var sampleSEXP1   = 'Kevin';
var expectedSEXP1 = "Kevin";
var sampleSEXP2   = '(Kevin A B C)';
var expectedSEXP2 = ["Kevin", "A", "B", "C"];
var sampleSEXP3   = '(Kevin (A B C) B C)';
var expectedSEXP3 = ["Kevin", ["A", "B", "C"], "B", "C"];
var sampleSEXP4   = '(Kevin)';
var expectedSEXP4 = ["Kevin"];
var sampleSEXP7   = '(a (a b c) (d e f (g h)) z)';
var expectedSEXP7 = ["a", ["a", "b", "c"], ["d", "e", "f", ["g", "h"]], "z"];
var sampleSEXP8   = '()';
var expectedSEXP8 = [];

var NORMAL = 0;
var STRING = 1;

function parseSEXP(s) {
  if (s) {
    if (s[0] == "(") { // Do some parsing
      var depth = 0;
      var cur = "";
      var out = [];
      for (var i = 1; i < s.length - 1; i++) {
        if (s[i] == "(") {
          depth++;
          cur += s[i];
        } else if (s[i] == ")") {
          depth--;
          cur += s[i];
          if (depth == 0) {
            if (cur) {
              out.push(parseSEXP(cur));
            }
            cur = "";
          }
        } else if (depth > 0) {
          cur += s[i];
        } else if (s[i] == " ") {
          if (cur) {
            out.push(parseSEXP(cur));
          }
          cur = "";
        } else {
          cur += s[i];
        }
      }
      if (cur) {
        out.push(parseSEXP(cur));
      }
      return out;
    } else {
      return s.replace(/_/g, " ");
    }
  } else {
    return "";
  }
}

function tokenize(psexp){
  if (Array.isArray(psexp)) {
    if (psexp.length == 0) {
      return false;
    } else {
      return {
        "OP"   : psexp[0],
        "ARGS" : psexp.slice(1).map(tokenize)
      }
    }
  } else {
    return psexp;
  }
}

function isValidServerRequest(tsexp) {
  if (typeof tsexp == "string") {
    return true;
  } else if (tsexp.OP == "OR") {
    return (tsexp.ARGS.length > 1) && tsexp.ARGS.reduce(function(acc, e){return acc&&isValidServerRequest(e)}, true);
  } else if (tsexp.OP == "AND") {
    return (tsexp.ARGS.length > 1) && tsexp.ARGS.reduce(function(acc, e){return acc&&isValidServerRequest(e)}, true);

  } else if (tsexp.OP == "NOT") {
    return (tsexp.ARGS.length == 1) && isValidServerRequest(tsexp.ARGS[0]);
  } else {
    return false;
  }
}

function checkExpect(a, b) {
  if (a.toString() != b.toString()) {
    console.error("Check expect failed. Actual:", a, " Expected:", b);
  } else {
    console.log("Check expect passed. Actual:", a, " Expected:", b);
  }
}

checkExpect(parseSEXP(sampleSEXP1), expectedSEXP1);
checkExpect(parseSEXP(sampleSEXP2), expectedSEXP2);
checkExpect(parseSEXP(sampleSEXP3), expectedSEXP3);
checkExpect(parseSEXP(sampleSEXP4), expectedSEXP4);
checkExpect(parseSEXP(sampleSEXP7), expectedSEXP7);
checkExpect(parseSEXP(sampleSEXP8), expectedSEXP8);