"""
Markdown Document Loader.

Loads pre-converted Markdown files, parses page boundaries and metadata,
and produces a ParsedDocument object for downstream processing.
"""

import os
import re
from typing import Dict, List, Optional
from src.ocr.base_parser import BaseDocumentParser, ParsedDocument, ParsedPage


class MarkdownDocumentLoader(BaseDocumentParser):
    """Loads and normalizes guideline Markdown files."""

    def parse(self, file_path: str) -> ParsedDocument:
        if not os.path.exists(file_path):
            raise FileNotFoundError(f"Markdown file not found: {file_path}")

        with open(file_path, "r", encoding="utf-8") as f:
            content = f.read()

        # Split into pages by '***' or '---' horizontal rules or page delimiters
        raw_pages = re.split(r"\n\s*(?:\*\*\*|---|___)\s*\n", content)
        if len(raw_pages) <= 1:
            # Fallback: check for page markers like "Page X of Y" or "\d+ of \d+"
            raw_pages = [content]

        parsed_pages: List[ParsedPage] = []
        for idx, page_text in enumerate(raw_pages, start=1):
            # Clean up repetitive footer/header lines from the page text
            cleaned_text = self._clean_page_artifacts(page_text)
            parsed_pages.append(
                ParsedPage(
                    page_number=idx,
                    markdown_content=cleaned_text.strip(),
                    bbox_metadata=[],
                )
            )

        return ParsedDocument(
            source_path=file_path,
            total_pages=len(parsed_pages),
            full_markdown=content,
            pages=parsed_pages,
            metadata={
                "file_name": os.path.basename(file_path),
                "file_size": os.path.getsize(file_path),
            },
        )

    def _clean_page_artifacts(self, page_text: str) -> str:
        # Remove trailing copyright and pagination footers if standard
        cleaned = re.sub(
            r"\n\s*(?:©\s*Royal College of Obstetricians and Gynaecologists|©\s*RCOG).*$",
            "",
            page_text,
            flags=re.IGNORECASE | re.MULTILINE,
        )
        return cleaned