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

use bevy::prelude::*;
use bevy_rapier2d::na::UnitComplex;
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},
    utils::target_and_other,
};

#[derive(Clone, Copy, Debug, Deref, DerefMut, Reflect)]
#[reflect(Component)]
pub struct BlocksVisibility(pub u8);

impl Default for BlocksVisibility {
    fn default() -> Self {
        Self(u8::MAX)
    }
}

#[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 range: u32,
    pub visible_points: HashSet<(i32, i32)>,
}

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

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

#[derive(Clone, Copy, Debug, Default, Reflect)]
struct VisibilityCollider;

#[derive(Clone, Debug, Default, Deref, DerefMut)]
pub struct VisibleEntities(HashSet<Entity>);

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

#[derive(Bundle, Default)]
pub struct ViewshedBundle {
    pub viewshed: Viewshed,
    pub visible_entities: VisibleEntities,
}

impl ViewshedBundle {
    pub fn new(range: u32) -> Self {
        Self {
            viewshed: Viewshed {
                range,
                ..Default::default()
            },
            ..Default::default()
        }
    }
}

pub enum VisibilityChanged {
    Gained { viewer: Entity, viewed: Entity },
    Lost { viewer: Entity, viewed: Entity },
}

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]));
    }
}

fn viewshed_added(mut commands: Commands, query: Query<Entity, Added<Viewshed>>) {
    for entity in query.iter() {
        let id = commands.spawn().insert(VisibilityCollider).id();
        commands.entity(entity).push_children(&[id]);
    }
}

fn viewshed_changed(
    mut commands: Commands,
    query: Query<(Entity, &Viewshed, &RigidBodyPosition), Changed<Viewshed>>,
    mut collider_data: Query<
        (&Parent, Entity, Option<&mut ColliderShape>),
        With<VisibilityCollider>,
    >,
) {
    for (entity, viewshed, position) in query.iter() {
        for (parent, child_entity, collider_shape) in collider_data.iter_mut() {
            if **parent != entity {
                continue;
            }
            if viewshed.visible_points.len() < 2 {
                commands.entity(child_entity).remove::<ColliderShape>();
            } else {
                let position = position.position;
                let mut points = vec![];
                for p in &viewshed.visible_points {
                    points.push(point!(
                        position.translation.x - p.x(),
                        position.translation.y - p.y()
                    ));
                }
                if let Some(shape) = ColliderShape::convex_hull(&points) {
                    //println!("Shape for {:?}", points);
                    if let Some(mut collider_shape) = collider_shape {
                        *collider_shape = shape;
                    } else {
                        //println!("Creating collider at {:?}", coordinates.i32());
                        commands.entity(child_entity).insert_bundle(ColliderBundle {
                            collider_type: ColliderType::Sensor,
                            shape,
                            flags: ActiveEvents::INTERSECTION_EVENTS.into(),
                            ..Default::default()
                        });
                    }
                }
            }
        }
    }
}

fn lock_rotation(
    mut query: Query<(&Parent, &mut ColliderPosition), With<VisibilityCollider>>,
    positions: Query<&RigidBodyPosition>,
) {
    for (parent, mut position) in query.iter_mut() {
        if let Ok(parent_position) = positions.get(**parent) {
            let delta = parent_position
                .position
                .rotation
                .angle_to(&UnitComplex::new(0.));
            println!("Syncing: {:?}", delta);
            position.rotation = UnitComplex::new(delta);
        }
    }
}

fn viewshed_removed(
    mut commands: Commands,
    query: RemovedComponents<Viewshed>,
    children: Query<&Children>,
    collider_shapes: Query<Entity, With<VisibilityCollider>>,
) {
    for entity in query.iter() {
        if let Ok(children) = children.get(entity) {
            for child in children.iter() {
                if collider_shapes.get(*child).is_ok() {
                    commands.entity(*child).despawn_recursive();
                    break;
                }
            }
        }
    }
}

pub struct VisibilityGrid<'a, F>(pub &'a Map, pub 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>,
) {
    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());
    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(blocks_visibility) = blocks_visibility.get(handle.entity()) {
                    opacity = **blocks_visibility;
                    false
                } else {
                    true
                }
            },
        );
        opacity
    });
    let mut new_visible = HashSet::new();
    context.for_each_visible(
        coord,
        &visibility_grid,
        &visibility_grid,
        vision_distance,
        255,
        |coord, _directions, _visibility| {
            new_visible.insert((coord.x, coord.y));
        },
    );
    if viewshed.visible_points != new_visible {
        viewshed.visible_points = new_visible;
    }
}

fn update_viewshed_for_coordinates(
    visible: Query<(Entity, &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>,
) {
    for (visible_entity, coordinates) in visible.iter() {
        for (viewer_entity, mut viewshed, start) in viewers.iter_mut() {
            if viewer_entity == visible_entity
                || 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,
                );
            }
        }
    }
}

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>,
) {
    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,
            );
        }
    }
}

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

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_points.iter() {
                let idx = v.to_index(map.width);
                if idx >= revealed_tiles.len() || idx >= visible_tiles.len() {
                    continue;
                }
                revealed_tiles[idx] = true;
                visible_tiles[idx] = true;
            }
        }
    }
}

fn intersection(
    mut events: EventReader<IntersectionEvent>,
    colliders: Query<&Parent, With<VisibilityCollider>>,
    mut viewers: Query<&mut VisibleEntities>,
    names: Query<&Name>,
    parents: Query<&Parent>,
    mut visibility_changed: EventWriter<VisibilityChanged>,
) {
    for event in events.iter() {
        println!("{:?}", event);
        if let Some((visibility_collider, other)) =
            target_and_other(event.collider1.entity(), event.collider2.entity(), |v| {
                colliders.get(v).is_ok()
            })
        {
            if let Ok(parent) = colliders.get(visibility_collider) {
                if let Ok(mut visible_entities) = viewers.get_mut(**parent) {
                    if event.intersecting {
                        println!("{:?} is visible: {:?}", other, names.get(other));
                        if let Ok(p) = parents.get(other) {
                            println!("{:?}", names.get(**p));
                        }
                        visibility_changed.send(VisibilityChanged::Gained {
                            viewer: **parent,
                            viewed: other,
                        });
                        visible_entities.insert(other);
                    } else {
                        println!("{:?} is not visible", other);
                        visibility_changed.send(VisibilityChanged::Lost {
                            viewer: **parent,
                            viewed: other,
                        });
                        visible_entities.remove(&other);
                    }
                }
            }
        }
    }
}

fn log_visible(
    time: Res<Time>,
    mut recently_lost: Local<HashMap<Entity, Timer>>,
    mut events: EventReader<IntersectionEvent>,
    mut log: Query<&mut Log>,
    viewer_colliders: Query<&Parent, With<VisibilityCollider>>,
    viewers: Query<(Entity, &Coordinates, &Transform), (With<Player>, With<Viewshed>)>,
    viewed: Query<
        (
            Entity,
            &Name,
            Option<&RigidBodyPosition>,
            Option<&ColliderPosition>,
        ),
        Without<DontLogWhenVisible>,
    >,
) {
    for timer in recently_lost.values_mut() {
        timer.tick(time.delta());
    }
    recently_lost.retain(|_entity, timer| !timer.finished());
    for event in events.iter() {
        if let Some((viewer_collider, other)) =
            target_and_other(event.collider1.entity(), event.collider2.entity(), |v| {
                viewer_colliders.get(v).is_ok()
            })
        {
            if let Ok((viewed_entity, name, rigid_body_position, collider_position)) =
                viewed.get(other)
            {
                if event.intersecting {
                    if recently_lost.contains_key(&viewed_entity) {
                        recently_lost.remove(&viewed_entity);
                    } else {
                        if let Ok(parent) = viewer_colliders.get(viewer_collider) {
                            if let Ok((viewer_entity, coordinates, transform)) =
                                viewers.get(**parent)
                            {
                                if viewer_entity == viewed_entity {
                                    continue;
                                }
                                if let Ok(mut log) = log.single_mut() {
                                    let viewed_coordinates = if let Some(p) = rigid_body_position {
                                        (p.position.translation.x, p.position.translation.y)
                                    } else if let Some(p) = collider_position {
                                        (p.translation.x, p.translation.y)
                                    } else {
                                        (0., 0.)
                                    };
                                    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));
                                }
                            }
                        }
                    }
                } else {
                    recently_lost.insert(viewed_entity, Timer::from_seconds(2., false));
                }
            }
        }
    }
}

pub const LOG_VISIBLE_LABEL: &str = "LOG_VISIBLE";

pub struct VisibilityPlugin;

impl Plugin for VisibilityPlugin {
    fn build(&self, app: &mut AppBuilder) {
        app.add_event::<VisibilityChanged>()
            .add_system(add_visibility_indices.system())
            .add_system(viewshed_added.system())
            .add_system(viewshed_changed.system())
            .add_system(lock_rotation.system())
            .add_system_to_stage(CoreStage::PostUpdate, viewshed_removed.system())
            .add_system(update_viewshed_for_coordinates.system())
            .add_system(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(intersection.system())
            .add_system_to_stage(CoreStage::PostUpdate, log_visible.system());
    }
}