export function setup(helper) {
  if (!helper.markdownIt) {
    return;
  }

  helper.allowList(["div.hledger-dashboard"]);

  helper.registerOptions((opts, siteSettings) => {
    opts.features.hledger = siteSettings.hledger_enabled;
  });

  helper.registerPlugin((md) => {
    if (!md.options.discourse.features.hledger) {
      return;
    }

    md.block.ruler.before(
      "fence",
      "hledger_dashboard",
      (state, startLine, endLine, silent) => {
        const start = state.bMarks[startLine] + state.tShift[startLine];
        const max = state.eMarks[startLine];
        const opening = state.src.slice(start, max);

        if (!/^\s*`{3,}hledger\s*$/.test(opening)) {
          return false;
        }

        let closingLine = startLine + 1;
        let closed = false;

        for (; closingLine < endLine; closingLine++) {
          const pos = state.bMarks[closingLine] + state.tShift[closingLine];
          const lineMax = state.eMarks[closingLine];
          if (/^\s*`{3,}\s*$/.test(state.src.slice(pos, lineMax))) {
            closed = true;
            break;
          }
        }

        if (!closed) {
          return false;
        }

        if (silent) {
          return true;
        }

        const token = state.push("hledger_dashboard", "div", 0);
        token.block = true;
        token.map = [startLine, closingLine + 1];
        state.line = closingLine + 1;

        return true;
      },
      { alt: ["paragraph", "reference", "blockquote", "list"] }
    );

    md.renderer.rules.hledger_dashboard = () =>
      `<div class="hledger-dashboard"></div>\n`;
  });
}