PhysicalConnectivity/src/main/kotlin/net/shadowfacts/phycon/network/block/terminal/TerminalScreenHandler.kt

package net.shadowfacts.phycon.network.block.terminal

import net.minecraft.screen.slot.Slot
import net.minecraft.screen.slot.SlotActionType
import net.minecraft.entity.player.PlayerEntity
import net.minecraft.entity.player.PlayerInventory
import net.minecraft.item.ItemStack
import net.minecraft.network.PacketByteBuf
import net.minecraft.screen.ScreenHandler
import net.minecraft.util.Identifier
import net.shadowfacts.phycon.PhysicalConnectivity
import net.shadowfacts.phycon.init.PhyBlocks
import net.shadowfacts.phycon.init.PhyScreens
import kotlin.math.ceil
import kotlin.math.min

/**
 * @author shadowfacts
 */
class TerminalScreenHandler(syncId: Int, playerInv: PlayerInventory, val terminal: TerminalBlockEntity): ScreenHandler(PhyScreens.TERMINAL_SCREEN_HANDLER, syncId) {

	companion object {
		val ID = Identifier(PhysicalConnectivity.MODID, "terminal")
	}

	constructor(syncId: Int, playerInv: PlayerInventory, buf: PacketByteBuf):
			this(syncId, playerInv, PhyBlocks.TERMINAL.getBlockEntity(playerInv.player.world, buf.readBlockPos())!!)

	init {
		// network
		for (y in 0 until 6) {
			for (x in 0 until 9) {
				addSlot(TerminalFakeSlot(terminal, y * 9 + x, 66 + x * 18, 18 + y * 18))
			}
		}

		// internal buffer
		for (y in 0 until 6) {
			for (x in 0 until 3) {
				addSlot(Slot(terminal.internalBuffer, y * 3 + x, 8 + x * 18, 18 + y * 18))
			}
		}

		// player inv
		for (y in 0 until 3) {
			for (x in 0 until 9) {
				addSlot(Slot(playerInv, x + y * 9 + 9, 66 + x * 18, 140 + y * 18))
			}
		}
		// hotbar
		for (x in 0 until 9) {
			addSlot(Slot(playerInv, x, 66 + x * 18, 198))
		}
	}

	override fun canUse(player: PlayerEntity): Boolean {
		return true
	}

	override fun close(player: PlayerEntity) {
		super.close(player)

		terminal.removeObserver()
	}

	override fun onSlotClick(slotId: Int, clickData: Int, actionType: SlotActionType, player: PlayerEntity): ItemStack {
		if (isNetworkSlot(slotId)) {
			// the slot clicked was one of the network stacks
			if (actionType == SlotActionType.QUICK_MOVE) {
				val stack = slots[slotId].stack
				if (!stack.isEmpty && !player.world.isClient) {
					terminal.requestItem(stack, min(stack.count, stack.maxCount))
				}
			} else if (actionType == SlotActionType.PICKUP && clickData == 1) {
				if (clickData == 1) {
					// right click, request half stack
					val stack = slots[slotId].stack
					if (!stack.isEmpty && !player.world.isClient) {
						terminal.requestItem(stack, ceil(min(stack.count, stack.maxCount) / 2f).toInt())
					}
				} else {
					// todo: left click, show amount dialog
				}
			}
			return ItemStack.EMPTY
		} else if (isBufferSlot(slotId)) {
			// internal buffer
			// todo: why does this think it's quick_craft sometimes?
			if ((actionType == SlotActionType.PICKUP || actionType == SlotActionType.QUICK_CRAFT) && !player.inventory.cursorStack.isEmpty) {
				// placing cursor stack into buffer
				val bufferSlot = slotId - bufferSlotsStart // subtract 54 to convert the handler slot ID to a valid buffer index
				terminal.internalBuffer.markSlot(bufferSlot, TerminalBufferInventory.Mode.TO_NETWORK)
			}
		}
		return super.onSlotClick(slotId, clickData, actionType, player)
	}

	override fun transferSlot(player: PlayerEntity, slotId: Int): ItemStack {
		if (isNetworkSlot(slotId)) {
			return ItemStack.EMPTY;
		}

		val slot = slots[slotId]
		if (!slot.hasStack()) {
			return ItemStack.EMPTY
		}

		val result = slot.stack.copy()

		if (isBufferSlot(slotId)) {
			if (!insertItem(slot.stack, playerSlotsStart, playerSlotsEnd, false)) {
				return ItemStack.EMPTY
			}
			if (slot.stack.isEmpty) {
				terminal.internalBuffer.markSlot(slotId - bufferSlotsStart, TerminalBufferInventory.Mode.UNASSIGNED)
			}
		} else if (isPlayerSlot(slotId)) {
			val slotsInsertedInto = tryInsertItem(slot.stack, bufferSlotsStart until playerSlotsStart) { terminal.internalBuffer.getMode(it - bufferSlotsStart) != TerminalBufferInventory.Mode.FROM_NETWORK }
			slotsInsertedInto.forEach { terminal.internalBuffer.markSlot(it - bufferSlotsStart, TerminalBufferInventory.Mode.TO_NETWORK) }
			if (slot.stack.isEmpty) {
				return ItemStack.EMPTY
			}
		}

		return result
	}

	private fun tryInsertItem(stack: ItemStack, slots: IntRange, slotPredicate: (Int) -> Boolean): Collection<Int> {
		val slotsInsertedInto = mutableListOf<Int>()
		for (index in slots) {
			if (stack.isEmpty) break
			if (!slotPredicate(index)) continue

			val slot = this.slots[index]
			val slotStack = slot.stack
			if (slotStack.isEmpty) {
				slot.stack = stack.copy()
				stack.count = 0

				slot.markDirty()
				slotsInsertedInto.add(index)
			} else if (canStacksCombine(slotStack, stack) && slotStack.count < slotStack.maxCount) {
				val maxToMove = slotStack.maxCount - slotStack.count
				val toMove = min(maxToMove, stack.count)
				slotStack.increment(toMove)
				stack.decrement(toMove)

				slot.markDirty()
				slotsInsertedInto.add(index)
			}
		}
		return slotsInsertedInto
	}

	val bufferSlotsStart = 54
	val playerSlotsStart = 72
	val playerSlotsEnd = 72 + 36
	fun isNetworkSlot(id: Int) = id in 0 until bufferSlotsStart
	fun isBufferSlot(id: Int) = id in bufferSlotsStart until playerSlotsStart
	fun isPlayerSlot(id: Int) = id >= playerSlotsStart
}