--- Server Shops Transaction Logic
--
-- @topic transaction.lua

local ss = server_shop
local S = core.get_translator(ss.modname)

local transaction = {}

function transaction.give_product(player, product)
	if not player or not product then return end
	local pinv = player:get_inventory()
	if not pinv:room_for_item("main", product) then
		core.chat_send_player(player:get_player_name(), S("WARNUNG: @1 @2 wurde auf den Boden fallen gelassen.", product:get_count(), product:get_description()))
		core.item_drop(product, player, player:get_pos())
	else
		pinv:add_item("main", product)
	end
end

function transaction.calculate_refund(total)
	local currencies = ss.get_currencies()
	local keys = {}; for k in pairs(currencies) do table.insert(keys, k) end
	table.sort(keys, function(kL, kR) return currencies[kL] > currencies[kR] end)
	local refund = {}; local remain = total
	for _, k in ipairs(keys) do
		local v = currencies[k]
		if v > 0 then
			local count = math.floor(remain / v)
			if count > 0 then
				local stack = ItemStack(k); stack:set_count(count); table.insert(refund, stack)
				remain = remain - (count * v)
			end
		end
	end
	return refund, remain
end

function transaction.calculate_currency_value(stack)
	local value = 0
	for c, v in pairs(ss.get_currencies()) do
		if stack:get_name() == c then
			return stack:get_count() * v
		end
	end
	return 0
end

function transaction.execute_purchase(pos, player, slot_index)
	local pmeta = player:get_meta()
	local player_inv = player:get_inventory()
	local shop = ss.get_shop(pos)

	if not shop then return end

	local quantity = 1

	-- KORREKTUR: Die fehlerhafte `slot_index - 1` Logik wurde entfernt.
	-- Wir verwenden `slot_index` direkt, so wie es in der funktionierenden Version war.
	local item_to_buy = shop.inv:get_stack("main", slot_index)
	local price_per_item = shop.prices[slot_index]

	if item_to_buy:is_empty() or not price_per_item or price_per_item <= 0 then
		core.chat_send_player(player:get_player_name(), S("Dieser Artikel ist nicht verfügbar."))
		return
	end

	if item_to_buy:get_count() < quantity then
		core.chat_send_player(player:get_player_name(), S("Nicht genügend Artikel auf Lager."))
		return
	end

	local purchase_stack = ItemStack(item_to_buy:get_name())
	purchase_stack:set_count(quantity)
	if not player_inv:room_for_item("main", purchase_stack) then
		core.chat_send_player(player:get_player_name(), S("Nicht genügend Platz im Inventar."))
		return
	end

	local total_cost_cents = price_per_item * quantity
	local player_name = player:get_player_name()
	local payment_method = pmeta:get_string(ss.modname..":payment_method")

	if payment_method == "bank_accounts:debit_card" or payment_method == "bank_accounts:credit_card" then
		local account_balance
		if payment_method == "bank_accounts:debit_card" then
			account_balance = bank_accounts.get_balance(player_name)
		else -- credit_card
			account_balance = bank_accounts.get_credit(player_name)
		end
		
		local total_cost_float = total_cost_cents / 100
		
		if account_balance < total_cost_float then
			core.chat_send_player(player_name, S("Dein Konto ist nicht ausreichend gedeckt."))
			return
		end

		if payment_method == "bank_accounts:debit_card" then
			bank_accounts.add_balance(player_name, -total_cost_float, "Shop-Kauf", shop.name, shop.owner)
		else -- credit_card
			bank_accounts.add_credit(player_name, -total_cost_float, "Shop-Kauf", shop.name, shop.owner)
		end

	else
		local credit = pmeta:get_int(ss.modname .. ":session_credit") or 0
		if credit < total_cost_cents then
			local needed = string.format("%.2f", (total_cost_cents - credit) / 100)
			core.chat_send_player(player_name, S("Du hast nicht genug Geld eingezahlt. (Es fehlen @1)", needed .. " " .. ss.currency_suffix))
			return
		end
		pmeta:set_int(ss.modname .. ":session_credit", credit - total_cost_cents)
	end

	local shop_meta = core.get_meta(pos)
	local current_reserve = shop_meta:get_int("cash_reserve")
	shop_meta:set_int("cash_reserve", current_reserve + total_cost_cents)

	item_to_buy:set_count(item_to_buy:get_count() - quantity)
	-- KORREKTUR: `set_stack` verwendet ebenfalls den direkten `slot_index`.
	shop.inv:set_stack("main", slot_index, item_to_buy)

	transaction.give_product(player, purchase_stack)

	local cost_str = string.format("%.2f", total_cost_cents / 100)
	core.chat_send_player(player_name, S("Du hast @1 @2 für @3 gekauft.", quantity, item_to_buy:get_description(), cost_str .. " " .. ss.currency_suffix))
	
	ss.update_infotext(pos)
end

return transaction