#ifndef DEVICE_STATE_MACHINE_H
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#define DEVICE_STATE_MACHINE_H
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#include <atomic>
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#include <functional>
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#include <mutex>
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#include <vector>
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#include "device_state.h"
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/**
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* DeviceStateMachine - Manages device state transitions with validation
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*
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* This class ensures strict state transition rules and provides a callback mechanism
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* for components to react to state changes.
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*/
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class DeviceStateMachine {
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public:
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DeviceStateMachine();
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~DeviceStateMachine() = default;
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// Delete copy constructor and assignment operator
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DeviceStateMachine(const DeviceStateMachine&) = delete;
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DeviceStateMachine& operator=(const DeviceStateMachine&) = delete;
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/**
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* Get the current device state
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*/
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DeviceState GetState() const { return current_state_.load(); }
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/**
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* Attempt to transition to a new state
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* @param new_state The target state
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* @return true if transition was successful, false if invalid transition
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*/
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bool TransitionTo(DeviceState new_state);
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/**
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* Check if transition to target state is valid from current state
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*/
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bool CanTransitionTo(DeviceState target) const;
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/**
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* State change callback type
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* Parameters: old_state, new_state
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*/
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using StateCallback = std::function<void(DeviceState, DeviceState)>;
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/**
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* Add a state change listener (observer pattern)
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* Callback is invoked in the context of the caller of TransitionTo()
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* @return listener id for removal
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*/
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int AddStateChangeListener(StateCallback callback);
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/**
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* Remove a state change listener by id
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*/
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void RemoveStateChangeListener(int listener_id);
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/**
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* Get state name string for logging
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*/
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static const char* GetStateName(DeviceState state);
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private:
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std::atomic<DeviceState> current_state_{kDeviceStateUnknown};
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std::vector<std::pair<int, StateCallback>> listeners_;
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int next_listener_id_{0};
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std::mutex mutex_;
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/**
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* Check if transition from source to target is valid
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*/
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bool IsValidTransition(DeviceState from, DeviceState to) const;
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/**
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* Notify callback of state change
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*/
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void NotifyStateChange(DeviceState old_state, DeviceState new_state);
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};
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#endif // DEVICE_STATE_MACHINE_H
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