use azalea_block::BlockState;
use azalea_core::{heightmap_kind::HeightmapKind as HeightmapKind_, math, position::ChunkBlockPos};
use azalea_registry::tags::blocks::LEAVES;
use tracing::warn;

use crate::{BitStorage, Section, chunk::get_block_state_from_sections};

// TODO: when removing this deprecated marker, also rename `HeightmapKind_` back
// to `HeightmapKind`.
#[deprecated = "moved to `azalea_core::heightmap_kind::HeightmapKind`."]
pub type HeightmapKind = azalea_core::heightmap_kind::HeightmapKind;

#[derive(Clone, Debug)]
pub struct Heightmap {
    pub data: BitStorage,
    pub min_y: i32,
    pub kind: HeightmapKind_,
}

fn blocks_motion(block_state: BlockState) -> bool {
    // TODO
    !block_state.is_air()
}

fn motion_blocking(block_state: BlockState) -> bool {
    // TODO
    !block_state.is_air()
        || block_state
            .property::<azalea_block::properties::Waterlogged>()
            .unwrap_or_default()
}

pub fn is_heightmap_opaque(heightmap: HeightmapKind_, block_state: BlockState) -> bool {
    let registry_block = block_state.as_block_kind();
    type K = HeightmapKind_;
    match heightmap {
        K::WorldSurfaceWg => !block_state.is_air(),
        K::WorldSurface => !block_state.is_air(),
        K::OceanFloorWg => blocks_motion(block_state),
        K::OceanFloor => blocks_motion(block_state),
        K::MotionBlocking => motion_blocking(block_state),
        K::MotionBlockingNoLeaves => {
            motion_blocking(block_state) && !LEAVES.contains(&registry_block)
        }
    }
}

impl Heightmap {
    pub fn new(kind: HeightmapKind_, dimension_height: u32, min_y: i32, data: Box<[u64]>) -> Self {
        let bits = math::ceil_log2(dimension_height + 1);
        let mut bit_storage = BitStorage::new(bits as usize, 16 * 16, None)
            .expect("data is empty, so this can't fail");
        if bit_storage.data.len() != data.len() {
            warn!(
                "Ignoring heightmap data, size does not match; expected: {}, got: {}",
                bit_storage.data.len(),
                data.len()
            );
        } else {
            bit_storage.data.copy_from_slice(&data);
        }
        Self {
            kind,
            data: bit_storage,
            min_y,
        }
    }

    pub fn get_index(x: u8, z: u8) -> usize {
        (x as usize) + (z as usize) * 16
    }

    pub fn get_first_available_at_index(&self, index: usize) -> i32 {
        self.data.get(index) as i32 + self.min_y
    }

    pub fn get_first_available(&self, x: u8, z: u8) -> i32 {
        self.get_first_available_at_index(Self::get_index(x, z))
    }

    pub fn get_highest_taken(&self, x: u8, z: u8) -> i32 {
        self.get_first_available(x, z) - 1
    }

    pub fn set_height(&mut self, x: u8, z: u8, height: i32) {
        self.data
            .set(Self::get_index(x, z), (height - self.min_y) as u64);
    }

    /// Updates the heightmap with the given block state at the given position.
    pub fn update(
        &mut self,
        pos: &ChunkBlockPos,
        block_state: BlockState,
        sections: &[Section],
    ) -> bool {
        let first_available_y = self.get_first_available(pos.x, pos.z);
        if pos.y <= first_available_y - 2 {
            return false;
        }
        if is_heightmap_opaque(self.kind, block_state) {
            // increase y
            if pos.y >= first_available_y {
                self.set_height(pos.x, pos.z, pos.y + 1);
                return true;
            }
        } else if first_available_y - 1 == pos.y {
            // decrease y
            for y in (self.min_y..pos.y).rev() {
                if is_heightmap_opaque(
                    self.kind,
                    get_block_state_from_sections(
                        sections,
                        &ChunkBlockPos::new(pos.x, y, pos.z),
                        self.min_y,
                    )
                    .unwrap_or_default(),
                ) {
                    self.set_height(pos.x, pos.z, y + 1);
                    return true;
                }
            }

            self.set_height(pos.x, pos.z, self.min_y);
            return true;
        }

        false
    }

    /// Get an iterator over the top available block positions in this
    /// heightmap.
    pub fn iter_first_available(&self) -> impl Iterator<Item = ChunkBlockPos> + '_ {
        self.data.iter().enumerate().map(move |(index, height)| {
            let x = (index % 16) as u8;
            let z = (index / 16) as u8;
            ChunkBlockPos::new(x, height as i32 + self.min_y, z)
        })
    }

    /// Get an iterator over the top block positions in this heightmap.
    pub fn iter_highest_taken(&self) -> impl Iterator<Item = ChunkBlockPos> + '_ {
        self.data.iter().enumerate().map(move |(index, height)| {
            let x = (index % 16) as u8;
            let z = (index / 16) as u8;
            ChunkBlockPos::new(x, height as i32 + self.min_y - 1, z)
        })
    }
}