Move ivert logic and trigger logic into Trigger

The base Trigger class is now responsible for inverting the trigger
state and also for signaling trigger activation to the target/indicator.

In addition the following non-function changes also occured:
 - The triggers moved into their own directory
 - The trigger code has been annotated to help lua-language-server
   deduce type information
 - AuraTrigger was moved into its own file

All these changes should make future development of other triggers easier

src/types/triggers/auratrigger.lua

@@ -0,0 +1,94 @@
+-- Copyright 2023 <omicron.me@protonmail.com>
+--
+-- This file is part of Omicron Frames
+-- 
+-- Omicron Frames is free software: you can redistribute it and/or modify it
+-- under the terms of the GNU General Public License as published by the Free
+-- Software Foundation, either version 3 of the License, or (at your option)
+-- any later version.
+--
+-- Omicron Frames is distributed in the hope that it will be useful, but
+-- WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+-- more details.
+--
+-- You should have received a copy of the GNU General Public License along with
+-- Omicron Frames. If not, see <https://www.gnu.org/licenses/>. 
+local omi = select(2, ...)
+local types = omi.GetModule("types")
+---@class Trigger
+local Trigger = types.Trigger
+
+---AuraTrigger is a Trigger that can be attached to AuraList as datasource
+---@class AuraTrigger: Trigger
+---@field spellId number
+---@field count number
+---@field requiredCount number
+local AuraTrigger = types.CreateClass("AuraTrigger", Trigger)
+types.AuraTrigger = AuraTrigger
+
+---@return AuraTrigger
+function AuraTrigger.new(cls, ...)
+    --- I really dislike duplicating this everywhere but it makes
+    --lua-language-server able to deduce the type of Object:new calls and that
+    --is honestly worth it
+    return types.Object.new(cls, ...)
+end
+
+--- Initialize a new AuraTrigger object
+---@param spellId number
+---@param own boolean
+---@param requiredCount number | nil
+---@param invert boolean | nil
+function AuraTrigger:Init(spellId, own, requiredCount, invert)
+    Trigger.Init(self, invert)
+    self.spellId = spellId
+    self.requiredCount = requiredCount or 1
+    self.own = own
+    self.count = 0
+end
+
+--- Reset the AuraTrigger to the default state
+function AuraTrigger:Reset()
+    self.count = 0
+    self:SetState(self.count >= self.requiredCount)
+end
+
+---Check if a given aura matches this AuraTrigger
+---@param aura UnitAuraInfo
+function AuraTrigger:IsMatching(aura)
+    if aura.spellId ~= aura.spellId then
+        return false
+    end
+    if self.own and aura.sourceUnit ~= "player" then
+        return false
+    end
+    return true
+end
+
+---Inform the trigger about an added aura
+---@param aura UnitAuraInfo
+function AuraTrigger:AddAura(aura)
+    if not self:IsMatching(aura) then
+        return
+    end
+    self.count = self.count + 1
+    self:SetState(self.count >= self.requiredCount)
+end
+
+---Inform the trigger about an updated aura
+---@param before UnitAuraInfo
+---@param after UnitAuraInfo
+function AuraTrigger:UpdateAura(before, after)
+    --
+end
+
+---Inform the trigger about an aura that got removed
+---@param aura UnitAuraInfo
+function AuraTrigger:RemoveAura(aura)
+    if not self:IsMatching(aura) then
+        return
+    end
+    self.count = self.count - 1
+    self:SetState(self.count >= self.requiredCount)
+end

src/types/triggers/trigger.lua

@@ -0,0 +1,67 @@
+-- Copyright 2023 <omicron.me@protonmail.com>
+--
+-- This file is part of Omicron Frames
+-- 
+-- Omicron Frames is free software: you can redistribute it and/or modify it
+-- under the terms of the GNU General Public License as published by the Free
+-- Software Foundation, either version 3 of the License, or (at your option)
+-- any later version.
+--
+-- Omicron Frames is distributed in the hope that it will be useful, but
+-- WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+-- more details.
+--
+-- You should have received a copy of the GNU General Public License along with
+-- Omicron Frames. If not, see <https://www.gnu.org/licenses/>. 
+local omi = select(2, ...)
+local types = omi.GetModule("types")
+
+--- Triggers objects provide a link between indicators and some data source. They
+-- can pass data from the data source into the indicator. This is a supertype for 
+-- all triggers and should not be constructed on its own. 
+---@class Trigger: Object
+---@field active boolean
+---@field invert boolean 
+local Trigger = types.CreateClass("Trigger")
+types.Trigger = Trigger
+
+
+--- Initialize a new Trigger object
+---@param invert boolean|nil
+function Trigger:Init(invert)
+    invert = invert or false
+    self.invert = invert
+    self.active = invert
+end
+
+--- Set the target of the Trigger.
+-- The target will get notified every time the trigger changes state. If the trigger
+-- is currently active when the target is set, it will get notified immediately.
+---@param target Indicator
+function Trigger:SetTarget(target)
+    self.indicator = target
+end
+
+---Set the state of the trigger. Will activate the indicator if needed.
+---@param data table<string,any> | nil
+---@param state boolean
+function Trigger:SetState(state, data)
+    state = state ~= self.invert -- state xor inverted
+
+    if self.active ~= state then
+        if state then
+            self.indicator:Show(data)
+        else
+            self.indicator:Hide()
+        end
+        self.active = state
+    end
+end
+
+-- Reset the trigger to the default state. If this changes the activation of the
+-- trigger then the target will be notified.
+function Trigger:Reset()
+    self:SetState(false)
+end
+