use bevy::{
    prelude::*,
    reflect::TypeUuid,
    render::{
        camera::{Camera as BevyCamera, RenderTarget},
        render_resource::{
            AsBindGroup, Extent3d, ShaderRef, TextureDescriptor, TextureDimension, TextureFormat,
            TextureUsages,
        },
        texture::BevyDefault,
        view::RenderLayers,
    },
    sprite::{Material2d, MaterialMesh2dBundle},
};
use bevy_mod_raycast::{RayCastMethod, RayCastSource};

use crate::{pillar::UnlitPillar, player::*, PALETTE};

pub struct MyRaycastSet;

#[derive(Component)]
pub struct Camera {
    distance_to_player: f32,
}

pub fn spawn_camera(
    mut commands: Commands,
    asset_server: Res<AssetServer>,
    mut windows: ResMut<Windows>,
    mut meshes: ResMut<Assets<Mesh>>,
    mut post_processing_materials: ResMut<Assets<PostProcessingMaterial>>,
    mut images: ResMut<Assets<Image>>,
) {
    let window = windows.get_primary_mut().unwrap();
    let size = Extent3d {
        width: window.physical_width(),
        height: window.physical_height(),
        ..default()
    };

    // This is the texture that will be rendered to.
    let mut image = Image {
        texture_descriptor: TextureDescriptor {
            label: None,
            size,
            dimension: TextureDimension::D2,
            format: TextureFormat::bevy_default(),
            mip_level_count: 1,
            sample_count: 1,
            usage: TextureUsages::TEXTURE_BINDING
                | TextureUsages::COPY_DST
                | TextureUsages::RENDER_ATTACHMENT,
        },
        ..default()
    };

    // fill image.data with zeroes
    image.resize(size);

    let image_handle = images.add(image);

    // Main camera, first to render
    commands
        .spawn_bundle(Camera3dBundle {
            camera: BevyCamera {
                target: RenderTarget::Image(image_handle.clone()),
                ..default()
            },
            ..default()
        })
        .insert(Camera {
            distance_to_player: 100.0,
        })
        .insert(RayCastSource::<MyRaycastSet>::new());

    // This specifies the layer used for the post processing camera, which will be attached to the post processing camera and 2d quad.
    let post_processing_pass_layer = RenderLayers::layer((RenderLayers::TOTAL_LAYERS - 1) as u8);

    let quad_handle = meshes.add(Mesh::from(shape::Quad::new(Vec2::new(
        size.width as f32,
        size.height as f32,
    ))));

    let noise = asset_server.load("textures/noise.png");

    // This material has the texture that has been rendered.
    let material_handle = post_processing_materials.add(PostProcessingMaterial {
        source_image: image_handle,
        noise,
        palette: PALETTE,
    });

    // Post processing 2d quad, with material using the render texture done by the main camera, with a custom shader.
    commands
        .spawn_bundle(MaterialMesh2dBundle {
            mesh: quad_handle.into(),
            material: material_handle,
            transform: Transform {
                translation: Vec3::new(0.0, 0.0, 1.5),
                ..default()
            },
            ..default()
        })
        .insert(post_processing_pass_layer);

    // The post-processing pass camera.
    commands
        .spawn_bundle(Camera2dBundle {
            camera: BevyCamera {
                // renders after the first main camera which has default value: 0.
                priority: 1,
                ..default()
            },
            ..Camera2dBundle::default()
        })
        .insert(post_processing_pass_layer);
}

#[derive(AsBindGroup, TypeUuid, Clone)]
#[uuid = "bc2f08eb-a0fb-43f1-a908-54871ea597d5"]
pub struct PostProcessingMaterial {
    /// In this example, this image will be the result of the main camera.
    #[texture(0)]
    #[sampler(1)]
    source_image: Handle<Image>,
    #[texture(2)]
    #[sampler(3)]
    noise: Handle<Image>,
    #[uniform(4)]
    palette: [Vec3; 16],
}

impl Material2d for PostProcessingMaterial {
    fn fragment_shader() -> ShaderRef {
        "shaders/post-processing.wgsl".into()
    }
}

pub fn camera_follow_player(
    player: Query<(&Transform, &Player), Without<Camera>>,
    mut camera: Query<(&mut Transform, &Camera), Without<Player>>,
) {
    let player_pos = if let Some(player) = player.iter().next() {
        player.0.translation
    } else {
        return;
    };

    for (mut trans, camera) in camera.iter_mut() {
        trans.translation = player_pos + Vec3::new(-1.0, 2.0, 1.0) * camera.distance_to_player;
        trans.look_at(player_pos, Vec3::Y);
    }
}

// update our `RayCastSource` with the current cursor position every frame.
pub fn update_raycast_with_cursor(
    mut cursor: EventReader<CursorMoved>,
    mut query: Query<&mut RayCastSource<MyRaycastSet>>,
) {
    for mut pick_source in query.iter_mut() {
        // Grab the most recent cursor event if it exists:
        if let Some(cursor_latest) = cursor.iter().last() {
            // the 2.0 is bc of post-processing, which messes up the coordinates
            pick_source.cast_method = RayCastMethod::Screenspace(cursor_latest.position * 2.0);
        }
    }
}

#[derive(Default)]
pub struct MouseCoords {
    /// The mouse coordinates on the floor, as they are
    pub raw: Vec3,
    /// The mouse coordinates, after being snapped to pillars and stuff
    pub processed: Vec3,
}

// Update our `RayCastSource` with the current cursor position every frame.
pub fn update_raw_mouse_coords(
    query: Query<&RayCastSource<MyRaycastSet>>,
    mut coords: ResMut<MouseCoords>,
) {
    for pick_source in query.iter() {
        if let Some((_, intersection)) = pick_source.intersect_top() {
            coords.raw = intersection.position();
        }
    }
}

/// checks for pillars and stuff
pub fn update_processed_mouse_coords(
    query: Query<(&Transform, &UnlitPillar)>,
    mut coords: ResMut<MouseCoords>,
) {
    let mut dis = 20.0;
    coords.processed = coords.raw;

    for (trans, _) in query.iter() {
        let d = trans.translation.distance(coords.raw);
        if d < dis {
            coords.processed = trans.translation;
            dis = d;
        }
    }
}

pub fn update_distance_to_player(input: Res<Input<KeyCode>>, mut camera: Query<&mut Camera>) {
    let pressed = input.pressed(KeyCode::Space);
    for mut camera in &mut camera {
        let dis = if pressed { 20.0 } else { 100.0 };
        camera.distance_to_player += (dis - camera.distance_to_player) / 80.0;
    }
}