//! The layout algorithms themselves

pub(crate) mod common;
pub(crate) mod leaf;

#[cfg(feature = "block_layout")]
pub(crate) mod block;

#[cfg(feature = "flexbox")]
pub(crate) mod flexbox;

#[cfg(feature = "grid")]
pub(crate) mod grid;

pub use leaf::compute_leaf_layout;

#[cfg(feature = "block_layout")]
pub use self::block::compute_block_layout;

#[cfg(feature = "flexbox")]
pub use self::flexbox::compute_flexbox_layout;

#[cfg(feature = "grid")]
pub use self::grid::compute_grid_layout;

use crate::geometry::{Line, Point, Size};
use crate::style::{AvailableSpace, Overflow};
use crate::tree::{
    Layout, LayoutInput, LayoutOutput, LayoutTree, NodeId, PartialLayoutTree, PartialLayoutTreeExt, SizingMode,
};
use crate::util::debug::{debug_log, debug_log_node, debug_pop_node, debug_push_node};
use crate::util::sys::round;
use crate::util::ResolveOrZero;

/// Updates the stored layout of the provided `node` and its children
pub fn compute_layout(tree: &mut impl PartialLayoutTree, root: NodeId, available_space: Size<AvailableSpace>) {
    // Recursively compute node layout
    let output = tree.perform_child_layout(
        root,
        Size::NONE,
        available_space.into_options(),
        available_space,
        SizingMode::InherentSize,
        Line::FALSE,
    );

    let style = tree.get_style(root);
    let padding = style.padding.resolve_or_zero(available_space.width.into_option());
    let border = style.border.resolve_or_zero(available_space.width.into_option());
    let scrollbar_size = Size {
        width: if style.overflow.y == Overflow::Scroll { style.scrollbar_width } else { 0.0 },
        height: if style.overflow.x == Overflow::Scroll { style.scrollbar_width } else { 0.0 },
    };

    tree.set_unrounded_layout(
        root,
        &Layout {
            order: 0,
            location: Point::ZERO,
            size: output.size,
            #[cfg(feature = "content_size")]
            content_size: output.content_size,
            scrollbar_size,
            padding,
            border,
        },
    );
}

/// Updates the stored layout of the provided `node` and its children
#[inline(always)]
pub fn compute_cached_layout<Tree: PartialLayoutTree + ?Sized, ComputeFunction>(
    tree: &mut Tree,
    node: NodeId,
    inputs: LayoutInput,
    mut compute_uncached: ComputeFunction,
) -> LayoutOutput
where
    ComputeFunction: FnMut(&mut Tree, NodeId, LayoutInput) -> LayoutOutput,
{
    debug_push_node!(node);
    let LayoutInput { known_dimensions, available_space, run_mode, .. } = inputs;

    // First we check if we have a cached result for the given input
    let cache_entry = tree.get_cache_mut(node).get(known_dimensions, available_space, run_mode);
    if let Some(cached_size_and_baselines) = cache_entry {
        debug_log!("CACHE", dbg:cached_size_and_baselines.size);
        debug_log_node!(known_dimensions, parent_size, available_space, run_mode, sizing_mode);
        debug_pop_node!();
        return cached_size_and_baselines;
    }

    let computed_size_and_baselines = compute_uncached(tree, node, inputs);

    // Cache result
    tree.get_cache_mut(node).store(known_dimensions, available_space, run_mode, computed_size_and_baselines);

    debug_log!("RESULT", dbg:computed_size_and_baselines.size);
    debug_pop_node!();

    computed_size_and_baselines
}

/// Rounds the calculated [`Layout`] to exact pixel values
///
/// In order to ensure that no gaps in the layout are introduced we:
///   - Always round based on the cumulative x/y coordinates (relative to the viewport) rather than
///     parent-relative coordinates
///   - Compute width/height by first rounding the top/bottom/left/right and then computing the difference
///     rather than rounding the width/height directly
/// See <https://github.com/facebook/yoga/commit/aa5b296ac78f7a22e1aeaf4891243c6bb76488e2> for more context
///
/// In order to prevent innacuracies caused by rounding already-rounded values, we read from `unrounded_layout`
/// and write to `final_layout`.
pub fn round_layout(tree: &mut impl LayoutTree, node_id: NodeId) {
    return round_layout_inner(tree, node_id, 0.0, 0.0);

    /// Recursive function to apply rounding to all descendents
    fn round_layout_inner(tree: &mut impl LayoutTree, node_id: NodeId, cumulative_x: f32, cumulative_y: f32) {
        let unrounded_layout = *tree.get_unrounded_layout(node_id);
        let mut layout = unrounded_layout;

        let cumulative_x = cumulative_x + unrounded_layout.location.x;
        let cumulative_y = cumulative_y + unrounded_layout.location.y;

        layout.location.x = round(unrounded_layout.location.x);
        layout.location.y = round(unrounded_layout.location.y);
        layout.size.width = round(cumulative_x + unrounded_layout.size.width) - round(cumulative_x);
        layout.size.height = round(cumulative_y + unrounded_layout.size.height) - round(cumulative_y);
        layout.scrollbar_size.width = round(unrounded_layout.scrollbar_size.width);
        layout.scrollbar_size.height = round(unrounded_layout.scrollbar_size.height);
        layout.border.left = round(cumulative_x + unrounded_layout.border.left) - round(cumulative_x);
        layout.border.right = round(cumulative_x + unrounded_layout.size.width)
            - round(cumulative_x + unrounded_layout.size.width - unrounded_layout.border.right);
        layout.border.top = round(cumulative_y + unrounded_layout.border.top) - round(cumulative_y);
        layout.border.bottom = round(cumulative_y + unrounded_layout.size.height)
            - round(cumulative_y + unrounded_layout.size.height - unrounded_layout.border.bottom);
        layout.padding.left = round(cumulative_x + unrounded_layout.padding.left) - round(cumulative_x);
        layout.padding.right = round(cumulative_x + unrounded_layout.size.width)
            - round(cumulative_x + unrounded_layout.size.width - unrounded_layout.padding.right);
        layout.padding.top = round(cumulative_y + unrounded_layout.padding.top) - round(cumulative_y);
        layout.padding.bottom = round(cumulative_y + unrounded_layout.size.height)
            - round(cumulative_y + unrounded_layout.size.height - unrounded_layout.padding.bottom);

        #[cfg(feature = "content_size")]
        round_content_size(&mut layout, unrounded_layout.content_size, cumulative_x, cumulative_y);

        tree.set_final_layout(node_id, &layout);

        let child_count = tree.child_count(node_id);
        for index in 0..child_count {
            let child = tree.get_child_id(node_id, index);
            round_layout_inner(tree, child, cumulative_x, cumulative_y);
        }
    }

    #[cfg(feature = "content_size")]
    #[inline(always)]
    /// Round content size variables.
    /// This is split into a separate function to make it easier to feature flag.
    fn round_content_size(
        layout: &mut Layout,
        unrounded_content_size: Size<f32>,
        cumulative_x: f32,
        cumulative_y: f32,
    ) {
        layout.content_size.width = round(cumulative_x + unrounded_content_size.width) - round(cumulative_x);
        layout.content_size.height = round(cumulative_y + unrounded_content_size.height) - round(cumulative_y);
    }
}

/// Creates a layout for this node and its children, recursively.
/// Each hidden node has zero size and is placed at the origin
pub fn compute_hidden_layout(tree: &mut impl PartialLayoutTree, node: NodeId) -> LayoutOutput {
    // Clear cache and set zeroed-out layout for the node
    tree.get_cache_mut(node).clear();
    tree.set_unrounded_layout(node, &Layout::with_order(0));

    // Perform hidden layout on all children
    for index in 0..tree.child_count(node) {
        let child_id = tree.get_child_id(node, index);
        tree.compute_child_layout(child_id, LayoutInput::HIDDEN);
    }

    LayoutOutput::HIDDEN
}

#[cfg(test)]
mod tests {
    use super::compute_hidden_layout;
    use crate::geometry::{Point, Size};
    use crate::style::{Display, Style};
    use crate::TaffyTree;

    #[test]
    fn hidden_layout_should_hide_recursively() {
        let mut taffy: TaffyTree<()> = TaffyTree::new();

        let style: Style = Style { display: Display::Flex, size: Size::from_lengths(50.0, 50.0), ..Default::default() };

        let grandchild_00 = taffy.new_leaf(style.clone()).unwrap();
        let grandchild_01 = taffy.new_leaf(style.clone()).unwrap();
        let child_00 = taffy.new_with_children(style.clone(), &[grandchild_00, grandchild_01]).unwrap();

        let grandchild_02 = taffy.new_leaf(style.clone()).unwrap();
        let child_01 = taffy.new_with_children(style.clone(), &[grandchild_02]).unwrap();

        let root = taffy
            .new_with_children(
                Style { display: Display::None, size: Size::from_lengths(50.0, 50.0), ..Default::default() },
                &[child_00, child_01],
            )
            .unwrap();

        compute_hidden_layout(&mut taffy.as_layout_tree(), root.into());

        // Whatever size and display-mode the nodes had previously,
        // all layouts should resolve to ZERO due to the root's DISPLAY::NONE

        for node in [root, child_00, child_01, grandchild_00, grandchild_01, grandchild_02] {
            let layout = taffy.layout(node.into()).unwrap();
            assert_eq!(layout.size, Size::zero());
            assert_eq!(layout.location, Point::zero());
        }
    }
}