--[[
roll(budget, max_slots, blacklist) returns a table with item-stacks
budget		-	the total value of the item stacks combined
max_slots	-	the maximum amount of item stacks to return
blacklist		-	optional list of item names that can not be rolled. example: {["substation"] = true, ["roboport"] = true,}
]]

local Public = {}

local table_shuffle_table = table.shuffle_table
local table_insert = table.insert
local table_remove = table.remove
local math_random = math.random
local math_floor = math.floor

local item_worths = {
	["wooden-chest"] = 4,
	["iron-chest"] = 8,
	["steel-chest"] = 64,
	["storage-tank"] = 64,
	["transport-belt"] = 4,
	["fast-transport-belt"] = 16,
	["express-transport-belt"] = 64,
	["underground-belt"] = 16,
	["fast-underground-belt"] = 64,
	["express-underground-belt"] = 256,
	["splitter"] = 16,
	["fast-splitter"] = 64,
	["express-splitter"] = 256,
	["loader"] = 64,
	["fast-loader"] = 256,
	["express-loader"] = 1024,
	["burner-inserter"] = 2,
	["inserter"] = 8,
	["long-handed-inserter"] = 16,
	["fast-inserter"] = 32,
	["filter-inserter"] = 40,
	["stack-inserter"] = 128,
	["stack-filter-inserter"] = 160,
	["small-electric-pole"] = 4,
	["medium-electric-pole"] = 32,
	["big-electric-pole"] = 64,
	["substation"] = 256,
	["pipe"] = 1,
	["pipe-to-ground"] = 15,
	["pump"] = 32,
	["rail"] = 8,
	["train-stop"] = 64,
	["rail-signal"] = 16,
	["rail-chain-signal"] = 16,
	["locomotive"] = 512,
	["cargo-wagon"] = 256,
	["fluid-wagon"] = 256,
	["artillery-wagon"] = 16384,
	["car"] = 128,
	["tank"] = 4096,
	["logistic-robot"] = 256,
	["construction-robot"] = 256,
	["logistic-chest-active-provider"] = 256,
	["logistic-chest-passive-provider"] = 256,
	["logistic-chest-storage"] = 256,
	["logistic-chest-buffer"] = 512,
	["logistic-chest-requester"] = 512,
	["roboport"] = 2048,
	["small-lamp"] = 16,
	["red-wire"] = 4,
	["green-wire"] = 4,
	["arithmetic-combinator"] = 16,
	["decider-combinator"] = 16,
	["constant-combinator"] = 16,
	["power-switch"] = 16,
	["programmable-speaker"] = 32,
	["stone-brick"] = 2,
	["concrete"] = 4,
	["hazard-concrete"] = 4,
	["refined-concrete"] = 16,
	["refined-hazard-concrete"] = 16,
	["cliff-explosives"] = 256,
	["repair-pack"] = 8,
	["boiler"] = 8,
	["steam-engine"] = 32,
	["solar-panel"] = 64,
	["accumulator"] = 64,
	["nuclear-reactor"] = 8192,
	["heat-pipe"] = 128,
	["heat-exchanger"] = 256,
	["steam-turbine"] = 256,
	["burner-mining-drill"] = 8,
	["electric-mining-drill"] = 32,
	["offshore-pump"] = 16,
	["pumpjack"] = 64,
	["stone-furnace"] = 4,
	["steel-furnace"] = 64,
	["electric-furnace"] = 256,
	["assembling-machine-1"] = 32,
	["assembling-machine-2"] = 128,
	["assembling-machine-3"] = 512,
	["oil-refinery"] = 256,
	["chemical-plant"] = 128,
	["centrifuge"] = 2048,
	["lab"] = 64,
	["beacon"] = 512,
	["speed-module"] = 128,
	["speed-module-2"] = 512,
	["speed-module-3"] = 2048,
	["effectivity-module"] = 128,
	["effectivity-module-2"] = 512,
	["effectivity-module-3"] = 2048,
	["productivity-module"] = 128,
	["productivity-module-2"] = 512,
	["productivity-module-3"] = 2048,
	["wood"] = 1,
	["raw-fish"] = 16,
	["iron-plate"] = 1,
	["copper-plate"] = 1,
	["solid-fuel"] = 16,
	["steel-plate"] = 8,
	["plastic-bar"] = 8,
	["sulfur"] = 4,
	["battery"] = 16,
	["explosives"] = 4,
	["crude-oil-barrel"] = 8,
	["heavy-oil-barrel"] = 16,
	["light-oil-barrel"] = 16,
	["lubricant-barrel"] = 16,
	["petroleum-gas-barrel"] = 16,
	["sulfuric-acid-barrel"] = 16,
	["water-barrel"] = 4,
	["copper-cable"] = 1,
	["iron-stick"] = 1,
	["iron-gear-wheel"] = 2,
	["empty-barrel"] = 4,
	["electronic-circuit"] = 4,
	["advanced-circuit"] = 16,
	["processing-unit"] = 128,
	["engine-unit"] = 8,
	["electric-engine-unit"] = 64,
	["flying-robot-frame"] = 128,
	["satellite"] = 32768,
	["rocket-control-unit"] = 256,
	["low-density-structure"] = 64,
	["rocket-fuel"] = 256,
	["nuclear-fuel"] = 1024,
	["uranium-235"] = 512,
	["uranium-238"] = 32,
	["uranium-fuel-cell"] = 128,
	["used-up-uranium-fuel-cell"] = 8,
	["automation-science-pack"] = 4,
	["logistic-science-pack"] = 16,
	["military-science-pack"] = 64,
	["chemical-science-pack"] = 128,
	["production-science-pack"] = 256,
	["utility-science-pack"] = 256,
	["space-science-pack"] = 512,
	["pistol"] = 4,
	["submachine-gun"] = 32,
	["shotgun"] = 16,
	["combat-shotgun"] = 256,
	["railgun"] = 512,
	["rocket-launcher"] = 128,
	["flamethrower"] = 512,
	["land-mine"] = 8,
	["firearm-magazine"] = 4,
	["piercing-rounds-magazine"] = 8,
	["uranium-rounds-magazine"] = 64,
	["shotgun-shell"] = 4,
	["piercing-shotgun-shell"] = 16,
	["railgun-dart"] = 16,
	["cannon-shell"] = 8,
	["explosive-cannon-shell"] = 16,
	["uranium-cannon-shell"] = 64,
	["explosive-uranium-cannon-shell"] = 64,
	["artillery-shell"] = 128,
	["rocket"] = 8,
	["explosive-rocket"] = 8,
	["atomic-bomb"] = 16384,
	["flamethrower-ammo"] = 32,
	["grenade"] = 16,
	["cluster-grenade"] = 64,
	["poison-capsule"] = 64,
	["slowdown-capsule"] = 16,
	["defender-capsule"] = 16,
	["distractor-capsule"] = 128,
	["destroyer-capsule"] = 256,
	["light-armor"] = 32,
	["heavy-armor"] = 256,
	["modular-armor"] = 1024,
	["power-armor"] = 4096,
	["power-armor-mk2"] = 32768,
	["solar-panel-equipment"] = 256,
	["fusion-reactor-equipment"] = 8192,
	["energy-shield-equipment"] = 512,
	["energy-shield-mk2-equipment"] = 4096,
	["battery-equipment"] = 128,
	["battery-mk2-equipment"] = 2048,
	["personal-laser-defense-equipment"] = 2048,
	["discharge-defense-equipment"] = 2048,
	["discharge-defense-remote"] = 32,
	["belt-immunity-equipment"] = 256,
	["exoskeleton-equipment"] = 1024,
	["personal-roboport-equipment"] = 512,
	["personal-roboport-mk2-equipment"] = 4096,
	["night-vision-equipment"] = 256,
	["stone-wall"] = 8,
	["gate"] = 16,
	["gun-turret"] = 64,
	["laser-turret"] = 1024,
	["flamethrower-turret"] = 2048,
	["artillery-turret"] = 8192,
	["radar"] = 32,
	["rocket-silo"] = 65536,
}

local item_names = {}
for k, v in pairs(item_worths) do table_insert(item_names, k) end
local size_of_item_names = #item_names

local function get_raffle_keys()
	local raffle_keys = {}
	for i = 1, size_of_item_names, 1 do
		raffle_keys[i] = i
	end
	table_shuffle_table(raffle_keys)
	return raffle_keys
end

function Public.roll_item_stack(remaining_budget, blacklist)
	if remaining_budget <= 0 then return end
	local raffle_keys = get_raffle_keys()
	local item_name = false
	local item_worth = 0
	for _, index in pairs(raffle_keys) do
		item_name = item_names[index]
		item_worth = item_worths[item_name]
		if not blacklist[item_name] and item_worth <= remaining_budget then break end
	end
	
	local stack_size = game.item_prototypes[item_name].stack_size
	
	local item_count = 1
	
	for c = 1, math_random(1, stack_size), 1 do
		local price = c * item_worth
		if price <= remaining_budget then
			item_count = c
		else
			break
		end
	end

	return {name = item_name, count = item_count}
end

local function roll_item_stacks(remaining_budget, max_slots, blacklist)
	local item_stack_set = {}
	local item_stack_set_worth = 0
	
	for i = 1, max_slots, 1 do
		if remaining_budget <= 0 then break end
		local item_stack = Public.roll_item_stack(remaining_budget, blacklist)
		item_stack_set[i] = item_stack
		remaining_budget = remaining_budget - item_stack.count * item_worths[item_stack.name]
		item_stack_set_worth = item_stack_set_worth + item_stack.count * item_worths[item_stack.name]
	end
	
	return item_stack_set, item_stack_set_worth	
end

function Public.roll(budget, max_slots, blacklist)
	if not budget then return end
	if not max_slots then return end
	
	local b
	if not blacklist then
		b = {}
	else
		b = blacklist
	end
	
	budget = math_floor(budget)	
	if budget == 0 then return end
	
	local final_stack_set
	local final_stack_set_worth = 0
	
	for attempt = 1, 5, 1 do
		local item_stack_set, item_stack_set_worth = roll_item_stacks(budget, max_slots, b)
		if item_stack_set_worth > final_stack_set_worth or item_stack_set_worth == budget then
			final_stack_set = item_stack_set
			final_stack_set_worth = item_stack_set_worth
		end
	end
	--[[
	for k, item_stack in pairs(final_stack_set) do
		game.print(item_stack.count .. "x " .. item_stack.name)
	end
	game.print(final_stack_set_worth)
	]]
	return final_stack_set
end

return Public