local _, ns = ...
local oUF = ns.oUF
local Private = oUF.Private

local argcheck = Private.argcheck
local frame_metatable = Private.frame_metatable

local CombatLogGetCurrentEventInfo = _G.CombatLogGetCurrentEventInfo

local event_metatable = {
    __call = function(funcs, ...)
        for self, func in next, funcs do
            if (self:IsVisible()) then
                func(self, ...)
            end
        end
    end,
}

local self_metatable = {
    __call = function(funcs, self, ...)
        for _, func in next, funcs do
            func(self, ...)
        end
    end
}

local listener = CreateFrame('Frame')
listener.activeEvents = 0

local function filter(_, event, ...)
    if(listener[event]) then
        listener[event](event, ...)
    end
end

listener:SetScript('OnEvent', function(self, event)
    filter(CombatLogGetCurrentEventInfo())
end)

--[[ CombatEvents: frame:RegisterCombatEvent(event, handler)
Used to register a frame for a combat log event and add an event handler.

* self     - frame that will be registered for the given event
* event    - name of the combat log event to register (string)
* handler  - function which will be executed when the combat log event fires. Multiple handlers can be added for the
             same frame and event (function)
--]]
function frame_metatable.__index:RegisterCombatEvent(event, handler)
    argcheck(event, 2, 'string')
    argcheck(handler, 3, 'function')

    if(not listener[event]) then
        listener[event] = setmetatable({}, event_metatable)
        listener.activeEvents = listener.activeEvents + 1
    end

    local current = listener[event][self]

    if(current) then
        for _, func in next, current do
            if(func == handler) then return end
        end

        table.insert(current, handler)
    else
        -- even with a single handler we want to make sure the frame is visible
        listener[event][self] = setmetatable({handler}, self_metatable)
    end

    if(listener.activeEvents > 0) then
        listener:RegisterEvent('COMBAT_LOG_EVENT_UNFILTERED')
    end
end

--[[ CombatEvents: frame:UnregisterCombatEvent(event, handler)
Used to remove a function from the event handler list for a combat log event.

* self    - the frame registered for the event
* event   - name of the registered combat log event (string)
* handler - function to be removed from the list of event handlers
--]]
function frame_metatable.__index:UnregisterCombatEvent(event, handler)
    argcheck(event, 2, 'string')

    if(not listener[event]) then return end

    local cleanUp = false
    local current = listener[event][self]
    if(current) then
        for i, func in next, current do
            if(func == handler) then
                current[i] = nil

                break
            end
        end

        if(not next(current)) then
            cleanUp = true
        end
    end

    if(cleanUp) then
        listener[event][self] = nil

        if(not next(listener[event])) then
            listener[event] = nil
            listener.activeEvents = listener.activeEvents - 1

            if(listener.activeEvents <= 0) then
                listener:UnregisterEvent('COMBAT_LOG_EVENT_UNFILTERED')
            end
        end
    end
end
