"""Backend-agnostic traversal of md2gost inline AST nodes."""

from __future__ import annotations

from abc import ABC, abstractmethod

#: Wording used when a `@Тип:id` reference is spelled out, per ГОСТ 7.32.
REFERENCE_FULL_NAMES = {
    "рисунок": "Рисунок",
    "таблица": "Таблица",
    "листинг": "Листинг",
    "формула": "формула",
}


def reference_full_name(ref_type: str) -> str:
    return REFERENCE_FULL_NAMES.get(ref_type.lower(), ref_type)


class InlineRenderer(ABC):
    """
    Formatting hooks for :func:`render_inline`.

    Defaults are provided only for the nodes every backend renders the same
    way; everything else is abstract so a new backend cannot silently drop a
    node type.
    """

    @abstractmethod
    def escape(self, text: str) -> str:
        ...

    @abstractmethod
    def code_span(self, node) -> str:
        ...

    @abstractmethod
    def emphasis(self, inner: str) -> str:
        ...

    @abstractmethod
    def strong_emphasis(self, inner: str) -> str:
        ...

    @abstractmethod
    def link(self, node, inner: str) -> str:
        ...

    @abstractmethod
    def reference(self, node) -> str:
        ...

    @abstractmethod
    def inline_equation(self, node) -> str:
        ...

    @abstractmethod
    def line_break(self) -> str:
        ...

    def raw_text(self, text: str) -> str:
        return self.escape(text)

    def image(self, node) -> str:
        return ""  # images carry a caption, so they are emitted at block level

    def unknown(self, node) -> str:
        return self.escape(str(node))


def render_inline(children, renderer: InlineRenderer) -> str:
    """Render a list of inline nodes into a backend-specific string."""
    parts: list[str] = []
    for child in children or []:
        node_type = type(child).__name__
        if node_type in ("RawText", "Literal"):
            parts.append(renderer.raw_text(getattr(child, "children", "") or ""))
        elif node_type == "CodeSpan":
            parts.append(renderer.code_span(child))
        elif node_type == "Emphasis":
            parts.append(renderer.emphasis(render_inline(child.children, renderer)))
        elif node_type == "StrongEmphasis":
            parts.append(renderer.strong_emphasis(render_inline(child.children, renderer)))
        elif node_type == "Link":
            parts.append(renderer.link(child, render_inline(child.children, renderer)))
        elif node_type == "Reference":
            parts.append(renderer.reference(child))
        elif node_type == "InlineEquation":
            parts.append(renderer.inline_equation(child))
        elif node_type == "Image":
            parts.append(renderer.image(child))
        elif node_type == "LineBreak":
            parts.append(renderer.line_break())
        elif hasattr(child, "children"):
            parts.append(render_inline(child.children, renderer))
        else:
            parts.append(renderer.unknown(child))
    return "".join(parts)