import sys
import os
from bs4 import BeautifulSoup, NavigableString

def sanitize_filename(title: str) -> str:
    return "".join(c if c.isalnum() or c in (' ', '-', '_') else '_' for c in title).strip()[:100]

def get_text_with_formatting(element) -> str:
    result = []

    for content in element.descendants:
        if isinstance(content, NavigableString):
            result.append(str(content))

        elif content.name in ("strong", "b"):
            inner = "".join(content.strings)
            result.append(f"**{inner}**")

        elif content.name in ("em", "i"):
            inner = "".join(content.strings)
            result.append(f"*{inner}*")

        elif content.name == "code":
            inner = "".join(content.strings)
            result.append(f"`{inner}`")

        # Skip tags already replaced (like <a>, handled before calling this)
        elif content.name in ("a", "img"):
            continue

    return " ".join(result).strip()

def extract_markdown_from_prose(prose: BeautifulSoup) -> str:
    md_lines = []

    for element in prose.children:
        if isinstance(element, NavigableString):
            text = element.strip()
            if text:
                md_lines.append(text)
            continue

        tag = element.name

        # Headings
        if tag.startswith("h") and tag[1:].isdigit():
            level = int(tag[1:])
            md_lines.append(f"{'#' * level} {get_text_with_formatting(element)}")

        # Paragraphs with possible links or inline formatting
        elif tag == "p":
            for link in element.find_all("a"):
                href = link.get("href", "#")
                link_text = link.get_text(strip=True)
                link.replace_with(f"[{link_text}]({href})")

            for code in element.find_all("code"):
                code_text = code.get_text()
                code.replace_with(f"`{code_text}`")

            md_lines.append(get_text_with_formatting(element))

        # Lists
        elif tag == "ul":
            for li in element.find_all("li"):
                md_lines.append(f"- {li.get_text(strip=True)}")
        elif tag == "ol":
            for idx, li in enumerate(element.find_all("li"), start=1):
                md_lines.append(f"{idx}. {li.get_text(strip=True)}")

        # Preformatted code blocks
        elif tag == "pre":
            code = element.find("code")
            if code:
                lang_class = code.get("class", [])
                language = ""
                for cls in lang_class:
                    if cls.startswith("language-"):
                        language = cls.replace("language-", "")
                        break
                code_text = code.get_text()
                md_lines.append(f"```{language}\n{code_text.strip()}\n```")

        # Images
        elif tag == "img":
            src = element.get("src", "")
            alt = element.get("alt", "")
            if src:
                md_lines.append(f"![{alt}]({src})")

        # Inline code
        elif tag == "code":
            code_text = get_text_with_formatting(element)
            md_lines.append(f"`{code_text}`")

        # Fallback
        else:
            text = get_text_with_formatting(element)
            if text:
                md_lines.append(text)

    return "\n\n".join(md_lines)

def convert_chat_html_to_markdown(html_path: str) -> str:
    with open(html_path, "r", encoding="utf-8") as f:
        soup = BeautifulSoup(f, "html.parser")

    title = soup.title.string.strip() if soup.title else "chatgpt_conversation"
    filename = sanitize_filename(title) + ".md"

    main = soup.find("main")
    if not main:
        raise ValueError("Could not find <main> in HTML. Is this a valid saved ChatGPT conversation?")

    h3_tags = main.find_all("h3")
    prose_blocks = main.find_all("div", class_="prose")

    messages = []
    for h3, prose in zip(h3_tags, prose_blocks):
        role = h3.get_text(strip=True)
        if "chatgpt" in role.lower():
            prefix = "**ChatGPT:**"
        else:
            prefix = "**You:**"

        body = extract_markdown_from_prose(prose)
        messages.append(f"{prefix}\n\n{body}")

    markdown = f"# {title}\n\n" + "\n\n---\n\n".join(messages)
    return filename, markdown

if __name__ == "__main__":
    if len(sys.argv) != 2:
        print("Usage: python html_to_markdown.py <path_to_saved_html>")
        sys.exit(1)

    input_html = sys.argv[1]
    if not os.path.isfile(input_html):
        print(f"File not found: {input_html}")
        sys.exit(1)

    output_name, markdown_text = convert_chat_html_to_markdown(input_html)
    output_path = os.path.join("output", output_name)

    with open(output_path, "w", encoding="utf-8") as f:
        f.write(markdown_text)

    print(f"Markdown saved to: {output_path}")