function getInstances()

in app/scripts/modules/core/utils/later/later.js [658:699]
42 lines of code
27 McCabe index (conditional complexity)

    function getInstances(dir, count, startDate, endDate, isRange) {
      let compare = compareFn(dir), loopCount = count, maxAttempts = 1e3, schedStarts = [], exceptStarts = [], next, end, results = [], isForward = dir === "next", lastResult, rStart = isForward ? 0 : 1, rEnd = isForward ? 1 : 0;
      startDate = startDate ? new Date(startDate) : new Date();
      if (!startDate || !startDate.getTime()) throw new Error("Invalid start date.");
      setNextStarts(dir, schedules, schedStarts, startDate);
      setRangeStarts(dir, exceptions, exceptStarts, startDate);
      while (maxAttempts-- && loopCount && (next = findNext(schedStarts, compare))) {
        if (endDate && compare(next, endDate)) {
          break;
        }
        if (exceptionsLen) {
          updateRangeStarts(dir, exceptions, exceptStarts, next);
          if (end = calcRangeOverlap(dir, exceptStarts, next)) {
            updateNextStarts(dir, schedules, schedStarts, end);
            continue;
          }
        }
        if (isRange) {
          let maxEndDate = calcMaxEndDate(exceptStarts, compare);
          end = calcEnd(dir, schedules, schedStarts, next, maxEndDate);
          let r = isForward ? [ new Date(Math.max(startDate, next)), end ? new Date(endDate ? Math.min(end, endDate) : end) : undefined ] : [ end ? new Date(endDate ? Math.max(endDate, end.getTime() + later.SEC) : end.getTime() + later.SEC) : undefined, new Date(Math.min(startDate, next.getTime() + later.SEC)) ];
          if (lastResult && r[rStart].getTime() === lastResult[rEnd].getTime()) {
            lastResult[rEnd] = r[rEnd];
            loopCount++;
          } else {
            lastResult = r;
            results.push(lastResult);
          }
          if (!end) break;
          updateNextStarts(dir, schedules, schedStarts, end);
        } else {
          results.push(isForward ? new Date(Math.max(startDate, next)) : getStart(schedules, schedStarts, next, endDate));
          tickStarts(dir, schedules, schedStarts, next);
        }
        loopCount--;
      }
      for (let i = 0, len = results.length; i < len; i++) {
        let result = results[i];
        results[i] = Object.prototype.toString.call(result) === "[object Array]" ? [ cleanDate(result[0]), cleanDate(result[1]) ] : cleanDate(result);
      }
      return results.length === 0 ? later.NEVER : count === 1 ? results[0] : results;
    }