use crate::{PrimitiveHandle, UiRegion};

/// Retains which box geometry follows when only the extent changes.
#[derive(Clone, Copy, Debug)]
pub enum DrawRegion {
    Frame(UiRegion),
    Extent(UiRegion),
}

impl DrawRegion {
    pub(crate) fn resolve(self, frame: UiRegion, extent: UiRegion) -> UiRegion {
        match self {
            Self::Frame(local) => local.within(&frame),
            Self::Extent(local) => local.within(&extent).within(&frame),
        }
    }

    pub(crate) fn map(self, f: impl FnOnce(UiRegion) -> UiRegion) -> Self {
        match self {
            Self::Frame(local) => Self::Frame(f(local)),
            Self::Extent(local) => Self::Extent(f(local)),
        }
    }
}

impl From<UiRegion> for DrawRegion {
    fn from(region: UiRegion) -> Self {
        Self::Frame(region)
    }
}

#[derive(Debug)]
pub struct RetainedPrimitive {
    pub handle: PrimitiveHandle,
    pub region: DrawRegion,
}