MVVM protocols setup for swift ios project

MVVM.swift

//
//  MVVM.swift
//  ios-app
//
//  Created by xue qi liao on 9/28/23.
//

// FIXME: this entire protocol stack needs to be related, as in ONE set of MVVM should be
// related and we shouldn't be passing unrelated Models to unrelated ViewModels or Views
// but that is beyond the scope of MVP
// actually now I'm not super sure, models are definitely sharable
// maybe ViewModels will be to some extent urghhh

// RULE: I think these protocols are more for documentation than anything else
// since I can't figure out how to make the vars in the protocols the specific
// instance of MVVM instead of generic protocols

protocol CustomModelProtocol: Equatable {
    // TODO: same todo as in the extension, we should be using this id
    // to test equality but it's not working for some reason
    var id: Int { get }
    
    // TODO: is there anything all models should implement???
    // RULE: in theory only relevant data from AppState should
    // added to the models when initilized from AppState
    // this might look more generic, the init might be optional
    // this used to init from AppState but I think that's too heavy handled
    // limit the scope helps with conceptual thinking and breaking down
    // the work, so leave this commented out for now
    // for larger views it definitely makes sense to initialize from AppState though
    // init(state: AppState)
}

// MARK: Equitable conformance
//extension CustomModelProtocol {
//    func isEqual(to other: CustomModelProtocol) -> Bool {
//        return self == other
//    }
//}

// TODO: figure out why this isn't working
extension CustomModelProtocol {
    static func == (lhs: any CustomModelProtocol, rhs: any CustomModelProtocol) -> Bool {
        return lhs.id == rhs.id
    }
}

protocol CustomViewModelProtocol {
    // RULE: in theory viewModels should only contain relevant data
    // TODO: I think we actually always have a 1:1 mapping for instances of model:viewModel
    // so it should be init and not update?
    // can't make inits generic? how to do???
//    init(model: CustomModelProtocol)
}

protocol CustomViewProtocol {
    // RULE: this should also update the models of subviews
    // was debating between having the view or viewmodel do this
    // but passing a callback down and then getting it called in view
    // because view holds subviews, seems like a lot?
    // just let the view do it for now and see what happens
    func update(viewModel: CustomViewModelProtocol)
    // TODO: this feels like it could be more generic but HOW
//    func updateState(oldState: AppState, newState: AppState)
}