PhysicalConnectivity/src/main/kotlin/net/shadowfacts/phycon/network/NetworkUtil.kt

package net.shadowfacts.phycon.network

import net.minecraft.util.math.BlockPos
import net.minecraft.util.math.Direction
import net.minecraft.world.World
import net.shadowfacts.phycon.api.NetworkCable
import net.shadowfacts.phycon.api.NetworkComponent
import net.shadowfacts.phycon.api.PacketSink
import net.shadowfacts.phycon.api.PhyAttributes
import java.util.*

/**
 * @author shadowfacts
 */
object NetworkUtil {

	fun findDestinations(world: World, startPos: BlockPos, direction: Direction? = null): List<PacketSink> {
		val results = LinkedList<PacketSink>()
		val visited = hashSetOf(startPos)
		val queue = LinkedList<BlockPos>()
		if (direction != null) {
			queue.add(startPos.offset(direction))
		} else {
			findEdges(queue, visited, world, startPos, includeNonCables = true)
		}

		while (queue.isNotEmpty()) {
			val pos = queue.pop()

			val sink = PhyAttributes.PACKET_SINK.getFirstOrNull(world, pos)
			if (sink != null) {
				results.add(sink)
			}

			findEdges(queue, visited, world, pos)

			visited.add(pos)
		}

		return results
	}

	private fun findEdges(queue: MutableList<BlockPos>, visited: Set<BlockPos>, world: World, pos: BlockPos, includeNonCables: Boolean = false) {
		val state = world.getBlockState(pos)
		val block = state.block
		if (block is NetworkComponent && (includeNonCables || block is NetworkCable)) {
			val connections = block.getNetworkConnectedSides(state, world, pos)
			for (side in connections) {
				val newPos = pos.offset(side)
				if (newPos !in visited) {
					queue.add(newPos)
				}
			}
		}
	}

}