KStarbound/src/main/kotlin/ru/dbotthepony/kstarbound/world/Chunk.kt

package ru.dbotthepony.kstarbound.world

import ru.dbotthepony.kommons.arrays.Object2DArray
import ru.dbotthepony.kommons.util.AABB
import ru.dbotthepony.kommons.vector.Vector2d
import ru.dbotthepony.kstarbound.network.LegacyNetworkCellState
import ru.dbotthepony.kstarbound.world.api.AbstractCell
import ru.dbotthepony.kstarbound.world.api.ICellAccess
import ru.dbotthepony.kstarbound.world.api.ImmutableCell
import ru.dbotthepony.kstarbound.world.api.OffsetCellAccess
import ru.dbotthepony.kstarbound.world.api.TileView
import java.util.concurrent.CopyOnWriteArraySet

/**
 * Чанк мира
 *
 * Хранит в себе тайлы и ентити внутри себя
 *
 * Считается, что один тайл имеет форму квадрата и сторона квадрата примерно равна полуметру,
 * что будет называться Starbound Unit
 *
 * Весь игровой мир будет измеряться в Starbound Unit'ах
 */
abstract class Chunk<WorldType : World<WorldType, This>, This : Chunk<WorldType, This>>(
	val world: WorldType,
	val pos: ChunkPos,
) : ICellAccess {
	var changeset = 0
		private set

	var tileChangeset = 0
		private set
	var liquidChangeset = 0
		private set
	var cellChangeset = 0
		private set

	var foregroundChangeset = 0
		private set
	var backgroundChangeset = 0
		private set

	val width = (world.geometry.size.x - pos.tileX).coerceAtMost(CHUNK_SIZE)
	val height = (world.geometry.size.y - pos.tileY).coerceAtMost(CHUNK_SIZE)

	// local cells' tile access
	val localBackgroundView = TileView.Background(this)
	val localForegroundView = TileView.Foreground(this)

	// relative world cells access (accessing 0, 0 will lookup cell in world, relative to this chunk)
	val worldView = OffsetCellAccess(world, pos.x * CHUNK_SIZE, pos.y * CHUNK_SIZE)
	val worldBackgroundView = TileView.Background(worldView)
	val worldForegroundView = TileView.Foreground(worldView)

	val aabb = aabbBase + Vector2d(pos.x * CHUNK_SIZE.toDouble(), pos.y * CHUNK_SIZE.toDouble())

	// TODO: maybe fit them into "width" and "height" variables added recently?
	protected val cells = lazy {
		Object2DArray(CHUNK_SIZE, CHUNK_SIZE, AbstractCell.NULL)
	}

	protected val tileHealthForeground = lazy {
		Object2DArray(CHUNK_SIZE, CHUNK_SIZE) { _, _ -> TileHealth.Tile() }
	}

	protected val tileHealthBackground = lazy {
		Object2DArray(CHUNK_SIZE, CHUNK_SIZE) { _, _ -> TileHealth.Tile() }
	}

	fun loadCells(source: Object2DArray<out AbstractCell>) {
		val ours = cells.value
		source.checkSizeEquals(ours)

		for (x in 0 until CHUNK_SIZE) {
			for (y in 0 until CHUNK_SIZE) {
				ours[x, y] = source[x, y].immutable()
			}
		}
	}

	override fun getCell(x: Int, y: Int): AbstractCell {
		if (!cells.isInitialized())
			return AbstractCell.NULL

		return cells.value[x, y]
	}

	override fun getCellDirect(x: Int, y: Int): AbstractCell {
		return getCell(x, y)
	}

	override fun setCell(x: Int, y: Int, cell: AbstractCell): Boolean {
		val old = if (cells.isInitialized()) cells.value[x, y] else AbstractCell.NULL
		val new = cell.immutable()

		if (old != new) {
			cells.value[x, y] = new

			if (old.foreground != new.foreground) {
				foregroundChanges(x, y, new)
			}

			if (old.background != new.background) {
				backgroundChanges(x, y, new)
			}

			if (old.liquid != new.liquid) {
				liquidChanges(x, y, new)
			}

			cellChanges(x, y, new)
		}

		return true
	}

	protected open fun foregroundChanges(x: Int, y: Int, cell: ImmutableCell) {
		cellChanges(x, y, cell)
		tileChangeset++
		foregroundChangeset++
	}

	protected open fun backgroundChanges(x: Int, y: Int, cell: ImmutableCell) {
		cellChanges(x, y, cell)
		tileChangeset++
		backgroundChangeset++
	}

	protected open fun liquidChanges(x: Int, y: Int, cell: ImmutableCell) {
		cellChanges(x, y, cell)
		liquidChangeset++
	}

	protected open fun cellChanges(x: Int, y: Int, cell: ImmutableCell) {
		changeset++
		cellChangeset++
	}

	protected inline fun forEachNeighbour(block: (This) -> Unit) {
		world.chunkMap[pos.left]?.let(block)
		world.chunkMap[pos.right]?.let(block)
		world.chunkMap[pos.top]?.let(block)
		world.chunkMap[pos.bottom]?.let(block)
		world.chunkMap[pos.topLeft]?.let(block)
		world.chunkMap[pos.topRight]?.let(block)
		world.chunkMap[pos.bottomLeft]?.let(block)
		world.chunkMap[pos.bottomRight]?.let(block)
	}

	override fun toString(): String {
		return "${this::class.simpleName}(pos=$pos, world=$world)"
	}

	open fun remove() {

	}

	open fun tick() {

	}

	companion object {
		private val aabbBase = AABB(
			Vector2d.ZERO,
			Vector2d(CHUNK_SIZE.toDouble(), CHUNK_SIZE.toDouble()),
		)
	}
}