import dataclasses

import re
import frontmatter
import marko
import marko.md_renderer


@dataclasses.dataclass(frozen=True)
class CardContents:
    name: str | None
    description: str | None
    tags: list[str]
    assignments: list[str]


class CardFileFormatter:
    """Component for formatting and parsing card files."""

    def __init__(self, obsidian_mode=True):
        self.obsidian_mode = obsidian_mode
        self.markdown = marko.Markdown()
        self.renderer = marko.md_renderer.MarkdownRenderer()

    def format_card_contents(self, card: CardContents) -> str:
        ls = []

        # Choose frontmatter data
        frontmatter_data = {}
        if card.name and self.obsidian_mode:
            frontmatter_data['aliases'] = [card.name]
        if card.tags:
            frontmatter_data['tags'] = card.tags
        if card.assignments:
            frontmatter_data['assignments'] = card.assignments
            if self.obsidian_mode:
                frontmatter_data['assignments'] = [
                    f'"[[{name}]]"' for name in frontmatter_data['assignments']
                ]

        # Frontmatter
        if frontmatter_data:
            ls.append('---\n')
            for key, values in frontmatter_data.items():
                ls.append(key)
                ls.append(':\n')
                for v in values:
                    ls.append('  - ')
                    ls.append(v)
                    ls.append('\n')
            ls.append('---\n\n')

        # Card name
        if card.name:
            ls.append('# ')
            ls.append(card.name)
            ls.append('\n\n')

        # Card contents
        if card.description:
            ls.append(card.description)
        return ''.join(ls)

    def parse_card_contents(self, contents: str) -> CardContents:
        """
        1. Strips frontmatter
        2. Parses header
        3. Finds content.
        """
        fm = frontmatter.loads(contents)
        del contents

        document = self.markdown.parse(fm.content.strip())
        name = None
        for elem in document.children:
            if isinstance(elem, marko.block.Heading):
                name = self.renderer.render_children(elem)
                document.children.remove(elem)
                break

        assignments: list[str] = fm.metadata.get('assignments', [])
        for idx in range(0, len(assignments)):
            if m := re.match(r'^\[\[(.*)\]\]$', assignments[idx]):
                assignments[idx] = m.group(1)

        description = self.renderer.render_children(document).strip()
        return CardContents(
            name,
            description,
            tags=fm.metadata.get('tags', []),
            assignments=assignments,
        )