From 74e1ad4d607232907741b20922e7f7a15531195b Mon Sep 17 00:00:00 2001
From: Per Malmberg <per.malmberg@gmail.com>
Date: Sun, 11 Mar 2018 20:09:06 +0100
Subject: [PATCH] Added the concept of a clock to Cron.

---
 libcron/CMakeLists.txt   |  2 +-
 libcron/Cron.cpp         |  6 +++---
 libcron/Cron.h           | 21 ++++++++++++++++++---
 libcron/CronClock.h      | 22 ++++++++++++++++++++++
 libcron/CronSchedule.cpp |  2 +-
 libcron/Task.h           |  6 +++---
 test/CronTest.cpp        |  2 +-
 7 files changed, 49 insertions(+), 12 deletions(-)
 create mode 100644 libcron/CronClock.h

diff --git a/libcron/CMakeLists.txt b/libcron/CMakeLists.txt
index 7287fc1..de6412a 100644
--- a/libcron/CMakeLists.txt
+++ b/libcron/CMakeLists.txt
@@ -17,4 +17,4 @@ add_library(${PROJECT_NAME}
         CronSchedule.h
         externals/date/date.h
         DateTime.h
-        Task.cpp)
+        Task.cpp CronClock.h)
diff --git a/libcron/Cron.cpp b/libcron/Cron.cpp
index 66ae942..e007bb6 100644
--- a/libcron/Cron.cpp
+++ b/libcron/Cron.cpp
@@ -13,7 +13,7 @@ namespace libcron
         {
 
             Task t{std::move(name), CronSchedule{cron}, std::move(work)};
-            if (t.calculate_next())
+            if (t.calculate_next(clock->now()))
             {
                 tasks.push(t);
             }
@@ -22,7 +22,7 @@ namespace libcron
         return res;
     }
 
-    std::chrono::system_clock::duration Cron::time_until_next(std::chrono::system_clock::time_point now) const
+    std::chrono::system_clock::duration Cron::time_until_next() const
     {
         system_clock::duration d{};
         if (tasks.empty())
@@ -31,7 +31,7 @@ namespace libcron
         }
         else
         {
-            d = tasks.top().time_until_expiry(now);
+            d = tasks.top().time_until_expiry(clock->now());
         }
 
         return d;
diff --git a/libcron/Cron.h b/libcron/Cron.h
index 2cd5431..0d50b50 100644
--- a/libcron/Cron.h
+++ b/libcron/Cron.h
@@ -5,13 +5,19 @@
 #include <queue>
 #include <memory>
 #include "Task.h"
+#include "CronClock.h"
 
 namespace libcron
 {
     class Cron
     {
-
         public:
+
+            explicit Cron(std::unique_ptr<ICronClock> clock = std::make_unique<UTCClock>())
+                    : clock(std::move(clock))
+            {
+            }
+
             bool add_schedule(std::string name, const std::string& schedule, std::function<void()> work);
 
             size_t count() const
@@ -20,14 +26,23 @@ namespace libcron
             }
 
             size_t
-            execute_expired_tasks(std::chrono::system_clock::time_point now = std::chrono::system_clock::now());
+            execute_expired_tasks()
+            {
+                return execute_expired_tasks(clock->now());
+            }
+
+            size_t
+            execute_expired_tasks(std::chrono::system_clock::time_point now);
 
             std::chrono::system_clock::duration
-            time_until_next(std::chrono::system_clock::time_point now = std::chrono::system_clock::now()) const;
+            time_until_next() const;
+
+            std::shared_ptr<ICronClock> get_clock() const { return clock; }
 
         private:
             // Priority queue placing smallest (i.e. nearest in time) items on top.
             std::priority_queue<Task, std::vector<Task>, std::greater<>> tasks{};
             void print_queue(std::priority_queue<Task, std::vector<Task>, std::greater<>> queue);
+            std::shared_ptr<ICronClock> clock{};
     };
 }
\ No newline at end of file
diff --git a/libcron/CronClock.h b/libcron/CronClock.h
new file mode 100644
index 0000000..b833b60
--- /dev/null
+++ b/libcron/CronClock.h
@@ -0,0 +1,22 @@
+#pragma once
+
+#include <chrono>
+
+namespace libcron
+{
+    class ICronClock
+    {
+        public:
+            virtual std::chrono::system_clock::time_point now() = 0;
+    };
+
+    class UTCClock
+            : public ICronClock
+    {
+        public:
+            std::chrono::system_clock::time_point now() override
+            {
+                return std::chrono::system_clock::now();
+            }
+    };
+}
\ No newline at end of file
diff --git a/libcron/CronSchedule.cpp b/libcron/CronSchedule.cpp
index bd50860..6e181c0 100644
--- a/libcron/CronSchedule.cpp
+++ b/libcron/CronSchedule.cpp
@@ -80,6 +80,6 @@ namespace libcron
             }
         }
 
-        return std::make_tuple(max_iterations > 0, max_iterations > 0 ? curr : system_clock::now());
+        return std::make_tuple(max_iterations > 0, curr);
     }
 }
\ No newline at end of file
diff --git a/libcron/Task.h b/libcron/Task.h
index 322e9e3..f44b03c 100644
--- a/libcron/Task.h
+++ b/libcron/Task.h
@@ -26,17 +26,17 @@ namespace libcron
 
             Task& operator=(const Task&) = default;
 
-            bool calculate_next(std::chrono::system_clock::time_point from = std::chrono::system_clock::now());
+            bool calculate_next(std::chrono::system_clock::time_point from);
 
             bool operator>(const Task& other) const
             {
                 return next_schedule > other.next_schedule;
             }
 
-            bool is_expired(std::chrono::system_clock::time_point now = std::chrono::system_clock::now()) const;
+            bool is_expired(std::chrono::system_clock::time_point now) const;
 
             std::chrono::system_clock::duration
-            time_until_expiry(std::chrono::system_clock::time_point now = std::chrono::system_clock::now()) const;
+            time_until_expiry(std::chrono::system_clock::time_point now) const;
 
             std::string get_name() const
             {
diff --git a/test/CronTest.cpp b/test/CronTest.cpp
index 5dde473..5e4b169 100644
--- a/test/CronTest.cpp
+++ b/test/CronTest.cpp
@@ -44,7 +44,7 @@ SCENARIO("Adding a task")
             THEN("Count is 1 and task was not expired two seconds ago")
             {
                 REQUIRE(c.count() == 1);
-                c.execute_expired_tasks(system_clock::now() - 2s);
+                c.execute_expired_tasks(c.get_clock()->now() - 2s);
                 REQUIRE_FALSE(expired);
             }
             AND_THEN("Task is expired when calculating based on current time")