use std::collections::VecDeque;
use std::iter;

use skulpin::skia_safe::canvas::{SaveLayerRec, SrcRectConstraint};
use skulpin::skia_safe::gpu::SurfaceOrigin;
use skulpin::skia_safe::{
    image_filters::blur, BlendMode, Budgeted, Canvas, Color, ImageInfo, Paint, Point, Rect, Surface,
};

use super::animation_utils::*;
use super::{Renderer, RendererSettings};
use crate::editor::WindowDrawCommand;
use crate::redraw_scheduler::REDRAW_SCHEDULER;

fn build_window_surface(
    parent_canvas: &mut Canvas,
    pixel_width: i32,
    pixel_height: i32,
) -> Surface {
    let dimensions = (pixel_width, pixel_height);
    let mut context = parent_canvas.gpu_context().unwrap();
    let budgeted = Budgeted::Yes;
    let parent_image_info = parent_canvas.image_info();
    let image_info = ImageInfo::new(
        dimensions,
        parent_image_info.color_type(),
        parent_image_info.alpha_type(),
        parent_image_info.color_space(),
    );
    let surface_origin = SurfaceOrigin::TopLeft;
    Surface::new_render_target(
        &mut context,
        budgeted,
        &image_info,
        None,
        surface_origin,
        None,
        None,
    )
    .expect("Could not create surface")
}

fn build_window_surface_with_grid_size(
    parent_canvas: &mut Canvas,
    renderer: &Renderer,
    grid_width: u64,
    grid_height: u64,
) -> Surface {
    let pixel_width = (grid_width as f32 * renderer.font_width) as i32;
    let pixel_height = (grid_height as f32 * renderer.font_height) as i32;
    build_window_surface(parent_canvas, pixel_width, pixel_height)
}

fn build_background_window_surface(
    parent_canvas: &mut Canvas,
    renderer: &Renderer,
    grid_width: u64,
    grid_height: u64,
) -> Surface {
    let mut surface =
        build_window_surface_with_grid_size(parent_canvas, renderer, grid_width, grid_height);
    let canvas = surface.canvas();
    canvas.clear(renderer.get_default_background());
    surface
}

fn clone_window_surface(surface: &mut Surface) -> Surface {
    let snapshot = surface.image_snapshot();
    let mut canvas = surface.canvas();
    let mut new_surface = build_window_surface(&mut canvas, snapshot.width(), snapshot.height());
    let new_canvas = new_surface.canvas();
    new_canvas.draw_image(snapshot, (0.0, 0.0), None);
    new_surface
}

pub struct SurfacePair {
    background: Surface,
    foreground: Surface,
    pub top_line: f32,
    bottom_line: f32,
}

impl SurfacePair {
    fn new(
        parent_canvas: &mut Canvas,
        renderer: &Renderer,
        grid_width: u64,
        grid_height: u64,
        top_line: f32,
        bottom_line: f32,
    ) -> SurfacePair {
        let background =
            build_background_window_surface(parent_canvas, renderer, grid_width, grid_height);
        let foreground =
            build_window_surface_with_grid_size(parent_canvas, renderer, grid_width, grid_height);

        SurfacePair {
            background,
            foreground,
            top_line,
            bottom_line,
        }
    }

    fn clone(&mut self) -> SurfacePair {
        let new_background = clone_window_surface(&mut self.background);
        let new_foreground = clone_window_surface(&mut self.foreground);
        SurfacePair {
            background: new_background,
            foreground: new_foreground,
            top_line: self.top_line,
            bottom_line: self.bottom_line,
        }
    }
}

pub struct RenderedWindow {
    old_surfaces: VecDeque<SurfacePair>,
    pub current_surfaces: SurfacePair,

    pub id: u64,
    pub hidden: bool,
    pub floating: bool,

    grid_width: u64,
    grid_height: u64,

    grid_start_position: Point,
    pub grid_current_position: Point,
    grid_destination: Point,
    position_t: f32,

    start_scroll: f32,
    pub current_scroll: f32,
    scroll_destination: f32,
    scroll_t: f32,
}

pub struct WindowDrawDetails {
    pub id: u64,
    pub region: Rect,
    pub floating: bool,
}

impl RenderedWindow {
    pub fn new(
        parent_canvas: &mut Canvas,
        renderer: &Renderer,
        id: u64,
        grid_position: Point,
        grid_width: u64,
        grid_height: u64,
    ) -> RenderedWindow {
        let current_surfaces =
            SurfacePair::new(parent_canvas, renderer, grid_width, grid_height, 0.0, 0.0);

        RenderedWindow {
            old_surfaces: VecDeque::new(),
            current_surfaces,
            id,
            hidden: false,
            floating: false,

            grid_width,
            grid_height,

            grid_start_position: grid_position,
            grid_current_position: grid_position,
            grid_destination: grid_position,
            position_t: 2.0, // 2.0 is out of the 0.0 to 1.0 range and stops animation

            start_scroll: 0.0,
            current_scroll: 0.0,
            scroll_destination: 0.0,
            scroll_t: 2.0, // 2.0 is out of the 0.0 to 1.0 range and stops animation
        }
    }

    pub fn pixel_region(&self, font_width: f32, font_height: f32) -> Rect {
        let current_pixel_position = Point::new(
            self.grid_current_position.x * font_width,
            self.grid_current_position.y * font_height,
        );

        let image_width = (self.grid_width as f32 * font_width) as i32;
        let image_height = (self.grid_height as f32 * font_height) as i32;

        Rect::from_point_and_size(current_pixel_position, (image_width, image_height))
    }

    pub fn update(&mut self, settings: &RendererSettings, dt: f32) -> bool {
        let mut animating = false;

        {
            if (self.position_t - 1.0).abs() < std::f32::EPSILON {
                // We are at destination, move t out of 0-1 range to stop the animation
                self.position_t = 2.0;
            } else {
                animating = true;
                self.position_t =
                    (self.position_t + dt / settings.position_animation_length).min(1.0);
            }

            self.grid_current_position = ease_point(
                ease_out_expo,
                self.grid_start_position,
                self.grid_destination,
                self.position_t,
            );
        }

        {
            if (self.scroll_t - 1.0).abs() < std::f32::EPSILON {
                // We are at destination, move t out of 0-1 range to stop the animation
                self.scroll_t = 2.0;
                self.old_surfaces.clear();
            } else {
                animating = true;
                self.scroll_t = (self.scroll_t + dt / settings.scroll_animation_length).min(1.0);
            }

            self.current_scroll = ease(
                ease_out_expo,
                self.start_scroll,
                self.scroll_destination,
                self.scroll_t,
            );
        }

        animating
    }

    pub fn draw(
        &mut self,
        root_canvas: &mut Canvas,
        settings: &RendererSettings,
        default_background: Color,
        font_width: f32,
        font_height: f32,
        dt: f32,
    ) -> WindowDrawDetails {
        if self.update(settings, dt) {
            REDRAW_SCHEDULER.queue_next_frame();
        }

        let pixel_region = self.pixel_region(font_width, font_height);

        root_canvas.save();
        root_canvas.clip_rect(&pixel_region, None, Some(false));

        if self.floating && settings.floating_blur {
            let blur = blur((2.0, 2.0), None, None, None).unwrap();
            let save_layer_rec = SaveLayerRec::default()
                .backdrop(&blur)
                .bounds(&pixel_region);

            root_canvas.save_layer(&save_layer_rec);
        }

        let mut paint = Paint::default();
        // We want each surface to overwrite the one underneath and will use layers to ensure
        // only lower priority surfaces will get clobbered and not the underlying windows
        paint.set_blend_mode(BlendMode::Src);

        {
            // Save layer so that setting the blend mode doesn't effect the blur
            root_canvas.save_layer(&SaveLayerRec::default());
            let mut a = 255;
            if self.floating {
                a = (settings.floating_opacity.min(1.0).max(0.0) * 255.0) as u8;
            }

            paint.set_color(default_background.with_a(a));
            root_canvas.draw_rect(pixel_region, &paint);

            paint.set_color(Color::from_argb(a, 255, 255, 255));

            for surface_pair in iter::once(&mut self.current_surfaces)
                .chain(self.old_surfaces.iter_mut())
                .rev()
            {
                let scroll_offset =
                    surface_pair.top_line * font_height - self.current_scroll * font_height;
                surface_pair.background.draw(
                    root_canvas.as_mut(),
                    (pixel_region.left(), pixel_region.top() + scroll_offset),
                    Some(&paint),
                );
            }
            root_canvas.restore();
        }

        {
            // Save layer so that text may safely overwrite images underneath
            root_canvas.save_layer(&SaveLayerRec::default());
            for surface_pair in iter::once(&mut self.current_surfaces)
                .chain(self.old_surfaces.iter_mut())
                .rev()
            {
                let scroll_offset =
                    surface_pair.top_line * font_height - self.current_scroll * font_height;
                surface_pair.foreground.draw(
                    root_canvas.as_mut(),
                    (pixel_region.left(), pixel_region.top() + scroll_offset),
                    Some(&paint),
                );
            }
            root_canvas.restore();
        }

        if self.floating {
            root_canvas.restore();
        }

        root_canvas.restore();

        WindowDrawDetails {
            id: self.id,
            region: pixel_region,
            floating: self.floating,
        }
    }

    pub fn handle_window_draw_command(
        mut self,
        renderer: &mut Renderer,
        draw_command: WindowDrawCommand,
    ) -> Self {
        match draw_command {
            WindowDrawCommand::Position {
                grid_left,
                grid_top,
                width: grid_width,
                height: grid_height,
                floating,
            } => {
                let new_destination: Point = (grid_left as f32, grid_top as f32).into();

                if self.grid_destination != new_destination {
                    if self.grid_start_position.x.abs() > f32::EPSILON
                        || self.grid_start_position.y.abs() > f32::EPSILON
                    {
                        self.position_t = 0.0; // Reset animation as we have a new destination.
                        self.grid_start_position = self.grid_current_position;
                        self.grid_destination = new_destination;
                    } else {
                        // We don't want to animate since the window is animating out of the start location,
                        // so we set t to 2.0 to stop animations.
                        self.position_t = 2.0;
                        self.grid_start_position = new_destination;
                        self.grid_destination = new_destination;
                    }
                }

                if grid_width != self.grid_width || grid_height != self.grid_height {
                    {
                        let mut old_background = self.current_surfaces.background;
                        self.current_surfaces.background = build_background_window_surface(
                            old_background.canvas(),
                            &renderer,
                            grid_width,
                            grid_height,
                        );
                        old_background.draw(
                            self.current_surfaces.background.canvas(),
                            (0.0, 0.0),
                            None,
                        );
                    }

                    {
                        let mut old_foreground = self.current_surfaces.foreground;
                        self.current_surfaces.foreground = build_window_surface_with_grid_size(
                            old_foreground.canvas(),
                            &renderer,
                            grid_width,
                            grid_height,
                        );
                        old_foreground.draw(
                            self.current_surfaces.foreground.canvas(),
                            (0.0, 0.0),
                            None,
                        );
                    }

                    self.grid_width = grid_width;
                    self.grid_height = grid_height;
                }

                self.floating = floating;

                if self.hidden {
                    self.hidden = false;
                    self.position_t = 2.0; // We don't want to animate since the window is becoming visible, so we set t to 2.0 to stop animations.
                    self.grid_start_position = new_destination;
                    self.grid_destination = new_destination;
                }
            }
            WindowDrawCommand::Cell {
                text,
                cell_width,
                window_left,
                window_top,
                style,
            } => {
                let grid_position = (window_left, window_top);

                {
                    let mut background_canvas = self.current_surfaces.background.canvas();
                    renderer.draw_background(
                        &mut background_canvas,
                        grid_position,
                        cell_width,
                        &style,
                    );
                }

                {
                    let mut foreground_canvas = self.current_surfaces.foreground.canvas();
                    renderer.draw_foreground(
                        &mut foreground_canvas,
                        &text,
                        grid_position,
                        cell_width,
                        &style,
                    );
                }
            }
            WindowDrawCommand::Scroll {
                top,
                bot,
                left,
                right,
                rows,
                cols,
            } => {
                let scrolled_region = Rect::new(
                    left as f32 * renderer.font_width,
                    top as f32 * renderer.font_height,
                    right as f32 * renderer.font_width,
                    bot as f32 * renderer.font_height,
                );

                {
                    let background_snapshot = self.current_surfaces.background.image_snapshot();
                    let background_canvas = self.current_surfaces.background.canvas();

                    background_canvas.save();
                    background_canvas.clip_rect(scrolled_region, None, Some(false));

                    let mut translated_region = scrolled_region;
                    translated_region.offset((
                        -cols as f32 * renderer.font_width,
                        -rows as f32 * renderer.font_height,
                    ));

                    background_canvas.draw_image_rect(
                        background_snapshot,
                        Some((&scrolled_region, SrcRectConstraint::Fast)),
                        translated_region,
                        &renderer.paint,
                    );

                    background_canvas.restore();
                }

                {
                    let foreground_snapshot = self.current_surfaces.foreground.image_snapshot();
                    let foreground_canvas = self.current_surfaces.foreground.canvas();

                    foreground_canvas.save();
                    foreground_canvas.clip_rect(scrolled_region, None, Some(false));

                    let mut translated_region = scrolled_region;
                    translated_region.offset((
                        -cols as f32 * renderer.font_width,
                        -rows as f32 * renderer.font_height,
                    ));

                    foreground_canvas.draw_image_rect(
                        foreground_snapshot,
                        Some((&scrolled_region, SrcRectConstraint::Fast)),
                        translated_region,
                        &renderer.paint,
                    );

                    foreground_canvas.restore();
                }
            }
            WindowDrawCommand::Clear => {
                let background_canvas = self.current_surfaces.background.canvas();
                self.current_surfaces.background = build_background_window_surface(
                    background_canvas,
                    &renderer,
                    self.grid_width,
                    self.grid_height,
                );

                let foreground_canvas = self.current_surfaces.foreground.canvas();
                self.current_surfaces.foreground = build_window_surface_with_grid_size(
                    foreground_canvas,
                    &renderer,
                    self.grid_width,
                    self.grid_height,
                );
            }
            WindowDrawCommand::Show => {
                if self.hidden {
                    self.hidden = false;
                    self.position_t = 2.0; // We don't want to animate since the window is becoming visible, so we set t to 2.0 to stop animations.
                    self.grid_start_position = self.grid_destination;
                }
            }
            WindowDrawCommand::Hide => self.hidden = true,
            WindowDrawCommand::Viewport {
                top_line,
                bottom_line,
            } => {
                if (self.current_surfaces.top_line - top_line as f32).abs() > std::f32::EPSILON {
                    let mut new_surfaces = self.current_surfaces.clone();
                    new_surfaces.top_line = top_line as f32;
                    new_surfaces.bottom_line = bottom_line as f32;

                    // Set new target viewport position and initialize animation timer
                    self.start_scroll = self.current_scroll;
                    self.scroll_destination = top_line as f32;
                    self.scroll_t = 0.0;

                    let current_surfaces = self.current_surfaces;
                    self.current_surfaces = new_surfaces;
                    self.old_surfaces.push_back(current_surfaces);

                    if self.old_surfaces.len() > 5 {
                        self.old_surfaces.pop_front();
                    }
                }
            }
            _ => {}
        };

        self
    }
}