--[[
# Element: ClassPower

Handles the visibility and updating of the player's class resources (like Chi Orbs or Holy Power) and combo points.

## Widget

ClassPower - An `table` consisting of as many StatusBars as the theoretical maximum return of [UnitPowerMax](https://warcraft.wiki.gg/wiki/API_UnitPowerMax).

## Notes

A default texture will be applied if the sub-widgets are StatusBars and don't have a texture set.
If the sub-widgets are StatusBars, their minimum and maximum values will be set to 0 and 1 respectively.

Supported class powers:
  - All          - Combo Points
  - Demon Hunter - Soul Fragments
  - Evoker       - Essence
  - Hunter       - Tip of the Spear
  - Mage         - Arcane Charges
  - Mage         - Icicles
  - Monk         - Chi Orbs
  - Paladin      - Holy Power
  - Shaman       - Maelstrom Weapon
  - Warlock      - Soul Shards

## Examples

    local ClassPower = {}
    for index = 1, 10 do
        local Bar = CreateFrame('StatusBar', nil, self)

        -- Position and size.
        Bar:SetSize(16, 16)
        Bar:SetPoint('TOPLEFT', self, 'BOTTOMLEFT', (index - 1) * Bar:GetWidth(), 0)

        ClassPower[index] = Bar
    end

    -- Register with oUF
    self.ClassPower = ClassPower
--]]

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

local unitIsUnit = Private.unitIsUnit

local playerClass = UnitClassBase('player')

-- sourced from Blizzard_FrameXMLBase/Constants.lua
local SPEC_DEMONHUNTER_DEVOURER = _G.SPEC_DEMONHUNTER_DEVOURER or 3
local SPEC_MAGE_ARCANE = _G.SPEC_MAGE_ARCANE or 1
local SPEC_MONK_WINDWALKER = _G.SPEC_MONK_WINDWALKER or 3
local SPEC_WARLOCK_DESTRUCTION = _G.SPEC_WARLOCK_DESTRUCTION or 3
local SPEC_MAGE_FROST = 3

local POWER_ID_ARCANE_CHARGES = Enum.PowerType.ArcaneCharges or 16
local POWER_ID_CHI = Enum.PowerType.Chi or 12
local POWER_ID_COMBO_POINTS = Enum.PowerType.ComboPoints or 4
local POWER_ID_ENERGY = Enum.PowerType.Energy or 3
local POWER_ID_ESSENCE = Enum.PowerType.Essence or 19
local POWER_ID_HOLY_POWER = Enum.PowerType.HolyPower or 9
local POWER_ID_SOUL_SHARDS = Enum.PowerType.SoulShards or 7

local POWER_TYPE_ARCANE_CHARGES = 'ARCANE_CHARGES'
local POWER_TYPE_CHI = 'CHI'
local POWER_TYPE_COMBO_POINTS = 'COMBO_POINTS'
local POWER_TYPE_ESSENCE = 'ESSENCE'
local POWER_TYPE_HOLY_POWER = 'HOLY_POWER'
local POWER_TYPE_ICICLES = 'ICICLES' -- fake
local POWER_TYPE_MAELSTROM = 'MAELSTROM'
local POWER_TYPE_SOUL_FRAGMENTS = 'SOUL_FRAGMENTS' -- fake, but it's present in PowerBarColor
local POWER_TYPE_SOUL_SHARDS = 'SOUL_SHARDS'
local POWER_TYPE_TIP_OF_THE_SPEAR = 'TIP_OF_THE_SPEAR' -- fake

local SPELL_DARK_HEART = Constants.UnitPowerSpellIDs.DARK_HEART_SPELL_ID or 1225789
local SPELL_ICICLES = 205473
local SPELL_ICICLES_TALENT = 1246832
local SPELL_MAELSTROM_WEAPON = 344179
local SPELL_MAELSTROM_WEAPON_TALENT = 187880
local SPELL_SHRED = 5221
local SPELL_SILENCE_THE_WHISPERS = Constants.UnitPowerSpellIDs.SILENCE_THE_WHISPERS_SPELL_ID or 1227702
local SPELL_TIP_OF_THE_SPEAR = 260286
local SPELL_TIP_OF_THE_SPEAR_TALENT = 260285
local SPELL_VOID_METAMORPHOSIS = Constants.UnitPowerSpellIDs.VOID_METAMORPHOSIS_SPELL_ID or 1217607

local SOUL_FRAGMENTS_NO_META_INDEX = 1
local SOUL_FRAGMENTS_META_INDEX = 2

local ClassPowerEnable, ClassPowerDisable
local GetPower, GetPowerMax, GetPowerColor, GetPowerUpdaters
local GetPowerInfo, GetAuraInfo

local function GetGenericPower(unit, powerID)
	return UnitPower(unit, powerID)
end

local function GetGenericPowerMax(unit, powerID)
	return UnitPowerMax(unit, powerID)
end

local function GetGenericPowerColor(element, powerType)
	return element.__owner.colors.power[powerType]
end

local function GetComboPoints(unit)
	return UnitPower(unit, POWER_ID_COMBO_POINTS), GetUnitChargedPowerPoints(unit)
end

local function GetComboPointsMax(unit)
	return UnitPowerMax(unit, POWER_ID_COMBO_POINTS)
end

if(playerClass == 'DEMONHUNTER') then
	local function GetSoulFragments()
		if(C_UnitAuras.GetPlayerAuraBySpellID(SPELL_VOID_METAMORPHOSIS)) then
			local auraInfo = C_UnitAuras.GetPlayerAuraBySpellID(SPELL_SILENCE_THE_WHISPERS)
			if(auraInfo) then
				return auraInfo.applications / GetCollapsingStarCost()
			end
		else
			local auraInfo = C_UnitAuras.GetPlayerAuraBySpellID(SPELL_DARK_HEART)
			if(auraInfo) then
				return auraInfo.applications / C_Spell.GetSpellMaxCumulativeAuraApplications(SPELL_DARK_HEART)
			end
		end

		return 0
	end

	local function GetSoulFragmentsMax()
		-- we use normalised cur so that there's only 1 bar instead of 30-50
		return 1
	end

	local function GetSoulFragmentsColor(element)
		local color = element.__owner.colors.power[POWER_TYPE_SOUL_FRAGMENTS]
		if(color) then
			if(C_UnitAuras.GetPlayerAuraBySpellID(SPELL_VOID_METAMORPHOSIS)) then
				return color[SOUL_FRAGMENTS_META_INDEX]
			end

			return color[SOUL_FRAGMENTS_NO_META_INDEX]
		end
	end

	GetPowerUpdaters = function()
		return GetSoulFragments, GetSoulFragmentsMax, GetSoulFragmentsColor
	end

	GetAuraInfo = function()
		if(C_SpecializationInfo.GetSpecialization() == SPEC_DEMONHUNTER_DEVOURER) then
			return POWER_TYPE_SOUL_FRAGMENTS
		end
	end
elseif(playerClass == 'DRUID') then
	GetPowerUpdaters = function()
		return GetComboPoints, GetComboPointsMax, GetGenericPowerColor
	end

	GetPowerInfo = function()
		if(UnitPowerType('player') == POWER_ID_ENERGY and C_SpellBook.IsSpellKnown(SPELL_SHRED)) then
			return POWER_TYPE_COMBO_POINTS, POWER_ID_COMBO_POINTS
		end
	end
elseif(playerClass == 'EVOKER') then
	GetPowerUpdaters = function()
		return GetGenericPower, GetGenericPowerMax, GetGenericPowerColor
	end

	GetPowerInfo = function() -- might as well be static
		return POWER_TYPE_ESSENCE, POWER_ID_ESSENCE
	end
elseif(playerClass == 'HUNTER') then
	local function GetTipOfTheSpear()
		local auraInfo = C_UnitAuras.GetPlayerAuraBySpellID(SPELL_TIP_OF_THE_SPEAR)
		if(auraInfo) then
			return auraInfo.applications
		end

		return 0
	end

	local function GetTipOfTheSpearMax()
		return C_Spell.GetSpellMaxCumulativeAuraApplications(SPELL_TIP_OF_THE_SPEAR)
	end

	local function GetTipOfTheSpearColor(element)
		return element.__owner.colors.power[POWER_TYPE_TIP_OF_THE_SPEAR]
	end

	GetPowerUpdaters = function()
		return GetTipOfTheSpear, GetTipOfTheSpearMax, GetTipOfTheSpearColor
	end

	GetAuraInfo = function()
		if(C_SpellBook.IsSpellKnownOrInSpellBook(SPELL_TIP_OF_THE_SPEAR_TALENT, 0, false)) then
			return POWER_TYPE_TIP_OF_THE_SPEAR
		end
	end
elseif(playerClass == 'MAGE') then
	local function GetIcicles(unit)
		local auraInfo = C_UnitAuras.GetPlayerAuraBySpellID(SPELL_ICICLES)
		if(auraInfo) then
			return auraInfo.applications
		end

		return 0
	end

	local function GetIciclesMax()
		return C_Spell.GetSpellMaxCumulativeAuraApplications(SPELL_ICICLES)
	end

	local function GetIciclesColor(element)
		local color = element.__owner.colors.power[POWER_TYPE_ICICLES]
		if(color) then
			return color
		end
	end

	GetPowerUpdaters = function()
		local specialization = C_SpecializationInfo.GetSpecialization()
		if(specialization == SPEC_MAGE_ARCANE) then
			return GetGenericPower, GetGenericPowerMax, GetGenericPowerColor
		elseif(specialization == SPEC_MAGE_FROST) then
			return GetIcicles, GetIciclesMax, GetIciclesColor
		end
	end

	GetPowerInfo = function()
		if(C_SpecializationInfo.GetSpecialization() == SPEC_MAGE_ARCANE) then
			return POWER_TYPE_ARCANE_CHARGES, POWER_ID_ARCANE_CHARGES
		end
	end

	GetAuraInfo = function()
		if(C_SpellBook.IsSpellKnownOrInSpellBook(SPELL_ICICLES_TALENT, 0, false)) then
			return POWER_TYPE_ICICLES
		end
	end
elseif(playerClass == 'MONK') then
	GetPowerUpdaters = function()
		return GetGenericPower, GetGenericPowerMax, GetGenericPowerColor
	end

	GetPowerInfo = function()
		if(C_SpecializationInfo.GetSpecialization() == SPEC_MONK_WINDWALKER) then
			return POWER_TYPE_CHI, POWER_ID_CHI
		end
	end
elseif(playerClass == 'PALADIN') then
	GetPowerUpdaters = function()
		return GetGenericPower, GetGenericPowerMax, GetGenericPowerColor
	end

	GetPowerInfo = function() -- might as well be static
		return POWER_TYPE_HOLY_POWER, POWER_ID_HOLY_POWER
	end
elseif(playerClass == 'ROGUE') then
	GetPowerUpdaters = function()
		return GetComboPoints, GetComboPointsMax, GetGenericPowerColor
	end

	GetPowerInfo = function() -- might as well be static
		return POWER_TYPE_COMBO_POINTS, POWER_ID_COMBO_POINTS
	end
elseif(playerClass == 'SHAMAN') then
	local function GetMaelstromWeapon()
		local auraInfo = C_UnitAuras.GetPlayerAuraBySpellID(SPELL_MAELSTROM_WEAPON)
		if(auraInfo) then
			return auraInfo.applications
		end

		return 0
	end

	local function GetMaelstromWeaponMax()
		return C_Spell.GetSpellMaxCumulativeAuraApplications(SPELL_MAELSTROM_WEAPON)
	end

	GetPowerUpdaters = function()
		return GetMaelstromWeapon, GetMaelstromWeaponMax, GetGenericPowerColor
	end

	GetAuraInfo = function()
		if(C_SpellBook.IsSpellKnownOrInSpellBook(SPELL_MAELSTROM_WEAPON_TALENT, 0, false)) then
			return POWER_TYPE_MAELSTROM -- we re-use the power type from elemental
		end
	end
elseif(playerClass == 'WARLOCK') then
	local function GetSoulShardsDestruction(unit)
		return UnitPower(unit, POWER_ID_SOUL_SHARDS, true) / UnitPowerDisplayMod(POWER_ID_SOUL_SHARDS)
	end

	GetPowerUpdaters = function()
		if(C_SpecializationInfo.GetSpecialization() == SPEC_WARLOCK_DESTRUCTION) then
			return GetSoulShardsDestruction, GetGenericPowerMax, GetGenericPowerColor
		end

		return GetGenericPower, GetGenericPowerMax, GetGenericPowerColor
	end

	GetPowerInfo = function() -- might as well be static
		return POWER_TYPE_SOUL_SHARDS, POWER_ID_SOUL_SHARDS
	end
end

local function UpdateColor(element, powerType)
	local color = GetPowerColor(element, powerType)
	if(color) then
		for i = 1, #element do
			local bar = element[i]
			bar:SetStatusBarColor(color:GetRGB())
		end
	end

	--[[ Callback: ClassPower:PostUpdateColor(color)
	Called after the element color has been updated.

	* self  - the ClassPower element
	* color - the used ColorMixin-based object (table?)
	--]]
	if(element.PostUpdateColor) then
		element:PostUpdateColor(color)
	end
end

local function ColorPath(self)
	local element = self.ClassPower

	local powerType = element.__powerType
	if(UnitHasVehicleUI('player')) then
		powerType = POWER_TYPE_COMBO_POINTS
	end

	--[[ Override: ClassPower:UpdateColor(powerType)
	Used to completely override the internal function for updating the widgets' colors.

	* self      - the ClassPower element
	* powerType - the active power type (string)
	--]]
	do
		(element.UpdateColor or UpdateColor) (element, powerType)
	end
end

local function Update(self, event, unit, powerType)
	local element = self.ClassPower
	if(not unit) then
		return
	elseif(unit == 'vehicle' and powerType ~= POWER_TYPE_COMBO_POINTS) then
		return
	elseif(not unitIsUnit(unit, 'player')) then -- is this redundant?
		return
	elseif(event == 'UNIT_AURA' or event == 'UNIT_POWER_POINT_CHARGE') then
		-- fake the power type for events that don't provide any
		powerType = element.__powerType
	elseif(not powerType or powerType ~= element.__powerType) then
		return
	end


	--[[ Callback: ClassPower:PreUpdate(unit)
	Called before the element has been updated.

	* self - the ClassPower element
	* unit - the unit for which the update has been triggered (string)
	]]
	if(element.PreUpdate) then
		element:PreUpdate(unit)
	end

	local cur, max, chargedPoints, hasMaxChanged
	if(event ~= 'ClassPowerDisable') then
		cur, chargedPoints = GetPower(unit, element.__powerID)
		max = GetPowerMax(unit, element.__powerID)

		hasMaxChanged = max ~= element.__max
		if(hasMaxChanged) then
			for i = 1, #element do
				element[i]:SetShown(i <= max)

				if(i > max) then
					element[i]:SetValue(0)
				end
			end

			element.__max = max
		end

		local hasCurChanged = cur ~= element.__cur
		if(hasCurChanged) then
			local numActive = cur + 0.9
			for i = 1, max do
				if(i > numActive) then
					element[i]:SetValue(0)
				else
					element[i]:SetValue(cur - i + 1)
				end
			end

			element.__cur = cur
		end
	end
	--[[ Callback: ClassPower:PostUpdate(cur, max, hasMaxChanged, powerType)
	Called after the element has been updated.

	* self          - the ClassPower element
	* cur           - the current amount of power (number)
	* max           - the maximum amount of power (number)
	* hasMaxChanged - indicates whether the maximum amount has changed since the last update (boolean)
	* powerType     - the active power type (string)
	* ...           - the indices of currently charged power points, if any
	--]]
	if(element.PostUpdate) then
		return element:PostUpdate(cur, max, hasMaxChanged, powerType, unpack(chargedPoints or {}))
	end
end

local function Path(self, ...)
	--[[ Override: ClassPower.Override(self, event, unit, ...)
	Used to completely override the internal update function.

	* self  - the parent object
	* event - the event triggering the update (string)
	* unit  - the unit accompanying the event (string)
	* ...   - the arguments accompanying the event
	--]]
	return (self.ClassPower.Override or Update) (self, ...)
end

local function Visibility(self, event, unit)
	local element = self.ClassPower
	local powerType, powerID, isAuraPower

	if(UnitHasVehicleUI('player')) then
		unit = 'vehicle'

		if(PlayerVehicleHasComboPoints()) then
			powerType = POWER_TYPE_COMBO_POINTS
		end
	else
		if(GetAuraInfo) then
			powerType = GetAuraInfo()
			if(powerType) then
				isAuraPower = true
				unit = 'player'
			end
		end

		if(not powerType and GetPowerInfo) then
			powerType, powerID = GetPowerInfo()
			if(powerType) then
				unit = 'player'
			end
		end
	end

	local wasEnabled = element.__isEnabled
	local shouldEnable = powerType ~= nil

	element.__powerType = powerType
	element.__powerID = powerID

	if(shouldEnable) then
		if(unit == 'vehicle') then
			GetPower, GetPowerMax, GetPowerColor = GetComboPoints, GetComboPointsMax, GetGenericPowerColor
		else
			GetPower, GetPowerMax, GetPowerColor = GetPowerUpdaters()
		end

		ColorPath(self)
	end

	if(shouldEnable ~= wasEnabled) then
		ClassPowerDisable(self, shouldEnable)

		if(shouldEnable) then
			ClassPowerEnable(self, isAuraPower)
		end

		--[[ Callback: ClassPower:PostVisibility(isVisible)
		Called after the element's visibility has been changed.

		* self      - the ClassPower element
		* isVisible - the current visibility state of the element (boolean)
		--]]
		if(element.PostVisibility) then
			element:PostVisibility(shouldEnable)
		end
	elseif(shouldEnable) then
		Path(self, event, unit, powerType)
	end
end

local function VisibilityPath(self, event, ...)
	if(event == 'TRAIT_CONFIG_UPDATED') then
		if(C_ClassTalents.GetActiveConfigID() ~= ...) then return end
	end

	--[[ Override: ClassPower.OverrideVisibility(self, event, unit)
	Used to completely override the internal visibility function.

	* self  - the parent object
	* event - the event triggering the update (string)
	* ...   - the arguments accompanying the event
	--]]
	return (self.ClassPower.OverrideVisibility or Visibility) (self, event, ...)
end

local function ForceUpdate(element)
	return VisibilityPath(element.__owner, 'ForceUpdate', element.__owner.unit)
end

do
	function ClassPowerEnable(self, registerAuraEvents)
		if(registerAuraEvents) then
			self:RegisterEvent('UNIT_AURA', Path)
		else
			self:RegisterEvent('UNIT_MAXPOWER', Path)
			self:RegisterEvent('UNIT_POWER_UPDATE', Path)

			-- according to Blizz any class may receive this event due to specific spell auras
			self:RegisterEvent('UNIT_POWER_POINT_CHARGE', Path)
		end

		self:RegisterEvent('SPELLS_CHANGED', ColorPath, true)

		local element = self.ClassPower
		element.__isEnabled = true

		if(UnitHasVehicleUI('player')) then
			Path(self, 'ClassPowerEnable', 'vehicle', POWER_TYPE_COMBO_POINTS)
		else
			Path(self, 'ClassPowerEnable', 'player', element.__powerType)
		end
	end

	function ClassPowerDisable(self, unregisterOnly)
		self:UnregisterEvent('UNIT_AURA', Path)
		self:UnregisterEvent('UNIT_POWER_UPDATE', Path)
		self:UnregisterEvent('UNIT_MAXPOWER', Path)
		self:UnregisterEvent('UNIT_POWER_POINT_CHARGE', Path)
		self:UnregisterEvent('SPELLS_CHANGED', ColorPath)

		if(not unregisterOnly) then
			local element = self.ClassPower
			for i = 1, #element do
				element[i]:Hide()
			end

			element.__max = 0
			element.__isEnabled = false
			Path(self, 'ClassPowerDisable', 'player', element.__powerType)
		end
	end
end

local function Enable(self, unit)
	local element = self.ClassPower
	if(element and unitIsUnit(unit, 'player')) then
		element.__owner = self
		element.__max = 0
		element.ForceUpdate = ForceUpdate

		self:RegisterEvent('PLAYER_LEVEL_UP', VisibilityPath, true)
		self:RegisterEvent('TRAIT_CONFIG_UPDATED', VisibilityPath, true)
		self:RegisterEvent('UNIT_DISPLAYPOWER', VisibilityPath)

		element.ClassPowerEnable = ClassPowerEnable
		element.ClassPowerDisable = ClassPowerDisable

		for i = 1, #element do
			local bar = element[i]
			if(bar:IsObjectType('StatusBar')) then
				if(not bar:GetStatusBarTexture()) then
					bar:SetStatusBarTexture([[Interface\TargetingFrame\UI-StatusBar]])
				end

				bar:SetMinMaxValues(0, 1)
			end
		end

		return true
	end
end

local function Disable(self)
	if(self.ClassPower) then
		ClassPowerDisable(self)

		self:UnregisterEvent('PLAYER_LEVEL_UP', VisibilityPath)
		self:UnregisterEvent('TRAIT_CONFIG_UPDATED', VisibilityPath)
		self:UnregisterEvent('UNIT_DISPLAYPOWER', VisibilityPath)
	end
end

oUF:AddElement('ClassPower', VisibilityPath, Enable, Disable)
