use bevy::diagnostic::{Diagnostics, FrameTimeDiagnosticsPlugin};
use bevy::prelude::*;
use bevy::render::texture::{Extent3d, TextureDimension, TextureFormat};
use mandelbrot::{Bounds, Mandelbrot, TEXTURE_HEIGHT, TEXTURE_WIDTH};
use std::time::Instant;

const MAX_ITERATION_COUNT: u32 = 1024;

fn main() {
    let window_settings = WindowDescriptor {
        width: TEXTURE_WIDTH as f32,
        height: TEXTURE_HEIGHT as f32,
        title: "Mandelbrot".to_string(),
        vsync: false,
        resizable: false,
        ..Default::default()
    };

    App::build()
        .insert_resource(window_settings)
        .add_plugins(DefaultPlugins)
        .add_plugin(FrameTimeDiagnosticsPlugin)
        .add_startup_system(setup.system())
        .insert_resource(TextureOptions::default())
        .add_system(performance_info_system.system())
        .add_system(mandelbrot_render_system.system())
        .add_system(user_input_system.system())
        .run();
}

struct PerformanceInfo;

struct TextureOptions {
    zoom: f64,
    horizontal: f64,
    vertical: f64,
    step: f64,
    iteration_limit: u32,
}

impl Default for TextureOptions {
    fn default() -> Self {
        Self {
            zoom: 1.0,
            horizontal: 0.0,
            vertical: 0.0,
            step: 0.01,
            iteration_limit: 64,
        }
    }
}

fn user_input_system(input: Res<Input<KeyCode>>, mut scale: ResMut<TextureOptions>) {
    // Zoom: E to Zoom In, Q to Zoom Out
    // Horizontal Movement: D to move right, A to move left
    // Vertical Movement: W to move up, S to move Down
    // R to increase the steps taken by zoom, horizontal movement, and vertical movement
    // T to increase the Iteration Limit, G to decrease the iteration limit
    let zoom = input.pressed(KeyCode::Q) as i8 - input.pressed(KeyCode::E) as i8;
    let horizontal = input.pressed(KeyCode::D) as i8 - input.pressed(KeyCode::A) as i8;
    let vertical = input.pressed(KeyCode::W) as i8 - input.pressed(KeyCode::S) as i8;
    let step_change = input.pressed(KeyCode::R) as i8 - input.pressed(KeyCode::F) as i8;
    let limit_change = input.just_pressed(KeyCode::T) as i8 - input.just_pressed(KeyCode::G) as i8;

    scale.step += (scale.step / 10.0) * step_change as f64;
    scale.vertical += scale.step * vertical as f64;
    scale.horizontal += scale.step * horizontal as f64;
    scale.zoom += scale.step * zoom as f64;

    if limit_change == 1 {
        scale.iteration_limit *= 2;

        if scale.iteration_limit > MAX_ITERATION_COUNT {
            scale.iteration_limit = MAX_ITERATION_COUNT;
        }
    } else if limit_change == -1 {
        scale.iteration_limit /= 2;

        if scale.iteration_limit < 32 {
            scale.iteration_limit = 32;
        }
    }

    if scale.zoom < 0.0 {
        // We can't go below 0
        scale.zoom -= scale.step * zoom as f64;

        // slow down our step function
        scale.step /= 10.0;
    }
}

fn performance_info_system(
    // time: Res<Time>,
    diag: Res<Diagnostics>,
    mut query: Query<&mut Text, With<PerformanceInfo>>,
) {
    for mut text in query.iter_mut() {
        let mut fps = 0.00;
        let mut frametime = 0.00;

        if let Some(fps_diag) = diag.get(FrameTimeDiagnosticsPlugin::FPS) {
            if let Some(average) = fps_diag.average() {
                fps = average;
            }
        }

        if let Some(frametime_diag) = diag.get(FrameTimeDiagnosticsPlugin::FRAME_TIME) {
            if let Some(average) = frametime_diag.average() {
                frametime = average;
            }
        }

        // FPS Number
        text.sections[1].value = format!("{:.1}", fps);

        // Frametime Number
        text.sections[3].value = format!("{:.3}", frametime * 1000.0);
    }
}

fn mandelbrot_render_system(
    materials: Res<Assets<ColorMaterial>>,
    mut textures: ResMut<Assets<Texture>>,
    scale: Res<TextureOptions>,
    mut query: Query<(&mut Mandelbrot, &Handle<ColorMaterial>)>,
) {
    for (mut fractal, handle) in query.iter_mut() {
        if let Some(material) = materials.get(handle) {
            if let Some(texture_handle) = &material.texture {
                if let Some(texture) = textures.get_mut(texture_handle) {
                    let z = scale.zoom;
                    let h = scale.horizontal;
                    let v = scale.vertical;
                    let limit = scale.iteration_limit;

                    let x = ((-2.5 * z) + h, (1.0 * z) + h);
                    let y = ((-1.0 * z) - v, (1.0 * z) - v);
                    let bounds = Bounds::new(x, y);

                    texture
                        .data
                        .copy_from_slice(fractal.scaled_image(bounds, limit));
                }
            }
        }
    }
}

fn setup(
    mut commands: Commands,
    mut textures: ResMut<Assets<Texture>>,
    mut materials: ResMut<Assets<ColorMaterial>>,
    asset_server: Res<AssetServer>,
) {
    let ui_font = asset_server.load("fonts/vcr_osd_mono.ttf");
    let white = Color::rgb(1.0, 1.0, 1.0);
    let mut fractal = Mandelbrot::default();

    let texture_size = Extent3d::new(TEXTURE_WIDTH as u32, TEXTURE_HEIGHT as u32, 1);
    let texture_data = fractal.image().to_vec();

    let texture_handle = textures.add(Texture::new(
        texture_size,
        TextureDimension::D2,
        texture_data,
        TextureFormat::Rgba8UnormSrgb,
    ));

    commands.spawn_bundle(OrthographicCameraBundle::new_2d());
    commands.spawn_bundle(UiCameraBundle::default());

    commands
        .spawn_bundle(SpriteBundle {
            material: materials.add(texture_handle.into()),
            ..Default::default()
        })
        .insert(fractal);

    commands
        .spawn_bundle(TextBundle {
            text: Text {
                sections: vec![
                    TextSection {
                        value: "FPS: ".to_string(),
                        style: TextStyle {
                            font: ui_font.clone(),
                            font_size: 40.0,
                            color: white,
                        },
                        ..Default::default()
                    },
                    TextSection {
                        value: "".to_string(),
                        style: TextStyle {
                            font: ui_font.clone(),
                            font_size: 40.0,
                            color: white,
                        },
                        ..Default::default()
                    },
                    TextSection {
                        value: "\nFrametime: ".to_string(),
                        style: TextStyle {
                            font: ui_font.clone(),
                            font_size: 40.0,
                            color: white,
                        },
                        ..Default::default()
                    },
                    TextSection {
                        value: "".to_string(),
                        style: TextStyle {
                            font: ui_font.clone(),
                            font_size: 40.0,
                            color: white,
                        },
                        ..Default::default()
                    },
                    TextSection {
                        value: "ms".to_string(),
                        style: TextStyle {
                            font: ui_font.clone(),
                            font_size: 40.0,
                            color: white,
                        },
                        ..Default::default()
                    },
                ],
                ..Default::default()
            },
            style: Style {
                ..Default::default()
            },

            ..Default::default()
        })
        .insert(PerformanceInfo);
}