Graphical layout

// crates/sentinel-display/src/ui.rs
// Graphical layout and state management engine for the ESP32-S3 rotary display interface.

#![no_std]

pub enum DisplayScreen {
    StatusOverview,
    MeshPeers,
    OpticalTransfer,
    SystemSettings,
}

pub struct UIRenderEngine {
    current_screen: DisplayScreen,
    selected_index: usize,
    max_options: usize,
}

impl UIRenderEngine {
    pub const fn new() -> Self {
        Self {
            current_screen: DisplayScreen::StatusOverview,
            selected_index: 0,
            max_options: 4,
        }
    }

    pub fn navigate(&mut self, direction: i8) {
        if direction > 0 {
            self.selected_index = (self.selected_index + 1) % self.max_options;
        } else {
            self.selected_index = if self.selected_index == 0 {
                self.max_options - 1
            } else {
                self.selected_index - 1
            };
        }
    }

    pub fn select_active_screen(&mut self) {
        self.current_screen = match self.selected_index {
            0 => DisplayScreen::StatusOverview,
            1 => DisplayScreen::MeshPeers,
            2 => DisplayScreen::OpticalTransfer,
            _ => DisplayScreen::SystemSettings,
        };
    }
}