-- luacheck: globals whosit, std luanti+luajit
whosit = _G.whosit or {}
_G.whosit = whosit

-- provide table.pack if luajit is built without LUA52COMPAT
local pack = table.pack or function(...) return {n = select("#", ...), ...} end
local unpack = unpack or table.unpack

-- use efficient deque or implement our own FIFO type of thing
local formspec_log = futil and futil.Deque and futil.Deque()
if not formspec_log then
    -- no deque implementation found
    local deq = {}
    deq.size = function(self)
        return #self
    end
    deq.push_front = function(self, v)
        table.insert(self, v)
    end
    deq.pop_back = function(self)
        local v = self[1]
        table.remove(self, 1)
        return v
    end
    deq.iterate = function(self)
        local i = 0
        return function()
            i = i + 1
            local v = self[i]
            if v then
                return v
            end
        end
    end
    deq.__index = deq
    formspec_log = setmetatable({}, deq)
end

local LOG_SIZE = 30

-- use deque for logging, pushing oldest log item out
local function log_add(msg)
    core.log('error', type(msg) == "string" and msg or dump(msg))
    formspec_log:push_front(msg)
    if formspec_log:size() > LOG_SIZE then
        formspec_log:pop_back()
    end
end


local function formspec_log_clear()
    formspec_log:clear()
end


-- passes to xpcall to be able to capture the call stack
local function error_printer(err)
    log_add(err)
    log_add(debug.traceback("----------------------", 2))
    return "error was logged"
end


-- Takes any function and returns a function that takes and returns
-- same [multiple] values if no error happens. On error, logs it.
local function safe_wrap(func)
    local function wrap_f(...)
        local res = pack(xpcall(func, error_printer, ...))
        if res[1] then
            -- no error, just return rest of the values
            return select(2, unpack(res))
        else
            -- error was logged by error_printer already
            local msg = dump(res[2])
            if msg then
                log_add(msg)
            end
            return nil
        end
    end
    return wrap_f
end


local function formspec_log_show(playername)
    local log_items = {}
    for item in formspec_log:iterate() do
        table.insert(log_items, type(item) == "string" and item or dump(item))
    end
    local formspec_template = [[ formspec_version[6] size[16,9] textarea[0.1,0.4;15.8,8.5;log;log;%s] ]]
    local log_text = core.formspec_escape(table.concat(log_items,'\n'))
    core.show_formspec(playername, "yl_commons:formspec_log", string.format(formspec_template, log_text))
end


-- These commands will allow us to see the errors saved in
-- the `formspec_log` after they happen.
core.register_chatcommand(
    "whosit_log_show",
    {
        privs = { server = true },
        func = function(playername, _params)
            formspec_log_show(playername)
            return true
        end,
    }
)

core.register_chatcommand(
    "whosit_log_clear",
    {
        privs = { server = true },
        func = function(playername, _params)
            formspec_log_clear(playername)
            return true
        end,
    }
)


whosit.original_callbacks = {}
local original_callbacks = whosit.original_callbacks

function whosit.safe_override_on_use(item_name, func)
    local def = core.registered_items[item_name]
    if not (original_callbacks[item_name] or {}).on_use then
        local orig = original_callbacks[item_name] or {}
        original_callbacks[item_name] = orig
        orig.on_use = def.on_use
    end

    def.on_use = function(itemstack, user, pointed_thing)
        local status, res = safe_wrap(func)(itemstack, user, pointed_thing)
        if status then
            return res
        else
            return nil
        end
    end
end