import os
import re
from markitdown import MarkItDown


def clean_markdown_wrap_none(text: str) -> str:
    """
    Joins all lines of each paragraph into a single line.
    Preserves structure (headings, lists, code blocks).
    """
    lines = text.splitlines()
    out = []
    buf = ""

    bullet = re.compile(r"^(\s*[-*+]\s+|\s*\d+\.\s+)")
    heading = re.compile(r"^\s{0,3}#{1,6}\s")
    codefence = re.compile(r"^\s*```")

    in_code = False

    def flush():
        nonlocal buf
        if buf.strip():
            out.append(buf.strip())
        buf = ""

    for raw in lines:
        line = raw.rstrip("\n")

        if codefence.match(line):
            in_code = not in_code
            flush()
            out.append(line)
            continue

        if in_code:
            out.append(line)
            continue

        if line.strip() == "":
            flush()
            out.append("")
            continue

        if heading.match(line) or bullet.match(line):
            flush()
            out.append(line)
            continue

        if not buf:
            buf = line.strip()
            continue

        # Remove hyphen when word is split
        if buf.endswith('-') and line.strip() and line.strip()[0].isalpha():
            buf = buf[:-1] + line.strip()
        else:
            buf = buf + " " + line.strip()

    flush()
    return "\n".join(out)


def convert_document_to_markdown(
    file_path: str,
    output_path: str = None,
    return_text: bool = True,
):
    """
    Converts a single document (PDF/DOCX and other MarkItDown-supported types) to Markdown.

    Parameters:
        file_path (str): Path to input file
        output_path (str, optional): Where to save the .md file
        return_text (bool): If True, returns markdown text

    Returns:
        str | None: Markdown content (if return_text=True)
    """
    if not os.path.isfile(file_path):
        raise FileNotFoundError(f"File not found: {file_path}")

    md = MarkItDown()

    try:
        result = md.convert(file_path)
        clean_text = clean_markdown_wrap_none(result.text_content)

        # Save file if requested
        if output_path:
            os.makedirs(os.path.dirname(output_path), exist_ok=True)
            with open(output_path, "w", encoding="utf-8") as f:
                f.write(clean_text)

        if return_text:
            return clean_text

        return None

    except Exception as e:
        raise RuntimeError(f"Error converting file to Markdown: {e}")


def convert_pdf_to_markdown(
    pdf_path: str,
    output_path: str = None,
    return_text: bool = True,
):
    """
    Backward-compatible wrapper for PDF conversion.
    """
    return convert_document_to_markdown(
        file_path=pdf_path,
        output_path=output_path,
        return_text=return_text,
    )