local base_util = require "util"

function on_hud_open()
    events.on("core:drop_outside_inventory", function(mode)
        local pid = hud.get_player()
        local invid = hud.get_exchange_inventory()
        local vp = gui.get_viewport()
        local dir_shift = table.map(input.get_mouse_pos(), function(i, v)
            return v / vp[i] - 0.5
        end)
        base_util.drop_from_slot(pid, invid, 0, mode, dir_shift)
    end)

    events.on("core:access_panel_slot_middle_click", function(itemid)
        local exc_invid = hud.get_exchange_inventory()
        inventory.set(exc_invid, 0, itemid, item.stack_size(itemid))
    end)

    events.on("core:slot_middle_click", function(invid, slot)
        if not player.is_infinite_items(hud.get_player()) then
            return
        end
        local exc_invid = hud.get_exchange_inventory()
        local exc_itemid = inventory.get(exc_invid, 0)
        local itemid = inventory.get(invid, slot)
        if itemid == 0 and exc_itemid ~= 0 then
            local stack_size = item.stack_size(exc_itemid)
            inventory.set(invid, slot, exc_itemid, stack_size)
        elseif exc_itemid == 0 then
            local stack_size = item.stack_size(itemid)
            inventory.set(exc_invid, 0, itemid, stack_size)
        elseif exc_itemid == itemid then
            local stack_size = item.stack_size(exc_itemid)
            inventory.set(invid, slot, exc_itemid, stack_size)
        end
    end)

    input.add_callback("player.drop", function()
        if hud.is_paused() or hud.is_inventory_open() then
            return
        end
        local pid = hud.get_player()
        local invid, slot = player.get_inventory(pid)
        local mode = 1
        if input.is_pressed("key:left-ctrl") or input.is_pressed("key:right-ctrl") then
            mode = 0
        end
        base_util.drop_from_slot(pid, invid, slot, mode)
    end)
    rules.create("do-loot-non-player", true)
end