mod blocks;
mod discrete_voxel_shape;
mod mergers;
mod shape;
mod world_collisions;

use std::{ops::Add, sync::LazyLock};

use azalea_block::{fluid_state::FluidState, BlockState};
use azalea_core::{
    aabb::AABB,
    direction::Axis,
    math::EPSILON,
    position::{BlockPos, Vec3},
};
use azalea_world::{ChunkStorage, Instance, MoveEntityError};
use bevy_ecs::world::Mut;
pub use blocks::BlockWithShape;
pub use discrete_voxel_shape::*;
pub use shape::*;
use tracing::warn;

use self::world_collisions::get_block_collisions;

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum MoverType {
    Own,
    Player,
    Piston,
    ShulkerBox,
    Shulker,
}

// private Vec3 collide(Vec3 var1) {
//     AABB var2 = this.getBoundingBox();
//     List var3 = this.level.getEntityCollisions(this,
// var2.expandTowards(var1));     Vec3 var4 = var1.lengthSqr() == 0.0D ?
// var1 : collideBoundingBox(this, var1, var2, this.level, var3);
//     boolean var5 = var1.x != var4.x;
//     boolean var6 = var1.y != var4.y;
//     boolean var7 = var1.z != var4.z;
//     boolean var8 = this.onGround || var6 && var1.y < 0.0D;
//     if (this.maxUpStep > 0.0F && var8 && (var5 || var7)) {
//        Vec3 var9 = collideBoundingBox(this, new Vec3(var1.x,
// (double)this.maxUpStep, var1.z), var2, this.level, var3);        Vec3
// var10 = collideBoundingBox(this, new Vec3(0.0D, (double)this.maxUpStep,
// 0.0D), var2.expandTowards(var1.x, 0.0D, var1.z), this.level, var3);
//        if (var10.y < (double)this.maxUpStep) {
//           Vec3 var11 = collideBoundingBox(this, new Vec3(var1.x, 0.0D,
// var1.z), var2.move(var10), this.level, var3).add(var10);           if
// (var11.horizontalDistanceSqr() > var9.horizontalDistanceSqr()) {
//              var9 = var11;
//           }
//        }

//        if (var9.horizontalDistanceSqr() > var4.horizontalDistanceSqr()) {
//           return var9.add(collideBoundingBox(this, new Vec3(0.0D, -var9.y +
// var1.y, 0.0D), var2.move(var9), this.level, var3));        }
//     }

//     return var4;
// }
fn collide(movement: &Vec3, world: &Instance, physics: &azalea_entity::Physics) -> Vec3 {
    let entity_bounding_box = physics.bounding_box;
    // TODO: get_entity_collisions
    // let entity_collisions = world.get_entity_collisions(self,
    // entity_bounding_box.expand_towards(movement));
    let entity_collisions = Vec::new();
    let collided_delta = if movement.length_squared() == 0.0 {
        *movement
    } else {
        collide_bounding_box(
            movement,
            &entity_bounding_box,
            world,
            entity_collisions.clone(),
        )
    };

    let x_collision = movement.x != collided_delta.x;
    let y_collision = movement.y != collided_delta.y;
    let z_collision = movement.z != collided_delta.z;

    let on_ground = physics.on_ground() || y_collision && movement.y < 0.;

    let max_up_step = 0.6;
    if max_up_step > 0. && on_ground && (x_collision || z_collision) {
        let mut step_to_delta = collide_bounding_box(
            &Vec3 {
                x: movement.x,
                y: max_up_step,
                z: movement.z,
            },
            &entity_bounding_box,
            world,
            entity_collisions.clone(),
        );
        let directly_up_delta = collide_bounding_box(
            &Vec3 {
                x: 0.,
                y: max_up_step,
                z: 0.,
            },
            &entity_bounding_box.expand_towards(&Vec3::new(movement.x, 0., movement.z)),
            world,
            entity_collisions.clone(),
        );
        if directly_up_delta.y < max_up_step {
            let target_movement = collide_bounding_box(
                &Vec3 {
                    x: movement.x,
                    y: 0.,
                    z: movement.z,
                },
                &entity_bounding_box.move_relative(directly_up_delta),
                world,
                entity_collisions.clone(),
            )
            .add(directly_up_delta);
            if target_movement.horizontal_distance_squared()
                > step_to_delta.horizontal_distance_squared()
            {
                step_to_delta = target_movement;
            }
        }

        if step_to_delta.horizontal_distance_squared()
            > collided_delta.horizontal_distance_squared()
        {
            return step_to_delta.add(collide_bounding_box(
                &Vec3 {
                    x: 0.,
                    y: -step_to_delta.y + movement.y,
                    z: 0.,
                },
                &entity_bounding_box.move_relative(step_to_delta),
                world,
                entity_collisions.clone(),
            ));
        }
    }

    collided_delta
}

/// Move an entity by a given delta, checking for collisions.
///
/// In Mojmap, this is `Entity.move`.
pub fn move_colliding(
    _mover_type: MoverType,
    movement: &Vec3,
    world: &Instance,
    position: &mut Mut<azalea_entity::Position>,
    physics: &mut azalea_entity::Physics,
) -> Result<(), MoveEntityError> {
    // TODO: do all these

    // if self.no_physics {
    //     return;
    // };

    // if (var1 == MoverType.PISTON) {
    //     var2 = this.limitPistonMovement(var2);
    //     if (var2.equals(Vec3.ZERO)) {
    //        return;
    //     }
    // }

    // if (this.stuckSpeedMultiplier.lengthSqr() > 1.0E-7D) {
    //     var2 = var2.multiply(this.stuckSpeedMultiplier);
    //     this.stuckSpeedMultiplier = Vec3.ZERO;
    //     this.setDeltaMovement(Vec3.ZERO);
    // }

    // movement = this.maybeBackOffFromEdge(movement, moverType);

    let collide_result = collide(movement, world, physics);

    let move_distance = collide_result.length_squared();

    if move_distance > EPSILON {
        // TODO: fall damage

        let new_pos = {
            Vec3 {
                x: position.x + collide_result.x,
                y: position.y + collide_result.y,
                z: position.z + collide_result.z,
            }
        };

        if new_pos != ***position {
            ***position = new_pos;
        }
    }

    let x_collision = movement.x != collide_result.x;
    let z_collision = movement.z != collide_result.z;
    let horizontal_collision = x_collision || z_collision;
    let vertical_collision = movement.y != collide_result.y;
    let on_ground = vertical_collision && movement.y < 0.;

    physics.horizontal_collision = horizontal_collision;
    physics.vertical_collision = vertical_collision;
    physics.set_on_ground(on_ground);

    // TODO: minecraft checks for a "minor" horizontal collision here

    let _block_pos_below = azalea_entity::on_pos_legacy(&world.chunks, position);
    // let _block_state_below = self
    //     .world
    //     .get_block_state(&block_pos_below)
    //     .expect("Couldn't get block state below");

    // self.check_fall_damage(collide_result.y, on_ground, block_state_below,
    // block_pos_below);

    // if self.isRemoved() { return; }

    if horizontal_collision {
        let delta_movement = &physics.velocity;
        physics.velocity = Vec3 {
            x: if x_collision { 0. } else { delta_movement.x },
            y: delta_movement.y,
            z: if z_collision { 0. } else { delta_movement.z },
        }
    }

    if vertical_collision {
        // blockBelow.updateEntityAfterFallOn(this.level, this);
        // the default implementation of updateEntityAfterFallOn sets the y movement to
        // 0
        physics.velocity.y = 0.;
    }

    if on_ground {
        // blockBelow.stepOn(this.level, blockPosBelow, blockStateBelow,
        // this);
    }

    // sounds

    // this.tryCheckInsideBlocks();

    // float var25 = this.getBlockSpeedFactor();
    // this.setDeltaMovement(this.getDeltaMovement().multiply((double)var25, 1.0D,
    // (double)var25)); if (this.level.getBlockStatesIfLoaded(this.
    // getBoundingBox().deflate(1.0E-6D)).noneMatch((var0) -> {
    //    return var0.is(BlockTags.FIRE) || var0.is(Blocks.LAVA);
    // })) {
    //    if (this.remainingFireTicks <= 0) {
    //       this.setRemainingFireTicks(-this.getFireImmuneTicks());
    //    }

    //    if (this.wasOnFire && (this.isInPowderSnow ||
    // this.isInWaterRainOrBubble())) {       this.
    // playEntityOnFireExtinguishedSound();    }
    // }

    // if (this.isOnFire() && (this.isInPowderSnow || this.isInWaterRainOrBubble()))
    // {    this.setRemainingFireTicks(-this.getFireImmuneTicks());
    // }

    Ok(())
}

fn collide_bounding_box(
    movement: &Vec3,
    entity_bounding_box: &AABB,
    world: &Instance,
    entity_collisions: Vec<VoxelShape>,
) -> Vec3 {
    let mut collision_boxes: Vec<VoxelShape> = Vec::with_capacity(entity_collisions.len() + 1);

    if !entity_collisions.is_empty() {
        collision_boxes.extend(entity_collisions);
    }

    // TODO: world border

    let block_collisions =
        get_block_collisions(world, entity_bounding_box.expand_towards(movement));
    collision_boxes.extend(block_collisions);
    collide_with_shapes(movement, *entity_bounding_box, &collision_boxes)
}

fn collide_with_shapes(
    movement: &Vec3,
    mut entity_box: AABB,
    collision_boxes: &Vec<VoxelShape>,
) -> Vec3 {
    if collision_boxes.is_empty() {
        return *movement;
    }

    let mut x_movement = movement.x;
    let mut y_movement = movement.y;
    let mut z_movement = movement.z;
    if y_movement != 0. {
        y_movement = Shapes::collide(&Axis::Y, &entity_box, collision_boxes, y_movement);
        if y_movement != 0. {
            entity_box = entity_box.move_relative(Vec3 {
                x: 0.,
                y: y_movement,
                z: 0.,
            });
        }
    }

    // whether the player is moving more in the z axis than x
    // this is done to fix a movement bug, minecraft does this too
    let more_z_movement = x_movement.abs() < z_movement.abs();

    if more_z_movement && z_movement != 0. {
        z_movement = Shapes::collide(&Axis::Z, &entity_box, collision_boxes, z_movement);
        if z_movement != 0. {
            entity_box = entity_box.move_relative(Vec3 {
                x: 0.,
                y: 0.,
                z: z_movement,
            });
        }
    }

    if x_movement != 0. {
        x_movement = Shapes::collide(&Axis::X, &entity_box, collision_boxes, x_movement);
        if x_movement != 0. {
            entity_box = entity_box.move_relative(Vec3 {
                x: x_movement,
                y: 0.,
                z: 0.,
            });
        }
    }

    if !more_z_movement && z_movement != 0. {
        z_movement = Shapes::collide(&Axis::Z, &entity_box, collision_boxes, z_movement);
    }

    Vec3 {
        x: x_movement,
        y: y_movement,
        z: z_movement,
    }
}

/// Get the [`VoxelShape`] for the given fluid state.
///
/// The instance and position are required so it can check if the block above is
/// also the same fluid type.
pub fn fluid_shape(
    fluid: &FluidState,
    world: &ChunkStorage,
    pos: &BlockPos,
) -> &'static VoxelShape {
    if fluid.amount == 9 {
        let fluid_state_above = world.get_fluid_state(&pos.up(1)).unwrap_or_default();
        if fluid_state_above.kind == fluid.kind {
            return &BLOCK_SHAPE;
        }
    }
    if fluid.amount > 9 {
        warn!("Tried to calculate shape for fluid with height > 9: {fluid:?} at {pos}");
        return &EMPTY_SHAPE;
    }

    // pre-calculate these in a LazyLock so this function can return a
    // reference instead

    static FLUID_SHAPES: LazyLock<[VoxelShape; 10]> = LazyLock::new(|| {
        [
            calculate_shape_for_fluid(0),
            calculate_shape_for_fluid(1),
            calculate_shape_for_fluid(2),
            calculate_shape_for_fluid(3),
            calculate_shape_for_fluid(4),
            calculate_shape_for_fluid(5),
            calculate_shape_for_fluid(6),
            calculate_shape_for_fluid(7),
            calculate_shape_for_fluid(8),
            calculate_shape_for_fluid(9),
        ]
    });

    &FLUID_SHAPES[fluid.amount as usize]
}
fn calculate_shape_for_fluid(amount: u8) -> VoxelShape {
    box_shape(0.0, 0.0, 0.0, 1.0, (f32::from(amount) / 9.0) as f64, 1.0)
}

/// Whether the block is treated as "motion blocking".
///
/// This is marked as deprecated in Minecraft.
pub fn legacy_blocks_motion(block: BlockState) -> bool {
    let registry_block = azalea_registry::Block::from(block);
    legacy_calculate_solid(block)
        && registry_block != azalea_registry::Block::Cobweb
        && registry_block != azalea_registry::Block::BambooSapling
}

pub fn legacy_calculate_solid(block: BlockState) -> bool {
    // force_solid has to be checked before anything else
    let block_trait = Box::<dyn azalea_block::Block>::from(block);
    if let Some(solid) = block_trait.behavior().force_solid {
        return solid;
    }

    let shape = block.collision_shape();
    if shape.is_empty() {
        return false;
    }
    let bounds = shape.bounds();
    bounds.size() >= 0.7291666666666666 || bounds.get_size(Axis::Y) >= 1.0
}