#pragma once

#include "esp_err.h"
#include "ui/apps/app.h"
#include "ui/events.h"
#include "ui/root_layout.h"
#include "ui/interaction_handler.h"
#include "lvgl.h"
#include <memory>
#include <vector>

/**
 * @brief UI Handler - manages app lifecycle and rendering
 *
 * The UIHandler manages:
 * - Creation and destruction of UI apps
 * - Switching between apps
 * - Main screen layout (header, app container, navigation bar)
 * - System event routing to active app
 * - Displaying special screens (shutdown, etc.)
 */
class UIHandler {
public:

  UIHandler() = default;
  ~UIHandler();

  /**
   * @brief Initialize the UI system with default layout
   *
   * Creates the main screen with:
   * - Header area (top)
   * - App container (middle)
   * - Navigation bar (bottom)
   *
   * And display the main screen.
   *
   * And initializes the InteractionHandler, callbacks, etc.
   *
   * @return ESP_OK on success, error code otherwise
   */
  esp_err_t init(void);

  /**
   * @brief Deinitialize the UI system
   *
   * Cleans up the current app and destroys the main screen.
   *
   * @return ESP_OK on success, error code otherwise
   */
  esp_err_t deinit(void);

  /**
   * @brief Switch to a new app by its descriptor
   *
   * Deinitializes the current app (if any), initializes the new app,
   * and updates the display. The descriptor must remain valid in the
   * AppRegistry for the lifetime of the app.
   *
   * @param app_descriptor Pointer to the app descriptor (managed by AppRegistry)
   * @return ESP_OK on success, error code otherwise
   */
  esp_err_t switch_app(AppDescriptor* app_descriptor);

  /**
   * @brief Display shutdown screen
   *
   * Shows a shutdown screen with a message. Typically called
   * before the system enters deep sleep or powers off.
   *
   * @param message Optional message to display (e.g., "Shutting down...")
   * @return ESP_OK on success, error code otherwise
   */
  esp_err_t show_shutdown_screen(const std::string& message = "");

  /**
   * @brief Get the main screen object
   *
   * @return lv_obj_t* pointer to the main screen
   */
  lv_obj_t* get_main_screen(void) const {
    return main_screen_;
  }

  esp_err_t update_header_title(const std::string& title);

  /**
   * @brief Return to main screen (deinit app and show app icons)
   *
   * Deinitializes the active app and displays the app icons
   * in the navigation bar, returning to the home screen.
   *
   * @return ESP_OK on success, error code otherwise
   */
  esp_err_t return_to_main_screen(void);

private:

  // Handle back button press, route to active app if any
  void on_back_button_pressed_(void);

  // Helper to create the main screen layout
  esp_err_t create_main_screen_(lv_obj_t* parent);

  // Helper to destroy the main screen layout
  esp_err_t destroy_main_screen_(void);

  // delete copy constructor and assignment operator
  // to prevent copying of the UIHandler instance
  UIHandler(const UIHandler&) = delete;
  UIHandler& operator=(const UIHandler&) = delete;


  InteractionHandler interaction_handler_;  ///< Manages user interactions

  lv_obj_t* main_screen_ = nullptr;    ///< Root screen
  RootLayout root_layout_;            ///< Main screen layout manager
  AppDescriptor* active_descriptor_ = nullptr;  ///< Currently active app descriptor (managed by AppRegistry)
  
  // Track allocated user data for cleanup
  std::vector<void*> app_click_user_data_;
};