//! Display vector graphics in your application.
use iced_runtime::core::widget::Id;

use crate::core::layout;
use crate::core::mouse;
use crate::core::renderer;
use crate::core::svg;
use crate::core::widget::Tree;
use crate::core::{
    ContentFit, Element, Layout, Length, Rectangle, Size, Vector, Widget,
};

#[cfg(feature = "a11y")]
use std::borrow::Cow;
use std::marker::PhantomData;
use std::path::PathBuf;

pub use crate::style::svg::{Appearance, StyleSheet};
pub use svg::Handle;

/// A vector graphics image.
///
/// An [`Svg`] image resizes smoothly without losing any quality.
///
/// [`Svg`] images can have a considerable rendering cost when resized,
/// specially when they are complex.
#[allow(missing_debug_implementations)]
pub struct Svg<'a, Theme = crate::Theme>
where
    Theme: StyleSheet,
{
    id: Id,
    #[cfg(feature = "a11y")]
    name: Option<Cow<'a, str>>,
    #[cfg(feature = "a11y")]
    description: Option<iced_accessibility::Description<'a>>,
    #[cfg(feature = "a11y")]
    label: Option<Vec<iced_accessibility::accesskit::NodeId>>,
    handle: Handle,
    width: Length,
    height: Length,
    content_fit: ContentFit,
    style: <Theme as StyleSheet>::Style,
    symbolic: bool,
    _phantom_data: PhantomData<&'a ()>,
}

impl<'a, Theme> Svg<'a, Theme>
where
    Theme: StyleSheet,
{
    /// Creates a new [`Svg`] from the given [`Handle`].
    pub fn new(handle: impl Into<Handle>) -> Self {
        Svg {
            id: Id::unique(),
            #[cfg(feature = "a11y")]
            name: None,
            #[cfg(feature = "a11y")]
            description: None,
            #[cfg(feature = "a11y")]
            label: None,
            handle: handle.into(),
            width: Length::Fill,
            height: Length::Shrink,
            content_fit: ContentFit::Contain,
            symbolic: false,
            style: Default::default(),
            _phantom_data: PhantomData::default(),
        }
    }

    /// Creates a new [`Svg`] that will display the contents of the file at the
    /// provided path.
    #[must_use]
    pub fn from_path(path: impl Into<PathBuf>) -> Self {
        Self::new(Handle::from_path(path))
    }

    /// Sets the width of the [`Svg`].
    #[must_use]
    pub fn width(mut self, width: impl Into<Length>) -> Self {
        self.width = width.into();
        self
    }

    /// Sets the height of the [`Svg`].
    #[must_use]
    pub fn height(mut self, height: impl Into<Length>) -> Self {
        self.height = height.into();
        self
    }

    /// Sets the [`ContentFit`] of the [`Svg`].
    ///
    /// Defaults to [`ContentFit::Contain`]
    #[must_use]
    pub fn content_fit(self, content_fit: ContentFit) -> Self {
        Self {
            content_fit,
            ..self
        }
    }

    /// Symbolic icons inherit their color from the renderer if a color is not defined.
    #[must_use]
    pub fn symbolic(mut self, symbolic: bool) -> Self {
        self.symbolic = symbolic;
        self
    }

    /// Sets the style variant of this [`Svg`].
    #[must_use]
    pub fn style(mut self, style: impl Into<Theme::Style>) -> Self {
        self.style = style.into();
        self
    }

    #[cfg(feature = "a11y")]
    /// Sets the name of the [`Button`].
    pub fn name(mut self, name: impl Into<Cow<'a, str>>) -> Self {
        self.name = Some(name.into());
        self
    }

    #[cfg(feature = "a11y")]
    /// Sets the description of the [`Button`].
    pub fn description_widget<T: iced_accessibility::Describes>(
        mut self,
        description: &T,
    ) -> Self {
        self.description = Some(iced_accessibility::Description::Id(
            description.description(),
        ));
        self
    }

    #[cfg(feature = "a11y")]
    /// Sets the description of the [`Button`].
    pub fn description(mut self, description: impl Into<Cow<'a, str>>) -> Self {
        self.description =
            Some(iced_accessibility::Description::Text(description.into()));
        self
    }

    #[cfg(feature = "a11y")]
    /// Sets the label of the [`Button`].
    pub fn label(mut self, label: &dyn iced_accessibility::Labels) -> Self {
        self.label =
            Some(label.label().into_iter().map(|l| l.into()).collect());
        self
    }
}

impl<'a, Message, Theme, Renderer> Widget<Message, Theme, Renderer>
    for Svg<'a, Theme>
where
    Theme: iced_style::svg::StyleSheet,
    Renderer: svg::Renderer,
{
    fn size(&self) -> Size<Length> {
        Size {
            width: self.width,
            height: self.height,
        }
    }

    fn layout(
        &self,
        _tree: &mut Tree,
        renderer: &Renderer,
        limits: &layout::Limits,
    ) -> layout::Node {
        // The raw w/h of the underlying image
        let Size { width, height } = renderer.dimensions(&self.handle);
        let image_size = Size::new(width as f32, height as f32);

        // The size to be available to the widget prior to `Shrink`ing
        let raw_size = limits.resolve(self.width, self.height, image_size);

        // The uncropped size of the image when fit to the bounds above
        let full_size = self.content_fit.fit(image_size, raw_size);

        // Shrink the widget to fit the resized image, if requested
        let final_size = Size {
            width: match self.width {
                Length::Shrink => f32::min(raw_size.width, full_size.width),
                _ => raw_size.width,
            },
            height: match self.height {
                Length::Shrink => f32::min(raw_size.height, full_size.height),
                _ => raw_size.height,
            },
        };

        layout::Node::new(final_size)
    }

    fn draw(
        &self,
        _state: &Tree,
        renderer: &mut Renderer,
        theme: &Theme,
        style: &renderer::Style,
        layout: Layout<'_>,
        cursor: mouse::Cursor,
        _viewport: &Rectangle,
    ) {
        let Size { width, height } = renderer.dimensions(&self.handle);
        let image_size = Size::new(width as f32, height as f32);

        let bounds = layout.bounds();
        let adjusted_fit = self.content_fit.fit(image_size, bounds.size());
        let is_mouse_over = cursor.is_over(bounds);

        let render = |renderer: &mut Renderer| {
            let offset = Vector::new(
                (bounds.width - adjusted_fit.width).max(0.0) / 2.0,
                (bounds.height - adjusted_fit.height).max(0.0) / 2.0,
            );

            let drawing_bounds = Rectangle {
                width: adjusted_fit.width,
                height: adjusted_fit.height,
                ..bounds
            };

            let mut appearance = if is_mouse_over {
                theme.hovered(&self.style)
            } else {
                theme.appearance(&self.style)
            };
            if self.symbolic && appearance.color.is_none() {
                appearance.color = Some(style.icon_color);
            }

            renderer.draw(
                self.handle.clone(),
                appearance.color,
                drawing_bounds + offset,
            );
        };

        if adjusted_fit.width > bounds.width
            || adjusted_fit.height > bounds.height
        {
            renderer.with_layer(bounds, render);
        } else {
            render(renderer);
        }
    }

    #[cfg(feature = "a11y")]
    fn a11y_nodes(
        &self,
        layout: Layout<'_>,
        _state: &Tree,
        _cursor: mouse::Cursor,
    ) -> iced_accessibility::A11yTree {
        use iced_accessibility::{
            accesskit::{NodeBuilder, NodeId, Rect, Role},
            A11yTree,
        };

        let bounds = layout.bounds();
        let Rectangle {
            x,
            y,
            width,
            height,
        } = bounds;
        let bounds = Rect::new(
            x as f64,
            y as f64,
            (x + width) as f64,
            (y + height) as f64,
        );
        let mut node = NodeBuilder::new(Role::Image);
        node.set_bounds(bounds);
        if let Some(name) = self.name.as_ref() {
            node.set_name(name.clone());
        }
        match self.description.as_ref() {
            Some(iced_accessibility::Description::Id(id)) => {
                node.set_described_by(
                    id.iter()
                        .cloned()
                        .map(|id| NodeId::from(id))
                        .collect::<Vec<_>>(),
                );
            }
            Some(iced_accessibility::Description::Text(text)) => {
                node.set_description(text.clone());
            }
            None => {}
        }

        if let Some(label) = self.label.as_ref() {
            node.set_labelled_by(label.clone());
        }

        A11yTree::leaf(node, self.id.clone())
    }

    fn id(&self) -> Option<Id> {
        Some(self.id.clone())
    }

    fn set_id(&mut self, id: Id) {
        self.id = id;
    }
}

impl<'a, Message, Theme, Renderer> From<Svg<'a, Theme>>
    for Element<'a, Message, Theme, Renderer>
where
    Theme: iced_style::svg::StyleSheet + 'a,
    Renderer: svg::Renderer + 'a,
{
    fn from(icon: Svg<'a, Theme>) -> Element<'a, Message, Theme, Renderer> {
        Element::new(icon)
    }
}