use skia_safe as skia;
use std::collections::HashMap;
use uuid::Uuid;

use crate::math;
use crate::matrix::Matrix;
use crate::view::Viewbox;

mod blend;
mod cache;
mod debug;
mod fills;
mod gpu_state;
mod images;
mod options;
mod shadows;
mod strokes;

use crate::shapes::{Kind, Shape};
use cache::CachedSurfaceImage;
use gpu_state::GpuState;
use options::RenderOptions;

pub use blend::BlendMode;
pub use images::*;

const DEFAULT_FONT_BYTES: &[u8] =
    include_bytes!("../../frontend/resources/fonts/RobotoMono-Regular.ttf");

const MAX_BLOCKING_TIME_MS: i32 = 32;
const NODE_BATCH_THRESHOLD: i32 = 10;

extern "C" {
    fn emscripten_run_script(script: *const i8);
    fn emscripten_run_script_int(script: *const i8) -> i32;
}

fn get_time() -> i32 {
    let script = std::ffi::CString::new("performance.now()").unwrap();
    unsafe { emscripten_run_script_int(script.as_ptr()) }
}

pub(crate) struct RenderState {
    gpu_state: GpuState,
    pub options: RenderOptions,
    pub final_surface: skia::Surface,
    pub render_surface: skia::Surface,
    pub drawing_surface: skia::Surface,
    pub shadow_surface: skia::Surface,
    pub debug_surface: skia::Surface,
    pub font_provider: skia::textlayout::TypefaceFontProvider,
    pub cached_surface_image: Option<CachedSurfaceImage>,
    pub viewbox: Viewbox,
    pub images: ImageStore,
    pub background_color: skia::Color,
    // Identifier of the current requestAnimationFrame call, if any.
    pub render_request_id: Option<i32>,
    // Indicates whether the rendering process has pending frames.
    pub render_in_progress: bool,
    // Stack of nodes pending to be rendered. The boolean flag indicates if the node has already been visited. The rect the optional bounds to clip.
    pub pending_nodes: Vec<(Uuid, bool, Option<math::Rect>)>,
}

impl RenderState {
    pub fn new(width: i32, height: i32) -> RenderState {
        // This needs to be done once per WebGL context.
        let mut gpu_state = GpuState::new();
        let mut final_surface = gpu_state.create_target_surface(width, height);
        let render_surface = final_surface
            .new_surface_with_dimensions((width, height))
            .unwrap();
        let shadow_surface = final_surface
            .new_surface_with_dimensions((width, height))
            .unwrap();
        let drawing_surface = final_surface
            .new_surface_with_dimensions((width, height))
            .unwrap();
        let debug_surface = final_surface
            .new_surface_with_dimensions((width, height))
            .unwrap();

        let mut font_provider = skia::textlayout::TypefaceFontProvider::new();
        let default_font = skia::FontMgr::default()
            .new_from_data(DEFAULT_FONT_BYTES, None)
            .expect("Failed to load font");
        font_provider.register_typeface(default_font, "robotomono-regular");

        RenderState {
            gpu_state,
            final_surface,
            render_surface,
            shadow_surface,
            drawing_surface,
            debug_surface,
            cached_surface_image: None,
            font_provider,
            options: RenderOptions::default(),
            viewbox: Viewbox::new(width as f32, height as f32),
            images: ImageStore::new(),
            background_color: skia::Color::TRANSPARENT,
            render_request_id: None,
            render_in_progress: false,
            pending_nodes: vec![],
        }
    }

    pub fn add_font(&mut self, family_name: String, font_data: &[u8]) -> Result<(), String> {
        let typeface = skia::FontMgr::default()
            .new_from_data(font_data, None)
            .expect("Failed to add font");
        self.font_provider
            .register_typeface(typeface, family_name.as_ref());
        Ok(())
    }

    pub fn add_image(&mut self, id: Uuid, image_data: &[u8]) -> Result<(), String> {
        self.images.add(id, image_data)
    }

    pub fn has_image(&mut self, id: &Uuid) -> bool {
        self.images.contains(id)
    }

    pub fn set_debug_flags(&mut self, debug: u32) {
        self.options.debug_flags = debug;
    }

    pub fn set_dpr(&mut self, dpr: f32) {
        if Some(dpr) != self.options.dpr {
            self.options.dpr = Some(dpr);
            self.resize(
                self.viewbox.width.floor() as i32,
                self.viewbox.height.floor() as i32,
            );
        }
    }

    pub fn set_background_color(&mut self, color: skia::Color) {
        self.background_color = color;
        let _ = self.render_from_cache();
    }

    pub fn resize(&mut self, width: i32, height: i32) {
        let dpr_width = (width as f32 * self.options.dpr()).floor() as i32;
        let dpr_height = (height as f32 * self.options.dpr()).floor() as i32;

        let surface = self.gpu_state.create_target_surface(dpr_width, dpr_height);
        self.final_surface = surface;
        self.render_surface = self
            .final_surface
            .new_surface_with_dimensions((dpr_width, dpr_height))
            .unwrap();
        self.shadow_surface = self
            .final_surface
            .new_surface_with_dimensions((dpr_width, dpr_height))
            .unwrap();
        self.drawing_surface = self
            .final_surface
            .new_surface_with_dimensions((dpr_width, dpr_height))
            .unwrap();
        self.debug_surface = self
            .final_surface
            .new_surface_with_dimensions((dpr_width, dpr_height))
            .unwrap();

        self.viewbox.set_wh(width as f32, height as f32);
    }

    pub fn flush(&mut self) {
        self.gpu_state
            .context
            .flush_and_submit_surface(&mut self.final_surface, None);
    }

    pub fn translate(&mut self, dx: f32, dy: f32) {
        self.drawing_surface.canvas().translate((dx, dy));
    }

    pub fn scale(&mut self, sx: f32, sy: f32) {
        self.drawing_surface.canvas().scale((sx, sy));
    }

    pub fn reset_canvas(&mut self) {
        self.drawing_surface.canvas().restore_to_count(1);
        self.render_surface.canvas().restore_to_count(1);
        self.drawing_surface
            .canvas()
            .clear(self.background_color)
            .reset_matrix();
        self.render_surface
            .canvas()
            .clear(self.background_color)
            .reset_matrix();
        self.shadow_surface
            .canvas()
            .clear(self.background_color)
            .reset_matrix();
        self.debug_surface
            .canvas()
            .clear(skia::Color::TRANSPARENT)
            .reset_matrix();
    }

    pub fn apply_render_to_final_canvas(&mut self) {
        self.render_surface.draw(
            &mut self.final_surface.canvas(),
            (0.0, 0.0),
            skia::SamplingOptions::new(skia::FilterMode::Linear, skia::MipmapMode::Nearest),
            Some(&skia::Paint::default()),
        );
    }

    pub fn apply_drawing_to_render_canvas(&mut self) {
        self.gpu_state
            .context
            .flush_and_submit_surface(&mut self.drawing_surface, None);

        self.drawing_surface.draw(
            &mut self.render_surface.canvas(),
            (0.0, 0.0),
            skia::SamplingOptions::new(skia::FilterMode::Linear, skia::MipmapMode::Nearest),
            Some(&skia::Paint::default()),
        );

        self.gpu_state
            .context
            .flush_and_submit_surface(&mut self.render_surface, None);

        self.shadow_surface.canvas().clear(skia::Color::TRANSPARENT);

        self.drawing_surface
            .canvas()
            .clear(skia::Color::TRANSPARENT);
    }

    pub fn render_shape(
        &mut self,
        shape: &mut Shape,
        modifiers: Option<&Matrix>,
        clip_bounds: Option<skia::Rect>,
    ) {
        if let Some(modifiers) = modifiers {
            self.drawing_surface
                .canvas()
                .concat(&modifiers.to_skia_matrix());
        }

        let transform = shape.transform.to_skia_matrix();

        // Check transform-matrix code from common/src/app/common/geom/shapes/transforms.cljc
        let center = shape.bounds().center();
        let mut matrix = skia::Matrix::new_identity();
        matrix.pre_translate(center);
        matrix.pre_concat(&transform);
        matrix.pre_translate(-center);

        self.drawing_surface.canvas().concat(&matrix);

        if let Some(bounds) = clip_bounds {
            self.drawing_surface
                .canvas()
                .clip_rect(bounds, skia::ClipOp::Intersect, true);
        }

        match &shape.kind {
            Kind::SVGRaw(sr) => {
                if let Some(svg) = shape.svg.as_ref() {
                    svg.render(self.drawing_surface.canvas())
                } else {
                    let font_manager = skia::FontMgr::from(self.font_provider.clone());
                    let dom_result = skia::svg::Dom::from_str(sr.content.to_string(), font_manager);
                    match dom_result {
                        Ok(dom) => {
                            dom.render(self.drawing_surface.canvas());
                            shape.set_svg(dom);
                        }
                        Err(e) => {
                            eprintln!("Error parsing SVG. Error: {}", e);
                        }
                    }
                }
            }
            _ => {
                for fill in shape.fills().rev() {
                    fills::render(self, shape, fill);
                }

                for stroke in shape.strokes().rev() {
                    strokes::render(self, shape, stroke);
                }
            }
        };

        for shadow in shape.drop_shadows().rev().filter(|s| !s.hidden()) {
            shadows::render_drop_shadow(self, shadow, self.viewbox.zoom * self.options.dpr());
        }

        self.apply_drawing_to_render_canvas();
    }

    pub fn start_render_loop(
        &mut self,
        tree: &mut HashMap<Uuid, Shape>,
        modifiers: &HashMap<Uuid, Matrix>,
        timestamp: i32,
    ) -> Result<(), String> {
        if self.render_in_progress {
            if let Some(frame_id) = self.render_request_id {
                self.cancel_animation_frame(frame_id);
            }
        }
        self.reset_canvas();
        self.scale(
            self.viewbox.zoom * self.options.dpr(),
            self.viewbox.zoom * self.options.dpr(),
        );
        self.translate(self.viewbox.pan_x, self.viewbox.pan_y);
        self.pending_nodes = vec![(Uuid::nil(), false, None)];
        self.render_in_progress = true;
        self.process_animation_frame(tree, modifiers, timestamp)?;
        Ok(())
    }

    pub fn request_animation_frame(&mut self) -> i32 {
        let script =
            std::ffi::CString::new("requestAnimationFrame(_process_animation_frame)").unwrap();
        unsafe { emscripten_run_script_int(script.as_ptr()) }
    }

    pub fn cancel_animation_frame(&mut self, frame_id: i32) {
        let cancel_script = format!("cancelAnimationFrame({})", frame_id);
        let c_cancel_script = std::ffi::CString::new(cancel_script).unwrap();
        unsafe {
            emscripten_run_script(c_cancel_script.as_ptr());
        }
    }

    pub fn process_animation_frame(
        &mut self,
        tree: &mut HashMap<Uuid, Shape>,
        modifiers: &HashMap<Uuid, Matrix>,
        timestamp: i32,
    ) -> Result<(), String> {
        if self.render_in_progress {
            self.render_shape_tree(tree, modifiers, timestamp)?;
            if self.render_in_progress {
                if let Some(frame_id) = self.render_request_id {
                    self.cancel_animation_frame(frame_id);
                }
                self.render_request_id = Some(self.request_animation_frame());
            }
        }

        // self.render_in_progress can have changed
        if !self.render_in_progress {
            self.cached_surface_image = Some(CachedSurfaceImage {
                image: self.render_surface.image_snapshot(),
                viewbox: self.viewbox,
            });
            if self.options.is_debug_visible() {
                self.render_debug();
            }

            debug::render_wasm_label(self);
            self.apply_render_to_final_canvas();
            self.flush();
        }
        Ok(())
    }

    pub fn render_from_cache(&mut self) -> Result<(), String> {
        let cached = self
            .cached_surface_image
            .as_ref()
            .ok_or("Uninitialized cached surface image")?;

        let image = &cached.image;
        let paint = skia::Paint::default();
        self.final_surface.canvas().save();
        self.drawing_surface.canvas().save();

        let navigate_zoom = self.viewbox.zoom / cached.viewbox.zoom;
        let navigate_x = cached.viewbox.zoom * (self.viewbox.pan_x - cached.viewbox.pan_x);
        let navigate_y = cached.viewbox.zoom * (self.viewbox.pan_y - cached.viewbox.pan_y);

        self.final_surface
            .canvas()
            .scale((navigate_zoom, navigate_zoom));
        self.final_surface.canvas().translate((
            navigate_x * self.options.dpr(),
            navigate_y * self.options.dpr(),
        ));
        self.final_surface
            .canvas()
            .draw_image(image, (0, 0), Some(&paint));

        self.final_surface.canvas().restore();
        self.drawing_surface.canvas().restore();

        self.flush();

        Ok(())
    }

    fn render_debug(&mut self) {
        debug::render(self);
    }

    pub fn render_shape_tree(
        &mut self,
        tree: &mut HashMap<Uuid, Shape>,
        modifiers: &HashMap<Uuid, Matrix>,
        timestamp: i32,
    ) -> Result<(), String> {
        if !self.render_in_progress {
            return Ok(());
        }

        let mut i = 0;
        while let Some((node_id, visited_children, clip_bounds)) = self.pending_nodes.pop() {
            let element = tree.get_mut(&node_id).ok_or(
                "Error: Element with root_id {node_id} not found in the tree.".to_string(),
            )?;

            if !visited_children {
                if !node_id.is_nil() {
                    if !element.bounds().intersects(self.viewbox.area) || element.hidden() {
                        debug::render_debug_element(self, &element, false);
                        continue;
                    } else {
                        debug::render_debug_element(self, &element, true);
                    }
                }

                let mut paint = skia::Paint::default();
                paint.set_blend_mode(element.blend_mode().into());
                paint.set_alpha_f(element.opacity());

                if let Some(image_filter) =
                    element.image_filter(self.viewbox.zoom * self.options.dpr())
                {
                    paint.set_image_filter(image_filter);
                }

                let layer_rec = skia::canvas::SaveLayerRec::default().paint(&paint);
                self.render_surface.canvas().save_layer(&layer_rec);

                self.drawing_surface.canvas().save();
                if !node_id.is_nil() {
                    self.render_shape(element, modifiers.get(&element.id), clip_bounds);
                } else {
                    self.apply_drawing_to_render_canvas();
                }
                self.drawing_surface.canvas().restore();

                // Set the node as visited before processing children
                self.pending_nodes.push((node_id, true, None));
                if element.is_recursive() {
                    let children_clip_bounds =
                        (!node_id.is_nil() & element.clip()).then(|| element.bounds());

                    for child_id in element.children_ids().iter().rev() {
                        self.pending_nodes
                            .push((*child_id, false, children_clip_bounds));
                    }
                }
            } else {
                self.render_surface.canvas().restore();
            }
            // We try to avoid doing too many calls to get_time
            if i % NODE_BATCH_THRESHOLD == 0 && get_time() - timestamp > MAX_BLOCKING_TIME_MS {
                return Ok(());
            }
            i += 1;
        }

        // If we finish processing every node rendering is complete
        self.render_in_progress = false;
        Ok(())
    }
}