Use bokky's timestamp library in scheduled checkpoint (#466)

* added enum TimeUnit

* update depends on timeUnit

* test for monthly checkpoint

* tests for monthly checkpoint

* use UTC instead of local time

* minor fix

* Tests for yearly checkpoint

* Tests for last day of month

* Updated tests for last day of month

* commented failed test

* fix for end of month schedule

* refactored _update function

* added TimeUnits: DAYS, WEEKS

Author: kostind

contracts/modules/Experimental/Mixed/ScheduledCheckpoint.sol

@@ -4,29 +4,34 @@ import "./../../Checkpoint/ICheckpoint.sol";
 import "../../TransferManager/ITransferManager.sol";
 import "../../../interfaces/ISecurityToken.sol";
 import "openzeppelin-solidity/contracts/math/SafeMath.sol";
+import "../../../libraries/BokkyPooBahsDateTimeLibrary.sol";
 
 /**
  * @title Burn module for burning tokens and keeping track of burnt amounts
  */
 contract ScheduledCheckpoint is ICheckpoint, ITransferManager {
     using SafeMath for uint256;
 
+    enum TimeUnit {SECONDS, DAYS, WEEKS, MONTHS, YEARS}
+
     struct Schedule {
         bytes32 name;
         uint256 startTime;
         uint256 nextTime;
         uint256 interval;
+        TimeUnit timeUnit;
         uint256 index;
         uint256[] checkpointIds;
         uint256[] timestamps;
         uint256[] periods;
+        uint256 totalPeriods;
     }
 
     bytes32[] public names;
 
     mapping (bytes32 => Schedule) public schedules;
 
-    event AddSchedule(bytes32 _name, uint256 _startTime, uint256 _interval, uint256 _timestamp);
+    event AddSchedule(bytes32 _name, uint256 _startTime, uint256 _interval, TimeUnit _timeUint, uint256 _timestamp);
     event RemoveSchedule(bytes32 _name, uint256 _timestamp);
 
     /**
@@ -51,17 +56,19 @@ contract ScheduledCheckpoint is ICheckpoint, ITransferManager {
      * @param _name name of the new schedule (must be unused)
      * @param _startTime start time of the schedule (first checkpoint)
      * @param _interval interval at which checkpoints should be created
+     * @param _timeUnit unit of time at which checkpoints should be created
      */
-    function addSchedule(bytes32 _name, uint256 _startTime, uint256 _interval) external onlyOwner {
+    function addSchedule(bytes32 _name, uint256 _startTime, uint256 _interval, TimeUnit _timeUnit) external onlyOwner {
         require(_startTime > now, "Start time must be in the future");
         require(schedules[_name].name == bytes32(0), "Name already in use");
         schedules[_name].name = _name;
         schedules[_name].startTime = _startTime;
         schedules[_name].nextTime = _startTime;
         schedules[_name].interval = _interval;
+        schedules[_name].timeUnit = _timeUnit;
         schedules[_name].index = names.length;
         names.push(_name);
-        emit AddSchedule(_name, _startTime, _interval, now);
+        emit AddSchedule(_name, _startTime, _interval, _timeUnit, now);
     }
 
     /**
@@ -99,15 +106,18 @@ contract ScheduledCheckpoint is ICheckpoint, ITransferManager {
      * @notice gets schedule details
      * @param _name name of the schedule
      */
-    function getSchedule(bytes32 _name) view external returns(bytes32, uint256, uint256, uint256, uint256[], uint256[], uint256[]) {
+    function getSchedule(bytes32 _name) view external returns(bytes32, uint256, uint256, uint256, TimeUnit, uint256[], uint256[], uint256[], uint256) {
+        Schedule storage schedule = schedules[_name];
         return (
-            schedules[_name].name,
-            schedules[_name].startTime,
-            schedules[_name].nextTime,
-            schedules[_name].interval,
-            schedules[_name].checkpointIds,
-            schedules[_name].timestamps,
-            schedules[_name].periods
+            schedule.name,
+            schedule.startTime,
+            schedule.nextTime,
+            schedule.interval,
+            schedule.timeUnit,
+            schedule.checkpointIds,
+            schedule.timestamps,
+            schedule.periods,
+            schedule.totalPeriods
         );
     }
 
@@ -123,10 +133,27 @@ contract ScheduledCheckpoint is ICheckpoint, ITransferManager {
         Schedule storage schedule = schedules[_name];
         if (schedule.nextTime <= now) {
             uint256 checkpointId = ISecurityToken(securityToken).createCheckpoint();
-            uint256 periods = now.sub(schedule.nextTime).div(schedule.interval).add(1);
-            schedule.timestamps.push(schedule.nextTime);
-            schedule.nextTime = periods.mul(schedule.interval).add(schedule.nextTime);
             schedule.checkpointIds.push(checkpointId);
+            schedule.timestamps.push(schedule.nextTime);
+            uint256 periods;
+            if (schedule.timeUnit == TimeUnit.SECONDS ) {
+                periods = now.sub(schedule.nextTime).div(schedule.interval).add(1);
+                schedule.nextTime = periods.mul(schedule.interval).add(schedule.nextTime);
+            } else if (schedule.timeUnit == TimeUnit.DAYS ) {
+                periods = BokkyPooBahsDateTimeLibrary.diffDays(schedule.nextTime, now).div(schedule.interval).add(1);
+                schedule.nextTime = BokkyPooBahsDateTimeLibrary.addDays(schedule.nextTime, periods.mul(schedule.interval));
+            } else if (schedule.timeUnit == TimeUnit.WEEKS ) {
+                periods = BokkyPooBahsDateTimeLibrary.diffDays(schedule.nextTime, now).div(7).div(schedule.interval).add(1);
+                schedule.nextTime = BokkyPooBahsDateTimeLibrary.addDays(schedule.nextTime, periods.mul(schedule.interval).mul(7));
+            } else if (schedule.timeUnit == TimeUnit.MONTHS ) {
+                periods = BokkyPooBahsDateTimeLibrary.diffMonths(schedule.nextTime, now).div(schedule.interval).add(1);
+                uint256 totalPeriods = schedule.totalPeriods.add(periods);
+                schedule.nextTime = BokkyPooBahsDateTimeLibrary.addMonths(schedule.startTime, totalPeriods.mul(schedule.interval));
+            } else if (schedule.timeUnit == TimeUnit.YEARS ) {
+                periods = BokkyPooBahsDateTimeLibrary.diffYears(schedule.nextTime, now).div(schedule.interval).add(1);
+                schedule.nextTime = BokkyPooBahsDateTimeLibrary.addYears(schedule.nextTime, periods.mul(schedule.interval));
+            }
+            schedule.totalPeriods = schedule.totalPeriods.add(periods);
             schedule.periods.push(periods);
         }
     }