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use freya_common::Layers;
use freya_native_core::{
    attributes::AttributeName,
    exports::shipyard::Component,
    node_ref::NodeView,
    prelude::{
        AttributeMaskBuilder,
        Dependancy,
        NodeMaskBuilder,
        State,
    },
    SendAnyMap,
};
use freya_native_core_macro::partial_derive_state;

use crate::{
    CustomAttributeValues,
    ParseAttribute,
    ParseError,
};

#[derive(Default, PartialEq, Clone, Debug, Component)]
pub struct LayerState {
    pub layer: i16,
    pub layer_for_children: i16,
}

impl ParseAttribute for LayerState {
    fn parse_attribute(
        &mut self,
        attr: freya_native_core::prelude::OwnedAttributeView<CustomAttributeValues>,
    ) -> Result<(), crate::ParseError> {
        #[allow(clippy::single_match)]
        match attr.attribute {
            AttributeName::Layer => {
                if let Some(value) = attr.value.as_text() {
                    let layer = value.parse::<i16>().map_err(|_| ParseError)?;
                    self.layer -= layer;
                    self.layer_for_children += layer;
                }
            }
            _ => {}
        }

        Ok(())
    }
}

#[partial_derive_state]
impl State<CustomAttributeValues> for LayerState {
    type ParentDependencies = (Self,);

    type ChildDependencies = ();

    type NodeDependencies = ();

    const NODE_MASK: NodeMaskBuilder<'static> = NodeMaskBuilder::new()
        .with_attrs(AttributeMaskBuilder::Some(&[AttributeName::Layer]))
        .with_tag();

    fn update<'a>(
        &mut self,
        node_view: NodeView<CustomAttributeValues>,
        _node: <Self::NodeDependencies as Dependancy>::ElementBorrowed<'a>,
        parent: Option<<Self::ParentDependencies as Dependancy>::ElementBorrowed<'a>>,
        _children: Vec<<Self::ChildDependencies as Dependancy>::ElementBorrowed<'a>>,
        context: &SendAnyMap,
    ) -> bool {
        if !node_view.node_type().is_visible_element() {
            return false;
        }

        let layers = context.get::<Layers>().unwrap();
        let inherited_layer = parent.map(|(p,)| p.layer_for_children).unwrap_or(0i16);

        let mut layer_state = LayerState {
            layer: node_view.height() as i16 - inherited_layer,
            layer_for_children: inherited_layer,
        };

        if let Some(attributes) = node_view.attributes() {
            for attr in attributes {
                layer_state.parse_safe(attr);
            }
        }

        let changed = &layer_state != self;

        if changed {
            layers.insert_node_in_layer(node_view.node_id(), layer_state.layer);
        }

        *self = layer_state;
        changed
    }
}