" href=\"(.*?)\".*?>(.*?)</a>""")


def render(rst: str):
    rst = RST_TEMPLATE.format(rst)
    html = publish_parts(
        source=rst, writer_name="html5", settings_overrides={
            "halt_level": 2, "syntax_highlight": "short", "initial_header_level": 3
        }
    )["html_body"]

    data = {
        "html": html,
        "headers": []
    }

    match = CONTENTS_REGEX.search(html)  # Find the contents HTML

    if match:
        data["html"] = html.replace(match.group(0), "")  # Remove the contents from the document HTML

        depth = 0
        headers = []
        current_header = {}

        group = match.group(1)

        # Sanitize the output so we can more easily parse it
        group = group.replace("<li>", "<li>\n")
        group = group.replace("</li>", "\n</li>")
        group = group.replace("<p>", "<p>\n")
        group = group.replace("</p>", "\n</p>")

        for line in group.split("\n"):
            line = line.strip()  # Remove excess whitespace

            if not line:  # Nothing to process
                continue

            if line.startswith("<li>") and depth <= 2:
                #  We've found a header, or the start of a header group
                depth += 1
            elif line.startswith("</li>") and depth >= 0:
                # That's the end of a header or header group

                if depth == 1:
                    # We just dealt with an entire header group, so store it
                    headers.append(current_header.copy())  # Store a copy, since we're clearing the dict
                    current_header.clear()

                depth -= 1
            elif line.startswith("<a") and depth <= 2:
                # We've found an actual URL
                match = HREF_REGEX.match(line)  # Parse the line for the ID and header title

                if depth == 1:  # Top-level header, so just store it in the current header
                    current_header["id"] = match.group(1)

                    title = match.group(2)

                    if title.startswith("<i"):  # We've found an icon, which needs to have a space after it
                        title = title.replace("</i> ", "</i> &nbsp;")

                    current_header["title"] = title
                else:  # Second-level (or deeper) header, should be stored in a list of sub-headers under the current
                    sub_headers = current_header.get("sub_headers", [])
                    title = match.group(2)

                    if title.startswith("<i"):  # We've found an icon, which needs to have a space after it
                        title = title.replace("</i> ", "</i> &nbsp;")

                    sub_headers.append({
                        "id": match.group(1),
                        "title": title
                    })
                    current_header["sub_headers"] = sub_headers

        data["headers"] = headers
    return data


register_canonical_role("icon", icon_role)
register_canonical_role("page", page_role)
register_canonical_role("url_for", url_for_role)