egui_arbor/

state.rs

//! State management for the outliner widget.
//!
//! This module provides the [`OutlinerState`] struct which tracks the expansion
//! and editing state of nodes in the outliner. The state integrates with egui's
//! memory system to persist across frames.

use crate::drag_drop::DragDropState;
use std::collections::HashSet;
use std::hash::Hash;

/// State for box selection operations.
///
/// Tracks the start position and whether a box selection is currently active.
#[derive(Clone, Debug, PartialEq)]
pub struct BoxSelectionState {
    /// The starting position of the box selection in screen coordinates.
    pub start_pos: egui::Pos2,
    /// Whether the box selection is currently active.
    pub active: bool,
}

impl BoxSelectionState {
    /// Creates a new box selection state.
    pub fn new(start_pos: egui::Pos2) -> Self {
        Self {
            start_pos,
            active: true,
        }
    }
}

/// State for an outliner widget instance.
///
/// This struct tracks which collection nodes are expanded and which node (if any)
/// is currently being edited. The state is generic over the node ID type and
/// integrates with egui's memory system for automatic persistence.
///
/// # Type Parameters
///
/// * `Id` - The type used to identify nodes. Must implement `Hash`, `Eq`, and `Clone`.
///
/// # Examples
///
/// ```
/// use egui_arbor::OutlinerState;
/// use std::collections::HashSet;
///
/// let mut state = OutlinerState::<String>::default();
/// 
/// // Toggle expansion state
/// state.toggle_expanded(&"node1".to_string());
/// assert!(state.is_expanded(&"node1".to_string()));
///
/// // Start editing a node
/// state.start_editing("node2".to_string(), "Node 2".to_string());
/// assert!(state.is_editing(&"node2".to_string()));
/// ```
#[derive(Clone, Debug)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub struct OutlinerState<Id>
where
    Id: Hash + Eq + Clone + Send + Sync,
{
    /// Set of expanded collection node IDs.
    ///
    /// A node ID in this set indicates that the collection node is expanded
    /// and its children should be visible.
    expanded: HashSet<Id>,

    /// The ID of the node currently being edited, if any.
    ///
    /// When `Some(id)`, the node with the given ID is in edit mode (e.g., for renaming).
    /// Only one node can be edited at a time.
    editing: Option<Id>,

    /// The text being edited for the current node.
    ///
    /// This stores the text content while editing is in progress.
    /// This field is not persisted across frames (it's transient state).
    #[cfg_attr(feature = "serde", serde(skip))]
    editing_text: String,

    /// Drag-and-drop state for this outliner.
    ///
    /// Tracks the current drag operation, hover targets, and drop positions.
    /// This field is not persisted across frames (it's transient state).
    #[cfg_attr(feature = "serde", serde(skip))]
    drag_drop: DragDropState<Id>,

    /// The ID of the last selected node for shift-click range selection.
    ///
    /// This is used to determine the range when shift-clicking.
    /// This field is not persisted across frames (it's transient state).
    #[cfg_attr(feature = "serde", serde(skip))]
    last_selected: Option<Id>,

    /// State for box selection.
    ///
    /// Tracks the start position and current state of a box selection operation.
    /// This field is not persisted across frames (it's transient state).
    #[cfg_attr(feature = "serde", serde(skip))]
    box_selection: Option<BoxSelectionState>,

    /// IDs of all nodes being dragged in a multi-drag operation.
    ///
    /// This is set when a drag starts and includes all selected nodes.
    /// This field is not persisted across frames (it's transient state).
    #[cfg_attr(feature = "serde", serde(skip))]
    dragging_nodes: Vec<Id>,
}

impl<Id> Default for OutlinerState<Id>
where
    Id: Hash + Eq + Clone + Send + Sync,
{
    /// Creates a new outliner state with no expanded nodes and no editing node.
    fn default() -> Self {
        Self {
            expanded: HashSet::new(),
            editing: None,
            editing_text: String::new(),
            drag_drop: DragDropState::new(),
            last_selected: None,
            box_selection: None,
            dragging_nodes: Vec::new(),
        }
    }
}

impl<Id> OutlinerState<Id>
where
    Id: Hash + Eq + Clone + Send + Sync,
{
    /// Loads the outliner state from egui's memory system.
    ///
    /// If no state exists for the given ID, returns a default empty state.
    ///
    /// # Parameters
    ///
    /// * `ctx` - The egui context to load state from
    /// * `id` - The unique identifier for this outliner instance
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use egui_arbor::OutlinerState;
    /// # fn example(ctx: &egui::Context) {
    /// let state = OutlinerState::<String>::load(ctx, egui::Id::new("my_outliner"));
    /// # }
    /// ```
    pub fn load(ctx: &egui::Context, id: egui::Id) -> Self
    where
        Id: 'static,
    {
        ctx.data_mut(|d| d.get_persisted(id).unwrap_or_default())
    }

    /// Stores the outliner state to egui's memory system.
    ///
    /// The state will be persisted across frames and can be retrieved using
    /// [`load`](Self::load) with the same ID.
    ///
    /// # Parameters
    ///
    /// * `ctx` - The egui context to store state in
    /// * `id` - The unique identifier for this outliner instance
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use egui_arbor::OutlinerState;
    /// # fn example(ctx: &egui::Context) {
    /// let mut state = OutlinerState::<String>::default();
    /// state.toggle_expanded(&"node1".to_string());
    /// state.store(ctx, egui::Id::new("my_outliner"));
    /// # }
    /// ```
    pub fn store(&self, ctx: &egui::Context, id: egui::Id)
    where
        Id: 'static,
    {
        ctx.data_mut(|d| d.insert_persisted(id, self.clone()));
    }

    /// Checks if a node is currently expanded.
    ///
    /// # Parameters
    ///
    /// * `id` - The ID of the node to check
    ///
    /// # Returns
    ///
    /// `true` if the node is expanded, `false` otherwise.
    ///
    /// # Examples
    ///
    /// ```
    /// # use egui_arbor::OutlinerState;
    /// let mut state = OutlinerState::<String>::default();
    /// state.set_expanded(&"node1".to_string(), true);
    /// assert!(state.is_expanded(&"node1".to_string()));
    /// ```
    pub fn is_expanded(&self, id: &Id) -> bool {
        self.expanded.contains(id)
    }

    /// Toggles the expansion state of a node.
    ///
    /// If the node is currently expanded, it will be collapsed.
    /// If the node is currently collapsed, it will be expanded.
    ///
    /// # Parameters
    ///
    /// * `id` - The ID of the node to toggle
    ///
    /// # Examples
    ///
    /// ```
    /// # use egui_arbor::OutlinerState;
    /// let mut state = OutlinerState::<String>::default();
    /// state.toggle_expanded(&"node1".to_string());
    /// assert!(state.is_expanded(&"node1".to_string()));
    /// state.toggle_expanded(&"node1".to_string());
    /// assert!(!state.is_expanded(&"node1".to_string()));
    /// ```
    pub fn toggle_expanded(&mut self, id: &Id) {
        if self.expanded.contains(id) {
            self.expanded.remove(id);
        } else {
            self.expanded.insert(id.clone());
        }
    }

    /// Sets the expansion state of a node.
    ///
    /// # Parameters
    ///
    /// * `id` - The ID of the node to modify
    /// * `expanded` - `true` to expand the node, `false` to collapse it
    ///
    /// # Examples
    ///
    /// ```
    /// # use egui_arbor::OutlinerState;
    /// let mut state = OutlinerState::<String>::default();
    /// state.set_expanded(&"node1".to_string(), true);
    /// assert!(state.is_expanded(&"node1".to_string()));
    /// state.set_expanded(&"node1".to_string(), false);
    /// assert!(!state.is_expanded(&"node1".to_string()));
    /// ```
    pub fn set_expanded(&mut self, id: &Id, expanded: bool) {
        if expanded {
            self.expanded.insert(id.clone());
        } else {
            self.expanded.remove(id);
        }
    }

    /// Checks if a node is currently being edited.
    ///
    /// # Parameters
    ///
    /// * `id` - The ID of the node to check
    ///
    /// # Returns
    ///
    /// `true` if the node is being edited, `false` otherwise.
    ///
    /// # Examples
    ///
    /// ```
    /// # use egui_arbor::OutlinerState;
    /// let mut state = OutlinerState::<String>::default();
    /// state.start_editing("node1".to_string(), "Node 1".to_string());
    /// assert!(state.is_editing(&"node1".to_string()));
    /// ```
    pub fn is_editing(&self, id: &Id) -> bool {
        self.editing.as_ref() == Some(id)
    }

    /// Starts editing a node.
    ///
    /// This will stop editing any previously edited node, as only one node
    /// can be edited at a time.
    ///
    /// # Parameters
    ///
    /// * `id` - The ID of the node to start editing
    /// * `initial_text` - The initial text to display in the edit field
    ///
    /// # Examples
    ///
    /// ```
    /// # use egui_arbor::OutlinerState;
    /// let mut state = OutlinerState::<String>::default();
    /// state.start_editing("node1".to_string(), "Initial Name".to_string());
    /// assert!(state.is_editing(&"node1".to_string()));
    /// ```
    pub fn start_editing(&mut self, id: Id, initial_text: String) {
        self.editing = Some(id);
        self.editing_text = initial_text;
    }

    /// Stops editing the currently edited node, if any.
    ///
    /// # Examples
    ///
    /// ```
    /// # use egui_arbor::OutlinerState;
    /// let mut state = OutlinerState::<String>::default();
    /// state.start_editing("node1".to_string(), "Name".to_string());
    /// state.stop_editing();
    /// assert!(!state.is_editing(&"node1".to_string()));
    /// ```
    pub fn stop_editing(&mut self) {
        self.editing = None;
        self.editing_text.clear();
    }

    /// Returns a mutable reference to the editing text.
    ///
    /// This allows the text edit widget to modify the text directly.
    pub fn editing_text_mut(&mut self) -> &mut String {
        &mut self.editing_text
    }

    /// Returns a reference to the editing text.
    pub fn editing_text(&self) -> &str {
        &self.editing_text
    }

    /// Returns a reference to the drag-drop state.
    ///
    /// # Examples
    ///
    /// ```
    /// # use egui_arbor::OutlinerState;
    /// let state = OutlinerState::<String>::default();
    /// assert!(!state.drag_drop().is_dragging());
    /// ```
    pub fn drag_drop(&self) -> &DragDropState<Id> {
        &self.drag_drop
    }

    /// Returns a mutable reference to the drag-drop state.
    ///
    /// # Examples
    ///
    /// ```
    /// # use egui_arbor::OutlinerState;
    /// let mut state = OutlinerState::<String>::default();
    /// state.drag_drop_mut().start_drag("node1".to_string());
    /// assert!(state.drag_drop().is_dragging());
    /// ```
    pub fn drag_drop_mut(&mut self) -> &mut DragDropState<Id> {
        &mut self.drag_drop
    }

    /// Sets the last selected node for shift-click range selection.
    ///
    /// # Parameters
    ///
    /// * `id` - The ID of the last selected node
    pub fn set_last_selected(&mut self, id: Option<Id>) {
        self.last_selected = id;
    }

    /// Returns the ID of the last selected node, if any.
    pub fn last_selected(&self) -> Option<&Id> {
        self.last_selected.as_ref()
    }

    /// Starts a box selection operation.
    ///
    /// # Parameters
    ///
    /// * `start_pos` - The starting position in screen coordinates
    pub fn start_box_selection(&mut self, start_pos: egui::Pos2) {
        self.box_selection = Some(BoxSelectionState {
            start_pos,
            active: true,
        });
    }

    /// Returns the current box selection state, if any.
    pub fn box_selection(&self) -> Option<&BoxSelectionState> {
        self.box_selection.as_ref()
    }

    /// Ends the current box selection operation.
    pub fn end_box_selection(&mut self) {
        self.box_selection = None;
    }

    /// Sets the nodes being dragged in a multi-drag operation.
    pub fn set_dragging_nodes(&mut self, nodes: Vec<Id>) {
        self.dragging_nodes = nodes;
    }

    /// Returns the nodes being dragged in a multi-drag operation.
    pub fn dragging_nodes(&self) -> &[Id] {
        &self.dragging_nodes
    }

    /// Clears the dragging nodes list.
    pub fn clear_dragging_nodes(&mut self) {
        self.dragging_nodes.clear();
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::traits::DropPosition;

    #[test]
    fn test_default_state() {
        let state = OutlinerState::<String>::default();
        assert!(!state.is_expanded(&"test".to_string()));
        assert!(!state.is_editing(&"test".to_string()));
        assert!(!state.drag_drop().is_dragging());
        assert_eq!(state.last_selected(), None);
        assert_eq!(state.box_selection(), None);
        assert!(state.dragging_nodes().is_empty());
    }

    #[test]
    fn test_expansion() {
        let mut state = OutlinerState::<String>::default();
        let id = "node1".to_string();

        assert!(!state.is_expanded(&id));

        state.set_expanded(&id, true);
        assert!(state.is_expanded(&id));

        state.set_expanded(&id, false);
        assert!(!state.is_expanded(&id));
    }

    #[test]
    fn test_toggle_expansion() {
        let mut state = OutlinerState::<String>::default();
        let id = "node1".to_string();

        state.toggle_expanded(&id);
        assert!(state.is_expanded(&id));

        state.toggle_expanded(&id);
        assert!(!state.is_expanded(&id));
    }

    #[test]
    fn test_multiple_expansions() {
        let mut state = OutlinerState::<String>::default();
        let id1 = "node1".to_string();
        let id2 = "node2".to_string();
        let id3 = "node3".to_string();

        state.set_expanded(&id1, true);
        state.set_expanded(&id2, true);
        state.set_expanded(&id3, true);

        assert!(state.is_expanded(&id1));
        assert!(state.is_expanded(&id2));
        assert!(state.is_expanded(&id3));

        state.set_expanded(&id2, false);
        assert!(state.is_expanded(&id1));
        assert!(!state.is_expanded(&id2));
        assert!(state.is_expanded(&id3));
    }

    #[test]
    fn test_editing() {
        let mut state = OutlinerState::<String>::default();
        let id1 = "node1".to_string();
        let id2 = "node2".to_string();

        assert!(!state.is_editing(&id1));

        state.start_editing(id1.clone(), "Node 1".to_string());
        assert!(state.is_editing(&id1));
        assert!(!state.is_editing(&id2));
        assert_eq!(state.editing_text(), "Node 1");

        state.start_editing(id2.clone(), "Node 2".to_string());
        assert!(!state.is_editing(&id1));
        assert!(state.is_editing(&id2));
        assert_eq!(state.editing_text(), "Node 2");

        state.stop_editing();
        assert!(!state.is_editing(&id1));
        assert!(!state.is_editing(&id2));
        assert_eq!(state.editing_text(), "");
    }

    #[test]
    fn test_editing_same_node_twice() {
        let mut state = OutlinerState::<String>::default();
        let id = "node1".to_string();

        state.start_editing(id.clone(), "First".to_string());
        assert!(state.is_editing(&id));
        assert_eq!(state.editing_text(), "First");

        state.start_editing(id.clone(), "Second".to_string());
        assert!(state.is_editing(&id));
        assert_eq!(state.editing_text(), "Second");
    }

    #[test]
    fn test_drag_drop_state_access() {
        let mut state = OutlinerState::<u64>::default();
        
        assert!(!state.drag_drop().is_dragging());
        
        state.drag_drop_mut().start_drag(42);
        assert!(state.drag_drop().is_dragging());
        assert_eq!(state.drag_drop().dragging_id(), Some(&42));
    }

    #[test]
    fn test_last_selected() {
        let mut state = OutlinerState::<u64>::default();
        
        assert_eq!(state.last_selected(), None);
        
        state.set_last_selected(Some(1));
        assert_eq!(state.last_selected(), Some(&1));
        
        state.set_last_selected(Some(2));
        assert_eq!(state.last_selected(), Some(&2));
        
        state.set_last_selected(None);
        assert_eq!(state.last_selected(), None);
    }

    #[test]
    fn test_box_selection_lifecycle() {
        let mut state = OutlinerState::<u64>::default();
        
        assert_eq!(state.box_selection(), None);
        
        let start_pos = egui::pos2(10.0, 20.0);
        state.start_box_selection(start_pos);
        
        let box_sel = state.box_selection();
        assert!(box_sel.is_some());
        assert_eq!(box_sel.unwrap().start_pos, start_pos);
        assert!(box_sel.unwrap().active);
        
        state.end_box_selection();
        assert_eq!(state.box_selection(), None);
    }

    #[test]
    fn test_box_selection_state_new() {
        let pos = egui::pos2(5.0, 10.0);
        let box_sel = BoxSelectionState::new(pos);
        
        assert_eq!(box_sel.start_pos, pos);
        assert!(box_sel.active);
    }

    #[test]
    fn test_dragging_nodes() {
        let mut state = OutlinerState::<u64>::default();
        
        assert!(state.dragging_nodes().is_empty());
        
        let nodes = vec![1, 2, 3];
        state.set_dragging_nodes(nodes.clone());
        assert_eq!(state.dragging_nodes(), &[1, 2, 3]);
        
        state.clear_dragging_nodes();
        assert!(state.dragging_nodes().is_empty());
    }

    #[test]
    fn test_dragging_nodes_update() {
        let mut state = OutlinerState::<u64>::default();
        
        state.set_dragging_nodes(vec![1, 2]);
        assert_eq!(state.dragging_nodes().len(), 2);
        
        state.set_dragging_nodes(vec![3, 4, 5]);
        assert_eq!(state.dragging_nodes().len(), 3);
        assert_eq!(state.dragging_nodes(), &[3, 4, 5]);
    }

    #[test]
    fn test_combined_state_operations() {
        let mut state = OutlinerState::<u64>::default();
        
        // Expand some nodes
        state.set_expanded(&1, true);
        state.set_expanded(&2, true);
        
        // Start editing
        state.start_editing(3, "Node 3".to_string());
        
        // Set last selected
        state.set_last_selected(Some(4));
        
        // Start drag
        state.drag_drop_mut().start_drag(5);
        
        // Verify all states are maintained
        assert!(state.is_expanded(&1));
        assert!(state.is_expanded(&2));
        assert!(state.is_editing(&3));
        assert_eq!(state.last_selected(), Some(&4));
        assert!(state.drag_drop().is_dragging_node(&5));
    }

    #[test]
    fn test_expansion_persistence() {
        let mut state = OutlinerState::<u64>::default();
        
        // Expand multiple nodes
        for i in 1..=10 {
            state.set_expanded(&i, true);
        }
        
        // Verify all are expanded
        for i in 1..=10 {
            assert!(state.is_expanded(&i));
        }
        
        // Collapse some
        state.set_expanded(&3, false);
        state.set_expanded(&7, false);
        
        // Verify correct state
        assert!(state.is_expanded(&1));
        assert!(state.is_expanded(&2));
        assert!(!state.is_expanded(&3));
        assert!(state.is_expanded(&4));
        assert!(!state.is_expanded(&7));
        assert!(state.is_expanded(&10));
    }

    #[test]
    fn test_drag_drop_integration() {
        let mut state = OutlinerState::<u64>::default();
        
        // Start drag
        state.drag_drop_mut().start_drag(1);
        state.set_dragging_nodes(vec![1, 2, 3]);
        
        // Update hover
        state.drag_drop_mut().update_hover(4, DropPosition::Inside);
        
        // Verify state
        assert!(state.drag_drop().is_dragging());
        assert_eq!(state.dragging_nodes(), &[1, 2, 3]);
        assert!(state.drag_drop().is_hover_target(&4));
        
        // End drag
        let result = state.drag_drop_mut().end_drag();
        assert!(result.is_some());
        
        // Clear dragging nodes
        state.clear_dragging_nodes();
        assert!(state.dragging_nodes().is_empty());
    }

    #[test]
    fn test_state_isolation() {
        let mut state1 = OutlinerState::<u64>::default();
        let mut state2 = OutlinerState::<u64>::default();
        
        state1.set_expanded(&1, true);
        state2.set_expanded(&2, true);
        
        assert!(state1.is_expanded(&1));
        assert!(!state1.is_expanded(&2));
        assert!(!state2.is_expanded(&1));
        assert!(state2.is_expanded(&2));
    }
}