--register stoppers for movestones/pistons

mesecon.mvps_stoppers = {}
mesecon.mvps_unsticky = {}
mesecon.mvps_droppers = {}
mesecon.on_mvps_move = {}
mesecon.mvps_unmov = {}

--- Objects (entities) that cannot be moved
function mesecon.register_mvps_unmov(objectname)
	mesecon.mvps_unmov[objectname] = true;
end

function mesecon.is_mvps_unmov(objectname)
	return mesecon.mvps_unmov[objectname]
end

function mesecon.is_mvps_dropper(node, pushdir, stack, stackid)
	local get_dropper = mesecon.mvps_droppers[node.name]
	if type (get_dropper) == "function" then
		get_dropper = get_dropper(node, pushdir, stack, stackid)
	end
	if not get_dropper then
		get_dropper = minetest.get_item_group(node.name, "dig_by_piston") == 1
	end
	return get_dropper
end

function mesecon.register_mvps_dropper(nodename, get_dropper)
	if get_dropper == nil then
		get_dropper = true
	end
	mesecon.mvps_droppers[nodename] = get_dropper
end

-- Nodes that cannot be pushed / pulled by movestones, pistons
function mesecon.is_mvps_stopper(node, pushdir, stack, stackid)
	-- unknown nodes are always stoppers
	if not minetest.registered_nodes[node.name] then
		return true
	end

	local get_stopper = mesecon.mvps_stoppers[node.name]
	if type (get_stopper) == "function" then
		get_stopper = get_stopper(node, pushdir, stack, stackid)
	end

	return get_stopper
end

function mesecon.register_mvps_stopper(nodename, get_stopper)
	if get_stopper == nil then
			get_stopper = true
	end
	mesecon.mvps_stoppers[nodename] = get_stopper
end

-- For nodes which ignore sticky sides.
-- They can't be pulled by sticky pistons and don't interact with slime blocks.
-- TODO: This has NOT any actual effect so far. The actual functionality
-- still needs to be implemented.
function mesecon.register_mvps_unsticky(nodename, get_unsticky)
	if get_unsticky == nil then
		get_unsticky = true
	end
	mesecon.mvps_unsticky[nodename] = get_unsticky
end

function mesecon.is_mvps_unsticky(node, pulldir, stack, stackid)
	-- unknown nodes are always unsticky
	if not minetest.registered_nodes[node.name] then
		return true
	end

	local get_unsticky = mesecon.mvps_unsticky[node.name]
	if type(get_unsticky) == "function" then
		get_unsticky = get_unsticky(node, pulldir, stack, stackid)
	end
	if get_unsticky == nil then
		get_unsticky = false
	end

	return get_unsticky
end

-- Functions to be called on mvps movement
function mesecon.register_on_mvps_move(callback)
	mesecon.on_mvps_move[#mesecon.on_mvps_move+1] = callback
end

local function on_mvps_move(moved_nodes)
	for _, callback in ipairs(mesecon.on_mvps_move) do
		callback(moved_nodes)
	end
end

function mesecon.mvps_process_stack(stack)
	-- update mesecons for placed nodes ( has to be done after all nodes have been added )
	for _, n in ipairs(stack) do
		mesecon.on_placenode(n.pos, minetest.get_node(n.pos))
	end
end

-- tests if the node can be pushed into, e.g. air, water, grass
local function node_replaceable(name)
	if name == "ignore" then return true end

	if minetest.registered_nodes[name] then
		return minetest.registered_nodes[name].buildable_to or false
	end

	return false
end

function mesecon.mvps_get_stack(pos, dir, maximum, all_pull_sticky)
	-- determine the number of nodes to be pushed
	local nodes = {}
	local frontiers = {pos}

	while #frontiers > 0 do
		local np = frontiers[1]
		local nn = minetest.get_node(np)
		if nn.name == "ignore" then
			minetest.get_voxel_manip():read_from_map(np, np)
			nn = minetest.get_node(np)
		end
		if not node_replaceable(nn.name) then
			if #nodes >= maximum then return nil end
			table.insert(nodes, {node = nn, pos = np})

			-- add connected nodes to frontiers, connected is a vector list
			-- the vectors must be absolute positions
			local connected = {}
			if minetest.registered_nodes[nn.name]
			and minetest.registered_nodes[nn.name].mvps_sticky then
				connected = minetest.registered_nodes[nn.name].mvps_sticky(np, nn)
			end

			table.insert(connected, vector.add(np, dir))

			-- If adjacent node is sticky block and connects add that
			-- position to the connected table
			for _, r in ipairs(mesecon.rules.alldirs) do
				local adjpos = vector.add(np, r)
				local adjnode = minetest.get_node(adjpos)
				if minetest.registered_nodes[adjnode.name]
				and minetest.registered_nodes[adjnode.name].mvps_sticky then
					local sticksto = minetest.registered_nodes[adjnode.name]
						.mvps_sticky(adjpos, adjnode)

					-- connects to this position?
					for _, link in ipairs(sticksto) do
						if vector.equals(link, np) then
							table.insert(connected, adjpos)
						end
					end
				end
			end

			if all_pull_sticky then
				table.insert(connected, vector.subtract(np, dir))
			end

			-- Make sure there are no duplicates in frontiers / nodes before
			-- adding nodes in "connected" to frontiers
			for _, cp in ipairs(connected) do
				local duplicate = false
				for _, rp in ipairs(nodes) do
					if vector.equals(cp, rp.pos) then
						duplicate = true
					end
				end
				for _, fp in ipairs(frontiers) do
					if vector.equals(cp, fp) then
						duplicate = true
					end
				end
				if not duplicate then
					table.insert(frontiers, cp)
				end
			end
		end
		table.remove(frontiers, 1)
	end

	return nodes
end

function mesecon.mvps_push(pos, dir, maximum)
	return mesecon.mvps_push_or_pull(pos, dir, dir, maximum, nil, false)
end

function mesecon.mvps_pull_all(pos, dir, maximum)
	return mesecon.mvps_push_or_pull(pos, vector.multiply(dir, -1), dir, maximum, true, true)
end

function mesecon.mvps_pull_single(pos, dir, maximum)
	return mesecon.mvps_push_or_pull(pos, vector.multiply(dir, -1), dir, maximum, nil, true)
end

-- pos: pos of mvps; stackdir: direction of building the stack
-- movedir: direction of actual movement
-- maximum: maximum nodes to be pushed
-- all_pull_sticky: All nodes are sticky in the direction that they are pulled from
function mesecon.mvps_push_or_pull(pos, stackdir, movedir, maximum, all_pull_sticky)
	local nodes = mesecon.mvps_get_stack(pos, movedir, maximum, all_pull_sticky)

	if not nodes then return end
	-- determine if one of the nodes blocks the push / pull
	for id, n in ipairs(nodes) do
		if mesecon.is_mvps_stopper(n.node, movedir, nodes, id) then
			return
		end
	end

	local first_dropper = nil
	-- remove all nodes
	for id, n in ipairs(nodes) do
		n.meta = minetest.get_meta(n.pos):to_table()
		local is_dropper = mesecon.is_mvps_dropper(n.node, movedir, nodes, id)
		if is_dropper then
			local drops = minetest.get_node_drops(n.node.name, "")
			minetest.dig_node(n.pos)
		else
			minetest.remove_node(n.pos)
		end
		if is_dropper then
			first_dropper = id
			break
		end
	end

	-- update mesecons for removed nodes ( has to be done after all nodes have been removed )
	for id, n in ipairs(nodes) do
		if first_dropper and id >= first_dropper then
			break
		end
		mesecon.on_dignode(n.pos, n.node)
	end

	-- add nodes
	for id, n in ipairs(nodes) do
		if first_dropper and id >= first_dropper then
			break
		end
		local np = vector.add(n.pos, movedir)
		minetest.add_node(np, n.node)
		minetest.get_meta(np):from_table(n.meta)
	end

	local moved_nodes = {}
	local oldstack = mesecon.tablecopy(nodes)
	for i in ipairs(nodes) do
		if first_dropper and i >= first_dropper then
			break
		end
		moved_nodes[i] = {}
		moved_nodes[i].oldpos = nodes[i].pos
		nodes[i].pos = vector.add(nodes[i].pos, movedir)
		moved_nodes[i].pos = nodes[i].pos
		moved_nodes[i].node = nodes[i].node
		moved_nodes[i].meta = nodes[i].meta
	end

	on_mvps_move(moved_nodes)

	return true, nodes, oldstack
end

function mesecon.mvps_move_objects(pos, dir, nodestack)
	local objects_to_move = {}

	-- Move object at tip of stack, pushpos is position at tip of stack
	local pushpos = vector.add(pos, vector.multiply(dir, #nodestack))

	local objects = minetest.get_objects_inside_radius(pushpos, 1)
	for _, obj in ipairs(objects) do
		table.insert(objects_to_move, obj)
	end

	-- Move objects lying/standing on the stack (before it was pushed - oldstack)
	if tonumber(minetest.settings:get("movement_gravity")) > 0 and dir.y == 0 then
		-- If gravity positive and dir horizontal, push players standing on the stack
		for _, n in ipairs(nodestack) do
			local p_above = vector.add(n.pos, {x=0, y=1, z=0})
			local objects = minetest.get_objects_inside_radius(p_above, 1)
			for _, obj in ipairs(objects) do
				table.insert(objects_to_move, obj)
			end
		end
	end

	for _, obj in ipairs(objects_to_move) do
		local entity = obj:get_luaentity()
		if not entity or not mesecon.is_mvps_unmov(entity.name) then
			local np = vector.add(obj:get_pos(), dir)

			--move only if destination is not solid
			local nn = minetest.get_node(np)
			if not ((not minetest.registered_nodes[nn.name])
			or minetest.registered_nodes[nn.name].walkable) then
				obj:set_pos(np)
			end
		end
	end
end

-- Unmovable by design
mesecon.register_mvps_stopper("mcl_core:barrier")
mesecon.register_mvps_stopper("mcl_core:realm_barrier")
mesecon.register_mvps_stopper("mcl_core:void")
mesecon.register_mvps_stopper("mcl_core:bedrock")
mesecon.register_mvps_stopper("mcl_core:obsidian")
mesecon.register_mvps_stopper("mcl_chests:ender_chest")
mesecon.register_mvps_stopper("mcl_mobspawners:spawner")
mesecon.register_mvps_stopper("mesecons_commandblock:commandblock_off")
mesecon.register_mvps_stopper("mesecons_commandblock:commandblock_on")
mesecon.register_mvps_stopper("mcl_portals:portal")
mesecon.register_mvps_stopper("mcl_portals:portal_end")
mesecon.register_mvps_stopper("mcl_portals:end_portal_frame")
mesecon.register_mvps_stopper("mcl_portals:end_portal_frame_eye")

-- Unmovable by technical restrictions.
-- Open formspec would screw up if node is destroyed (minor problem)
mesecon.register_mvps_stopper("mcl_furnaces:furnace")
mesecon.register_mvps_stopper("mcl_furnaces:furnace_active")
mesecon.register_mvps_stopper("mcl_hoppers:hopper")
mesecon.register_mvps_stopper("mcl_hoppers:hopper_side")
mesecon.register_mvps_stopper("mcl_droppers:dropper")
mesecon.register_mvps_stopper("mcl_droppers:dropper_up")
mesecon.register_mvps_stopper("mcl_droppers:dropper_down")
mesecon.register_mvps_stopper("mcl_dispensers:dispenser")
mesecon.register_mvps_stopper("mcl_dispensers:dispenser_up")
mesecon.register_mvps_stopper("mcl_dispensers:dispenser_down")
mesecon.register_mvps_stopper("mcl_anvils:anvil")
mesecon.register_mvps_stopper("mcl_anvils:anvil_damage_1")
mesecon.register_mvps_stopper("mcl_anvils:anvil_damage_2")
-- Would screw up on/off state of trapped chest (big problem)

-- Glazed terracotta: unpullable
mesecon.register_mvps_unsticky("mcl_colorblocks:glazed_terracotta_red")
mesecon.register_mvps_unsticky("mcl_colorblocks:glazed_terracotta_orange")
mesecon.register_mvps_unsticky("mcl_colorblocks:glazed_terracotta_yellow")
mesecon.register_mvps_unsticky("mcl_colorblocks:glazed_terracotta_green")
mesecon.register_mvps_unsticky("mcl_colorblocks:glazed_terracotta_lime")
mesecon.register_mvps_unsticky("mcl_colorblocks:glazed_terracotta_purple")
mesecon.register_mvps_unsticky("mcl_colorblocks:glazed_terracotta_magenta")
mesecon.register_mvps_unsticky("mcl_colorblocks:glazed_terracotta_blue")
mesecon.register_mvps_unsticky("mcl_colorblocks:glazed_terracotta_cyan")
mesecon.register_mvps_unsticky("mcl_colorblocks:glazed_terracotta_white")
mesecon.register_mvps_unsticky("mcl_colorblocks:glazed_terracotta_grey")
mesecon.register_mvps_unsticky("mcl_colorblocks:glazed_terracotta_silver")
mesecon.register_mvps_unsticky("mcl_colorblocks:glazed_terracotta_black")
mesecon.register_mvps_unsticky("mcl_colorblocks:glazed_terracotta_brown")
mesecon.register_mvps_unsticky("mcl_colorblocks:glazed_terracotta_light_blue")
mesecon.register_mvps_unsticky("mcl_colorblocks:glazed_terracotta_pink")

mesecon.register_on_mvps_move(mesecon.move_hot_nodes)

-- Check for falling after moving node
mesecon.register_on_mvps_move(function(moved_nodes)
	for i = 1, #moved_nodes do
		local moved_node = moved_nodes[i]
		mesecon.on_placenode(moved_node.pos, moved_node.node)
		minetest.after(0, function()
			minetest.check_for_falling(moved_node.oldpos)
			minetest.check_for_falling(moved_node.pos)
		end)
		local node_def = minetest.registered_nodes[moved_node.node.name]
		if node_def and node_def.mesecon and node_def.mesecon.on_mvps_move then
			node_def.mesecon.on_mvps_move(moved_node.pos, moved_node.node,
					moved_node.oldpos, moved_node.meta)
		end
	end
end)