//
//  VDSLabel.swift
//  VDS
//
//  Created by Matt Bruce on 7/28/22.
//

import Foundation
import UIKit
import VDSColorTokens
import Combine

open class DefaultLabelModel: VDSLabelModel {
    public var fontCategory: VDSFontCategory = .body
    public var fontSize: VDSFontSize = .large
    public var fontWeight: VDSFontWeight = .regular
    public var textPosition: VDSTextPosition = .left
    public var surface: Surface = .light
    required public init(){}
}

open class VDSLabel: UILabel, Modelable {
    @Published public var model: VDSLabelModel = DefaultLabelModel()
    private var cancellable: AnyCancellable?

    public var fontSize: VDSFontSize {
        get { model.fontSize }
        set {
            if model.fontSize != newValue {
                model.fontSize = newValue
            }
        }
    }
    
    public var textPosition: VDSTextPosition {
        get { model.textPosition }
        set {
            if model.textPosition != newValue {
                model.textPosition = newValue
            }
        }
    }
    
    public var fontWeight: VDSFontWeight {
        get { model.fontWeight }
        set {
            if model.fontWeight != newValue {
                model.fontWeight = newValue
            }
        }
    }
    
    public var fontCategory: VDSFontCategory {
        get { model.fontCategory }
        set {
            if model.fontCategory != newValue {
                model.fontCategory = newValue
            }
        }
    }
    
    public var surface: Surface {
        get { model.surface }
        set {
            if model.surface != newValue {
                model.surface = newValue
            }
        }
    }

    //Initializers
    public convenience init() {
        self.init(frame: .zero)
    }
    
    public override init(frame: CGRect) {
        super.init(frame: frame)
        setup()
    }
    
    required public init?(coder: NSCoder) {
        super.init(coder: coder)
        setup()
    }
    
    func setup() {
        cancellable = $model.debounce(for: .seconds(ModelStateDebounce), scheduler: RunLoop.main).sink { [weak self] viewModel in
            self?.onStateChange(viewModel: viewModel)
        }
    }
    
    //functions
    private func onStateChange(viewModel: VDSLabelModel) {
        textAlignment = viewModel.textPosition.textAlignment
        textColor = viewModel.surface == .dark ? VDSColor.elementsPrimaryOndark : VDSColor.elementsPrimaryOnlight
       
        guard let vdsFont = try? VDSFontStyle.font(for: viewModel.fontCategory, fontWeight: viewModel.fontWeight, fontSize: viewModel.fontSize) else {
            font = VDSFontStyle.RegularBodyLarge.font
            return
        }
        font = vdsFont
    }
    
    //Modelable
    public func set(with model: VDSLabelModel) {
        self.model = model
    }
}