x11_overlay/ui/

layout.rs

use crate::graphics::{GraphicsContext, Rectangle};
use crate::ui::Component;
use anyhow::Result;

/// Represents different layout strategies for arranging components
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum LayoutType {
    /// Fixed positioning - components maintain their exact positions
    #[allow(dead_code)]
    Fixed,
    /// Horizontal flow - components arranged left to right
    HorizontalFlow,
    /// Vertical flow - components arranged top to bottom
    VerticalFlow,
    /// Grid layout - components arranged in rows and columns
    Grid { columns: usize },
}

/// Alignment options for layout containers
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum Alignment {
    Start,
    Center,
    End,
}

/// Spacing configuration for layouts
#[derive(Debug, Clone, Copy)]
pub struct Spacing {
    pub top: i16,
    pub right: i16,
    pub bottom: i16,
    pub left: i16,
}

impl Spacing {
    pub fn new(top: i16, right: i16, bottom: i16, left: i16) -> Self {
        Self {
            top,
            right,
            bottom,
            left,
        }
    }

    pub fn uniform(spacing: i16) -> Self {
        Self::new(spacing, spacing, spacing, spacing)
    }

    #[allow(dead_code)]
    pub fn horizontal_vertical(horizontal: i16, vertical: i16) -> Self {
        Self::new(vertical, horizontal, vertical, horizontal)
    }
}

impl Default for Spacing {
    fn default() -> Self {
        Self::uniform(0)
    }
}

/// A positioned component with layout metadata
pub struct LayoutItem {
    pub component: Box<dyn Component>,
    pub computed_bounds: Rectangle,
    pub margin: Spacing,
    pub visible: bool,
}

impl LayoutItem {
    pub fn new(component: Box<dyn Component>) -> Self {
        let bounds = component.bounds();
        Self {
            component,
            computed_bounds: bounds,
            margin: Spacing::default(),
            visible: true,
        }
    }

    #[allow(dead_code)]
    pub fn with_margin(mut self, margin: Spacing) -> Self {
        self.margin = margin;
        self
    }

    #[allow(dead_code)]
    pub fn set_visible(mut self, visible: bool) -> Self {
        self.visible = visible;
        self
    }
}

/// Layout container that manages the positioning and sizing of components
pub struct LayoutContainer {
    layout_type: LayoutType,
    bounds: Rectangle,
    items: Vec<LayoutItem>,
    gap: i16,
    alignment: Alignment,
    padding: Spacing,
    needs_layout: bool,
}

impl LayoutContainer {
    pub fn new(layout_type: LayoutType, bounds: Rectangle) -> Self {
        Self {
            layout_type,
            bounds,
            items: Vec::new(),
            gap: 0,
            alignment: Alignment::Start,
            padding: Spacing::default(),
            needs_layout: true,
        }
    }

    pub fn with_gap(mut self, gap: i16) -> Self {
        self.gap = gap;
        self.needs_layout = true;
        self
    }

    pub fn with_alignment(mut self, alignment: Alignment) -> Self {
        self.alignment = alignment;
        self.needs_layout = true;
        self
    }

    pub fn with_padding(mut self, padding: Spacing) -> Self {
        self.padding = padding;
        self.needs_layout = true;
        self
    }

    pub fn add_item(&mut self, item: LayoutItem) {
        self.items.push(item);
        self.needs_layout = true;
    }

    pub fn add_component(&mut self, component: Box<dyn Component>) {
        self.add_item(LayoutItem::new(component));
    }

    #[allow(dead_code)]
    pub fn set_bounds(&mut self, bounds: Rectangle) {
        self.bounds = bounds;
        self.needs_layout = true;
    }

    pub fn layout(&mut self) -> Result<()> {
        if !self.needs_layout {
            return Ok(());
        }

        let content_bounds = self.calculate_content_bounds();

        match self.layout_type {
            LayoutType::Fixed => self.layout_fixed(),
            LayoutType::HorizontalFlow => self.layout_horizontal_flow(content_bounds),
            LayoutType::VerticalFlow => self.layout_vertical_flow(content_bounds),
            LayoutType::Grid { columns } => self.layout_grid(content_bounds, columns),
        }?;

        self.needs_layout = false;
        Ok(())
    }

    fn calculate_content_bounds(&self) -> Rectangle {
        let x = self.bounds.x + self.padding.left;
        let y = self.bounds.y + self.padding.top;
        let width = self
            .bounds
            .width
            .saturating_sub((self.padding.left + self.padding.right) as u16);
        let height = self
            .bounds
            .height
            .saturating_sub((self.padding.top + self.padding.bottom) as u16);

        Rectangle {
            x,
            y,
            width,
            height,
        }
    }

    fn layout_fixed(&mut self) -> Result<()> {
        // Fixed layout keeps original component bounds
        for item in &mut self.items {
            item.computed_bounds = item.component.bounds();
        }
        Ok(())
    }

    fn layout_horizontal_flow(&mut self, content_bounds: Rectangle) -> Result<()> {
        let mut current_x = content_bounds.x;
        let alignment = self.alignment;

        for item in &mut self.items {
            if !item.visible {
                continue;
            }

            let original_bounds = item.component.bounds();

            // Calculate vertical position
            let y = match alignment {
                Alignment::Start => content_bounds.y + item.margin.top,
                Alignment::Center => {
                    content_bounds.y
                        + (content_bounds.height as i16 - original_bounds.height as i16) / 2
                        + item.margin.top
                }
                Alignment::End => {
                    content_bounds.y + content_bounds.height as i16 - original_bounds.height as i16
                        + item.margin.top
                }
            };

            // Position item
            item.computed_bounds = Rectangle {
                x: current_x + item.margin.left,
                y,
                width: original_bounds.width,
                height: original_bounds.height,
            };

            current_x +=
                original_bounds.width as i16 + item.margin.left + item.margin.right + self.gap;
        }
        Ok(())
    }

    fn layout_vertical_flow(&mut self, content_bounds: Rectangle) -> Result<()> {
        let mut current_y = content_bounds.y;
        let alignment = self.alignment;

        for item in &mut self.items {
            if !item.visible {
                continue;
            }

            let original_bounds = item.component.bounds();

            // Calculate horizontal position
            let x = match alignment {
                Alignment::Start => content_bounds.x + item.margin.left,
                Alignment::Center => {
                    content_bounds.x
                        + (content_bounds.width as i16 - original_bounds.width as i16) / 2
                        + item.margin.left
                }
                Alignment::End => {
                    content_bounds.x + content_bounds.width as i16 - original_bounds.width as i16
                        + item.margin.left
                }
            };

            // Position item
            item.computed_bounds = Rectangle {
                x,
                y: current_y + item.margin.top,
                width: original_bounds.width,
                height: original_bounds.height,
            };

            current_y +=
                original_bounds.height as i16 + item.margin.top + item.margin.bottom + self.gap;
        }
        Ok(())
    }

    fn layout_grid(&mut self, content_bounds: Rectangle, columns: usize) -> Result<()> {
        if columns == 0 {
            return Ok(());
        }

        let visible_items: Vec<&mut LayoutItem> =
            self.items.iter_mut().filter(|item| item.visible).collect();

        if visible_items.is_empty() {
            return Ok(());
        }

        let rows_needed = visible_items.len().div_ceil(columns);
        let cell_width = content_bounds.width / columns as u16;
        let cell_height = if rows_needed > 0 {
            content_bounds.height / rows_needed as u16
        } else {
            content_bounds.height
        };

        for (index, item) in visible_items.into_iter().enumerate() {
            let col = index % columns;
            let row = index / columns;

            let cell_x = content_bounds.x + (col as u16 * cell_width) as i16;
            let cell_y = content_bounds.y + (row as u16 * cell_height) as i16;

            let original_bounds = item.component.bounds();

            item.computed_bounds = Rectangle {
                x: cell_x + item.margin.left,
                y: cell_y + item.margin.top,
                width: cell_width.min(original_bounds.width),
                height: cell_height.min(original_bounds.height),
            };
        }
        Ok(())
    }
}

impl Component for LayoutContainer {
    fn render(&self, graphics: &mut GraphicsContext) -> Result<()> {
        for item in &self.items {
            if item.visible && item.component.is_visible() {
                // Calculate offset from component's original position to computed position
                let component_bounds = item.component.bounds();
                let offset_x = item.computed_bounds.x - component_bounds.x;
                let offset_y = item.computed_bounds.y - component_bounds.y;

                // If we have a cairo context, use translation to position the component
                if let Ok(Some(cairo_ctx)) = graphics.get_cairo_context() {
                    cairo_ctx.save().unwrap();
                    cairo_ctx.translate(offset_x as f64, offset_y as f64);
                    item.component.render(graphics)?;
                    cairo_ctx.restore().unwrap();
                } else {
                    // Fallback: render at original position (better than nothing)
                    item.component.render(graphics)?;
                }
            }
        }
        Ok(())
    }

    fn bounds(&self) -> Rectangle {
        self.bounds
    }

    fn update(&mut self, delta_time: f64) -> bool {
        let mut needs_redraw = false;

        for item in &mut self.items {
            if item.component.update(delta_time) {
                needs_redraw = true;
                self.needs_layout = true; // Layout might need recalculation
            }
        }

        if self.needs_layout {
            let _ = self.layout(); // Ignore layout errors in update
            needs_redraw = true;
        }

        needs_redraw
    }

    fn is_visible(&self) -> bool {
        self.items
            .iter()
            .any(|item| item.visible && item.component.is_visible())
    }

    fn should_remove(&self) -> bool {
        self.items.iter().all(|item| item.component.should_remove())
    }
}

/// Simple layout builder for common layout patterns
pub struct LayoutBuilder;

impl LayoutBuilder {
    /// Create a horizontal layout container
    pub fn horizontal(bounds: Rectangle) -> LayoutContainer {
        LayoutContainer::new(LayoutType::HorizontalFlow, bounds)
    }

    /// Create a vertical layout container
    pub fn vertical(bounds: Rectangle) -> LayoutContainer {
        LayoutContainer::new(LayoutType::VerticalFlow, bounds)
    }

    /// Create a grid layout container
    pub fn grid(bounds: Rectangle, columns: usize) -> LayoutContainer {
        LayoutContainer::new(LayoutType::Grid { columns }, bounds)
    }

    /// Create a fixed layout container
    #[allow(dead_code)]
    pub fn fixed(bounds: Rectangle) -> LayoutContainer {
        LayoutContainer::new(LayoutType::Fixed, bounds)
    }
}

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

    // Mock component for testing
    struct MockComponent {
        bounds: Rectangle,
        updated: bool,
    }

    impl MockComponent {
        fn new(x: i16, y: i16, width: u16, height: u16) -> Self {
            Self {
                bounds: Rectangle::new(x, y, width, height),
                updated: false,
            }
        }
    }

    impl Component for MockComponent {
        fn render(&self, _graphics: &mut crate::graphics::GraphicsContext) -> anyhow::Result<()> {
            Ok(())
        }

        fn bounds(&self) -> Rectangle {
            self.bounds
        }

        fn update(&mut self, _delta_time: f64) -> bool {
            self.updated = !self.updated;
            self.updated
        }
    }

    #[test]
    fn test_spacing_creation() {
        let spacing = Spacing::new(10, 20, 30, 40);
        assert_eq!(spacing.top, 10);
        assert_eq!(spacing.right, 20);
        assert_eq!(spacing.bottom, 30);
        assert_eq!(spacing.left, 40);

        let uniform = Spacing::uniform(15);
        assert_eq!(uniform.top, 15);
        assert_eq!(uniform.right, 15);
        assert_eq!(uniform.bottom, 15);
        assert_eq!(uniform.left, 15);
    }

    #[test]
    fn test_layout_item_creation() {
        let component = MockComponent::new(10, 20, 100, 50);
        let item = LayoutItem::new(Box::new(component));

        assert_eq!(item.computed_bounds.x, 10);
        assert_eq!(item.computed_bounds.y, 20);
        assert_eq!(item.computed_bounds.width, 100);
        assert_eq!(item.computed_bounds.height, 50);
        assert!(item.visible);
    }

    #[test]
    fn test_layout_container_creation() {
        let bounds = Rectangle::new(0, 0, 800, 600);
        let container = LayoutContainer::new(LayoutType::HorizontalFlow, bounds);

        assert_eq!(container.bounds().x, 0);
        assert_eq!(container.bounds().y, 0);
        assert_eq!(container.bounds().width, 800);
        assert_eq!(container.bounds().height, 600);
    }

    #[test]
    fn test_layout_builder() {
        let bounds = Rectangle::new(0, 0, 400, 300);

        let horizontal = LayoutBuilder::horizontal(bounds);
        matches!(horizontal.layout_type, LayoutType::HorizontalFlow);

        let vertical = LayoutBuilder::vertical(bounds);
        matches!(vertical.layout_type, LayoutType::VerticalFlow);

        let grid = LayoutBuilder::grid(bounds, 3);
        matches!(grid.layout_type, LayoutType::Grid { columns: 3 });
    }

    #[test]
    fn test_horizontal_layout() {
        let bounds = Rectangle::new(0, 0, 400, 100);
        let mut container = LayoutBuilder::horizontal(bounds)
            .with_gap(10)
            .with_alignment(Alignment::Start);

        // Add two components
        let comp1 = MockComponent::new(0, 0, 50, 30);
        let comp2 = MockComponent::new(0, 0, 80, 40);

        container.add_component(Box::new(comp1));
        container.add_component(Box::new(comp2));

        // Layout should position components horizontally
        container.layout().unwrap();

        // First component should be at the start
        assert_eq!(container.items[0].computed_bounds.x, 0);
        assert_eq!(container.items[0].computed_bounds.y, 0);

        // Second component should be positioned after first + gap
        assert_eq!(container.items[1].computed_bounds.x, 50 + 10); // width of first + gap
        assert_eq!(container.items[1].computed_bounds.y, 0);
    }

    #[test]
    fn test_vertical_layout() {
        let bounds = Rectangle::new(0, 0, 100, 400);
        let mut container = LayoutBuilder::vertical(bounds)
            .with_gap(5)
            .with_alignment(Alignment::Start);

        // Add two components
        let comp1 = MockComponent::new(0, 0, 50, 30);
        let comp2 = MockComponent::new(0, 0, 60, 40);

        container.add_component(Box::new(comp1));
        container.add_component(Box::new(comp2));

        // Layout should position components vertically
        container.layout().unwrap();

        // First component should be at the start
        assert_eq!(container.items[0].computed_bounds.x, 0);
        assert_eq!(container.items[0].computed_bounds.y, 0);

        // Second component should be positioned after first + gap
        assert_eq!(container.items[1].computed_bounds.x, 0);
        assert_eq!(container.items[1].computed_bounds.y, 30 + 5); // height of first + gap
    }

    #[test]
    fn test_grid_layout() {
        let bounds = Rectangle::new(0, 0, 200, 200);
        let mut container = LayoutBuilder::grid(bounds, 2); // 2 columns

        // Add four components
        for _i in 0..4 {
            let comp = MockComponent::new(0, 0, 40, 30);
            container.add_component(Box::new(comp));
        }

        container.layout().unwrap();

        // Cell dimensions should be 100x100 (200/2 columns, 200/2 rows)
        let cell_width = 200 / 2;
        let cell_height = 200 / 2;

        // Check positioning of first component (top-left)
        assert_eq!(container.items[0].computed_bounds.x, 0);
        assert_eq!(container.items[0].computed_bounds.y, 0);

        // Check positioning of second component (top-right)
        assert_eq!(container.items[1].computed_bounds.x, cell_width as i16);
        assert_eq!(container.items[1].computed_bounds.y, 0);

        // Check positioning of third component (bottom-left)
        assert_eq!(container.items[2].computed_bounds.x, 0);
        assert_eq!(container.items[2].computed_bounds.y, cell_height as i16);

        // Check positioning of fourth component (bottom-right)
        assert_eq!(container.items[3].computed_bounds.x, cell_width as i16);
        assert_eq!(container.items[3].computed_bounds.y, cell_height as i16);
    }

    #[test]
    fn test_alignment_center() {
        let bounds = Rectangle::new(0, 0, 200, 100);
        let mut container = LayoutBuilder::horizontal(bounds).with_alignment(Alignment::Center);

        // Add a component smaller than the container
        let comp = MockComponent::new(0, 0, 50, 30);
        container.add_component(Box::new(comp));

        container.layout().unwrap();

        // Component should be centered vertically (horizontal layout centers in cross-axis)
        let expected_y = (100 - 30) / 2; // (container_height - component_height) / 2
        assert_eq!(container.items[0].computed_bounds.y, expected_y as i16);
    }

    #[test]
    fn test_padding() {
        let bounds = Rectangle::new(0, 0, 200, 100);
        let padding = Spacing::uniform(10);
        let mut container = LayoutBuilder::horizontal(bounds).with_padding(padding);

        let comp = MockComponent::new(0, 0, 50, 30);
        container.add_component(Box::new(comp));

        container.layout().unwrap();

        // Component should be positioned considering padding
        assert_eq!(container.items[0].computed_bounds.x, 10); // left padding
        assert_eq!(container.items[0].computed_bounds.y, 10); // top padding
    }

    #[test]
    fn test_container_visibility() {
        let bounds = Rectangle::new(0, 0, 100, 100);
        let mut container = LayoutContainer::new(LayoutType::Fixed, bounds);

        // Empty container should not be visible
        assert!(!container.is_visible());

        // Add a component
        let comp = MockComponent::new(0, 0, 50, 30);
        container.add_component(Box::new(comp));

        // Now container should be visible
        assert!(container.is_visible());
    }

    #[test]
    fn test_container_update() {
        let bounds = Rectangle::new(0, 0, 100, 100);
        let mut container = LayoutContainer::new(LayoutType::Fixed, bounds);

        // Add a component
        let comp = MockComponent::new(0, 0, 50, 30);
        container.add_component(Box::new(comp));

        // Update should return true if any component needs redraw
        let needs_redraw = container.update(0.016);
        assert!(needs_redraw); // MockComponent alternates its update return value
    }
}