function mcl_enchanting.is_book(itemname)
	return itemname == "mcl_books:book" or itemname == "mcl_enchanting:book_enchanted"
end

function mcl_enchanting.get_enchantments(itemstack)
	return minetest.deserialize(itemstack:get_meta():get_string("mcl_enchanting:enchantments")) or {}
end

function mcl_enchanting.set_enchantments(itemstack, enchantments)
	itemstack:get_meta():set_string("mcl_enchanting:enchantments", minetest.serialize(enchantments))
	local itemdef = itemstack:get_definition()
	if not mcl_enchanting.is_book(itemstack:get_name()) then
		if itemdef.tool_capabilities then
			itemstack:get_meta():set_tool_capabilities(itemdef.tool_capabilities)
		end
		for enchantment, level in pairs(enchantments) do
			local enchantment_def = mcl_enchanting.enchantments[enchantment]
			if enchantment_def.on_enchant then
				enchantment_def.on_enchant(itemstack, level)
			end
		end
	end
	tt.reload_itemstack_description(itemstack)
end

function mcl_enchanting.get_enchantment(itemstack, enchantment)
	return mcl_enchanting.get_enchantments(itemstack)[enchantment] or 0
end

function mcl_enchanting.has_enchantment(itemstack, enchantment)
	return mcl_enchanting.get_enchantment(itemstack, enchantment) > 0
end

function mcl_enchanting.get_enchantment_description(enchantment, level)
	local enchantment_def = mcl_enchanting.enchantments[enchantment]
	return enchantment_def.name .. (enchantment_def.max_level == 1 and "" or " " .. mcl_enchanting.roman_numerals.toRoman(level))
end

function mcl_enchanting.get_colorized_enchantment_description(enchantment, level)
	return minetest.colorize(mcl_enchanting.enchantments[enchantment].curse and "#FC5454" or "#A8A8A8", mcl_enchanting.get_enchantment_description(enchantment, level))
end

function mcl_enchanting.get_enchanted_itemstring(itemname)
	local def = minetest.registered_items[itemname]
	return def and def._mcl_enchanting_enchanted_tool
end

function mcl_enchanting.set_enchanted_itemstring(itemstack)
	itemstack:set_name(mcl_enchanting.get_enchanted_itemstring(itemstack:get_name()))
end

function mcl_enchanting.is_enchanted(itemname)
	return minetest.get_item_group(itemname, "enchanted") > 0
end

function mcl_enchanting.is_enchantable(itemname)
	return mcl_enchanting.get_enchantability(itemname) > 0
end

function mcl_enchanting.can_enchant_freshly(itemname)
	return mcl_enchanting.is_enchantable(itemname) and not mcl_enchanting.is_enchanted(itemname)
end

function mcl_enchanting.get_enchantability(itemname)
	return minetest.get_item_group(itemname, "enchantability")
end

function mcl_enchanting.item_supports_enchantment(itemname, enchantment, early)
	if not mcl_enchanting.is_enchantable(itemname) then
		return false
	end
	local enchantment_def = mcl_enchanting.enchantments[enchantment]
	if mcl_enchanting.is_book(itemname) then
		return true, (not enchantment_def.treasure)
	end
	local itemdef = minetest.registered_items[itemname]
	if itemdef.type ~= "tool" and enchantment_def.requires_tool then
		return false
	end
	for disallow in pairs(enchantment_def.disallow) do
		if minetest.get_item_group(itemname, disallow) > 0 then
			return false
		end
	end
	for group in pairs(enchantment_def.primary) do
		if minetest.get_item_group(itemname, group) > 0 then
			return true, true
		end
	end
	for group in pairs(enchantment_def.secondary) do
		if minetest.get_item_group(itemname, group) > 0 then
			return true, false
		end
	end
	return false
end

function mcl_enchanting.can_enchant(itemstack, enchantment, level)
	local enchantment_def = mcl_enchanting.enchantments[enchantment]
	if not enchantment_def then
		return false, "enchantment invalid"
	end
	local itemname = itemstack:get_name()
	if itemname == "" then
		return false, "item missing"
	end
	local supported, primary = mcl_enchanting.item_supports_enchantment(itemstack:get_name(), enchantment)
	if not supported then
		return false, "item not supported"
	end
	if not level then
		return false, "level invalid"
	end
	if level > enchantment_def.max_level then
		return false, "level too high", enchantment_def.max_level
	elseif  level < 1 then
		return false, "level too small", 1
	end
	local item_enchantments = mcl_enchanting.get_enchantments(itemstack)
	local enchantment_level = item_enchantments[enchantment]
	if enchantment_level then
		return false, "incompatible", mcl_enchanting.get_enchantment_description(enchantment, enchantment_level)
	end
	if not mcl_enchanting.is_book(itemname) then
		for incompatible in pairs(enchantment_def.incompatible) do
			local incompatible_level = item_enchantments[incompatible]
			if incompatible_level then
				return false, "incompatible", mcl_enchanting.get_enchantment_description(incompatible, incompatible_level)
			end
		end
	end
	return true, nil, nil, primary
end

function mcl_enchanting.enchant(itemstack, enchantment, level)
	mcl_enchanting.set_enchanted_itemstring(itemstack)
	local enchantments = mcl_enchanting.get_enchantments(itemstack)
	enchantments[enchantment] = level
	mcl_enchanting.set_enchantments(itemstack, enchantments)
	return itemstack
end

function mcl_enchanting.combine(itemstack, combine_with)
	local itemname = itemstack:get_name()
	local combine_name = combine_with:get_name()
	local enchanted_itemname = mcl_enchanting.get_enchanted_itemstring(itemname)
	if enchanted_itemname ~= mcl_enchanting.get_enchanted_itemstring(combine_name) and not mcl_enchanting.is_book(itemname) then
		return false
	end
	local enchantments = mcl_enchanting.get_enchantments(itemstack)
	for enchantment, combine_level in pairs(mcl_enchanting.get_enchantments(combine_with)) do
		local enchantment_def = mcl_enchanting.enchantments[enchantment]
		local enchantment_level = enchantments[enchantment]
		if enchantment_level then
			if enchantment_level == combine_level then
				enchantment_level = math.min(enchantment_level + 1, enchantment_def.max_level)
			else
				enchantment_level = math.max(enchantment_level, combine_level)
			end
		elseif mcl_enchanting.item_supports_enchantment(itemname, enchantment) then
			local supported = true
			for incompatible in pairs(enchantment_def.incompatible) do
				if enchantments[incompatible] then
					supported = false
					break
				end
			end
			if supported then
				enchantment_level = combine_level
			end
		end
		if enchantment_level and enchantment_level > 0 then
			enchantments[enchantment] = enchantment_level
		end
	end
	local any_enchantment = false
	for enchantment, enchantment_level in pairs(enchantments) do
		if enchantment_level > 0 then
			any_enchantment = true
			break
		end
	end
	if any_enchantment then
		itemstack:set_name(enchanted_itemname)
	end
	mcl_enchanting.set_enchantments(itemstack, enchantments)
	return true
end

function mcl_enchanting.enchantments_snippet(_, _, itemstack)
	if not itemstack then
		return
	end
	local enchantments = mcl_enchanting.get_enchantments(itemstack)
	local text = ""
	for enchantment, level in pairs(enchantments) do
		text = text ..  mcl_enchanting.get_colorized_enchantment_description(enchantment, level) .. "\n"
	end
	if text ~= "" then
		if not itemstack:get_definition()._tt_original_description then
			text = text:sub(1, text:len() - 1)
		end
		return text, false
	end
end

function mcl_enchanting.initialize()
	local register_tool_list = {}
	local register_item_list = {}
	for itemname, itemdef in pairs(minetest.registered_items) do
		if mcl_enchanting.can_enchant_freshly(itemname) then
			local new_name = itemname .. "_enchanted"
			minetest.override_item(itemname, {_mcl_enchanting_enchanted_tool = new_name})
			local new_def = table.copy(itemdef)
			new_def.inventory_image = itemdef.inventory_image .. mcl_enchanting.overlay
			if new_def.wield_image then
				new_def.wield_image = new_def.wield_image .. mcl_enchanting.overlay
			end
			new_def.groups.not_in_creative_inventory = 1
			new_def.groups.enchanted = 1
			new_def.texture = itemdef.texture or itemname:gsub("%:", "_")
			new_def._mcl_enchanting_enchanted_tool = new_name
			local register_list = register_item_list
			if itemdef.type == "tool" then
				register_list = register_tool_list
			end
			register_list[":" .. new_name] = new_def
		end
	end
	for new_name, new_def in pairs(register_item_list) do
		minetest.register_craftitem(new_name, new_def)
	end
	for new_name, new_def in pairs(register_tool_list) do
		minetest.register_tool(new_name, new_def)
	end
end

function mcl_enchanting.get_possible_enchantments(itemstack, enchantment_level, treasure)
	local possible_enchantments, weights, accum_weight = {}, {}, 0
	for enchantment, enchantment_def in pairs(mcl_enchanting.enchantments) do
		local supported, _, _, primary = mcl_enchanting.can_enchant(itemstack, enchantment, 1)
		if primary or treasure then
			table.insert(possible_enchantments, enchantment)
			accum_weight = accum_weight + enchantment_def.weight
			weights[enchantment] = accum_weight
		end
	end
	return possible_enchantments, weights, accum_weight
end

function mcl_enchanting.generate_random_enchantments(itemstack, enchantment_level, treasure, no_reduced_bonus_chance)
	local itemname = itemstack:get_name()
	if not mcl_enchanting.can_enchant_freshly(itemname) then
		return
	end
	itemstack = ItemStack(itemstack)
	local enchantability = minetest.get_item_group(itemname, "enchantability")
	enchantability = 1 + math.random(0, math.floor(enchantability / 4)) + math.random(0, math.floor(enchantability / 4))
	enchantment_level = enchantment_level + enchantability
	enchantment_level = enchantment_level + enchantment_level * (math.random() + math.random() - 1) * 0.15
	enchantment_level = math.max(math.floor(enchantment_level + 0.5), 1)
	local enchantments = {}
	local description
	enchantment_level = enchantment_level * 2
	repeat
		enchantment_level = math.floor(enchantment_level / 2)
		if enchantment_level == 0 then
			break
		end
		local possible, weights, accum_weight = mcl_enchanting.get_possible_enchantments(itemstack, enchantment_level, treasure)
		local selected_enchantment, enchantment_power
		if #possible > 0 then
			local r = math.random(accum_weight)
			for _, enchantment in ipairs(possible) do
				if weights[enchantment] >= r then
					selected_enchantment = enchantment
					break
				end	
			end
			local enchantment_def = mcl_enchanting.enchantments[selected_enchantment]
			local power_range_table = enchantment_def.power_range_table
			for i = enchantment_def.max_level, 1, -1 do
				local power_range = power_range_table[i]
				if enchantment_level >= power_range[1] and enchantment_level <= power_range[2] then
					enchantment_power = i
					break
				end
			end
			if not description then
				if not enchantment_power then
					return
				end
				description = mcl_enchanting.get_enchantment_description(selected_enchantment, enchantment_power)
			end
			if enchantment_power then
				enchantments[selected_enchantment] = enchantment_power
				mcl_enchanting.enchant(itemstack, selected_enchantment, enchantment_power)
			end
		else
			break
		end
	until not no_reduced_bonus_chance and math.random() >= (enchantment_level + 1) / 50
	return enchantments, description
end

function mcl_enchanting.enchant_randomly(itemstack, enchantment_level, treasure, no_reduced_bonus_chance)
	local enchantments = mcl_enchanting.generate_random_enchantments(itemstack, enchantment_level, treasure, no_reduced_bonus_chance)
	if enchantments then
		mcl_enchanting.set_enchanted_itemstring(itemstack)
		mcl_enchanting.set_enchantments(itemstack, enchantments)
	end
	return itemstack
end

function mcl_enchanting.get_randomly_enchanted_book(enchantment_level, treasure, no_reduced_bonus_chance)
	return mcl_enchanting.enchant_randomly(enchantment_level, treasure, no_reduced_bonus_chance)
end

function mcl_enchanting.get_random_glyph_row()
	local glyphs = ""
	local x = 1.3
	for i = 1, 9 do			
		glyphs = glyphs .. "image[".. x .. ",0.1;0.5,0.5;mcl_enchanting_glyph_" .. math.random(18) .. ".png^[colorize:#675D49:255]"
		x = x + 0.6
	end
	return glyphs
end

function mcl_enchanting.generate_random_table_slots(itemstack, num_bookshelves)
	local base = math.random(8) + math.floor(num_bookshelves / 2) + math.random(0, num_bookshelves)
	local required_levels = {
		math.max(base / 3, 1),
		(base * 2) / 3 + 1,
		math.max(base, num_bookshelves * 2)
	}
	local slots = {}
	for i, enchantment_level in ipairs(required_levels) do
		local slot = false
		local enchantments, description = mcl_enchanting.generate_random_enchantments(itemstack, enchantment_level)
		if enchantments then
			slot = {
				enchantments = enchantments,
				description = description,
				glyphs = mcl_enchanting.get_random_glyph_row(),
				level_requirement = math.max(i, math.floor(enchantment_level)),
			}
		end
		slots[i] = slot
	end
	return slots
end

function mcl_enchanting.get_table_slots(player, itemstack, num_bookshelves)
	if not mcl_enchanting.can_enchant_freshly(itemstack:get_name()) then
		return {false, false, false}
	end
	local itemname = itemstack:get_name()
	local meta = player:get_meta()
	local player_slots = minetest.deserialize(meta:get_string("mcl_enchanting:slots")) or {}
	local player_bookshelves_slots = player_slots[num_bookshelves] or {}
	local player_bookshelves_item_slots = player_bookshelves_slots[itemname]
	if player_bookshelves_item_slots then
		return player_bookshelves_item_slots
	else
		player_bookshelves_item_slots = mcl_enchanting.generate_random_table_slots(itemstack, num_bookshelves)
		if player_bookshelves_item_slots then
			player_bookshelves_slots[itemname] = player_bookshelves_item_slots
			player_slots[num_bookshelves] = player_bookshelves_slots
			meta:set_string("mcl_enchanting:slots", minetest.serialize(player_slots))
			return player_bookshelves_item_slots
		else
			return {false, false, false}
		end
	end
end

function mcl_enchanting.reset_table_slots(player)
	player:get_meta():set_string("mcl_enchanting:slots", "")
end

function mcl_enchanting.show_enchanting_formspec(player)
	local C = minetest.get_color_escape_sequence
	local name = player:get_player_name()
	local meta = player:get_meta()
	local inv = player:get_inventory()
	local num_bookshelves = meta:get_int("mcl_enchanting:num_bookshelves")
	local table_name = meta:get_string("mcl_enchanting:table_name")
	local formspec = ""
		.. "size[9.07,8.6;]"
		.. "formspec_version[3]"
		.. "label[0,0;" .. C("#313131") .. table_name .. "]"
		.. mcl_formspec.get_itemslot_bg(0.2, 2.4, 1, 1)
		.. "list[detached:" .. name .. "_enchanting;enchanting;0.2,2.4;1,1;1]"
		.. mcl_formspec.get_itemslot_bg(1.1, 2.4, 1, 1)
		.. "image[1.1,2.4;1,1;mcl_enchanting_lapis_background.png]"
		.. "list[detached:" .. name .. "_enchanting;enchanting;1.1,2.4;1,1;2]"
		.. "label[0,4;" .. C("#313131") .. "Inventory]"
		.. mcl_formspec.get_itemslot_bg(0, 4.5, 9, 3)
		.. mcl_formspec.get_itemslot_bg(0, 7.74, 9, 1)
		.. "list[current_player;main;0,4.5;9,3;9]"
		.. "listring[detached:" .. name .. "_enchanting;enchanting]"
		.. "listring[current_player;main]"
		.. "list[current_player;main;0,7.74;9,1;]"
		.. "real_coordinates[true]"
		.. "image[3.15,0.6;7.6,4.1;mcl_enchanting_button_background.png]"
	local itemstack = inv:get_stack("enchanting_item", 1)
	local player_levels = mcl_experience.get_player_xp_level(player)
	local y = 0.65
	local any_enchantment = false
	local table_slots = mcl_enchanting.get_table_slots(player, itemstack, num_bookshelves)
	for i, slot in ipairs(table_slots) do
		any_enchantment = any_enchantment or slot
		local enough_lapis = inv:contains_item("enchanting_lapis", ItemStack({name = "mcl_dye:blue", count = i}))
		local enough_levels = slot and slot.level_requirement <= player_levels
		local can_enchant = (slot and enough_lapis and enough_levels)
		local ending = (can_enchant and "" or "_off")
		local hover_ending = (can_enchant and "_hovered" or "_off")
		formspec = formspec
			.. "container[3.2," .. y .. "]"
			.. (slot and "tooltip[button_" .. i .. ";" .. C("#818181") .. slot.description .. " " .. C("#FFFFFF") .. " . . . ?\n\n" .. (enough_levels and C(enough_lapis and "#818181" or "#FC5454") .. i .. " Lapis Lazuli\n" .. C("#818181") .. i .. " Enchantment Levels" or C("#FC5454") .. "Level Requirement: " .. slot.level_requirement) .. "]" or "")
			.. "style[button_" .. i .. ";bgimg=mcl_enchanting_button" .. ending .. ".png;bgimg_hovered=mcl_enchanting_button" .. hover_ending .. ".png;bgimg_pressed=mcl_enchanting_button" .. hover_ending .. ".png]"
			.. "button[0,0;7.5,1.3;button_" .. i .. ";]"
			.. (slot and "image[0,0;1.3,1.3;mcl_enchanting_number_" .. i .. ending .. ".png]" or "")
			.. (slot and "label[7.2,1.1;" .. C(can_enchant and "#80FF20" or "#407F10") .. slot.level_requirement .. "]" or "")
			.. (slot and slot.glyphs or "")
			.. "container_end[]"
		y = y + 1.35
	end
	formspec = formspec
		.. "image[" .. (any_enchantment and 0.58 or 1.15) .. ",1.2;" .. (any_enchantment and 2 or 0.87) .. ",1.43;mcl_enchanting_book_" .. (any_enchantment and "open" or "closed") .. ".png]"
	minetest.show_formspec(name, "mcl_enchanting:table", formspec)
end

function mcl_enchanting.handle_formspec_fields(player, formname, fields)
	if formname == "mcl_enchanting:table" then
		local button_pressed
		for i = 1, 3 do
			if fields["button_" .. i] then
				button_pressed = i
			end
		end
		if not button_pressed then return end
		local name = player:get_player_name()
		local inv = player:get_inventory()
		local meta = player:get_meta()
		local num_bookshelfes = meta:get_int("mcl_enchanting:num_bookshelves")
		local itemstack = inv:get_stack("enchanting_item", 1)
		local cost = ItemStack({name = "mcl_dye:blue", count = button_pressed})
		if not inv:contains_item("enchanting_lapis", cost) then
			return
		end
		local slots = mcl_enchanting.get_table_slots(player, itemstack, num_bookshelfes)
		local slot = slots[button_pressed]
		if not slot then
			return
		end
		local player_level = mcl_experience.get_player_xp_level(player)
		if player_level < slot.level_requirement then
			return
		end
		mcl_experience.set_player_xp_level(player, player_level - button_pressed)
		inv:remove_item("enchanting_lapis", cost)
		mcl_enchanting.set_enchanted_itemstring(itemstack)
		mcl_enchanting.set_enchantments(itemstack, slot.enchantments)
		inv:set_stack("enchanting_item", 1, itemstack)
		minetest.sound_play("mcl_enchanting_enchant", {to_player = name, gain = 5.0})
		mcl_enchanting.reset_table_slots(player)
		mcl_enchanting.reload_inventory(player)
		mcl_enchanting.show_enchanting_formspec(player)
	end
end

function mcl_enchanting.initialize_player(player)
	local player_inv = player:get_inventory()
	player_inv:set_size("enchanting_lapis", 1)
	player_inv:set_size("enchanting_item", 1)
	local name = player:get_player_name()
	local detached_inv = minetest.create_detached_inventory(name .. "_enchanting", {
		allow_put = function(inv, listname, index, stack, player)
			if player:get_player_name() ~= name then
				return 0
			end
			if stack:get_name() == "mcl_dye:blue" and index ~= 2 then
				return math.min(inv:get_stack(listname, 3):get_free_space(), stack:get_count())
			elseif index ~= 3 and inv:get_stack(listname, 2):get_count() == 0 then
				return 1
			else
				return 0
			end
		end,
		allow_take = function(inv, listname, index, stack, player)
			if player:get_player_name() ~= name or index == 1 then
				return 0
			end
			return stack:get_count()
		end,
		allow_move = function(inv, from_list, from_index, to_list, to_index, count, player)
			return 0
		end,
		on_put = function(inv, listname, index, stack, player)
			local result_list
			if index == 1 then
				if stack:get_name() == "mcl_dye:blue" then
					result_list = "lapis"
					stack:add_item(inv:get_stack(listname, 3))
					inv:set_stack(listname, 1, nil)
					inv:set_stack(listname, 3, stack)
				else
					result_list = "item"
					inv:set_stack(listname, 1, nil)
					inv:set_stack(listname, 2, stack)
				end
			elseif index == 2 then
				result_list = "item"
			elseif index == 3 then
				result_list = "lapis"
				stack = inv:get_stack(listname, 3)
			end
			player:get_inventory():set_stack("enchanting_" .. result_list, 1, stack)
			mcl_enchanting.show_enchanting_formspec(player)
		end,
		on_take = function(inv, listname, index, stack, player)
			local result_list
			if index == 2 then
				result_list = "item"
			elseif index == 3 then
				result_list = "lapis"
			end
			player:get_inventory():set_stack("enchanting_" .. result_list, 1, nil)
			mcl_enchanting.show_enchanting_formspec(player)
		end
	}, name)
	detached_inv:set_size("enchanting", 3)
	mcl_enchanting.reload_inventory(player)
end

function mcl_enchanting.reload_inventory(player)
	local player_inv = player:get_inventory()
	local detached_inv = minetest.get_inventory({type = "detached", name = player:get_player_name() .. "_enchanting"})
	detached_inv:set_stack("enchanting", 2, player_inv:get_stack("enchanting_item", 1))
	detached_inv:set_stack("enchanting", 3, player_inv:get_stack("enchanting_lapis", 1))
end

function mcl_enchanting.schedule_book_animation(self, anim)
	self.scheduled_anim = {timer = self.anim_length, anim = anim}
end

function mcl_enchanting.set_book_animation(self, anim)
	local anim_index = mcl_enchanting.book_animations[anim]
	local start, stop = mcl_enchanting.book_animation_steps[anim_index], mcl_enchanting.book_animation_steps[anim_index + 1]
	self.object:set_animation({x = start, y = stop}, mcl_enchanting.book_animation_speed)
	self.scheduled_anim = nil
	self.anim_length = (stop - start) / 40
end

function mcl_enchanting.check_animation_schedule(self, dtime)
	local schedanim = self.scheduled_anim
	if schedanim then
		schedanim.timer = schedanim.timer - dtime
		if schedanim.timer <= 0 then
			 mcl_enchanting.set_book_animation(self, schedanim.anim)
		end
	end
end

function mcl_enchanting.look_at(self, pos2)
	local pos1 = self.object:get_pos()
	local vec = vector.subtract(pos1, pos2)
	local yaw = math.atan(vec.z / vec.x) - math.pi/2
	yaw = yaw + (pos1.x >= pos2.x and math.pi or 0)
	self.object:set_yaw(yaw + math.pi)
end

function mcl_enchanting.check_book(pos)
	local obj_pos = vector.add(pos, mcl_enchanting.book_offset)
	for _, obj in pairs(minetest.get_objects_inside_radius(obj_pos, 0.1)) do
		local luaentity = obj:get_luaentity()
		if luaentity and luaentity.name == "mcl_enchanting:book" then
			if minetest.get_node(pos).name ~= "mcl_enchanting:table" then
				obj:remove()
			end
			return
		end
	end
	minetest.add_entity(obj_pos, "mcl_enchanting:book")
end

function mcl_enchanting.get_bookshelves(pos)
	local absolute, relative = {}, {}
	for i, rp in ipairs(mcl_enchanting.bookshelf_positions) do
		local airp = vector.add(pos, mcl_enchanting.air_positions[i])
		local ap = vector.add(pos, rp)
		if minetest.get_node(ap).name == "mcl_books:bookshelf" and minetest.get_node(airp).name == "air" then
			table.insert(absolute, ap)
			table.insert(relative, rp)
		end
	end
	return absolute, relative
end