-- Credits: Vika, Cladhaire, Tekkub
--[[
# Element: Tags

Provides a system for text-based display of information by binding a tag string to a font string widget which in turn is
tied to a unit frame.

## Widget

A FontString to hold a tag string. Unlike other elements, this widget must not have a preset name.

## Notes

A `Tag` is a Lua string consisting of a function name surrounded by square brackets. The tag will be replaced by the
output of the function and displayed as text on the font string widget with that the tag has been registered.

A `Tag String` is a Lua string consisting of one or multiple tags with optional literals and parameters around them.
Each tag will be updated individually and the output will follow the tags order. Literals will be displayed in the
output string regardless of whether the surrounding tag functions return a value. I.e. `"[curhp]/[maxhp]"` will resolve
to something like `2453/5000`.

There's also an optional prefix and suffix that are separated from the tag name by `$>` and `<$` respectively,
for example, `"[==$>name<$==]"` will resolve to `==Thrall==`, and `"[perhp<$%]"` will resole to `100%`, however, said
affixes will only be added if the tag function returns a non-empty string, if it returns `nil` or `""` affixes will be
omitted.

Additionally, it's possible to pass optional arguments to a tag function to alter its behaviour. Optional arguments are
defined via `()` at the end of a tag and separated by commas (`,`). For example, `"[name(a,r,g,s)]"`, in this case 4
additional arguments, `"a"`, `"r"`, `"g"`, and `"s"` will be passed to the name tag function, what to do with them,
however, is up to a developer to decide.

The full tag syntax looks like this: `"[prefix$>tag<$suffix(a,r,g,s)]"`. The order of optional elements is important,
while they can be independently omitted, they can't be reordered.

A `Tag Function` is used to replace a single tag in a tag string by its output. A tag function receives only two
arguments - the unit and the realUnit of the unit frame used to register the tag (see Options for further details). The
tag function is called when the unit frame is shown or when a specified event has fired. It the tag is registered on an
eventless frame (i.e. one holding the unit "targettarget"), then the tag function is called in a set time interval.

A number of built-in tag functions exist. The layout can also define its own tag functions by adding them to the
`oUF.Tags.Methods` table. The events upon which the function will be called are specified in a white-space separated
list added to the `oUF.Tags.Events` table. Should an event fire without unit information, then it should also be listed
in the `oUF.Tags.SharedEvents` table as follows: `oUF.Tags.SharedEvents.EVENT_NAME = true`.

## Options

.overrideUnit    - if specified on the font string widget, the frame's realUnit will be passed as the second argument to
                   every tag function whose name is contained in the relevant tag string. Otherwise the second argument
                   is always nil (boolean)
.frequentUpdates - defines how often the corresponding tag function(s) should be called. This will override the events
                   for the tag(s), if any. If the value is a number, it is taken as a time interval in seconds. If the
                   value is a boolean, the time interval is set to 0.5 seconds (number or boolean)

## Attributes

.parent - the unit frame on which the tag has been registered

## Examples

### Example 1

    -- define the tag function
    oUF.Tags.Methods['mylayout:threatname'] = function(unit, realUnit)
        local color = _TAGS['threatcolor'](unit)
        local name = _TAGS['name'](unit, realUnit)
        return string.format('%s%s|r', color, name)
    end

    -- add the events
    oUF.Tags.Events['mylayout:threatname'] = 'UNIT_NAME_UPDATE UNIT_THREAT_SITUATION_UPDATE'

    -- create the text widget
    local info = self.Health:CreateFontString(nil, 'OVERLAY', 'GameFontNormal')
    info:SetPoint('LEFT')

    -- register the tag on the text widget with oUF
    self:Tag(info, '[mylayout:threatname]')

### Example 2

    -- define the tag function that accepts optional arguments
    oUF.Tags.Methods['mylayout:name'] = function(unit, realUnit, ...)
        local name = _TAGS['name'](unit, realUnit)
        local length = tonumber(...)
        if(length) then
            return name:sub(1, length) -- please note, this code doesn't support UTF-8 chars
        else
            return name
        end
    end

    -- add the events
    oUF.Tags.Events['mylayout:name'] = 'UNIT_NAME_UPDATE'

    -- create the text widget
    local info = self.Health:CreateFontString(nil, 'OVERLAY', 'GameFontNormal')
    info:SetPoint('LEFT')

    -- register the tag on the text widget with oUF
    self:Tag(info, '[mylayout:name(5)]') -- the output will be shortened to 5 characters
    -- self:Tag(info, '[mylayout:name]') -- alternative, the output won't be adjusted
    -- self:Tag(info, '[mylayout:name(10)]') -- alternative, the output will be shortened to 10 characters
--]]

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

local xpcall = Private.xpcall
local unitExists = Private.unitExists

local _PATTERN = '%[..-%]+'

local _ENV = {
	Hex = function(r, g, b)
		if(type(r) == 'table') then
			if(r.r) then
				r, g, b = r.r, r.g, r.b
			else
				r, g, b = unpack(r)
			end
		end
		return string.format('|cff%02x%02x%02x', r * 255, g * 255, b * 255)
	end,
}
_ENV.ColorGradient = function(...)
	return _ENV._FRAME:ColorGradient(...)
end

local _PROXY = setmetatable(_ENV, {__index = _G})

local tagStrings = {
	['affix'] = [[function(u)
		local c = UnitClassification(u)
		if(c == 'minus') then
			return 'Affix'
		end
	end]],

	['arcanecharges'] = [[function()
		if(GetSpecialization() == SPEC_MAGE_ARCANE) then
			local num = UnitPower('player', Enum.PowerType.ArcaneCharges)
			if(num > 0) then
				return num
			end
		end
	end]],

	['arenaspec'] = [[function(u)
		local id = u:match('arena(%d)$')
		if(id) then
			local specID = GetArenaOpponentSpec(tonumber(id))
			if(specID and specID > 0) then
				local _, specName = GetSpecializationInfoByID(specID)
				return specName
			end
		end
	end]],

	['chi'] = [[function()
		if(GetSpecialization() == SPEC_MONK_WINDWALKER) then
			local num = UnitPower('player', Enum.PowerType.Chi)
			if(num > 0) then
				return num
			end
		end
	end]],

	['classification'] = [[function(u)
		local c = UnitClassification(u)
		if(c == 'rare') then
			return 'Rare'
		elseif(c == 'rareelite') then
			return 'Rare Elite'
		elseif(c == 'elite') then
			return 'Elite'
		elseif(c == 'worldboss') then
			return 'Boss'
		elseif(c == 'minus') then
			return 'Affix'
		end
	end]],

	['cpoints'] = [[function(u)
		local cp = UnitPower(u, Enum.PowerType.ComboPoints)

		if(cp > 0) then
			return cp
		end
	end]],

	['creature'] = [[function(u)
		return UnitCreatureFamily(u) or UnitCreatureType(u)
	end]],

	['curmana'] = [[function(unit)
		return UnitPower(unit, Enum.PowerType.Mana)
	end]],

	['dead'] = [[function(u)
		if(UnitIsDead(u)) then
			return 'Dead'
		elseif(UnitIsGhost(u)) then
			return 'Ghost'
		end
	end]],

	['deficit:name'] = [[function(u)
		local missinghp = _TAGS['missinghp'](u)
		if(missinghp) then
			return '-' .. missinghp
		else
			return _TAGS['name'](u)
		end
	end]],

	['difficulty'] = [[function(u)
		if UnitCanAttack('player', u) then
			local l = UnitEffectiveLevel(u)
			return Hex(GetCreatureDifficultyColor((l > 0) and l or 999))
		end
	end]],

	['group'] = [[function(unit)
		local name, server = UnitName(unit)
		if(server and server ~= '') then
			name = string.format('%s-%s', name, server)
		end

		for i=1, GetNumGroupMembers() do
			local raidName, _, group = GetRaidRosterInfo(i)
			if( raidName == name ) then
				return group
			end
		end
	end]],

	['holypower'] = [[function()
		if(GetSpecialization() == SPEC_PALADIN_RETRIBUTION) then
			local num = UnitPower('player', Enum.PowerType.HolyPower)
			if(num > 0) then
				return num
			end
		end
	end]],

	['leader'] = [[function(u)
		if(UnitIsGroupLeader(u)) then
			return 'L'
		end
	end]],

	['leaderlong']  = [[function(u)
		if(UnitIsGroupLeader(u)) then
			return 'Leader'
		end
	end]],

	['level'] = [[function(u)
		local l = UnitLevel(u)
		if(UnitIsWildBattlePet and UnitIsWildBattlePet(u) or UnitIsWildBattlePet and UnitIsBattlePetCompanion(u)) then
			l = UnitBattlePetLevel(u)
		end

		if(l > 0) then
			return l
		else
			return '??'
		end
	end]],

	['maxmana'] = [[function(unit)
		return UnitPowerMax(unit, Enum.PowerType.Mana)
	end]],

	['missinghp'] = [[function(u)
		local current = UnitHealthMax(u) - UnitHealth(u)
		if(current > 0) then
			return current
		end
	end]],

	['missingpp'] = [[function(u)
		local current = UnitPowerMax(u) - UnitPower(u)
		if(current > 0) then
			return current
		end
	end]],

	['name'] = [[function(u, r)
		return UnitName(r or u)
	end]],

	['offline'] = [[function(u)
		if(not UnitIsConnected(u)) then
			return 'Offline'
		end
	end]],

	['perhp'] = [[function(u)
		local m = UnitHealthMax(u)
		if(m == 0) then
			return 0
		else
			return math.floor(UnitHealth(u) / m * 100 + .5)
		end
	end]],

	['perpp'] = [[function(u)
		local m = UnitPowerMax(u)
		if(m == 0) then
			return 0
		else
			return math.floor(UnitPower(u) / m * 100 + .5)
		end
	end]],

	['plus'] = [[function(u)
		local c = UnitClassification(u)
		if(c == 'elite' or c == 'rareelite') then
			return '+'
		end
	end]],

	['powercolor'] = [[function(u)
		local pType, pToken, altR, altG, altB = UnitPowerType(u)
		local t = _COLORS.power[pToken]

		if(not t) then
			if(altR) then
				if(altR > 1 or altG > 1 or altB > 1) then
					return Hex(altR / 255, altG / 255, altB / 255)
				else
					return Hex(altR, altG, altB)
				end
			else
				return Hex(_COLORS.power[pType] or _COLORS.power.MANA)
			end
		end

		return Hex(t)
	end]],

	['pvp'] = [[function(u)
		if(UnitIsPVP(u)) then
			return 'PvP'
		end
	end]],

	['raidcolor'] = [[function(u)
		local _, class = UnitClass(u)
		if(class) then
			return Hex(_COLORS.class[class])
		else
			local id = u:match('arena(%d)$')
			if(id) then
				local specID = GetArenaOpponentSpec(tonumber(id))
				if(specID and specID > 0) then
					_, _, _, _, _, class = GetSpecializationInfoByID(specID)
					return Hex(_COLORS.class[class])
				end
			end
		end
	end]],

	['rare'] = [[function(u)
		local c = UnitClassification(u)
		if(c == 'rare' or c == 'rareelite') then
			return 'Rare'
		end
	end]],

	['resting'] = [[function(u)
		if(u == 'player' and IsResting()) then
			return 'zzz'
		end
	end]],

	['runes'] = [[function()
		local amount = 0

		for i = 1, 6 do
			local _, _, ready = GetRuneCooldown(i)
			if(ready) then
				amount = amount + 1
			end
		end

		return amount
	end]],

	['sex'] = [[function(u)
		local s = UnitSex(u)
		if(s == 2) then
			return 'Male'
		elseif(s == 3) then
			return 'Female'
		end
	end]],

	['shortclassification'] = [[function(u)
		local c = UnitClassification(u)
		if(c == 'rare') then
			return 'R'
		elseif(c == 'rareelite') then
			return 'R+'
		elseif(c == 'elite') then
			return '+'
		elseif(c == 'worldboss') then
			return 'B'
		elseif(c == 'minus') then
			return '-'
		end
	end]],

	['smartclass'] = [[function(u)
		if(UnitIsPlayer(u)) then
			return _TAGS['class'](u)
		end

		return _TAGS['creature'](u)
	end]],

	['smartlevel'] = [[function(u)
		local c = UnitClassification(u)
		if(c == 'worldboss') then
			return 'Boss'
		else
			local plus = _TAGS['plus'](u)
			local level = _TAGS['level'](u)
			if(plus) then
				return level .. plus
			else
				return level
			end
		end
	end]],

	['soulshards'] = [[function()
		local num = UnitPower('player', Enum.PowerType.SoulShards)
		if(num > 0) then
			return num
		end
	end]],

	['status'] = [[function(u)
		if(UnitIsDead(u)) then
			return 'Dead'
		elseif(UnitIsGhost(u)) then
			return 'Ghost'
		elseif(not UnitIsConnected(u)) then
			return 'Offline'
		else
			return _TAGS['resting'](u)
		end
	end]],

	['threat'] = [[function(u)
		local s = UnitThreatSituation(u)
		if(s == 1) then
			return '++'
		elseif(s == 2) then
			return '--'
		elseif(s == 3) then
			return 'Aggro'
		end
	end]],

	['threatcolor'] = [[function(u)
		return Hex(GetThreatStatusColor(UnitThreatSituation(u)))
	end]],
}

local tags = setmetatable(
	{
		curhp = UnitHealth,
		curpp = UnitPower,
		maxhp = UnitHealthMax,
		maxpp = UnitPowerMax,
		class = UnitClass,
		faction = UnitFactionGroup,
		race = UnitRace,
	},
	{
		__index = function(self, key)
			local tagString = tagStrings[key]
			if(tagString) then
				self[key] = tagString
				tagStrings[key] = nil
			end

			return rawget(self, key)
		end,
		__newindex = function(self, key, val)
			if(type(val) == 'string') then
				local func, err = loadstring('return ' .. val)
				if(func) then
					val = func()
				else
					error(err, 3)
				end
			end

			assert(type(val) == 'function', 'Tag function must be a function or a string that evaluates to a function.')

			-- We don't want to clash with any custom envs
			if(getfenv(val) == _G) then
				-- pcall is needed for cases when Blizz functions are passed as
				-- strings, for intance, 'UnitPowerMax', an attempt to set a
				-- custom env will result in an error
				pcall(setfenv, val, _PROXY)
			end

			rawset(self, key, val)
		end,
	}
)

_ENV._TAGS = tags

local vars = setmetatable({}, {
	__newindex = function(self, key, val)
		if(type(val) == 'string') then
			local func = loadstring('return ' .. val)
			if(func) then
				val = func() or val
			end
		end

		rawset(self, key, val)
	end,
})

_ENV._VARS = vars

local tagEvents = {
	['affix']               = 'UNIT_CLASSIFICATION_CHANGED',
	['arcanecharges']       = 'UNIT_POWER_UPDATE PLAYER_TALENT_UPDATE',
	['arenaspec']           = 'ARENA_PREP_OPPONENT_SPECIALIZATIONS',
	['chi']                 = 'UNIT_POWER_UPDATE PLAYER_TALENT_UPDATE',
	['classification']      = 'UNIT_CLASSIFICATION_CHANGED',
	['cpoints']             = 'UNIT_POWER_FREQUENT PLAYER_TARGET_CHANGED',
	['curhp']               = 'UNIT_HEALTH UNIT_MAXHEALTH',
	['curmana']             = 'UNIT_POWER_UPDATE UNIT_MAXPOWER',
	['curpp']               = 'UNIT_POWER_UPDATE UNIT_MAXPOWER',
	['dead']                = 'UNIT_HEALTH',
	['deficit:name']        = 'UNIT_HEALTH UNIT_MAXHEALTH UNIT_NAME_UPDATE',
	['difficulty']          = 'UNIT_FACTION',
	['faction']             = 'NEUTRAL_FACTION_SELECT_RESULT',
	['group']               = 'GROUP_ROSTER_UPDATE',
	['holypower']           = 'UNIT_POWER_UPDATE PLAYER_TALENT_UPDATE',
	['leader']              = 'PARTY_LEADER_CHANGED',
	['leaderlong']          = 'PARTY_LEADER_CHANGED',
	['level']               = 'UNIT_LEVEL PLAYER_LEVEL_UP',
	['maxhp']               = 'UNIT_MAXHEALTH',
	['maxmana']             = 'UNIT_POWER_UPDATE UNIT_MAXPOWER',
	['maxpp']               = 'UNIT_MAXPOWER',
	['missinghp']           = 'UNIT_HEALTH UNIT_MAXHEALTH',
	['missingpp']           = 'UNIT_MAXPOWER UNIT_POWER_UPDATE',
	['name']                = 'UNIT_NAME_UPDATE',
	['offline']             = 'UNIT_HEALTH UNIT_CONNECTION',
	['perhp']               = 'UNIT_HEALTH UNIT_MAXHEALTH',
	['perpp']               = 'UNIT_MAXPOWER UNIT_POWER_UPDATE',
	['plus']                = 'UNIT_CLASSIFICATION_CHANGED',
	['powercolor']          = 'UNIT_DISPLAYPOWER',
	['pvp']                 = 'UNIT_FACTION',
	['rare']                = 'UNIT_CLASSIFICATION_CHANGED',
	['resting']             = 'PLAYER_UPDATE_RESTING',
	['runes']               = 'RUNE_POWER_UPDATE',
	['shortclassification'] = 'UNIT_CLASSIFICATION_CHANGED',
	['smartlevel']          = 'UNIT_LEVEL PLAYER_LEVEL_UP UNIT_CLASSIFICATION_CHANGED',
	['soulshards']          = 'UNIT_POWER_UPDATE',
	['status']              = 'UNIT_HEALTH PLAYER_UPDATE_RESTING UNIT_CONNECTION',
	['threat']              = 'UNIT_THREAT_SITUATION_UPDATE',
	['threatcolor']         = 'UNIT_THREAT_SITUATION_UPDATE',
}

local unitlessEvents = {
	ARENA_PREP_OPPONENT_SPECIALIZATIONS = true,
	GROUP_ROSTER_UPDATE = true,
	NEUTRAL_FACTION_SELECT_RESULT = true,
	PARTY_LEADER_CHANGED = true,
	PLAYER_LEVEL_UP = true,
	PLAYER_TALENT_UPDATE = true,
	PLAYER_TARGET_CHANGED = true,
	PLAYER_UPDATE_RESTING = true,
	RUNE_POWER_UPDATE = true,
}

local events = {}
local eventFrame = CreateFrame('Frame')
eventFrame:SetScript('OnEvent', function(self, event, unit)
	local strings = events[event]
	if(strings) then
		for _, fs in next, strings do
			if(fs:IsVisible() and (unitlessEvents[event] or fs.parent.unit == unit or (fs.extraUnits and fs.extraUnits[unit]))) then
				fs:UpdateTag()
			end
		end
	end
end)

local onUpdates = {}
local eventlessUnits = {}

local function createOnUpdate(timer)
	if(not onUpdates[timer]) then
		local total = timer
		local frame = CreateFrame('Frame')
		local strings = eventlessUnits[timer]

		frame:SetScript('OnUpdate', function(self, elapsed)
			if(total >= timer) then
				for _, fs in next, strings do
					if(fs.parent:IsShown() and unitExists(fs.parent.unit)) then
						fs:UpdateTag()
					end
				end

				total = 0
			end

			total = total + elapsed
		end)

		onUpdates[timer] = frame
	end
end

--[[ Tags: frame:UpdateTags()
Used to update all tags on a frame.

* self - the unit frame from which to update the tags
--]]
local function Update(self)
	if(self.__tags) then
		for fs in next, self.__tags do
			fs:UpdateTag()
		end
	end
end

local tagPool = {}
local funcPool = {}
local tmp = {}

local function getBracketData(tag)
	-- full tag syntax: '[prefix$>tag-name<$suffix(a,r,g,s)]'
	local suffixEnd = (tag:match('()%(') or -1) - 1

	local prefixEnd, prefixOffset = tag:match('()$>'), 1
	if(not prefixEnd) then
		prefixEnd = 1
	else
		prefixEnd = prefixEnd - 1
		prefixOffset = 3
	end

	local suffixStart, suffixOffset = tag:match('<$()', prefixEnd), 1
	if(not suffixStart) then
		suffixStart = suffixEnd + 1
	else
		suffixOffset = 3
	end

	return tag:sub(prefixEnd + prefixOffset, suffixStart - suffixOffset), prefixEnd, suffixStart, suffixEnd, tag:match('%((.-)%)')
end

local function getTagFunc(tagstr)
	local func = tagPool[tagstr]
	if(not func) then
		local format, numTags = tagstr:gsub('%%', '%%%%'):gsub(_PATTERN, '%%s')
		local args = {}

		for bracket in tagstr:gmatch(_PATTERN) do
			local tagFunc = funcPool[bracket] or tags[bracket:sub(2, -2)]
			if(not tagFunc) then
				local tagName, prefixEnd, suffixStart, suffixEnd, customArgs = getBracketData(bracket)
				local tag = tags[tagName]
				if(tag) then
					if(prefixEnd ~= 1 and suffixStart - suffixEnd ~= 1) then
						local prefix = bracket:sub(2, prefixEnd)
						local suffix = bracket:sub(suffixStart, suffixEnd)

						tagFunc = function(unit, realUnit)
							local str
							if(customArgs) then
								str = tag(unit, realUnit, strsplit(',', customArgs))
							else
								str = tag(unit, realUnit)
							end

							if(str and str ~= '') then
								return prefix .. str .. suffix
							end
						end
					elseif(prefixEnd ~= 1) then
						local prefix = bracket:sub(2, prefixEnd)

						tagFunc = function(unit, realUnit)
							local str
							if(customArgs) then
								str = tag(unit, realUnit, strsplit(',', customArgs))
							else
								str = tag(unit, realUnit)
							end

							if(str and str ~= '') then
								return prefix .. str
							end
						end
					elseif(suffixStart - suffixEnd ~= 1) then
						local suffix = bracket:sub(suffixStart, suffixEnd)

						tagFunc = function(unit, realUnit)
							local str
							if(customArgs) then
								str = tag(unit, realUnit, strsplit(',', customArgs))
							else
								str = tag(unit, realUnit)
							end

							if(str and str ~= '') then
								return str .. suffix
							end
						end
					else
						tagFunc = function(unit, realUnit)
							local str
							if(customArgs) then
								str = tag(unit, realUnit, strsplit(',', customArgs))
							else
								str = tag(unit, realUnit)
							end

							if(str and str ~= '') then
								return str
							end
						end
					end

					funcPool[bracket] = tagFunc
				end
			end

			if(tagFunc) then
				table.insert(args, tagFunc)
			else
				return error(string.format('Attempted to use invalid tag %s.', bracket), 3)
			end
		end

		func = function(self)
			local parent = self.parent
			local unit = parent.unit
			local realUnit
			if(self.overrideUnit) then
				realUnit = parent.realUnit
			end

			_ENV._COLORS = parent.colors
			_ENV._FRAME = parent
			for i, f in next, args do
				tmp[i] = f(unit, realUnit) or ''
			end

			-- We do 1, numTags because tmp can hold several unneeded variables.
			return self:SetFormattedText(format, unpack(tmp, 1, numTags))
		end

		tagPool[tagstr] = func
	end

	return func
end

local function registerEvent(fontstr, event)
	if(not events[event]) then events[event] = {} end

	local isOK = xpcall(eventFrame.RegisterEvent, eventFrame, event)
	if(isOK) then
		table.insert(events[event], fontstr)
	end
end

local function registerEvents(fontstr, tagstr)
	for tag in tagstr:gmatch(_PATTERN) do
		tag = getBracketData(tag)
		local tagevents = tagEvents[tag]
		if(tagevents) then
			for event in tagevents:gmatch('%S+') do
				registerEvent(fontstr, event)
			end
		end
	end
end

local function unregisterEvents(fontstr)
	for event, data in next, events do
		local index = 1
		local tagfsstr = data[index]
		while tagfsstr do
			if(tagfsstr == fontstr) then
				if(#data == 1) then
					eventFrame:UnregisterEvent(event)
				end

				table.remove(data, index)
			else
				index = index + 1
			end

			tagfsstr = data[index]
		end
	end
end

local taggedFS = {}

--[[ Tags: frame:Tag(fs, tagstr, ...)
Used to register a tag on a unit frame.

* self   - the unit frame on which to register the tag
* fs     - the font string to display the tag (FontString)
* tagstr - the tag string (string)
* ...    - additional optional unitID(s) the tag should update for
--]]
local function Tag(self, fs, tagstr, ...)
	if(not fs or not tagstr) then return end

	if(not self.__tags) then
		self.__tags = {}
		table.insert(self.__elements, Update)
	elseif(self.__tags[fs]) then
		-- We don't need to remove it from the __tags table as Untag handles
		-- that for us.
		self:Untag(fs)
	end

	fs.parent = self
	fs.UpdateTag = getTagFunc(tagstr)

	if(self.__eventless or fs.frequentUpdates) then
		local timer
		if(type(fs.frequentUpdates) == 'number') then
			timer = fs.frequentUpdates
		else
			timer = .5
		end

		if(not eventlessUnits[timer]) then eventlessUnits[timer] = {} end
		table.insert(eventlessUnits[timer], fs)

		createOnUpdate(timer)
	else
		registerEvents(fs, tagstr)

		if(...) then
			if(not fs.extraUnits) then
				fs.extraUnits = {}
			end

			for index = 1, select('#', ...) do
				fs.extraUnits[select(index, ...)] = true
			end
		end
	end

	taggedFS[fs] = tagstr
	self.__tags[fs] = true
end

--[[ Tags: frame:Untag(fs)
Used to unregister a tag from a unit frame.

* self - the unit frame from which to unregister the tag
* fs   - the font string holding the tag (FontString)
--]]
local function Untag(self, fs)
	if(not fs or not self.__tags) then return end

	unregisterEvents(fs)
	for _, timers in next, eventlessUnits do
		local index = 1
		local fontstr = timers[index]
		while fontstr do
			if(fs == fontstr) then
				table.remove(timers, index)
			else
				index = index + 1
			end

			fontstr = timers[index]
		end
	end

	fs.UpdateTag = nil

	taggedFS[fs] = nil
	self.__tags[fs] = nil
end

local function strip(tag)
	-- remove prefix, custom args, and suffix
	return tag:gsub('%[.-$>', '['):gsub('%(.-%)%]', ']'):gsub('<$.-%]', ']')
end

oUF.Tags = {
	Methods = tags,
	Events = tagEvents,
	SharedEvents = unitlessEvents,
	Vars = vars,
	RefreshMethods = function(self, tag)
		if(not tag) then return end

		-- If a tag's name contains magic chars, there's a chance that
		-- string.match will fail to find the match.
		tag = '%[' .. tag:gsub('[%^%$%(%)%%%.%*%+%-%?]', '%%%1') .. '%]'

		for func in next, funcPool do
			if(strip(func):match(tag)) then
				funcPool[func] = nil
			end
		end

		for tagstr, func in next, tagPool do
			if(strip(tagstr):match(tag)) then
				tagPool[tagstr] = nil

				for fs in next, taggedFS do
					if(fs.UpdateTag == func) then
						fs.UpdateTag = getTagFunc(tagstr)

						if(fs:IsVisible()) then
							fs:UpdateTag()
						end
					end
				end
			end
		end
	end,
	RefreshEvents = function(self, tag)
		if(not tag) then return end

		-- If a tag's name contains magic chars, there's a chance that
		-- string.match will fail to find the match.
		tag = '%[' .. tag:gsub('[%^%$%(%)%%%.%*%+%-%?]', '%%%1') .. '%]'
		for tagstr in next, tagPool do
			if(strip(tagstr):match(tag)) then
				for fs, ts in next, taggedFS do
					if(ts == tagstr) then
						unregisterEvents(fs)
						registerEvents(fs, tagstr)
					end
				end
			end
		end
	end,
}

oUF:RegisterMetaFunction('Tag', Tag)
oUF:RegisterMetaFunction('Untag', Untag)
oUF:RegisterMetaFunction('UpdateTags', Update)