Refactored preset parsing

[FedorZaytsev]

In this PR I am refactored current preset parsing system to make it easier to use and scale.

Problems with current parsing

1. It uses enums which is not very scalable. In current system we have a switch for 20 cases which represent types. Parameters for the presets are mixed up - all of them (29) lies in a single CodingKeys enum.
2. It is too broad. There is no single place where all the parameters are read. Some params are read in the ItemType initializator, some in GeneralParameter and so on.
3. We need 5 additional objects to parse:

• ItemType, ActionType, LongActionType, GeneralParameter - initial parsing
• BarItemDefinition - storage for items above

4. Parameters parsing is separated from an actual object. This limits some of the future changes (import preset from BTT)

TL;DR: Current system is good enough, but probably we can do it more scalable?

Proposal

I propose to make all widgets to be based on a single base class CustomTouchBarItem which would satisfy Decodable interface and put all parameter parsing into init(from decoder: Decoder).

Pros

• Parameter parsing and object creation are close to each other.
• Simpler (in some sense, read below) creation of a new widgets. You only need to correctly implement your class and register it in one(!) place.

Cons

• Parsing is now mixed up with business logic which is not good too

Implementation details

All classes are inherited from a base class CustomTouchBarItem which satisfy Decodable. Each widget inherited from this class override class var typeIdentifier to expose its type identifier (for example appleScriptTitledButton or brightnessDown). Class also need to override init(from: Decoder) and parse all custom params. To make this class be visible for the parser you need to add this class into BarItemDefinition.types in ItemParsing.swift. Here is example how it looks like:

class NetworkBarItem: CustomButtonTouchBarItem {    
    private let flip: Bool
    
    private enum CodingKeys: String, CodingKey {
        case flip
    }
    
    override class var typeIdentifier: String {
        return "network"
    }
    
    init(identifier: NSTouchBarItem.Identifier, flip: Bool = false) {
        self.flip = flip
        super.init(identifier: identifier, title: " ")
        startMonitoringProcess()
    }

    required init?(coder _: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    required init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.flip = try container.decodeIfPresent(Bool.self, forKey: .flip) ?? false
        
        try super.init(from: decoder)
        startMonitoringProcess()
    }
....
}

Implementation limitations

1. I made typeIdentifier to be class var because I wanted to access it before creating class (need in ItemParsing.swift). Because of this I cannot enforce that everyone has overrided it and if someone would forget about it it wouldn't be able to load his class even if it is registered.
2. It is easy to create a class which is inherited from NSCustomTouchBarItem, but not so simple to inherit from some other types like NSSlider or NSPopoverTouchBarItem. However it can be done (BrightnessViewController, GroupBarItem)
3. When creating new Widget you may forget to call super.init(from: decoder). In this case it wouldn't decode basing params like width or text. Again, no way to enforce it.

Testing

While implementing I have tested all supported widgets. No regression was found. I would provide test preset later

TODO

1. README
2. Fix tests. Right now they are completely broken and I have no idea how to fix them, because it is some problem with libraries and stuff.

[FedorZaytsev]

I know that it is a big commit, but I hope that someone can take a glance at it. Ready to fix anything.

P.S. I will be happy if someone will help me with tests - it seems that MTMRTest doesn't have some libraries or something.

[Toxblh]

tests is failed