freya-core 0.5.0

use std::{
    fmt::{
        self,
        Pointer,
    },
    hash::{
        Hash,
        Hasher,
    },
    mem::discriminant,
};

use freya_engine::prelude::{
    Paint,
    SkColor,
    TextStyle,
};
use torin::prelude::Area;

use crate::{
    data::TextStyleState,
    prelude::Color,
    style::{
        gradient::{
            ConicGradient,
            LinearGradient,
            RadialGradient,
        },
        render_callback::{
            RenderCallback,
            RenderContext,
            RenderTarget,
        },
        shader::ShaderFill,
    },
};

/// A paint source for backgrounds and text: a solid [`Color`], a gradient or a custom shader.
///
/// A [`Color`], [`LinearGradient`], [`RadialGradient`], [`ConicGradient`] or [`ShaderFill`]
/// all convert into a [`Fill`] automatically, so APIs that take an `impl Into<Fill>` accept
/// any of them directly:
///
/// ```
/// # use freya::prelude::*;
/// let gradient: Fill = LinearGradient::new()
///     .stop((Color::RED, 0.0))
///     .stop((Color::BLUE, 100.0))
///     .into();
/// ```
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
#[derive(Clone, Debug, PartialEq)]
pub enum Fill {
    /// A solid [`Color`].
    Color(Color),
    /// A custom SkSL shader. See [`ShaderFill`].
    Shader(Box<ShaderFill>),
    /// A [`LinearGradient`].
    LinearGradient(Box<LinearGradient>),
    /// A [`RadialGradient`].
    RadialGradient(Box<RadialGradient>),
    /// A [`ConicGradient`].
    ConicGradient(Box<ConicGradient>),
    /// Custom background or text paint.
    Callback(#[cfg_attr(feature = "serde", serde(skip))] RenderCallback),
}

impl Fill {
    pub fn set_a(&mut self, a: u8) {
        if let Fill::Color(color) = self {
            *color = color.with_a(a);
        }
    }

    /// Returns the inner [Color] when this is a [Fill::Color].
    pub fn as_color(&self) -> Option<Color> {
        match self {
            Fill::Color(color) => Some(*color),
            _ => None,
        }
    }

    /// Applies this fill as a text color.
    pub fn apply_to_text_style(
        &self,
        text_style: &mut TextStyle,
        area: Area,
        text_style_state: &TextStyleState,
        scale_factor: f64,
    ) {
        match self {
            Self::Color(color) => {
                text_style.set_color(*color);
            }
            Self::Callback(callback) => {
                text_style.set_color(Color::TRANSPARENT);
                callback.call(&mut RenderContext {
                    target: RenderTarget::TextStyle(text_style),
                    scale_factor,
                    origin: area.origin,
                    size: area.size,
                    text_style_state,
                });
            }
            _ => {
                let mut paint = Paint::default();
                paint.set_anti_alias(true);
                self.apply_to_paint(&mut paint, area);
                text_style.set_foreground_paint(&paint);
            }
        }
    }

    pub fn render_callback(&self) -> Option<&RenderCallback> {
        match self {
            Self::Callback(callback) => Some(callback),
            _ => None,
        }
    }

    pub fn apply_to_paint(&self, paint: &mut Paint, area: Area) {
        match self {
            Fill::Color(color) => {
                paint.set_color(*color);
            }
            Fill::LinearGradient(gradient) => {
                paint.set_dither(gradient.dither);
                paint.set_shader(gradient.prepare_shader(area));
            }
            Fill::RadialGradient(gradient) => {
                paint.set_dither(gradient.dither);
                paint.set_shader(gradient.prepare_shader(area));
            }
            Fill::ConicGradient(gradient) => {
                paint.set_dither(gradient.dither);
                paint.set_shader(gradient.prepare_shader(area));
            }
            Fill::Shader(shader) => {
                paint.set_shader(shader.prepare_shader(area));
            }
            Fill::Callback(_) => {
                paint.set_color(Color::TRANSPARENT);
            }
        }
    }
}

impl Default for Fill {
    fn default() -> Self {
        Self::Color(Color::default())
    }
}

impl Hash for Fill {
    fn hash<H: Hasher>(&self, state: &mut H) {
        discriminant(self).hash(state);
        match self {
            Fill::Color(color) => color.hash(state),
            Fill::Shader(shader) => shader.hash(state),
            Fill::LinearGradient(gradient) => gradient.hash(state),
            Fill::RadialGradient(gradient) => gradient.hash(state),
            Fill::ConicGradient(gradient) => gradient.hash(state),
            Fill::Callback(callback) => callback.hash(state),
        }
    }
}

impl From<RenderCallback> for Fill {
    fn from(callback: RenderCallback) -> Self {
        Self::Callback(callback)
    }
}

impl From<Color> for Fill {
    fn from(color: Color) -> Self {
        Fill::Color(color)
    }
}

impl From<(u8, u8, u8)> for Fill {
    fn from(color: (u8, u8, u8)) -> Self {
        Fill::Color(color.into())
    }
}

impl From<(u8, u8, u8, f32)> for Fill {
    fn from(color: (u8, u8, u8, f32)) -> Self {
        Fill::Color(color.into())
    }
}

impl From<(u8, u8, u8, u8)> for Fill {
    fn from(color: (u8, u8, u8, u8)) -> Self {
        Fill::Color(color.into())
    }
}

impl From<u32> for Fill {
    fn from(color: u32) -> Self {
        Fill::Color(color.into())
    }
}

impl From<SkColor> for Fill {
    fn from(color: SkColor) -> Self {
        Fill::Color(color.into())
    }
}

impl From<LinearGradient> for Fill {
    fn from(gradient: LinearGradient) -> Self {
        Fill::LinearGradient(Box::new(gradient))
    }
}

impl From<RadialGradient> for Fill {
    fn from(gradient: RadialGradient) -> Self {
        Fill::RadialGradient(Box::new(gradient))
    }
}

impl From<ConicGradient> for Fill {
    fn from(gradient: ConicGradient) -> Self {
        Fill::ConicGradient(Box::new(gradient))
    }
}

impl From<ShaderFill> for Fill {
    fn from(shader: ShaderFill) -> Self {
        Fill::Shader(Box::new(shader))
    }
}

impl fmt::Display for Fill {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            Self::Color(color) => color.fmt(f),
            Self::Shader(shader) => shader.as_ref().fmt(f),
            Self::LinearGradient(gradient) => gradient.as_ref().fmt(f),
            Self::RadialGradient(gradient) => gradient.as_ref().fmt(f),
            Self::ConicGradient(gradient) => gradient.as_ref().fmt(f),
            Self::Callback(callback) => callback.fmt(f),
        }
    }
}