mod mouse_event;
mod mouse_region;
mod region;

#[cfg(debug_assertions)]
use collections::HashSet;
use derive_more::Mul;
use schemars::JsonSchema;
use serde::Deserialize;
use serde_derive::Serialize;
use std::{
    any::{Any, TypeId},
    borrow::Cow,
    rc::Rc,
    sync::Arc,
};

use crate::{
    color::Color,
    fonts::{FontId, GlyphId},
    geometry::{rect::RectF, vector::Vector2F},
    platform::{current::Surface, CursorStyle},
    ImageData, WindowContext,
};
pub use mouse_event::*;
pub use mouse_region::*;

pub struct SceneBuilder {
    stacking_contexts: Vec<StackingContext>,
    active_stacking_context_stack: Vec<usize>,
    /// Used by the gpui2 crate.
    pub event_handlers: Vec<EventHandler>,
    #[cfg(debug_assertions)]
    mouse_region_ids: HashSet<MouseRegionId>,
}

pub struct Scene {
    scale_factor: f32,
    stacking_contexts: Vec<StackingContext>,
    event_handlers: Vec<EventHandler>,
}

struct StackingContext {
    layers: Vec<Layer>,
    active_layer_stack: Vec<usize>,
    z_index: usize,
}

#[derive(Default)]
pub struct Layer {
    clip_bounds: Option<RectF>,
    quads: Vec<Quad>,
    underlines: Vec<Underline>,
    images: Vec<Image>,
    surfaces: Vec<Surface>,
    shadows: Vec<Shadow>,
    glyphs: Vec<Glyph>,
    image_glyphs: Vec<ImageGlyph>,
    icons: Vec<Icon>,
    paths: Vec<Path>,
    cursor_regions: Vec<CursorRegion>,
    mouse_regions: Vec<MouseRegion>,
}

#[derive(Copy, Clone)]
pub struct CursorRegion {
    pub bounds: RectF,
    pub style: CursorStyle,
}

#[derive(Default, Debug)]
pub struct Quad {
    pub bounds: RectF,
    pub background: Option<Color>,
    pub border: Border,
    pub corner_radii: CornerRadii,
}

#[derive(Default, Debug, Mul, Clone, Copy, Serialize, JsonSchema)]
pub struct CornerRadii {
    pub top_left: f32,
    pub top_right: f32,
    pub bottom_right: f32,
    pub bottom_left: f32,
}

impl<'de> Deserialize<'de> for CornerRadii {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: serde::Deserializer<'de>,
    {
        #[derive(Deserialize)]
        pub struct CornerRadiiHelper {
            pub top_left: Option<f32>,
            pub top_right: Option<f32>,
            pub bottom_right: Option<f32>,
            pub bottom_left: Option<f32>,
        }

        #[derive(Deserialize)]
        #[serde(untagged)]
        enum RadiusOrRadii {
            Radius(f32),
            Radii(CornerRadiiHelper),
        }

        let json = RadiusOrRadii::deserialize(deserializer)?;

        let result = match json {
            RadiusOrRadii::Radius(radius) => CornerRadii::from(radius),
            RadiusOrRadii::Radii(CornerRadiiHelper {
                top_left,
                top_right,
                bottom_right,
                bottom_left,
            }) => CornerRadii {
                top_left: top_left.unwrap_or(0.0),
                top_right: top_right.unwrap_or(0.0),
                bottom_right: bottom_right.unwrap_or(0.0),
                bottom_left: bottom_left.unwrap_or(0.0),
            },
        };

        Ok(result)
    }
}

impl From<f32> for CornerRadii {
    fn from(radius: f32) -> Self {
        Self {
            top_left: radius,
            top_right: radius,
            bottom_right: radius,
            bottom_left: radius,
        }
    }
}

#[derive(Debug)]
pub struct Shadow {
    pub bounds: RectF,
    pub corner_radii: CornerRadii,
    pub sigma: f32,
    pub color: Color,
}

#[derive(Debug, Clone, Copy)]
pub struct Glyph {
    pub font_id: FontId,
    pub font_size: f32,
    pub id: GlyphId,
    pub origin: Vector2F,
    pub color: Color,
}

#[derive(Debug)]
pub struct ImageGlyph {
    pub font_id: FontId,
    pub font_size: f32,
    pub id: GlyphId,
    pub origin: Vector2F,
}

pub struct Icon {
    pub bounds: RectF,
    pub svg: usvg::Tree,
    pub path: Cow<'static, str>,
    pub color: Color,
}

#[derive(Clone, Copy, Default, Debug)]
pub struct Border {
    pub color: Color,
    pub top: f32,
    pub right: f32,
    pub bottom: f32,
    pub left: f32,
}

#[derive(Clone, Copy, Default, Debug)]
pub struct Underline {
    pub origin: Vector2F,
    pub width: f32,
    pub thickness: f32,
    pub color: Color,
    pub squiggly: bool,
}

#[derive(Debug)]
pub struct Path {
    pub bounds: RectF,
    pub color: Color,
    pub vertices: Vec<PathVertex>,
}

#[derive(Debug)]
pub struct PathVertex {
    pub xy_position: Vector2F,
    pub st_position: Vector2F,
}

pub struct Image {
    pub bounds: RectF,
    pub border: Border,
    pub corner_radii: CornerRadii,
    pub grayscale: bool,
    pub data: Arc<ImageData>,
}

impl Scene {
    pub fn scale_factor(&self) -> f32 {
        self.scale_factor
    }

    pub fn layers(&self) -> impl Iterator<Item = &Layer> {
        self.stacking_contexts.iter().flat_map(|s| &s.layers)
    }

    pub fn cursor_regions(&self) -> Vec<CursorRegion> {
        self.layers()
            .flat_map(|layer| &layer.cursor_regions)
            .copied()
            .collect()
    }

    pub fn mouse_regions(&self) -> Vec<(MouseRegion, usize)> {
        self.stacking_contexts
            .iter()
            .flat_map(|context| {
                context
                    .layers
                    .iter()
                    .flat_map(|layer| &layer.mouse_regions)
                    .map(|region| (region.clone(), context.z_index))
            })
            .collect()
    }

    pub fn take_event_handlers(&mut self) -> Vec<EventHandler> {
        self.event_handlers
            .sort_by(|a, b| a.order.cmp(&b.order).reverse());
        std::mem::take(&mut self.event_handlers)
    }
}

impl SceneBuilder {
    pub fn new() -> Self {
        let mut this = SceneBuilder {
            stacking_contexts: Vec::new(),
            active_stacking_context_stack: Vec::new(),
            #[cfg(debug_assertions)]
            mouse_region_ids: HashSet::default(),
            event_handlers: Vec::new(),
        };
        this.clear();
        this
    }

    pub fn clear(&mut self) {
        self.stacking_contexts.clear();
        self.stacking_contexts.push(StackingContext::new(None, 0));
        self.active_stacking_context_stack.clear();
        self.active_stacking_context_stack.push(0);
        #[cfg(debug_assertions)]
        self.mouse_region_ids.clear();
    }

    pub fn build(&mut self, scale_factor: f32) -> Scene {
        let mut stacking_contexts = std::mem::take(&mut self.stacking_contexts);
        stacking_contexts.sort_by_key(|context| context.z_index);
        let event_handlers = std::mem::take(&mut self.event_handlers);
        self.clear();

        Scene {
            scale_factor,
            stacking_contexts,
            event_handlers,
        }
    }

    pub fn push_stacking_context(&mut self, clip_bounds: Option<RectF>, z_index: Option<usize>) {
        let z_index = z_index.unwrap_or_else(|| self.active_stacking_context().z_index + 1);
        self.active_stacking_context_stack
            .push(self.stacking_contexts.len());
        self.stacking_contexts
            .push(StackingContext::new(clip_bounds, z_index))
    }

    pub fn pop_stacking_context(&mut self) {
        self.active_stacking_context_stack.pop();
        assert!(!self.active_stacking_context_stack.is_empty());
    }

    pub fn push_layer(&mut self, clip_bounds: Option<RectF>) {
        self.active_stacking_context().push_layer(clip_bounds);
    }

    pub fn pop_layer(&mut self) {
        self.active_stacking_context().pop_layer();
    }

    pub fn push_quad(&mut self, quad: Quad) {
        self.active_layer().push_quad(quad)
    }

    pub fn push_cursor_region(&mut self, region: CursorRegion) {
        if can_draw(region.bounds) {
            self.active_layer().push_cursor_region(region);
        }
    }

    pub fn push_mouse_region(&mut self, region: MouseRegion) {
        if can_draw(region.bounds) {
            // Ensure that Regions cannot be added to a scene with the same region id.
            #[cfg(debug_assertions)]
            let region_id;
            #[cfg(debug_assertions)]
            {
                region_id = region.id();
            }

            if self.active_layer().push_mouse_region(region) {
                #[cfg(debug_assertions)]
                {
                    if !self.mouse_region_ids.insert(region_id) {
                        let tag_name = region_id.tag_type_name();
                        panic!("Same MouseRegionId: {region_id:?} inserted multiple times to the same scene. \
                            Will cause problems! Look for MouseRegion that uses Tag: {tag_name}");
                    }
                }
            }
        }
    }

    pub fn push_image(&mut self, image: Image) {
        self.active_layer().push_image(image)
    }

    pub fn push_surface(&mut self, surface: Surface) {
        self.active_layer().push_surface(surface)
    }

    pub fn push_underline(&mut self, underline: Underline) {
        self.active_layer().push_underline(underline)
    }

    pub fn push_shadow(&mut self, shadow: Shadow) {
        self.active_layer().push_shadow(shadow)
    }

    pub fn push_glyph(&mut self, glyph: Glyph) {
        self.active_layer().push_glyph(glyph)
    }

    pub fn push_image_glyph(&mut self, image_glyph: ImageGlyph) {
        self.active_layer().push_image_glyph(image_glyph)
    }

    pub fn push_icon(&mut self, icon: Icon) {
        self.active_layer().push_icon(icon)
    }

    pub fn push_path(&mut self, path: Path) {
        self.active_layer().push_path(path);
    }

    fn active_stacking_context(&mut self) -> &mut StackingContext {
        let ix = *self.active_stacking_context_stack.last().unwrap();
        &mut self.stacking_contexts[ix]
    }

    fn active_layer(&mut self) -> &mut Layer {
        self.active_stacking_context().active_layer()
    }
}

impl StackingContext {
    fn new(clip_bounds: Option<RectF>, z_index: usize) -> Self {
        Self {
            layers: vec![Layer::new(clip_bounds)],
            active_layer_stack: vec![0],
            z_index,
        }
    }

    fn active_layer(&mut self) -> &mut Layer {
        &mut self.layers[*self.active_layer_stack.last().unwrap()]
    }

    fn push_layer(&mut self, clip_bounds: Option<RectF>) {
        let parent_clip_bounds = self.active_layer().clip_bounds();
        let clip_bounds = clip_bounds
            .map(|clip_bounds| {
                clip_bounds
                    .intersection(parent_clip_bounds.unwrap_or(clip_bounds))
                    .unwrap_or_else(|| {
                        if !clip_bounds.is_empty() {
                            log::warn!("specified clip bounds are disjoint from parent layer");
                        }
                        RectF::default()
                    })
            })
            .or(parent_clip_bounds);

        let ix = self.layers.len();
        self.layers.push(Layer::new(clip_bounds));
        self.active_layer_stack.push(ix);
    }

    fn pop_layer(&mut self) {
        self.active_layer_stack.pop().unwrap();
        assert!(!self.active_layer_stack.is_empty());
    }
}

impl Layer {
    pub fn new(clip_bounds: Option<RectF>) -> Self {
        Self {
            clip_bounds,
            quads: Default::default(),
            underlines: Default::default(),
            images: Default::default(),
            surfaces: Default::default(),
            shadows: Default::default(),
            image_glyphs: Default::default(),
            glyphs: Default::default(),
            icons: Default::default(),
            paths: Default::default(),
            cursor_regions: Default::default(),
            mouse_regions: Default::default(),
        }
    }

    pub fn clip_bounds(&self) -> Option<RectF> {
        self.clip_bounds
    }

    fn push_quad(&mut self, quad: Quad) {
        if can_draw(quad.bounds) {
            self.quads.push(quad);
        }
    }

    pub fn quads(&self) -> &[Quad] {
        self.quads.as_slice()
    }

    fn push_cursor_region(&mut self, region: CursorRegion) {
        if let Some(bounds) = region
            .bounds
            .intersection(self.clip_bounds.unwrap_or(region.bounds))
        {
            if can_draw(bounds) {
                self.cursor_regions.push(region);
            }
        }
    }

    fn push_mouse_region(&mut self, region: MouseRegion) -> bool {
        if let Some(bounds) = region
            .bounds
            .intersection(self.clip_bounds.unwrap_or(region.bounds))
        {
            if can_draw(bounds) {
                self.mouse_regions.push(region);
                return true;
            }
        }
        false
    }

    fn push_underline(&mut self, underline: Underline) {
        if underline.width > 0. {
            self.underlines.push(underline);
        }
    }

    pub fn underlines(&self) -> &[Underline] {
        self.underlines.as_slice()
    }

    fn push_image(&mut self, image: Image) {
        if can_draw(image.bounds) {
            self.images.push(image);
        }
    }

    pub fn images(&self) -> &[Image] {
        self.images.as_slice()
    }

    fn push_surface(&mut self, surface: Surface) {
        if can_draw(surface.bounds) {
            self.surfaces.push(surface);
        }
    }

    pub fn surfaces(&self) -> &[Surface] {
        self.surfaces.as_slice()
    }

    fn push_shadow(&mut self, shadow: Shadow) {
        if can_draw(shadow.bounds) {
            self.shadows.push(shadow);
        }
    }

    pub fn shadows(&self) -> &[Shadow] {
        self.shadows.as_slice()
    }

    fn push_image_glyph(&mut self, glyph: ImageGlyph) {
        self.image_glyphs.push(glyph);
    }

    pub fn image_glyphs(&self) -> &[ImageGlyph] {
        self.image_glyphs.as_slice()
    }

    fn push_glyph(&mut self, glyph: Glyph) {
        self.glyphs.push(glyph);
    }

    pub fn glyphs(&self) -> &[Glyph] {
        self.glyphs.as_slice()
    }

    pub fn push_icon(&mut self, icon: Icon) {
        if can_draw(icon.bounds) {
            self.icons.push(icon);
        }
    }

    pub fn icons(&self) -> &[Icon] {
        self.icons.as_slice()
    }

    fn push_path(&mut self, path: Path) {
        if can_draw(path.bounds) {
            self.paths.push(path);
        }
    }

    pub fn paths(&self) -> &[Path] {
        self.paths.as_slice()
    }
}

impl MouseRegion {
    pub fn id(&self) -> MouseRegionId {
        self.id
    }
}

pub struct EventHandler {
    pub order: u32,
    // The &dyn Any parameter below expects an event.
    pub handler: Rc<dyn Fn(&dyn Any, &mut WindowContext) -> bool>,
    pub event_type: TypeId,
}

fn can_draw(bounds: RectF) -> bool {
    let size = bounds.size();
    size.x() > 0. && size.y() > 0.
}