text: /* Process inline math */
  /*
  Like markdown-it-simplemath, this is a stripped down, simplified version of:
  https://github.com/runarberg/markdown-it-math
  It differs in that it takes (a subset of) LaTeX as input and relies on KaTeX
  for rendering output.
  */
  /* eslint-disable */
  // var katex = require("katex");
  
  // Test if potential opening or closing delimieter
  // Assumes that there is a "$" at state.src[pos]
  function isValidDelim(state, pos) {
    var prevChar,
      nextChar,
      max = state.posMax,
      can_open = true,
      can_close = true;
  
    prevChar = pos > 0 ? state.src.charCodeAt(pos - 1) : -1;
    nextChar = pos + 1 <= max ? state.src.charCodeAt(pos + 1) : -1;
  
    // Check non-whitespace conditions for opening and closing, and
    // check that closing delimeter isn't followed by a number
    if (
      prevChar === 0x20 /* " " */ ||
      prevChar === 0x09 /* \t */ ||
      (nextChar >= 0x30 /* "0" */ && nextChar <= 0x39) /* "9" */
    ) {
      can_close = false;
    }
    if (nextChar === 0x20 /* " " */ || nextChar === 0x09 /* \t */) {
      can_open = false;
    }
  
    return {
      can_open: can_open,
      can_close: can_close,
    };
  }
  
  function math_inline(state, silent) {
    var start, match, token, res, pos, esc_count;
  
    if (state.src[state.pos] !== "$") {
      return false;
    }
  
    res = isValidDelim(state, state.pos);
    if (!res.can_open) {
      if (!silent) {
        state.pending += "$";
      }
      state.pos += 1;
      return true;
    }
  
    // First check for and bypass all properly escaped delimieters
    // This loop will assume that the first leading backtick can not
    // be the first character in state.src, which is known since
    // we have found an opening delimieter already.
    start = state.pos + 1;
    match = start;
    while ((match = state.src.indexOf("$", match)) !== -1) {
      // Found potential $, look for escapes, pos will point to
      // first non escape when complete
      pos = match - 1;
      while (state.src[pos] === "\\") {
        pos -= 1;
      }
  
      // Even number of escapes, potential closing delimiter found
      if ((match - pos) % 2 == 1) {
        break;
      }
      match += 1;
    }
  
    // No closing delimter found.  Consume $ and continue.
    if (match === -1) {
      if (!silent) {
        state.pending += "$";
      }
      state.pos = start;
      return true;
    }
  
    // Check if we have empty content, ie: $$.  Do not parse.
    if (match - start === 0) {
      if (!silent) {
        state.pending += "$$";
      }
      state.pos = start + 1;
      return true;
    }
  
    // Check for valid closing delimiter
    res = isValidDelim(state, match);
    if (!res.can_close) {
      if (!silent) {
        state.pending += "$";
      }
      state.pos = start;
      return true;
    }
  
    if (!silent) {
      token = state.push("math_inline", "math", 0);
      token.markup = "$";
      token.content = state.src.slice(start, match);
    }
  
    state.pos = match + 1;
    return true;
  }
  
  function math_block(state, start, end, silent) {
    var firstLine,
      lastLine,
      next,
      lastPos,
      found = false,
      token,
      pos = state.bMarks[start] + state.tShift[start],
      max = state.eMarks[start];
  
    if (pos + 2 > max) {
      return false;
    }
    if (state.src.slice(pos, pos + 2) !== "$$") {
      return false;
    }
  
    pos += 2;
    firstLine = state.src.slice(pos, max);
  
    if (silent) {
      return true;
    }
    if (firstLine.trim().slice(-2) === "$$") {
      // Single line expression
      firstLine = firstLine.trim().slice(0, -2);
      found = true;
    }
  
    for (next = start; !found; ) {
      next++;
  
      if (next >= end) {
        break;
      }
  
      pos = state.bMarks[next] + state.tShift[next];
      max = state.eMarks[next];
  
      if (pos < max && state.tShift[next] < state.blkIndent) {
        // non-empty line with negative indent should stop the list:
        break;
      }
  
      if (
        state.src
          .slice(pos, max)
          .trim()
          .slice(-2) === "$$"
      ) {
        lastPos = state.src.slice(0, max).lastIndexOf("$$");
        lastLine = state.src.slice(pos, lastPos);
        found = true;
      }
    }
  
    state.line = next + 1;
  
    token = state.push("math_block", "math", 0);
    token.block = true;
    token.content =
      (firstLine && firstLine.trim() ? firstLine + "\n" : "") +
      state.getLines(start + 1, next, state.tShift[start], true) +
      (lastLine && lastLine.trim() ? lastLine : "");
    token.map = [start, state.line];
    token.markup = "$$";
    return true;
  }
  
  export default (md, options) => {
    // Default options
  
    options = options || {};
  
    // set KaTeX as the renderer for markdown-it-simplemath
    var katexInline = function(latex) {
      options.displayMode = false;
      try {
        return "$" + latex + "$";
        // return katex.renderToString(latex, options);
      } catch (error) {
        if (options.throwOnError) {
          console.log(error);
        }
        return latex;
      }
    };
  
    var inlineRenderer = function(tokens, idx) {
      return katexInline(tokens[idx].content);
    };
  
    var katexBlock = function(latex) {
      options.displayMode = true;
      try {
        // console.log(latex);
        return "$$" + latex + "$$";
        // return "<p>" + katex.renderToString(latex, options) + "</p>";
      } catch (error) {
        if (options.throwOnError) {
          console.log(error);
        }
        return latex;
      }
    };
  
    var blockRenderer = function(tokens, idx) {
      return katexBlock(tokens[idx].content) + "\n";
    };
  
    md.inline.ruler.after("escape", "math_inline", math_inline);
    md.block.ruler.after("blockquote", "math_block", math_block, {
      alt: ["paragraph", "reference", "blockquote", "list"],
    });
    md.renderer.rules.math_inline = inlineRenderer;
    md.renderer.rules.math_block = blockRenderer;
  };
  