UiHideModule.lua

local folderName, Addon = ...


-- For debugging:
-- We have to work with frame name, because some frames do not exist yet at startup.
-- local debugFrameName = "ClassTrainerFrame"


-- Have to store uiHiddenTime and currentConfig globally,
-- because several addons may use this module simultaneously.
if not ludius_UiHideModule then
  ludius_UiHideModule = {}

  -- Flag indicating if the UI is currently faded out.
  ludius_UiHideModule.uiHiddenTime = 0

  -- Save for each addon separately whether they have hidden the UI.
  ludius_UiHideModule.addonsHiddenStatus = {}

  -- The current configuration passed by the addon calling HideUI.
  ludius_UiHideModule.currentConfig = nil

  -- Collect alert frames that are created.
  ludius_UiHideModule.collectedAlertFrames = {}
end

-- For quick access.
local currentConfig = ludius_UiHideModule.currentConfig
local collectedAlertFrames = ludius_UiHideModule.collectedAlertFrames




-- Call Addon.HideUI(fadeOutTime, config) to hide UI keeping configured frames.
-- Call Addon.ShowUI(fadeInTime, true) when entering combat while UI is hidden.
--   This will show the actually hidden frames, that cannot be shown during combat,
--   but the fade out state will remain. You only see tooltips of faded-out frames.
-- Call Addon.ShowUI(fadeInTime, false) to show UI.

-- Accepted options for config argument of HideUI():
--   config.hideFrameRate
--   config.keepAlertFrames
--   config.keepTooltip
--   config.keepMinimap
--   config.keepChatFrame
--   config.keepPartyRaidFrame
--   config.keepTrackingBar
--   config.keepEncounterBar
--   config.keepCustomFrames
--   config.customFramesToKeep
--   config.UIParentAlpha     (while faded out)


-- Lua API
local _G = _G

local tonumber = tonumber
local tinsert = tinsert
local string_find = string.find
local string_match = string.match

local GetTime            = _G.GetTime
local InCombatLockdown   = _G.InCombatLockdown
local UnitInParty        = _G.UnitInParty


local CompactRaidFrameContainer = _G.CompactRaidFrameContainer





-- The user can define custom frames to keep visible.
-- To prevent these user settings from clashing with the other frames,
-- we store the names of frames handled by the addon.

-- Frames whose visibility is defined via explicit UI checkboxes/flags.
local flagFrames = {

  -- config.hideFrameRate
  ["FramerateLabel"] = true,
  ["FramerateText"] = true,

  -- config.keepAlertFrames
  ["CovenantRenownToast"] = true,


  -- config.keepMinimap
  ["MinimapCluster"] = true,
  -- Minimap is needed, because Immersion sets it to IgnoreParentAlpha.
  ["Minimap"] = true,

  -- config.keepTooltip
  ["GameTooltip"] = true,
  ["AceGUITooltip"] = true,
  ["AceConfigDialogTooltip"] = true,


  -- config.keepTrackingBar
  -- Retail
  ["StatusTrackingBarManager"] = true,
  ["BT4BarStatus"] = true,
  -- Classic
  ["MainMenuExpBar"] = true,
  ["ReputationWatchBar"] = true,
  -- GW2 UI
  ["GwExperienceFrame"] = true,


  -- config.keepEncounterBar
  ["EncounterBar"] = true,
}



-- config.keepChatFrame
for i = 1, 12, 1 do
  flagFrames["ChatFrame" .. i] = true
  flagFrames["ChatFrame" .. i .. "Tab"] = true
  flagFrames["ChatFrame" .. i .. "EditBox"] = true
  flagFrames["GwChatContainer" .. i] = true
end


-- config.keepPartyRaidFrame
for i = 1, 4, 1 do
  flagFrames["PartyMemberFrame" .. i] = true
  flagFrames["PartyMemberFrame" .. i .. "NotPresentIcon"] = true
end



-- Frames which are hidden by default.
local defaultHiddenFrames = {
  ["QuickJoinToastButton"] = true,
  ["PlayerFrame"] = true,
  ["PetFrame"] = true,
  ["TargetFrame"] = true,
  ["BuffFrame"] = true,
  ["DebuffFrame"] = true,
  ["ObjectiveTrackerFrame"] = true,
  -- TODO: Would have to fade every single 3D model separately.
  ["WardrobeFrame"] = true,
  ["CollectionsJournal"] = true,
}




if Bartender4 then
  defaultHiddenFrames["BT4Bar1"] = true
  defaultHiddenFrames["BT4Bar2"] = true
  defaultHiddenFrames["BT4Bar3"] = true
  defaultHiddenFrames["BT4Bar4"] = true
  defaultHiddenFrames["BT4Bar5"] = true
  defaultHiddenFrames["BT4Bar6"] = true
  defaultHiddenFrames["BT4Bar7"] = true
  defaultHiddenFrames["BT4Bar8"] = true
  defaultHiddenFrames["BT4Bar9"] = true
  defaultHiddenFrames["BT4Bar10"] = true
  defaultHiddenFrames["BT4Bar11"] = true
  defaultHiddenFrames["BT4Bar12"] = true
  defaultHiddenFrames["BT4Bar13"] = true
  defaultHiddenFrames["BT4Bar14"] = true
  defaultHiddenFrames["BT4Bar15"] = true
  defaultHiddenFrames["BT4BarBagBar"] = true
  defaultHiddenFrames["BT4BarMicroMenu"] = true
  defaultHiddenFrames["BT4BarStanceBar"] = true
  defaultHiddenFrames["BT4BarPetBar"] = true
else
  defaultHiddenFrames["MainMenuBar"] = true
  defaultHiddenFrames["MultiBarLeft"] = true
  defaultHiddenFrames["MultiBarRight"] = true
  defaultHiddenFrames["MultiBarBottomLeft"] = true
  defaultHiddenFrames["MultiBarBottomRight"] = true
  defaultHiddenFrames["MultiBar5"] = true
  defaultHiddenFrames["MultiBar6"] = true
  defaultHiddenFrames["MultiBar7"] = true
  defaultHiddenFrames["MultiBar8"] = true
  defaultHiddenFrames["ExtraAbilityContainer"] = true
  defaultHiddenFrames["MainMenuBarVehicleLeaveButton"] = true
  defaultHiddenFrames["MicroButtonAndBagsBar"] = true
  defaultHiddenFrames["MultiCastActionBarFrame"] = true
  defaultHiddenFrames["StanceBar"] = true
  defaultHiddenFrames["PetActionBar"] = true
  defaultHiddenFrames["PossessBar"] = true
end


local keepDefaultHiddenFramesAsParent = {}


-- We need a function to change a frame's alpha without automatically showing the frame
-- (as done by the original UIFrameFade() defined in UIParent.lua).

if not ludius_FADEFRAMES then ludius_FADEFRAMES = {} end

local frameFadeManager = CreateFrame("FRAME")

local function UIFrameFadeRemoveFrame(frame)
  tDeleteItem(ludius_FADEFRAMES, frame)
end



-- Changed this to work with GetTime() instead of "elapsed" argument.
-- Because the first elapsed after login is always very long and we want
-- to be able to start a smooth fade out beginning at the first update.
local lastUpdate
local function UIFrameFade_OnUpdate(self)

  local elapsed = 0
  if lastUpdate then
    elapsed = GetTime() - lastUpdate
  end
  lastUpdate = GetTime()

  local index = 1
  local frame, fadeInfo
  while ludius_FADEFRAMES[index] do
    frame = ludius_FADEFRAMES[index]
    fadeInfo = frame.fadeInfo
    -- Reset the timer if there isn't one, this is just an internal counter
    if not fadeInfo.fadeTimer then
      fadeInfo.fadeTimer = 0
    end
    fadeInfo.fadeTimer = fadeInfo.fadeTimer + elapsed

    -- If the fadeTimer is less then the desired fade time then set the alpha otherwise hold the fade state, call the finished function, or just finish the fade
    if tonumber(fadeInfo.fadeTimer) < tonumber(fadeInfo.timeToFade) then
      if fadeInfo.mode == "IN" then
        frame:SetAlpha((fadeInfo.fadeTimer / fadeInfo.timeToFade) * (fadeInfo.endAlpha - fadeInfo.startAlpha) + fadeInfo.startAlpha)
      elseif fadeInfo.mode == "OUT" then
        frame:SetAlpha(((fadeInfo.timeToFade - fadeInfo.fadeTimer) / fadeInfo.timeToFade) * (fadeInfo.startAlpha - fadeInfo.endAlpha) + fadeInfo.endAlpha)
      end

      -- if frame:GetName() == debugFrameName then print("UIFrameFade_OnUpdate", elapsed, frame:GetName(), fadeInfo.fadeTimer, fadeInfo.timeToFade, "Setting alpha", frame:GetAlpha()) end

    else

      -- if frame:GetName() == debugFrameName then print("Last call of UIFrameFade_OnUpdate.", frame:GetName(), "Setting endAlpha", fadeInfo.endAlpha) end

      frame:SetAlpha(fadeInfo.endAlpha)
      -- Complete the fade and call the finished function if there is one
      UIFrameFadeRemoveFrame(frame)
      if fadeInfo.finishedFunc then
        fadeInfo.finishedFunc(fadeInfo.finishedArg1, fadeInfo.finishedArg2, fadeInfo.finishedArg3, fadeInfo.finishedArg4)
        fadeInfo.finishedFunc = nil
      end
    end

    index = index + 1
  end

  if #ludius_FADEFRAMES == 0 then
    self:SetScript("OnUpdate", nil)
    lastUpdate = nil
  end
end

local function UIFrameFade(frame, fadeInfo)
  if not frame then return end

  -- We make sure that we always call this with mode, startAlpha and endAlpha.
  assert(fadeInfo.mode)
  assert(fadeInfo.startAlpha)
  assert(fadeInfo.endAlpha)

  -- if frame:GetName() == debugFrameName then print("UIFrameFade", frame:GetName(), fadeInfo.mode, fadeInfo.startAlpha, fadeInfo.endAlpha) end

  frame.fadeInfo = fadeInfo
  frame:SetAlpha(fadeInfo.startAlpha)

  local index = 1
  while ludius_FADEFRAMES[index] do
    -- If frame is already set to fade then return
    if ludius_FADEFRAMES[index] == frame then
      return
    end
    index = index + 1
  end
  tinsert(ludius_FADEFRAMES, frame)

  if #ludius_FADEFRAMES == 1 then
    frameFadeManager:SetScript("OnUpdate", UIFrameFade_OnUpdate)
  end

end



-- A function to set a frame's alpha depending on mouse over and
-- whether we are fading/faded out or not.
local function SetMouseOverAlpha(frame)
  -- Only do something to frames for which the hovering was activated.
  if frame.ludius_mouseOver == nil then return end

  -- Fading or faded out.
  if frame.ludius_fadeout then

    -- If the mouse is hovering over the status bar, show it with alpha 1.
    if frame.ludius_mouseOver then
      -- In case we are currently fading out,
      -- interrupt the fade out in progress.
      UIFrameFadeRemoveFrame(frame)
      frame.ludius_alreadyOnIt = nil
      frame:SetAlpha(1)

    -- Otherwise use the faded out alpha.
    else
      frame:SetAlpha(frame.ludius_alphaAfterFadeOut)
    end

  end
end



if WOW_PROJECT_ID == WOW_PROJECT_MAINLINE then

  local function SetMouseOverFading(barManager)
    -- Have to do this for the single bars.
    -- Otherwise the text does not pop up any more when hovering over the bars.
    -- It seems that OnEnter of a parent prevents the OnEnter of children to be triggered.
    -- But only the OnEnter of single bars shows the bar text.
    for _, frame in pairs(barManager.bars) do
      if not frame.ludius_hooked then
        frame:HookScript("OnEnter", function()
          StatusTrackingBarManager.ludius_mouseOver = true
          SetMouseOverAlpha(StatusTrackingBarManager)
        end)
        frame:HookScript("OnLeave", function()
          StatusTrackingBarManager.ludius_mouseOver = false
          SetMouseOverAlpha(StatusTrackingBarManager)
        end)
        frame.ludius_hooked = true
      end
    end

  end
  SetMouseOverFading(MainStatusTrackingBarContainer)
  SetMouseOverFading(SecondaryStatusTrackingBarContainer)

else

  -- Dirty work around with global flag until fade UI has become a lib to share between addons.
  if not ludius_bars_hooked then
    for _, frame in pairs({ReputationWatchBar, MainMenuExpBar}) do

      frame:HookScript("OnEnter", function()
        ReputationWatchBar.IEF_tempAlpha = ReputationWatchBar:GetAlpha()
        ReputationWatchBar:SetAlpha(1)
        MainMenuExpBar.IEF_tempAlpha = MainMenuExpBar:GetAlpha()
        MainMenuExpBar:SetAlpha(1)
      end )

      frame:HookScript("OnLeave", function()
        if (ReputationWatchBar.IEF_tempAlpha ~= nil) then
          ReputationWatchBar:SetAlpha(ReputationWatchBar.IEF_tempAlpha)
        end
        if (MainMenuExpBar.IEF_tempAlpha ~= nil) then
          MainMenuExpBar:SetAlpha(MainMenuExpBar.IEF_tempAlpha)
        end
      end )
      
    end
    ludius_bars_hooked = true
    
  end
end



if C_AddOns.IsAddOnLoaded("GW2_UI") then
  -- GW2_UI seems to offer no way of hooking any of its functions.
  -- So we have to do it like this.
  local enterWorldFrame = CreateFrame("Frame")
  enterWorldFrame:RegisterEvent("PLAYER_ENTERING_WORLD")
  enterWorldFrame:SetScript("OnEvent", function()
    if GwExperienceFrame then
      GwExperienceFrame:HookScript("OnEnter", function()
        GwExperienceFrame.ludius_mouseOver = true
        SetMouseOverAlpha(GwExperienceFrame)
      end)
      GwExperienceFrame:HookScript("OnLeave", function()
        GwExperienceFrame.ludius_mouseOver = false
        SetMouseOverAlpha(GwExperienceFrame)
      end)
    end
  end)
end



-- To hide the tooltip of bag items.
-- (While we are actually hiding other frames to suppress their tooltips,
-- this is not practical for the bag, as opening may cause an annoying FPS drop.)
local function GameTooltipHider(self)

  if ludius_UiHideModule.uiHiddenTime == 0 or not self then return end

  local ownerName = nil
  if self:GetOwner() then
    ownerName = self:GetOwner():GetName()
  end
  if ownerName == nil then return end

  if string_find(ownerName, "^ContainerFrame") or ownerName == "ChatFrameChannelButton" then
    self:Hide()
  -- else
    -- print(ownerName)
  end
end



if WOW_PROJECT_ID == WOW_PROJECT_MAINLINE then
  TooltipDataProcessor.AddTooltipPostCall(Enum.TooltipDataType.Item, GameTooltipHider)
else
  GameTooltip:HookScript("OnTooltipSetItem", GameTooltipHider)
end
GameTooltip:HookScript("OnTooltipSetDefaultAnchor", GameTooltipHider)
GameTooltip:HookScript("OnShow", GameTooltipHider)



local function ConditionalHide(frame)
  if not frame then return end

  -- if frame:GetName() == debugFrameName then print("ConditionalHide", frame:GetName(), frame:GetParent():GetName(), frame:IsIgnoringParentAlpha()) end

  -- Checking for combat lockdown is not this function's concern.
  -- Functions calling it must make sure, it is not  called in combat lockdown.

  -- TODO: What if the combat started while the fade out was already happening???
  if frame:IsProtected() and InCombatLockdown() then
    print("ERROR: Should not try to hide", frame:GetName(), "in combat lockdown!")
  end

  if frame.ludius_shownBeforeFadeOut == nil then
    -- if frame:GetName() == debugFrameName then print("Remember it was shown", frame:IsShown()) end
    frame.ludius_shownBeforeFadeOut = frame:IsShown()
  end

  if frame:IsShown() then
    frame:Hide()
  end
end


local function ConditionalShow(frame)
  if not frame or frame.ludius_shownBeforeFadeOut == nil then return end

  -- if frame:GetName() == debugFrameName then print("ConditionalShow", frame:GetName(), frame.ludius_shownBeforeFadeOut) end

  if frame:IsProtected() and InCombatLockdown() then
    print("ERROR: Should not try to show", frame:GetName(), "in combat lockdown!")
  end


  -- If the frame is already shown, we leave it be.
  if not frame:IsShown() then

    -- For party and raid member frames, we cannot rely on ludius_shownBeforeFadeOut,
    -- so some more complex checks are necessary.

    -- Party member frames.
    if string_find(frame:GetName(), "^PartyMemberFrame") then

      -- The NotPresentIcon is taken care of by PartyMemberFrame_UpdateNotPresentIcon below.
      -- So we only handle the actual PartyMemberFrame and do nothing otherwise.
      if string_find(frame:GetName(), "^PartyMemberFrame(%d+)$") then

        -- Only show the party member frames, if we are in a party that is not a raid.
        -- (Use CompactRaidFrameContainer:IsShown() instead of UnitInRaid("player") because people might use
        -- an addon like SoloRaidFrame to show the raid frame even while not in raid.)
        if UnitInParty("player") and not CompactRaidFrameContainer:IsShown() then
          -- Only for as many frames as there are party members.
          local numGroupMembers = GetNumGroupMembers()
          local frameNumber = tonumber(string_match(frame:GetName(), "^PartyMemberFrame(%d+)"))
          if frameNumber < numGroupMembers then
            frame:Show()
            PartyMemberFrame_UpdateNotPresentIcon(frame)
            -- The above functions set the alpha, but we want to do the fade in ourselves.
            frame:SetAlpha(0)
            frame.notPresentIcon:SetAlpha(0)
          end
        end

      end


    -- Only show the CompactRaidFrameContainer, if the player is still in a party.
    elseif frame == CompactRaidFrameContainer then

      -- (Again also use CompactRaidFrameContainer:IsShown() because people might use
      -- an addon like SoloRaidFrame to show the raid frame even while not in raid.)
      if UnitInParty("player") or CompactRaidFrameContainer:IsShown() then
        frame:Show()
      end


    elseif frame.ludius_shownBeforeFadeOut then
      -- if frame:GetName() == debugFrameName then print("Have to show it again!") end
      frame:Show()
    end

  end

  frame.ludius_shownBeforeFadeOut = nil
end




-- To prevent other addons (Immersion, I'm looking in your direction) from
-- setting Minimap's and MinimapCluster's ignoreParentAlpha to false, when DynamicCam does not.
local function ParentAlphaGuard(self, ignoreParentAlpha)
  -- print(self:GetName(), "SetIgnoreParentAlpha", ignoreParentAlpha, self.ludius_intendedIgnoreParentAlpha)
  if self.ludius_intendedIgnoreParentAlpha ~= nil and ignoreParentAlpha ~= self.ludius_intendedIgnoreParentAlpha then
      -- print("no")
      self:SetIgnoreParentAlpha(self.ludius_intendedIgnoreParentAlpha)
  -- else
      -- print("ok")
  end
end

hooksecurefunc(MinimapCluster, "SetIgnoreParentAlpha", ParentAlphaGuard)
hooksecurefunc(Minimap, "SetIgnoreParentAlpha", ParentAlphaGuard)




-- To restore frames to their pre-hide ignore-parent-alpha state,
-- we remember it in the ludius_ignoreParentAlphaBeforeFadeOut variable.
local function ConditionalSetIgnoreParentAlpha(frame, ignoreParentAlpha)
  -- if frame:GetName() == debugFrameName then print("ConditionalSetIgnoreParentAlpha", ignoreParentAlpha) end

  if not frame or ignoreParentAlpha == nil then return end

  if frame.ludius_ignoreParentAlphaBeforeFadeOut == nil then
    frame.ludius_ignoreParentAlphaBeforeFadeOut = frame:IsIgnoringParentAlpha()
  end

  if frame:IsIgnoringParentAlpha() ~= ignoreParentAlpha then
    frame.ludius_intendedIgnoreParentAlpha = ignoreParentAlpha
    frame:SetIgnoreParentAlpha(ignoreParentAlpha)
  end
end

local function ConditionalResetIgnoreParentAlpha(frame)
  -- if frame:GetName() == debugFrameName then print("ConditionalSetIgnoreParentAlpha", ignoreParentAlpha) end

  if not frame or frame.ludius_ignoreParentAlphaBeforeFadeOut == nil then return end

  if frame:IsIgnoringParentAlpha() ~= frame.ludius_ignoreParentAlphaBeforeFadeOut then
    frame.ludius_intendedIgnoreParentAlpha = frame.ludius_ignoreParentAlphaBeforeFadeOut
    frame:SetIgnoreParentAlpha(frame.ludius_ignoreParentAlphaBeforeFadeOut)
  end
  frame.ludius_ignoreParentAlphaBeforeFadeOut = nil
end




-- The alert frames have to be dealt with as they are created.
-- https://www.wowinterface.com/forums/showthread.php?p=337803
-- For testing:
-- /run UIParent:SetAlpha(0.5)
-- /run NewMountAlertSystem:ShowAlert("123") NewMountAlertSystem:ShowAlert("123")
-- /run CovenantRenownToast:ShowRenownLevelUpToast(C_Covenants.GetActiveCovenantID(), 40)


-- A flag for alert frames that are created/collected while the UI is hidden.
local currentAlertFramesIgnoreParentAlpha = false

local function AlertFramesSetIgnoreParentAlpha(ignoreParentAlpha)
  currentAlertFramesIgnoreParentAlpha = ignoreParentAlpha
  for _, v in pairs(collectedAlertFrames) do
    ConditionalSetIgnoreParentAlpha(v, ignoreParentAlpha)
  end
end

local function AlertFramesResetIgnoreParentAlpha()
  currentAlertFramesIgnoreParentAlpha = false
  for _, v in pairs(collectedAlertFrames) do
    ConditionalResetIgnoreParentAlpha(v)
  end
end


local function CollectAlertFrame(_, frame)
  -- print("CollectAlertFrame", frame, currentAlertFramesIgnoreParentAlpha, frame.ludius_collected)

  if frame and not frame.ludius_collected then
    tinsert(collectedAlertFrames, frame)
    frame.ludius_collected = true
  end

  if currentAlertFramesIgnoreParentAlpha and not frame:IsIgnoringParentAlpha() then
    ConditionalSetIgnoreParentAlpha(frame, currentAlertFramesIgnoreParentAlpha)
  end
end

for _, subSystem in pairs(AlertFrame.alertFrameSubSystems) do
  local pool = type(subSystem) == "table" and subSystem.alertFramePool
  if type(pool) == "table" and type(pool.resetterFunc) == "function" then
    hooksecurefunc(pool, "resetterFunc", CollectAlertFrame)
  end
end




-- targetIgnoreParentAlpha == true:  frame ignores parent alpha, and itself fades to targetAlpha (maybe different from UIParent's alpha).
-- targetIgnoreParentAlpha == false: frame adheres to parent alpha, but gets hidden, if targetAlpha (UIParent's alpha) is 0.
--
-- targetIgnoreParentAlpha == nil: Ignoring this frame!
-- This is needed for example, if the keeping or fading of a frame should be governed by another addon.
-- Like MinimapCluster is governed by Immersion and should therefore not be modified by IEF.
-- FadeInFrame() will automatically ignore non-faded frames as it will not find our ludius_ flags.
local function FadeOutFrame(frame, duration, targetIgnoreParentAlpha, targetAlpha)

  if not frame or targetIgnoreParentAlpha == nil then return end
  
  

  -- If another addon is already handling this, we don't touch it.
  if frame.ludius_alreadyOnIt ~= nil and frame.ludius_alreadyOnIt ~= folderName then
    return
  else
    frame.ludius_alreadyOnIt = folderName
  end

  assert(targetAlpha)

  -- Prevent callback functions of currently active timers.
  UIFrameFadeRemoveFrame(frame)

  -- if frame:GetName() == debugFrameName then print("FadeOutFrame", frame:GetName(), duration, targetIgnoreParentAlpha, frame:IsIgnoringParentAlpha(), targetAlpha, frame:GetAlpha()) end


  -- If a frame to be kept is not a direct child of UIParent,
  -- we have to make sure that the parent gets not hidden later.
  -- (e.g. In classic, the status tracking bars are children of MainMenuBar,
  -- which normally is in defaultHiddenFrames.)
  if targetIgnoreParentAlpha and targetAlpha > 0 then
    local currentParent = frame:GetParent()
    while currentParent and currentParent ~= UIParent and currentParrent ~= WorldFrame do
      keepDefaultHiddenFramesAsParent[currentParent] = true
      currentParent = currentParent:GetParent()
    end
  end


  -- ludius_alphaBeforeFadeOut is only set, if this is a fresh FadeOutFrame().
  -- It is set to nil after a FadeOutFrame() is completed.
  -- Otherwise, we might falsely asume a wrong ludius_alphaBeforeFadeOut
  -- value while a fade-in is still in progress.
  if frame.ludius_alphaBeforeFadeOut == nil then
    frame.ludius_alphaBeforeFadeOut = frame:GetAlpha()
  end


  -- To use UIFrameFade() which is the same as UIFrameFadeOut, but with a callback function.
  local fadeInfo = {}
  fadeInfo.mode = "OUT"
  fadeInfo.timeToFade = duration
  fadeInfo.finishedArg1 = frame
  fadeInfo.finishedArg2 = targetAlpha
  fadeInfo.finishedFunc = function(finishedArg1, finishedArg2)
    -- if finishedArg1:GetName() == debugFrameName then print("Fade out finished", finishedArg1:GetName(), finishedArg2) end
    if finishedArg2 == 0 and (not finishedArg1:IsProtected() or not InCombatLockdown()) and not keepDefaultHiddenFramesAsParent[finishedArg1] then
      -- if finishedArg1:GetName() == debugFrameName then print("...and hiding!", finishedArg2) end
      ConditionalHide(finishedArg1)
    end

    finishedArg1.ludius_alreadyOnIt = nil
  end




  -- Frame should henceforth ignore parent alpha.
  if targetIgnoreParentAlpha then

    -- This is to let SetMouseOverAlpha() know whether we are
    -- currently fading/faded in or fading/faded out.
    -- Notice that we cannot use ludius_alphaBeforeFadeOut or ludius_alphaAfterFadeOut as this flag,
    -- because ludius_fadeout is unset at the beginning of a fade out
    -- and ludius_alphaBeforeFadeOut is unset at the end of a fade out.
    -- For an OnEnable/OnLeave during fade out, we do not want the alpha to change.
    frame.ludius_fadeout = true
    -- This is to let SetMouseOverAlpha() know which
    -- alpha to go back to OnLeave while the frame is faded or fading out.
    frame.ludius_alphaAfterFadeOut = targetAlpha
    SetMouseOverAlpha(frame)


    -- Frame was adhering to parent alpha before.
    -- Start the fade with parent's current alpha.
    if not frame:IsIgnoringParentAlpha() then
      local parent = frame:GetParent()
      fadeInfo.startAlpha = parent and parent:GetAlpha() or 1

    -- Frame was already ignoring parent alpha before.
    else
      fadeInfo.startAlpha = frame:GetAlpha()

    end
    fadeInfo.endAlpha = targetAlpha

    ConditionalSetIgnoreParentAlpha(frame, true)


  -- Frame should henceforth adhere to parent alpha.
  else

    -- Frame was ignoring parent alpha before.
    -- Start the fade with the frame's alpha, fade to UIParent's target alpha
    -- and only then unset ignore parent alpha.
    -- Notice that the frame's alpha is not overriden by parent alpha but combined.
    -- So we have to set the child's alpha to 1 at the same time as we stop ignoring
    -- parent alpha.
    if frame:IsIgnoringParentAlpha() then

      fadeInfo.startAlpha = frame:GetAlpha()
      fadeInfo.endAlpha = targetAlpha

      fadeInfo.finishedFunc = function(finishedArg1, finishedArg2)
        -- if finishedArg1:GetName() == debugFrameName then print("Fade out finished", finishedArg1:GetName(), finishedArg2) end
        finishedArg1:SetAlpha(1)
        ConditionalSetIgnoreParentAlpha(finishedArg1, false)
        if finishedArg2 == 0 and (not finishedArg1:IsProtected() or not InCombatLockdown()) and not keepDefaultHiddenFramesAsParent[finishedArg1] then
          ConditionalHide(finishedArg1)
        end

        finishedArg1.ludius_alreadyOnIt = nil
      end

    -- Frame was already adhering to parent alpha.
    -- We are not changing it.
    else

      -- if frame:GetName() == debugFrameName then print("was already adhering to parent alpha") end

      fadeInfo.startAlpha = frame:GetAlpha()
      fadeInfo.endAlpha = frame:GetAlpha()
    end

  end


  -- Cannot rely on UIFrameFade to finish within the same frame.
  if duration == 0 then
    frame:SetAlpha(fadeInfo.endAlpha)
    fadeInfo.finishedFunc(frame, targetAlpha)

  -- This is for some frames to not being shown in between situations that are both hiding them.
  elseif (frame == MinimapCluster or frame == ObjectiveTrackerFrame) and targetAlpha == 0 and targetIgnoreParentAlpha == false and frame:GetParent():GetAlpha() == 0 and frame:IsShown() then
    fadeInfo.finishedFunc(frame, targetAlpha)

  else
    -- if frame:GetName() == debugFrameName then print("Starting fade with", fadeInfo.startAlpha, fadeInfo.endAlpha, fadeInfo.mode, fadeInfo.timeToFade) end
    UIFrameFade(frame, fadeInfo)
  end

end


local function FadeInFrame(frame, duration, enteringCombat)

  if not frame then return end

  -- If another addon is already handling this, we don't touch it.
  if frame.ludius_alreadyOnIt ~= nil and frame.ludius_alreadyOnIt ~= folderName then
    -- print(folderName, "not touching", frame:GetName())
    return
  else
    frame.ludius_alreadyOnIt = folderName
  end


  -- Prevent callback functions of currently active timers.
  UIFrameFadeRemoveFrame(frame)

  -- Only do something if we have touched this frame before.
  if frame.ludius_shownBeforeFadeOut == nil and frame.ludius_alphaBeforeFadeOut == nil and frame.ludius_ignoreParentAlphaBeforeFadeOut == nil then
    frame.ludius_alreadyOnIt = nil
    return
  end

  -- if frame:GetName() == debugFrameName then print("FadeInFrame", frame:GetName(), frame:IsIgnoringParentAlpha()) end


  if enteringCombat then
    -- When entering combat we have to show protected frames, which cannot be shown any more during combat.
    if frame:IsProtected() then
      ConditionalShow(frame)
    end
    frame.ludius_alreadyOnIt = nil
    -- But we do not yet do the fade in.
    return
  else
    ConditionalShow(frame)
  end


  -- To use UIFrameFade() which is the same as UIFrameFadeOut, but with a callback function.
  local fadeInfo = {}
  fadeInfo.mode = "IN"
  fadeInfo.timeToFade = duration
  fadeInfo.finishedArg1 = frame
  fadeInfo.finishedFunc = function(finishedArg1)
      finishedArg1.ludius_alphaBeforeFadeOut = nil
      finishedArg1.ludius_alphaAfterFadeOut = nil
      finishedArg1.ludius_alreadyOnIt = nil
    end


  -- Frame should henceforth ignore parent alpha.
  if frame.ludius_ignoreParentAlphaBeforeFadeOut == true then

    -- Frame was adhering to parent alpha before.
    -- Start the fade with parent's current alpha.
    if not frame:IsIgnoringParentAlpha() then
      fadeInfo.startAlpha = frame:GetParent():GetAlpha()
    -- Frame was already ignoring parent alpha before.
    else
      fadeInfo.startAlpha = frame:GetAlpha()
    end
    fadeInfo.endAlpha = frame.ludius_alphaBeforeFadeOut

    ConditionalResetIgnoreParentAlpha(frame)

  -- Frame should henceforth adhere to parent alpha.
  elseif frame.ludius_ignoreParentAlphaBeforeFadeOut == false then

    -- Frame was ignoring parent alpha before.
    -- Start the fade with the frame's alpha, fade to UIParent's target alpha
    -- (which is always 1 when we fade the UI back in) and only then unset
    -- ignore parent alpha.
    if frame:IsIgnoringParentAlpha() then
      fadeInfo.startAlpha = frame:GetAlpha()
      fadeInfo.endAlpha = 1

      fadeInfo.finishedFunc = function(finishedArg1)
        ConditionalResetIgnoreParentAlpha(finishedArg1)
        finishedArg1.ludius_alphaBeforeFadeOut = nil
        finishedArg1.ludius_alphaAfterFadeOut = nil
        finishedArg1.ludius_alreadyOnIt = nil
      end

    -- Frame was already adhering to parent alpha.
    -- We are not changing it.
    else
      fadeInfo.startAlpha = frame:GetAlpha()
      fadeInfo.endAlpha = frame:GetAlpha()
    end

  -- No stored value in ludius_ignoreParentAlphaBeforeFadeOut.
  else
    fadeInfo.startAlpha = frame:GetAlpha()
    fadeInfo.endAlpha = frame.ludius_alphaBeforeFadeOut or frame:GetAlpha()
  end

  -- if frame:GetName() == debugFrameName then print("Starting fade with", fadeInfo.startAlpha, fadeInfo.endAlpha, fadeInfo.mode) end


  -- Cannot rely on UIFrameFade to finish within the same frame.
  if duration == 0 then
    frame:SetAlpha(fadeInfo.endAlpha)
    fadeInfo.finishedFunc(frame)
  else
    UIFrameFade(frame, fadeInfo)
  end

  -- We can do this always when fading in.
  frame.ludius_fadeout = nil
  SetMouseOverAlpha(frame)

end


-- So the GameTooltip stays hidden while UI is faded.
local hideGameTooltip = nil
GameTooltip:HookScript("OnShow", function(self)
  if hideGameTooltip and self:GetOwner() == UIParent then
    self:Hide()
  end
end)


Addon.HideUI = function(fadeOutTime, config)

  -- print("HideUI", folderName, fadeOutTime, config.UIParentAlpha)

  keepDefaultHiddenFramesAsParent = {}


  -- Remember that the UI is faded.
  ludius_UiHideModule.uiHiddenTime = GetTime()
  ludius_UiHideModule.addonsHiddenStatus[folderName] = true

  currentConfig = config

  if config.hideFrameRate then
    -- The framerate label is a child of WorldFrame, while we just fade UIParent.
    -- That's why we have to set targetIgnoreParentAlpha to true.
    FadeOutFrame(FramerateLabel, fadeOutTime, true, config.UIParentAlpha)
    FadeOutFrame(FramerateText, fadeOutTime, true, config.UIParentAlpha)
  end

  AlertFramesSetIgnoreParentAlpha(config.keepAlertFrames)
  FadeOutFrame(CovenantRenownToast, fadeOutTime, config.keepAlertFrames, config.keepAlertFrames and 1 or config.UIParentAlpha)

  FadeOutFrame(MinimapCluster, fadeOutTime, config.keepMinimap, config.keepMinimap and 1 or config.UIParentAlpha)
  -- Minimap is needed, because Immersion sets it to IgnoreParentAlpha.
  FadeOutFrame(Minimap, fadeOutTime, config.keepMinimap, config.keepMinimap and 1 or config.UIParentAlpha)

  FadeOutFrame(GameTooltip, fadeOutTime, config.keepTooltip, config.keepTooltip and 1 or config.UIParentAlpha)
  C_Timer.After(fadeOutTime, function() hideGameTooltip = (config.keepTooltip == false) end)
  local shoppingTooltip1, shoppingTooltip2 = unpack(GameTooltip.shoppingTooltips)
  FadeOutFrame(shoppingTooltip1, fadeOutTime, config.keepTooltip, config.keepTooltip and 1 or config.UIParentAlpha)
  FadeOutFrame(shoppingTooltip2, fadeOutTime, config.keepTooltip, config.keepTooltip and 1 or config.UIParentAlpha)

  FadeOutFrame(AceGUITooltip, fadeOutTime, config.keepTooltip, config.keepTooltip and 1 or config.UIParentAlpha)
  FadeOutFrame(AceConfigDialogTooltip, fadeOutTime, config.keepTooltip, config.keepTooltip and 1 or config.UIParentAlpha)


  for i = 1, 12, 1 do
    if _G["ChatFrame" .. i] then
      FadeOutFrame(_G["ChatFrame" .. i], fadeOutTime, config.keepChatFrame, config.keepChatFrame and 1 or config.UIParentAlpha)
      FadeOutFrame(_G["ChatFrame" .. i .. "Tab"], fadeOutTime, config.keepChatFrame, config.keepChatFrame and 1 or config.UIParentAlpha)
      FadeOutFrame(_G["ChatFrame" .. i .. "EditBox"], fadeOutTime, config.keepChatFrame, config.keepChatFrame and 1 or config.UIParentAlpha)
    end

    if _G["GwChatContainer" .. i] then
      FadeOutFrame(_G["GwChatContainer" .. i], fadeOutTime, config.keepChatFrame, config.keepChatFrame and 1 or config.UIParentAlpha)
    end
  end


  -- Status tracking bars.
  -- Retail
  FadeOutFrame(StatusTrackingBarManager, fadeOutTime, config.keepTrackingBar, config.keepTrackingBar and config.trackingBarAlpha or config.UIParentAlpha)
  FadeOutFrame(BT4BarStatus, fadeOutTime, config.keepTrackingBar, config.keepTrackingBar and config.trackingBarAlpha or config.UIParentAlpha)
  -- Classic
  FadeOutFrame(MainMenuExpBar, fadeOutTime, config.keepTrackingBar, config.keepTrackingBar and config.trackingBarAlpha or config.UIParentAlpha)
  FadeOutFrame(ReputationWatchBar, fadeOutTime, config.keepTrackingBar, config.keepTrackingBar and config.trackingBarAlpha or config.UIParentAlpha)
  -- GW2 UI
  FadeOutFrame(GwExperienceFrame, fadeOutTime, config.keepTrackingBar, config.keepTrackingBar and config.trackingBarAlpha or config.UIParentAlpha)


  FadeOutFrame(EncounterBar, fadeOutTime, config.keepEncounterBar, config.keepEncounterBar and 1 or config.UIParentAlpha)

  FadeOutFrame(CompactRaidFrameContainer, fadeOutTime, config.keepPartyRaidFrame, config.keepPartyRaidFrame and 1 or config.UIParentAlpha)



  -- Non-configurable frames that we just want to hide in case UIParentAlpha is 0.
  for k in pairs(defaultHiddenFrames) do
    -- Using "not not" to convert nil to false.
    local keepFrame = not not config.keepCustomFrames and not not config.customFramesToKeep[k]
    FadeOutFrame(_G[k], fadeOutTime, keepFrame, keepFrame and 1 or config.UIParentAlpha)
  end


  -- Keep frames that are in config.customFramesToKeep but not in defaultHiddenFrames or flagFrames.
  if config.keepCustomFrames then
    for k in pairs(config.customFramesToKeep) do
      -- print(k, _G[k])
      if not defaultHiddenFrames[k] and not flagFrames[k] then

        -- If the frame does not exist yet (e.g. ClassTrainerFrame), try again after a short time.
        if not _G[k] then
          C_Timer.After(0.3, function() FadeOutFrame(_G[k], fadeOutTime, true, 1) end)
        else
          -- At the moment we are not supporting custom alphas for kept frames, so we set it to 1.
          FadeOutFrame(_G[k], fadeOutTime, true, 1)
        end
      end
    end
  end

  if Addon.frameShowTimer then LibStub("AceTimer-3.0"):CancelTimer(Addon.frameShowTimer) end

end




-- If enteringCombat we only show the hidden frames (which cannot be shown
-- during combat lockdown). But we skip the SetIgnoreParentAlpha(false).
-- This can be done when the intended ShowUI() is called.
Addon.ShowUI = function(fadeInTime, enteringCombat)

  -- Just to be on the safe side.
  keepDefaultHiddenFramesAsParent = {}

  ludius_UiHideModule.addonsHiddenStatus[folderName] = false

  -- Only do something once per closing.
  if ludius_UiHideModule.uiHiddenTime == 0 then return end

  -- print("ShowUI", folderName, fadeInTime, enteringCombat)

  if not enteringCombat then
    ludius_UiHideModule.uiHiddenTime = 0
    currentConfig = nil
  end

  FadeInFrame(FramerateLabel, fadeInTime, enteringCombat)
  FadeInFrame(FramerateText, fadeInTime, enteringCombat)


  FadeInFrame(CompactRaidFrameContainer, fadeInTime, enteringCombat)


  for k in pairs(defaultHiddenFrames) do
    FadeInFrame(_G[k], fadeInTime, enteringCombat)
  end


  -- Fade in the (possibly only partially) faded status bar.
  -- Retail.
  FadeInFrame(StatusTrackingBarManager, fadeInTime, enteringCombat)
  FadeInFrame(BT4BarStatus, fadeInTime, enteringCombat)
  -- Classic
  FadeInFrame(MainMenuExpBar, fadeInTime, enteringCombat)
  FadeInFrame(ReputationWatchBar, fadeInTime, enteringCombat)
  -- GW2 UI
  FadeInFrame(GwExperienceFrame, fadeInTime, enteringCombat)


  FadeInFrame(CovenantRenownToast, fadeInTime, enteringCombat)

  FadeInFrame(MinimapCluster, fadeInTime, enteringCombat)
  FadeInFrame(Minimap, fadeInTime, enteringCombat)

  hideGameTooltip = false
  FadeInFrame(GameTooltip, fadeInTime, enteringCombat)
  local shoppingTooltip1, shoppingTooltip2 = unpack(GameTooltip.shoppingTooltips)
  FadeInFrame(shoppingTooltip1, fadeInTime, enteringCombat)
  FadeInFrame(shoppingTooltip2, fadeInTime, enteringCombat)

  FadeInFrame(AceGUITooltip, fadeInTime, enteringCombat)
  FadeInFrame(AceConfigDialogTooltip, fadeInTime, enteringCombat)


  for i = 1, 12, 1 do
    if _G["ChatFrame" .. i] then
      FadeInFrame(_G["ChatFrame" .. i], fadeInTime, enteringCombat)
      FadeInFrame(_G["ChatFrame" .. i .. "Tab"], fadeInTime, enteringCombat)
      FadeInFrame(_G["ChatFrame" .. i .. "EditBox"], fadeInTime, enteringCombat)
    end

    if _G["GwChatContainer" .. i] then
      FadeInFrame(_G["GwChatContainer" .. i], fadeInTime, enteringCombat)
    end
  end


  FadeInFrame(EncounterBar, fadeInTime, enteringCombat)


  -- Cancel timers that may still be in progress.
  if Addon.frameShowTimer then LibStub("AceTimer-3.0"):CancelTimer(Addon.frameShowTimer) end

  if not enteringCombat then
    -- Reset the IgnoreParentAlpha after the UI fade-in is finished.
    Addon.frameShowTimer = LibStub("AceTimer-3.0"):ScheduleTimer(function()
      AlertFramesResetIgnoreParentAlpha()
    end, fadeInTime)
  end

end



-- If party/raid members join/leave while the UI is faded, we prevent the frames from being shown again.
-- This code is similar to the respective part of HideUI(), see comments there.

-- We have to do the OnShow hook, because the GROUP_ROSTER_UPDATE event comes too late.
for i = 1, 4, 1 do
  if _G["PartyMemberFrame" .. i] then
    _G["PartyMemberFrame" .. i]:HookScript("OnShow", function()
      if not currentConfig or ludius_UiHideModule.uiHiddenTime == 0 then return end
      FadeOutFrame(_G["PartyMemberFrame" .. i .. "NotPresentIcon"], 0, true, currentConfig.keepPartyRaidFrame and 1 or currentConfig.UIParentAlpha)
      FadeOutFrame(_G["PartyMemberFrame" .. i], 0, currentConfig.keepPartyRaidFrame, currentConfig.keepPartyRaidFrame and 1 or currentConfig.UIParentAlpha)
    end)
  end
end



-- The CompactRaidFrameContainer frame gets shown every time the raid roster changes.
-- While the UI is hidden, we have to hide it again.
CompactRaidFrameContainer:HookScript("OnShow", function()
  if not currentConfig or ludius_UiHideModule.uiHiddenTime == 0 then return end
  if currentConfig.keepPartyRaidFrame == false then
    FadeOutFrame(CompactRaidFrameContainer, 0, false, currentConfig.UIParentAlpha)
  end
end)