1 files changed, 64 insertions, 0 deletions
diff --git a/src/timer_state.hh b/src/timer_state.hh
new file mode 100644
index 0000000..0a3c1d1
--- /dev/null
+++ b/src/timer_state.hh
@@ -0,0 +1,64 @@
+#ifndef TIMER_STATE_HH
+#define TIMER_STATE_HH
+
+#include <chrono>
+#include <filesystem>
+#include <memory>
+
+class TimerState {
+public:
+  virtual ~TimerState() = default;
+
+  /**
+   * Delegate methods must be thread-safe, they will be called on
+   * a thread owned by TimerState.
+   */
+  class Delegate {
+  public:
+    virtual ~Delegate() = default;
+
+    virtual void start(
+        std::chrono::minutes total,
+        std::chrono::time_point<std::chrono::system_clock> epoch) = 0;
+
+    virtual void stop(std::chrono::minutes total) = 0;
+
+    virtual void reset() = 0;
+
+    virtual void restart() = 0;
+
+  protected:
+    Delegate() = default;
+  };
+
+  /**
+   * Start timer. If already started nothing happens.
+   * Method must be called on the same thread as create.
+   */
+  virtual void start() = 0;
+  /**
+   * Stop timer. If already stopped nothing happens.
+   * Method must be called on the same thread as create.
+   */
+  virtual void stop() = 0;
+  /**
+   * Clear total if stopped. If started nothing happens.
+   * Method must be called on the same thread as create.
+   */
+  virtual void reset() = 0;
+
+  /**
+   * Sets up a shared TimerState. state is stored in state_file.
+   * Note that delegate may be called before method returns.
+   * Returns nullptr in case of error.
+   */
+  static std::unique_ptr<TimerState> create(std::filesystem::path state_file,
+                                            Delegate* delegate);
+
+protected:
+  TimerState() = default;
+  TimerState(TimerState const&) = delete;
+  TimerState& operator=(TimerState const&) = delete;
+};
+
+#endif  // TIMER_STATE_HH