mcl_util = {}

-- Based on minetest.rotate_and_place

--[[
Attempt to predict the desired orientation of the pillar-like node
defined by `itemstack`, and place it accordingly in one of 3 possible
orientations (X, Y or Z).

Stacks are handled normally if the `infinitestacks`
field is false or omitted (else, the itemstack is not changed).
* `invert_wall`: if `true`, place wall-orientation on the ground and ground-
  orientation on wall

This function is a simplified version of minetest.rotate_and_place.
The Minetest function is seen as inappropriate because this includes mirror
images of possible orientations, causing problems with pillar shadings.
]]
function mcl_util.rotate_axis_and_place(itemstack, placer, pointed_thing, infinitestacks, invert_wall)
	local unode = minetest.get_node_or_nil(pointed_thing.under)
	if not unode then
		return
	end
	local undef = minetest.registered_nodes[unode.name]
	if undef and undef.on_rightclick then
		undef.on_rightclick(pointed_thing.under, unode, placer,
				itemstack, pointed_thing)
		return
	end
	local fdir = minetest.dir_to_facedir(placer:get_look_dir())
	local wield_name = itemstack:get_name()

	local above = pointed_thing.above
	local under = pointed_thing.under
	local is_x = (above.x ~= under.x)
	local is_y = (above.y ~= under.y)
	local is_z = (above.z ~= under.z)

	local anode = minetest.get_node_or_nil(above)
	if not anode then
		return
	end
	local pos = pointed_thing.above
	local node = anode

	if undef and undef.buildable_to then
		pos = pointed_thing.under
		node = unode
	end

	if minetest.is_protected(pos, placer:get_player_name()) then
		minetest.record_protection_violation(pos, placer:get_player_name())
		return
	end

	local ndef = minetest.registered_nodes[node.name]
	if not ndef or not ndef.buildable_to then
		return
	end

	local p2
	if is_y then
		if invert_wall then
			if fdir == 3 or fdir == 1 then
				p2 = 12
			else
				p2 = 6
			end
		end
	elseif is_x then
		if invert_wall then
			p2 = 0
		else
			p2 = 12
		end
	elseif is_z then
		if invert_wall then
			p2 = 0
		else
			p2 = 6
		end
	end
	minetest.set_node(pos, {name = wield_name, param2 = p2})

	if not infinitestacks then
		itemstack:take_item()
		return itemstack
	end
end

-- Wrapper of above function for use as `on_place` callback (Recommended).
-- Similar to minetest.rotate_node.
function mcl_util.rotate_axis(itemstack, placer, pointed_thing)
	mcl_util.rotate_axis_and_place(itemstack, placer, pointed_thing,
		core.setting_getbool("creative_mode"),
		placer:get_player_control().sneak)
	return itemstack
end

-- Returns position of the neighbor of a double chest node
-- or nil if node is invalid.
-- This function assumes that the large chest is actually intact
-- * pos: Position of the node to investigate
-- * param2: param2 of that node
-- * side: Which "half" the investigated node is. "left" or "right"
function mcl_util.get_double_container_neighbor_pos(pos, param2, side)
	if side == "right" then
		if param2 == 0 then
			return {x=pos.x-1, y=pos.y, z=pos.z}
		elseif param2 == 1 then
			return {x=pos.x, y=pos.y, z=pos.z+1}
		elseif param2 == 2 then
			return {x=pos.x+1, y=pos.y, z=pos.z}
		elseif param2 == 3 then
			return {x=pos.x, y=pos.y, z=pos.z-1}
		end
	else
		if param2 == 0 then
			return {x=pos.x+1, y=pos.y, z=pos.z}
		elseif param2 == 1 then
			return {x=pos.x, y=pos.y, z=pos.z-1}
		elseif param2 == 2 then
			return {x=pos.x-1, y=pos.y, z=pos.z}
		elseif param2 == 3 then
			return {x=pos.x, y=pos.y, z=pos.z+1}
		end
	end
end

-- Iterates through all items in the given inventory and
-- returns the slot of the first item which matches a condition.
-- Returns nil if no item was found.
--- source_inventory: Inventory to take the item from
--- source_list: List name of the source inventory from which to take the item
--- destination_inventory: Put item into this inventory
--- destination_list: List name of the destination inventory to which to put the item into
--- condition: Function which takes an itemstack and returns true if it matches the desired item condition.
---            If set to nil, the slot of the first item stack will be taken unconditionally.
-- dst_inventory and dst_list can also be nil if condition is nil.
function mcl_util.get_eligible_transfer_item_slot(src_inventory, src_list, dst_inventory, dst_list, condition)
	local size = src_inventory:get_size(src_list)
	local stack
	for i=1, size do
		stack = src_inventory:get_stack(src_list, i)
		if not stack:is_empty() and (condition == nil or condition(stack, src_inventory, src_list, dst_inventory, dst_list)) then
			return i
		end
	end
	return nil
end

-- Returns true if given itemstack is a shulker box
local is_not_shulker_box = function(itemstack)
	local g = minetest.get_item_group(itemstack:get_name(), "shulker_box")
	return g == 0 or g == nil
end

-- Moves a single item from one inventory to another.
--- source_inventory: Inventory to take the item from
--- source_list: List name of the source inventory from which to take the item
--- source_stack_id: The inventory position ID of the source inventory to take the item from (-1 for first occupied slot)
--- destination_inventory: Put item into this inventory
--- destination_list: List name of the destination inventory to which to put the item into

-- Returns true on success and false on failure
-- Possible failures: No item in source slot, destination inventory full
function mcl_util.move_item(source_inventory, source_list, source_stack_id, destination_inventory, destination_list)
	if source_stack_id == -1 then
		source_stack_id = mcl_util.get_first_occupied_inventory_slot(source_inventory, source_list)
		if source_stack_id == nil then
			return false
		end
	end

	if not source_inventory:is_empty(source_list) then
		local stack = source_inventory:get_stack(source_list, source_stack_id)
		local item = stack:get_name()
		if not stack:is_empty() then
			if not destination_inventory:room_for_item(destination_list, item) then
				return false
			end
			stack:take_item()
			source_inventory:set_stack(source_list, source_stack_id, stack)
			destination_inventory:add_item(destination_list, item)
			return true
		end
	end
	return false
end

-- Moves a single item from one container node into another. Performs a variety of high-level
-- checks to prevent invalid transfers such as shulker boxes into shulker boxes
--- source_pos: Position ({x,y,z}) of the node to take the item from
--- destination_pos: Position ({x,y,z}) of the node to put the item into
--- source_list (optional): List name of the source inventory from which to take the item. Default is normally "main"; "dst" for furnace
--- source_stack_id (optional): The inventory position ID of the source inventory to take the item from (-1 for slot of the first valid item; -1 is default)
--- destination_list (optional): List name of the destination inventory. Default is normally "main"; "src" for furnace
-- Returns true on success and false on failure.
function mcl_util.move_item_container(source_pos, destination_pos, source_list, source_stack_id, destination_list)
	local dpos = table.copy(destination_pos)
	local spos = table.copy(source_pos)
	local snode = minetest.get_node(spos)
	local dnode = minetest.get_node(dpos)

	local dctype = minetest.get_item_group(dnode.name, "container")
	local sctype = minetest.get_item_group(snode.name, "container")

	-- Normalize double container by forcing to always use the left segment first
	local normalize_double_container = function(pos, node, ctype)
		if ctype == 6 then
			pos = mcl_util.get_double_container_neighbor_pos(pos, node.param2, "right")
			if not pos then
				return false
			end
			node = minetest.get_node(pos)
			ctype = minetest.get_item_group(node.name, "container")
			-- The left segment seems incorrect? We better bail out!
			if ctype ~= 5 then
				return false
			end
		end
		return pos, node, ctype
	end

	spos, snode, sctype = normalize_double_container(spos, snode, sctype)
	dpos, dnode, dctype = normalize_double_container(dpos, dnode, dctype)
	if not spos or not dpos then return false end

	local smeta = minetest.get_meta(spos)
	local dmeta = minetest.get_meta(dpos)

	local sinv = smeta:get_inventory()
	local dinv = dmeta:get_inventory()

	-- Default source lists
	if not source_list then
		-- Main inventory for most container types
		if sctype == 2 or sctype == 3 or sctype == 5 or sctype == 6 then
			source_list = "main"
		-- Furnace: output
		elseif sctype == 4 then
			source_list = "dst"
		-- Unknown source container type. Bail out
		else
			return false
		end
	end

	-- Automatically select stack slot ID if set to automatic
	if not source_stack_id then
		source_stack_id = -1
	end
	if source_stack_id == -1 then
		local cond = nil
		-- Prevent shulker box inception
		if dctype == 3 then
			cond = is_not_shulker_box
		end
		source_stack_id = mcl_util.get_eligible_transfer_item_slot(sinv, source_list, dinv, dpos, cond)
		if not source_stack_id then
			-- Try again if source is a double container
			if sctype == 5 then
				spos = mcl_util.get_double_container_neighbor_pos(spos, snode.param2, "left")
				smeta = minetest.get_meta(spos)
				sinv = smeta:get_inventory()

				source_stack_id = mcl_util.get_eligible_transfer_item_slot(sinv, source_list, dinv, dpos, cond)
				if not source_stack_id then
					return false
				end
			else
				return false
			end
		end
	end

	-- Abort transfer if shulker box wants to go into shulker box
	if dctype == 3 then
		local stack = sinv:get_stack(source_list, source_stack_id)
		if stack and minetest.get_item_group(stack:get_name(), "shulker_box") == 1 then
			return false
		end
	end

	-- If it's a container, put it into the container
	if dctype ~= 0 then
		-- Automatically select a destination list if omitted
		if not destination_list then
			-- Main inventory for most container types
			if dctype == 2 or dctype == 3 or dctype == 5 or dctype == 6 then
				destination_list = "main"
			-- Furnace source slot
			elseif dctype == 4 then
				destination_list = "src"
			end
		end
		if destination_list then
			-- Move item
			local ok = mcl_util.move_item(sinv, source_list, source_stack_id, dinv, destination_list)

			-- Try transfer to neighbor node if transfer failed and double container
			if not ok and dctype == 5 then
				dpos = mcl_util.get_double_container_neighbor_pos(dpos, dnode.param2, "left")
				dmeta = minetest.get_meta(dpos)
				dinv = dmeta:get_inventory()

				ok = mcl_util.move_item(sinv, source_list, source_stack_id, dinv, destination_list)
			end

			-- Update furnace
			if ok and dctype == 4 then
				-- Start furnace's timer function, it will sort out whether furnace can burn or not.
				minetest.get_node_timer(dpos):start(1.0)
			end

			return ok
		end
	end
	return false
end

-- Returns the ID of the first non-empty slot in the given inventory list
-- or nil, if inventory is empty.
function mcl_util.get_first_occupied_inventory_slot(inventory, listname)
	return mcl_util.get_eligible_transfer_item_slot(inventory, listname)
end

-- Returns true if item (itemstring or ItemStack) can be used as a furnace fuel.
-- Returns false otherwise
function mcl_util.is_fuel(item)
	return minetest.get_craft_result({method="fuel", width=1, items={item}}).time ~= 0
end

-- For a given position, returns a 2-tuple:
-- 1st return value: true if pos is in void
-- 2nd return value: true if it is in the deadly part of the void
function mcl_util.is_in_void(pos)
	local void, void_deadly
	void = pos.y < mcl_vars.mg_overworld_min
	void_deadly = pos.y < mcl_vars.mg_overworld_min - 64
	return void, void_deadly
end

-- Here come 2 simple converter functions which are important for map generators and mob spawning

-- Takes an Y coordinate as input and returns:
-- 1) The corresponding Minecraft layer (can be nil if void)
-- 2) The corresponding Minecraft dimension ("overworld", "nether" or "end") or "void" if it is in the void
-- If the Y coordinate is not located in any dimension, it will return:
--     nil, "void"
function mcl_util.y_to_layer(y)
	if y >= mcl_vars.mg_overworld_min then
		return y - mcl_vars.mg_overworld_min, "overworld"
	else
		return nil, "void"
	end
end

-- Takes a Minecraft layer and a “dimension” name
-- and returns the corresponding Y coordinate for
-- MineClone 2.
-- minecraft_dimension parameter is ignored at the moment
-- TODO: Implement dimensions
function mcl_util.layer_to_y(layer, minecraft_dimension)
	return layer + mcl_vars.mg_overworld_min
end

-- Returns a on_place function for plants
-- * condition: function(pos, node)
--    * A function which is called by the on_place function to check if the node can be placed
--    * Must return true, if placement is allowed, false otherwise
--    * pos, node: Position and node table of plant node
function mcl_util.generate_on_place_plant_function(condition)
	return function(itemstack, placer, pointed_thing)
		if pointed_thing.type ~= "node" then
			-- no interaction possible with entities
			return itemstack
		end

		-- Call on_rightclick if the pointed node defines it
		local node = minetest.get_node(pointed_thing.under)
		if placer and not placer:get_player_control().sneak then
			if minetest.registered_nodes[node.name] and minetest.registered_nodes[node.name].on_rightclick then
				return minetest.registered_nodes[node.name].on_rightclick(pointed_thing.under, node, placer, itemstack) or itemstack
			end
		end

		local place_pos
		local def_under = minetest.registered_nodes[minetest.get_node(pointed_thing.under).name]
		local def_above = minetest.registered_nodes[minetest.get_node(pointed_thing.above).name]
		if not def_under or not def_above then
			return itemstack
		end
		if def_under.buildable_to then
			place_pos = pointed_thing.under
		elseif def_above.buildable_to then
			place_pos = pointed_thing.above
		else
			return itemstack
		end

		-- Check placement rules
		if (condition(place_pos, node) == true) then
			local idef = itemstack:get_definition()
			local new_itemstack, success = minetest.item_place_node(itemstack, placer, pointed_thing)

			if success then
				if idef.sounds and idef.sounds.place then
					minetest.sound_play(idef.sounds.place, {pos=pointed_thing.above, gain=1})
				end
			end
			itemstack = new_itemstack
		end

		return itemstack
	end
end