--[[
Copyright (c) 2015, Robert 'Bobby' Zenz
All rights reserved.

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modification, are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright notice, this
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* Redistributions in binary form must reproduce the above copyright notice,
  this list of conditions and the following disclaimer in the documentation
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
--]]


--- A util for working with inventories.
inventoryutil = {}


--- Gets the difference between the given inventory and the hash. The difference
-- is returned in the same format as the hash, with the count being
-- the amount of difference.
--
-- @param inventory The InvRef object.
-- @param name The inventory name.
-- @param hash The hash to compare against.
-- @return The difference between the inventory and the hash.
function inventoryutil.difference_hash(inventory, name, hash)
	local difference = {}
	
	for index = 1, inventory:get_size(name), 1 do
		local stack = inventory:get_stack(name, index)
		local item_hash = hash[index]
		
		local item_difference = {
			id = 0,
			count = 0
		}
		
		if item_hash.id >= 0 then
			item_difference.id = item_hash.id
			
			if not stack:is_empty() then
				if item_hash.id == minetest.get_content_id(stack:get_name()) then
					item_difference.count = stack:get_count() - item_hash.count
				else
					item_difference.count = -item_hash.count
				end
			else
				item_difference.count = -item_hash.count
			end
		end
		
		difference[index] = item_difference
	end
	
	return difference
end

--- Test if the given inventory equals the given hash.
--
-- @param inventory The InvRef object.
-- @param name The name of the inventory.
-- @param hash The hash.
-- @return true If the inventory equals the hash.
function inventoryutil.equals_hash(inventory, name, hash)
	if hash == nil then
		return false
	end
	
	for index = 1, inventory:get_size(name), 1 do
		local stack = inventory:get_stack(name, index)
		local item_hash = hash[index]
		
		if not stack:is_empty()  then
			if item_hash.id ~= minetest.get_content_id(stack:get_name()) or item_hash.count ~= stack:get_count() then
				return false
			end
		else
			if item_hash.id >= 0 or item_hash.count ~= 0 then
				return false
			end
		end
	end
	
	return true
end

--- Creates a hash for the given inventory.
-- The hash is a 2D table containing the ID and the stack count of all items.
--
-- @param inventory The InvRef object.
-- @param name The name of the inventory.
-- @return The hash.
function inventoryutil.hash(inventory, name)
	local hash = {}
	
	for index = 1, inventory:get_size(name), 1 do
		local stack = inventory:get_stack(name, index)
		
		if not stack:is_empty()  then
			hash[index] = {
				id = minetest.get_content_id(stack:get_name()),
				count = stack:get_count()
			}
		else
			hash[index] = {
				id = -1,
				count = 0
			}
		end
	end
	
	return hash
end