import html
import re
from html.parser import HTMLParser


class HTMLToTextParser(HTMLParser):
    def __init__(self):
        super().__init__()
        self._parts: list[str] = []
        self._skip_depth = 0
        self._current_href: str | None = None

    def handle_starttag(self, tag, attrs):
        if tag in ("script", "style", "head", "meta", "link"):
            self._skip_depth += 1
        if tag == "a":
            for name, value in attrs:
                if name == "href":
                    self._current_href = value
                    break

    def handle_endtag(self, tag):
        if tag in ("script", "style", "head", "meta", "link") and self._skip_depth > 0:
            self._skip_depth -= 1
        if tag in ("p", "br", "li", "div", "tr", "h1", "h2", "h3", "h4", "h5", "h6"):
            self._parts.append("\n")
        if tag == "a" and self._current_href:
            self._parts.append(f" ({self._current_href})")
            self._current_href = None

    def handle_data(self, data):
        if self._skip_depth == 0:
            self._parts.append(data)

    def get_text(self) -> str:
        return "".join(self._parts).strip()


def html_to_text(html_body: str) -> str:
    parser = HTMLToTextParser()
    parser.feed(html_body)
    return parser.get_text()


def markdown_to_html(md_text: str) -> str:
    text = html.escape(md_text)

    text = re.sub(r"```(\w+)?\n?(.*?)```", r"<pre><code>\2</code></pre>", text, flags=re.DOTALL)
    text = re.sub(r"`([^`]+)`", r"<code>\1</code>", text)
    text = re.sub(r"\*\*(.+?)\*\*", r"<strong>\1</strong>", text)
    text = re.sub(r"\*(.+?)\*", r"<em>\1</em>", text)
    text = re.sub(r"~~(.+?)~~", r"<s>\1</s>", text)
    text = re.sub(r"\[([^\]]+)\]\(([^)]+)\)", r'<a href="\2">\1</a>', text)

    lines = text.split("\n")
    result: list[str] = []
    list_buffer: list[str] = []
    in_list = False

    for line in lines:
        stripped = line.strip()

        ul_match = re.match(r"^[\-\*]\s+(.+)$", stripped)
        ol_match = re.match(r"^\d+\.\s+(.+)$", stripped)

        if ul_match:
            if not in_list:
                in_list = True
                list_buffer = []
            list_buffer.append(f"<li>{ul_match.group(1)}</li>")
            continue

        if ol_match:
            if not in_list:
                in_list = True
                list_buffer = []
            list_buffer.append(f"<li>{ol_match.group(1)}</li>")
            continue

        if in_list:
            in_list = False
            result.append(f"<ul>{''.join(list_buffer)}</ul>")
            list_buffer = []

        heading_match = re.match(r"^#{1,6}\s+(.+)$", stripped)
        if heading_match:
            result.append(f"<p><strong>{heading_match.group(1)}</strong></p>")
            continue

        if not stripped:
            result.append("<br>")
        elif stripped.startswith("<") and not stripped.startswith("<br"):
            result.append(stripped)
        else:
            result.append(f"<p>{stripped}</p>")

    if in_list and list_buffer:
        result.append(f"<ul>{''.join(list_buffer)}</ul>")

    return "\n".join(result)


def get_agent_prompt_rules() -> list[str]:
    from yuxi.channel.extensions.intercom.constants import INTERCOM_AGENT_PROMPT_RULES

    return INTERCOM_AGENT_PROMPT_RULES