"""Markdown parser.

Contains parser for md files.

"""
import re
from pathlib import Path
from typing import Any, Dict, List, Optional, Tuple, cast

from llama_index.readers.base import BaseReader
from llama_index.schema import Document


class MarkdownReader(BaseReader):
    """Markdown parser.

    Extract text from markdown files.
    Returns dictionary with keys as headers and values as the text between headers.

    """

    def __init__(
        self,
        *args: Any,
        remove_hyperlinks: bool = True,
        remove_images: bool = True,
        **kwargs: Any,
    ) -> None:
        """Init params."""
        super().__init__(*args, **kwargs)
        self._remove_hyperlinks = remove_hyperlinks
        self._remove_images = remove_images

    def markdown_to_tups(self, markdown_text: str) -> List[Tuple[Optional[str], str]]:
        """Convert a markdown file to a dictionary.

        The keys are the headers and the values are the text under each header.

        """
        markdown_tups: List[Tuple[Optional[str], str]] = []
        lines = markdown_text.split("\n")

        current_header = None
        current_text = ""

        for line in lines:
            header_match = re.match(r"^#+\s", line)
            if header_match:
                if current_header is not None:
                    if current_text == "" or None:
                        continue
                    markdown_tups.append((current_header, current_text))

                current_header = line
                current_text = ""
            else:
                current_text += line + "\n"
        markdown_tups.append((current_header, current_text))

        if current_header is not None:
            # pass linting, assert keys are defined
            markdown_tups = [
                (re.sub(r"#", "", cast(str, key)).strip(), re.sub(r"<.*?>", "", value))
                for key, value in markdown_tups
            ]
        else:
            markdown_tups = [
                (key, re.sub("<.*?>", "", value)) for key, value in markdown_tups
            ]

        return markdown_tups

    def remove_images(self, content: str) -> str:
        """Get a dictionary of a markdown file from its path."""
        pattern = r"!{1}\[\[(.*)\]\]"
        content = re.sub(pattern, "", content)
        return content

    def remove_hyperlinks(self, content: str) -> str:
        """Get a dictionary of a markdown file from its path."""
        pattern = r"\[(.*?)\]\((.*?)\)"
        content = re.sub(pattern, r"\1", content)
        return content

    def _init_parser(self) -> Dict:
        """Initialize the parser with the config."""
        return {}

    def parse_tups(
        self, filepath: Path, errors: str = "ignore"
    ) -> List[Tuple[Optional[str], str]]:
        """Parse file into tuples."""
        with open(filepath, "r", encoding="utf-8") as f:
            content = f.read()
        if self._remove_hyperlinks:
            content = self.remove_hyperlinks(content)
        if self._remove_images:
            content = self.remove_images(content)
        markdown_tups = self.markdown_to_tups(content)
        return markdown_tups

    def load_data(
        self, file: Path, extra_info: Optional[Dict] = None
    ) -> List[Document]:
        """Parse file into string."""
        tups = self.parse_tups(file)
        results = []
        # TODO: don't include headers right now
        for header, value in tups:
            if header is None:
                results.append(Document(text=value, metadata=extra_info or {}))
            else:
                results.append(
                    Document(text=f"\n\n{header}\n{value}", metadata=extra_info or {})
                )
        return results
