import { MarkdownRenderer } from "obsidian";
import type { App, Component } from "obsidian";

export interface MarkdownOptions {
  app: App;
  component: Component;
  sourcePath: string;
  text: string;
}

function unwrap(node: HTMLElement): void {
  let child = node.firstElementChild;
  while (
    node.childElementCount === 1 &&
    child &&
    (child.tagName === "P" || child.tagName === "DIV")
  ) {
    child.replaceWith(...child.childNodes);
    child = node.firstElementChild;
  }
}

export function markdown(node: HTMLElement, options: MarkdownOptions) {
  let current = options;
  let generation = 0;

  const render = async (): Promise<void> => {
    const mine = (generation += 1);
    const { app, component, sourcePath, text } = current;
    if (typeof MarkdownRenderer?.render !== "function") {
      node.textContent = text;
      return;
    }
    const staging = document.createElement("div");
    await MarkdownRenderer.render(app, text, staging, sourcePath, component);
    if (mine !== generation) return;
    unwrap(staging);
    node.replaceChildren(...staging.childNodes);
  };

  void render();

  return {
    update(next: MarkdownOptions) {
      const changed =
        next.text !== current.text || next.sourcePath !== current.sourcePath;
      current = next;
      if (changed) void render();
    },
    destroy() {
      generation += 1;
    },
  };
}

export function followLink(
  app: App,
  event: MouseEvent,
  sourcePath: string,
): boolean {
  const anchor = (event.target as HTMLElement).closest("a");
  if (!anchor) return false;
  event.preventDefault();
  event.stopPropagation();
  const href = anchor.getAttribute("href") ?? "";
  if (anchor.classList.contains("internal-link")) {
    void app.workspace.openLinkText(href, sourcePath, event.ctrlKey || event.metaKey);
  } else if (href) {
    window.open(href, "_blank");
  }
  return true;
}