/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

use bitflags::bitflags;
use style::selector_parser::RestyleDamage;

bitflags! {
    /// Individual layout actions that may be necessary after restyling. This is an extension
    /// of `RestyleDamage` from stylo, which only uses the 4 lower bits.
    #[derive(Clone, Copy, Default, Eq, PartialEq)]
    pub struct LayoutDamage: u16 {
        /// Recollect the box children for this element, because some of the them will be
        /// rebuilt.
        const RECOLLECT_BOX_TREE_CHILDREN = 0b011111111111 << 4;
        /// Rebuild the entire box for this element, which means that every part of layout
        /// needs to happena again.
        const REBUILD_BOX = 0b111111111111 << 4;
    }
}

impl LayoutDamage {
    pub fn recollect_box_tree_children() -> RestyleDamage {
        RestyleDamage::from_bits_retain(LayoutDamage::RECOLLECT_BOX_TREE_CHILDREN.bits()) |
            RestyleDamage::RELAYOUT
    }

    pub fn rebuild_box_tree() -> RestyleDamage {
        RestyleDamage::from_bits_retain(LayoutDamage::REBUILD_BOX.bits()) | RestyleDamage::RELAYOUT
    }

    pub fn has_box_damage(&self) -> bool {
        self.intersects(Self::REBUILD_BOX)
    }
}

impl From<RestyleDamage> for LayoutDamage {
    fn from(restyle_damage: RestyleDamage) -> Self {
        LayoutDamage::from_bits_retain(restyle_damage.bits())
    }
}

impl std::fmt::Debug for LayoutDamage {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        if self.contains(Self::REBUILD_BOX) {
            f.write_str("REBUILD_BOX")
        } else if self.contains(Self::RECOLLECT_BOX_TREE_CHILDREN) {
            f.write_str("RECOLLECT_BOX_TREE_CHILDREN")
        } else {
            f.write_str("EMPTY")
        }
    }
}