decal 0.6.0

use crate::{
    filters::{
        FilterRegion,
        HasFilterRegion,
        primitives::PrimitiveBuilder,
    },
    paint::ResourceIri,
    primitives::{
        BlendMode,
        ColorInterpolation,
        FilterInput,
    },
    utils::{
        ElementWriter,
        IsDefault,
    },
};
use smart_default::SmartDefault;
use std::fmt::{
    Display,
    Formatter,
};

/// The blend filter primitive.
#[derive(Debug, Hash, Eq, PartialEq, Copy, Clone, SmartDefault)]
pub struct Blend {
    input: Option<FilterInput>,
    input2: Option<FilterInput>,
    mode: BlendMode,
    region: FilterRegion,
    #[default(ColorInterpolation::LinearRgb)]
    color_interpolation: ColorInterpolation,
}

impl Blend {
    /// Creates a new [`Blend`] primitive.
    ///
    /// # Returns
    /// - [`Self`]
    pub(crate) fn new() -> Self {
        Blend::default()
    }
}

impl HasFilterRegion for Blend {
    fn region_mut(&mut self) -> &mut FilterRegion {
        &mut self.region
    }
}

impl ResourceIri for Blend {}

impl Display for Blend {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        ElementWriter::new(f, "feBlend")?
            .write(|out| self.region.fmt(out))?
            .attrs([
                ("in", self.input.map(|x| (x,))),
                ("in2", self.input2.map(|x| (x,))),
            ])?
            .attr_if("mode", (self.mode,), !self.mode.is_default())?
            .attr_if(
                "color-interpolation-filters",
                (&self.color_interpolation,),
                self.color_interpolation != ColorInterpolation::LinearRgb,
            )?
            .attr("result", (self.iri(),))?
            .close()
    }
}

impl<'a> PrimitiveBuilder<'a, Blend> {
    /// Sets the first input for the blend operation.
    ///
    /// # Arguments
    /// - `input`: The [`FilterInput`] used as the first operand.
    ///
    /// # Returns
    /// - [`Self`]
    pub fn input<T>(mut self, input: T) -> Self
    where
        T: Into<FilterInput>,
    {
        self.inner.input = Some(input.into());
        self
    }

    /// Sets the second input for the blend operation.
    ///
    /// # Arguments
    /// - `input`: The [`FilterInput`] used as the second operand.
    ///
    /// # Returns
    /// - [`Self`]
    pub fn input2<T>(mut self, input2: T) -> Self
    where
        T: Into<FilterInput>,
    {
        self.inner.input2 = Some(input2.into());
        self
    }

    /// Sets the blend mode used to combine the two inputs.
    ///
    /// # Arguments
    /// - `mode`: The [`BlendMode`] to apply.
    ///
    /// # Returns
    /// - [`Self`]
    pub fn mode(mut self, mode: BlendMode) -> Self {
        self.inner.mode = mode;
        self
    }

    /// Sets the color interpolation space used during blending.
    ///
    /// # Arguments
    /// - `value`: The [`ColorInterpolation`] space to apply.
    ///
    /// # Returns
    /// - [`Self`]
    pub fn color_interpolation(mut self, value: ColorInterpolation) -> Self {
        self.inner.color_interpolation = value;
        self
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::{
        filters::{
            FilterContext,
            FilterRegionConfig,
        },
        test_utils::assert_xml,
    };

    #[test]
    fn renders_with_filter_region() {
        let ctx = FilterContext::default();
        ctx.blend().x(0.5).y(0.6).width(110).height(120).finish();
        let node = &ctx.into_primitives()[0];

        assert_xml(
            node.to_string(),
            format!(
                r#"<feBlend x="0.5" y="0.6" width="110" height="120" result="{}" />"#,
                node.iri()
            ),
        );
    }

    #[test]
    fn renders() {
        let ctx = FilterContext::default();
        ctx.blend().finish();
        let node = &ctx.into_primitives()[0];

        assert_xml(
            node.to_string(),
            format!(r#"<feBlend result="{}" />"#, node.iri()),
        );
    }

    #[test]
    fn renders_with_attrs() {
        let ctx = FilterContext::default();
        let input = FilterInput::source_graphic();
        let input2 = FilterInput::source_alpha();
        let mode = BlendMode::Multiply;
        let color_interpolation = ColorInterpolation::SRgb;

        ctx.blend()
            .input(input)
            .input2(input2)
            .mode(mode)
            .color_interpolation(color_interpolation)
            .finish();

        let node = &ctx.into_primitives()[0];

        assert_xml(
            node.to_string(),
            format!(
                r#"
<feBlend
    in="{input}"
    in2="{input2}"
    mode="{mode}"
    color-interpolation-filters="{color_interpolation}"
    result="{}"
/>
"#,
                node.iri()
            ),
        );
    }
}