use std::collections::{HashMap, HashSet};

use bevy::prelude::*;
use coord_2d::{Coord, Size};
use derive_more::{Deref, DerefMut};
use shadowcast::{vision_distance, Context, InputGrid};

use crate::{
    bevy_rapier2d::prelude::*,
    core::{Angle, Coordinates, Player, PointLike},
    log::Log,
    map::{ITileType, Map, MapConfig},
};

#[derive(Clone, Copy, Debug, Default, Reflect)]
#[reflect(Component)]
pub struct BlocksVisibility;

#[derive(Clone, Copy, Debug, Default, Reflect)]
#[reflect(Component)]
pub struct DontLogWhenVisible;

#[derive(Clone, Debug, Default, Deref, DerefMut, Reflect)]
#[reflect(Component)]
pub struct RevealedTiles(pub Vec<bool>);

#[derive(Clone, Debug, Eq, PartialEq)]
pub struct Viewshed {
    pub visible: HashSet<(i32, i32)>,
    pub range: u32,
}

impl Default for Viewshed {
    fn default() -> Self {
        Self {
            range: 15,
            visible: HashSet::new(),
        }
    }
}

impl Viewshed {
    pub fn is_visible(&self, point: &dyn PointLike) -> bool {
        self.visible.contains(&point.into())
    }
}

#[derive(Clone, Debug, Default, Deref, DerefMut, Reflect)]
#[reflect(Component)]
pub struct VisibleTiles(pub Vec<bool>);

impl PointLike for Coord {
    fn x(&self) -> f32 {
        self.x as f32
    }

    fn y(&self) -> f32 {
        self.y as f32
    }
}

fn add_visibility_indices(
    mut commands: Commands,
    query: Query<(Entity, &Map), (Added<Map>, Without<VisibleTiles>, Without<RevealedTiles>)>,
    map_config: Res<MapConfig>,
) {
    for (entity, map) in query.iter() {
        let count = map.width * map.height;
        commands
            .entity(entity)
            .insert(VisibleTiles(vec![false; count]));
        commands
            .entity(entity)
            .insert(RevealedTiles(vec![map_config.start_revealed; count]));
    }
}

struct VisibilityGrid<'a, F>(&'a Map, F);

impl<'a, F> InputGrid for VisibilityGrid<'a, F>
where
    F: Fn(Coord) -> u8,
{
    type Grid = VisibilityGrid<'a, F>;

    type Opacity = u8;

    fn size(&self, grid: &Self::Grid) -> Size {
        Size::new(grid.0.width as u32, grid.0.height as u32)
    }

    fn get_opacity(&self, _grid: &Self::Grid, coord: Coord) -> Self::Opacity {
        self.1(coord)
    }
}

fn update_viewshed(
    viewer_entity: &Entity,
    viewshed: &mut Viewshed,
    start: &dyn PointLike,
    query_pipeline: &QueryPipeline,
    collider_query: &QueryPipelineColliderComponentsQuery,
    map: &Map,
    blocks_visibility: &Query<&BlocksVisibility>,
    coordinates: &Query<&Coordinates>,
) {
    let mut context: Context<u8> = Context::default();
    let vision_distance = vision_distance::Circle::new(viewshed.range);
    let coord = Coord::new(start.x_i32(), start.y_i32());
    viewshed.visible.clear();
    let shape = Cuboid::new(Vec2::new(0.49, 0.49).into());
    let range = viewshed.range as f32;
    let collider_set = QueryPipelineColliderComponentsSet(&collider_query);
    let visibility_grid = VisibilityGrid(map, |coord: Coord| {
        if coord.distance(start) > range {
            return 255;
        }
        let shape_pos = (Vec2::new(coord.x as f32 + 0.5, coord.y as f32 + 0.5), 0.);
        let mut opacity = 0;
        query_pipeline.intersections_with_shape(
            &collider_set,
            &shape_pos.into(),
            &shape,
            InteractionGroups::all(),
            Some(&|v| v.entity() != *viewer_entity && blocks_visibility.get(v.entity()).is_ok()),
            |handle| {
                if let Ok(coordinates) = coordinates.get(handle.entity()) {
                    if coordinates.i32() == (coord.x, coord.y) {
                        opacity = 255;
                        false
                    } else {
                        true
                    }
                } else {
                    opacity = 255;
                    false
                }
            },
        );
        opacity
    });
    context.for_each_visible(
        coord,
        &visibility_grid,
        &visibility_grid,
        vision_distance,
        255,
        |coord, _directions, _visibility| {
            viewshed.visible.insert((coord.x, coord.y));
        },
    );
}

fn update_viewshed_for_coordinates(
    visible: Query<&Coordinates, (Changed<Coordinates>, With<BlocksVisibility>)>,
    mut viewers: Query<(Entity, &mut Viewshed, &Coordinates)>,
    map: Query<&Map>,
    query_pipeline: Res<QueryPipeline>,
    collider_query: QueryPipelineColliderComponentsQuery,
    blocks_visibility: Query<&BlocksVisibility>,
    coordinates_query: Query<&Coordinates>,
) {
    for coordinates in visible.iter() {
        for (viewer_entity, mut viewshed, start) in viewers.iter_mut() {
            if coordinates.distance(start) > viewshed.range as f32 {
                continue;
            }
            if let Ok(map) = map.single() {
                update_viewshed(
                    &viewer_entity,
                    &mut viewshed,
                    start,
                    &*query_pipeline,
                    &collider_query,
                    map,
                    &blocks_visibility,
                    &coordinates_query,
                );
            }
        }
    }
}

fn update_viewshed_for_start(
    mut viewers: Query<(Entity, &mut Viewshed, &Coordinates), Changed<Coordinates>>,
    map: Query<&Map>,
    query_pipeline: Res<QueryPipeline>,
    collider_query: QueryPipelineColliderComponentsQuery,
    blocks_visibility: Query<&BlocksVisibility>,
    coordinates_query: Query<&Coordinates>,
) {
    for (viewer_entity, mut viewshed, start) in viewers.iter_mut() {
        if let Ok(map) = map.single() {
            update_viewshed(
                &viewer_entity,
                &mut viewshed,
                start,
                &*query_pipeline,
                &collider_query,
                map,
                &blocks_visibility,
                &coordinates_query,
            );
        }
    }
}

fn remove_blocks_visibility(
    removed: RemovedComponents<BlocksVisibility>,
    mut viewers: Query<(Entity, &mut Viewshed, &Coordinates)>,
    map: Query<&Map>,
    query_pipeline: Res<QueryPipeline>,
    collider_query: QueryPipelineColliderComponentsQuery,
    blocks_visibility: Query<&BlocksVisibility>,
    coordinates_query: Query<&Coordinates>,
) {
    for _ in removed.iter() {
        for (viewer_entity, mut viewshed, start) in viewers.iter_mut() {
            if let Ok(map) = map.single() {
                update_viewshed(
                    &viewer_entity,
                    &mut viewshed,
                    start,
                    &*query_pipeline,
                    &collider_query,
                    map,
                    &blocks_visibility,
                    &coordinates_query,
                );
            }
        }
    }
}

fn update_visible_and_revealed_tiles(
    mut map: Query<(&Map, &mut RevealedTiles, &mut VisibleTiles)>,
    viewers: Query<&Viewshed, With<Player>>,
) {
    for (map, mut revealed_tiles, mut visible_tiles) in map.iter_mut() {
        for viewshed in viewers.iter() {
            for t in visible_tiles.iter_mut() {
                *t = false
            }
            for v in viewshed.visible.iter() {
                let idx = v.to_index(map.width);
                revealed_tiles[idx] = true;
                visible_tiles[idx] = true;
            }
        }
    }
}

fn log_visible(
    time: Res<Time>,
    mut seen: Local<HashSet<Entity>>,
    mut recently_lost: Local<HashMap<Entity, Timer>>,
    query_pipeline: Res<QueryPipeline>,
    collider_query: QueryPipelineColliderComponentsQuery,
    mut log: Query<&mut Log>,
    viewers: Query<(Entity, &Viewshed, &Coordinates, &Transform), With<Player>>,
    names: Query<&Name>,
    dont_log_when_visible: Query<&DontLogWhenVisible>,
) {
    for timer in recently_lost.values_mut() {
        timer.tick(time.delta());
    }
    let recently_lost_clone = recently_lost.clone();
    for (entity, timer) in recently_lost_clone.iter() {
        if timer.finished() {
            recently_lost.remove(&entity);
        }
    }
    let mut new_seen = HashSet::new();
    if let Ok(mut log) = log.single_mut() {
        for (viewer_entity, viewshed, coordinates, transform) in viewers.iter() {
            let collider_set = QueryPipelineColliderComponentsSet(&collider_query);
            let shape = Cuboid::new(Vec2::new(0.49, 0.49).into());
            for viewed_coordinates in &viewshed.visible {
                let shape_pos = (
                    Vec2::new(viewed_coordinates.x() + 0.5, viewed_coordinates.y() + 0.5),
                    0.0,
                )
                    .into();
                query_pipeline.intersections_with_shape(
                    &collider_set,
                    &shape_pos,
                    &shape,
                    InteractionGroups::all(),
                    Some(&|v| v.entity() != viewer_entity),
                    |handle| {
                        let entity = handle.entity();
                        if recently_lost.contains_key(&entity) {
                            new_seen.insert(entity);
                            recently_lost.remove(&entity);
                            return true;
                        }
                        if let Ok(name) = names.get(entity) {
                            if !seen.contains(&entity)
                                && !new_seen.contains(&entity)
                                && dont_log_when_visible.get(entity).is_err()
                            {
                                let name = name.to_string();
                                let forward = transform.local_x();
                                let yaw = Angle::Radians(forward.y.atan2(forward.x));
                                let location = coordinates
                                    .direction_and_distance(viewed_coordinates, Some(yaw));
                                log.push(format!("{}: {}", name, location));
                            }
                            new_seen.insert(entity);
                        }
                        true
                    },
                );
            }
        }
    }
    let recently_lost_entities = seen.difference(&new_seen);
    for entity in recently_lost_entities {
        recently_lost.insert(*entity, Timer::from_seconds(2., false));
    }
    *seen = new_seen;
}

pub const LOG_VISIBLE_LABEL: &str = "LOG_VISIBLE";

pub struct VisibilityPlugin;

impl Plugin for VisibilityPlugin {
    fn build(&self, app: &mut AppBuilder) {
        app.add_system(add_visibility_indices.system())
            .add_system_to_stage(
                CoreStage::PostUpdate,
                update_viewshed_for_coordinates.system(),
            )
            .add_system_to_stage(CoreStage::PostUpdate, update_viewshed_for_start.system())
            .add_system_to_stage(CoreStage::PostUpdate, remove_blocks_visibility.system())
            .add_system_to_stage(
                CoreStage::PostUpdate,
                update_visible_and_revealed_tiles.system(),
            )
            .add_system_to_stage(CoreStage::PostUpdate, log_visible.system());
    }
}