implement Milestone 11: Camera interface with permission and user gesture requirements

src/main/cpp/sandbox/camera_interface.h

@@ -0,0 +1,125 @@
+#pragma once
+
+#include <string>
+#include <memory>
+#include <functional>
+#include <mutex>
+#include <atomic>
+#include <vector>
+#include <chrono>
+
+struct lua_State;
+
+namespace mosis {
+
+class PermissionGate;
+
+enum class CameraFacing {
+    Front,
+    Back
+};
+
+enum class CameraResolution {
+    VGA,      // 640x480
+    HD,       // 1280x720
+    FullHD    // 1920x1080
+};
+
+struct CameraConfig {
+    CameraFacing facing = CameraFacing::Back;
+    CameraResolution resolution = CameraResolution::HD;
+    int max_fps = 30;
+};
+
+struct CameraFrame {
+    std::vector<uint8_t> data;  // RGBA or JPEG data
+    int width = 0;
+    int height = 0;
+    uint64_t timestamp_ms = 0;
+    bool is_jpeg = false;
+};
+
+class CameraSession {
+public:
+    using FrameCallback = std::function<void(const CameraFrame& frame)>;
+
+    CameraSession(int id, const CameraConfig& config);
+    ~CameraSession();
+
+    int GetId() const { return m_id; }
+    const CameraConfig& GetConfig() const { return m_config; }
+    bool IsActive() const { return m_active; }
+
+    // Capture single photo (returns copy of current frame)
+    CameraFrame Capture();
+
+    // Set frame callback (for preview)
+    void SetOnFrame(FrameCallback cb) { m_on_frame = std::move(cb); }
+
+    // Stop session
+    void Stop();
+
+    // For mock mode - simulate frame arrival
+    void SimulateFrame(const CameraFrame& frame);
+
+private:
+    int m_id;
+    CameraConfig m_config;
+    std::atomic<bool> m_active{true};
+    FrameCallback m_on_frame;
+    CameraFrame m_last_frame;
+    mutable std::mutex m_mutex;
+};
+
+class CameraInterface {
+public:
+    CameraInterface(const std::string& app_id, PermissionGate* permissions);
+    ~CameraInterface();
+
+    // Start camera session
+    // Returns session on success, nullptr on failure (sets error)
+    // Requires camera permission and user gesture
+    std::shared_ptr<CameraSession> StartSession(const CameraConfig& config, std::string& error);
+
+    // Stop active session
+    void StopSession();
+
+    // Check if session is active
+    bool HasActiveSession() const;
+
+    // Check if recording indicator should be shown
+    bool IsIndicatorVisible() const;
+
+    // Cleanup on app stop
+    void Shutdown();
+
+    // For testing
+    void SetMockMode(bool enabled) { m_mock_mode = enabled; }
+    bool IsMockMode() const { return m_mock_mode; }
+
+    // Simulate user gesture for testing
+    void SimulateUserGesture();
+
+private:
+    std::string m_app_id;
+    PermissionGate* m_permissions;
+    std::shared_ptr<CameraSession> m_active_session;
+    mutable std::mutex m_mutex;
+    bool m_mock_mode = true;
+    std::atomic<bool> m_indicator_visible{false};
+    int m_next_session_id = 1;
+
+    // Track user gesture timing
+    std::chrono::steady_clock::time_point m_last_gesture_time;
+    bool m_has_gesture = false;
+    static constexpr int GESTURE_VALIDITY_MS = 5000;  // 5 seconds
+
+    bool HasRecentUserGesture() const;
+    void ShowIndicator();
+    void HideIndicator();
+};
+
+// Register camera.* APIs as globals
+void RegisterCameraAPI(lua_State* L, CameraInterface* camera);
+
+} // namespace mosis