import { editor, markdown, system } from "$sb/silverbullet-syscall/mod.ts";
import { nodeAtPos } from "$sb/lib/tree.ts";
import { replaceAsync } from "$sb/lib/util.ts";
import { directiveRegex, renderDirectives } from "./directives.ts";
import { extractMeta } from "./data.ts";

export async function updateDirectivesOnPageCommand() {
  const pageName = await editor.getCurrentPage();
  const text = await editor.getText();
  const tree = await markdown.parseMarkdown(text);
  const metaData = extractMeta(tree, ["$disableDirectives"]);
  if (metaData.$disableDirectives) {
    // Not updating, directives disabled
    return;
  }

  // Collect all directives and their body replacements
  const replacements: { startInst: string; text?: string }[] = [];

  await replaceAsync(
    text,
    directiveRegex,
    async (fullMatch, startInst, _type, _arg, _body, endInst, index) => {
      const replacement: { startInst: string; text?: string } = { startInst };
      // Pushing to the replacement array
      replacements.push(replacement);
      const currentNode = nodeAtPos(tree, index + 1);
      if (currentNode?.type !== "CommentBlock") {
        // If not a comment block, it's likely a code block, ignore
        // console.log("Not comment block, ingoring", fullMatch);
        return fullMatch;
      }
      try {
        const replacementText = await system.invokeFunction(
          "server",
          "serverRenderDirective",
          pageName,
          fullMatch,
        );
        replacement.text = replacementText;
        return replacementText;
      } catch (e: any) {
        return `${startInst}\n**ERROR:** ${e.message}\n${endInst}`;
      }
    },
  );
  let counter = 0;
  // Iterate again and replace the bodies. Iterating again (not using previous positions)
  // because text may have changed in the mean time (directive processing may take some time)
  // Hypothetically in the mean time directives in text may have been changed/swapped, in which
  // case this will break. This would be a rare edge case, however.
  await replaceAsync(
    text,
    directiveRegex,
    async (fullMatch, startInst, _type, _arg, _body, endInst, index) => {
      const replacement = replacements[counter++];
      if (!replacement.text) {
        return `${startInst}\n$**ERROR:** Internal error, no replacement found\n${endInst}`;
      }
      if (replacement.text === fullMatch) {
        // No change, no need to dispatch
        return fullMatch;
      }
      // Dispatch the change as a somewhat minimal diff in order not to interfere with current editing
      await editor.dispatch({
        changes: {
          from: index,
          to: index + fullMatch.length,
          insert: replacement.text,
        },
      });
      return replacement.text;
    },
  );
}

// Called from client, running on server
// The text passed here is going to be a single directive block (not a full page)
export function serverRenderDirective(
  pageName: string,
  text: string,
): Promise<string> {
  return renderDirectives(pageName, text);
}