//
//  Icon.swift
//  VDS
//
//  Created by Matt Bruce on 1/9/23.
//

import Foundation
import UIKit
import VDSColorTokens
import Combine

/// An icon is a graphical element that conveys information at a glance. It helps orient
/// a customer, explain functionality and draw attention to interactive elements. Icons
/// should have a functional purpose and should never be used for decoration.
@objc(VDSIcon)
open class Icon: View {
    
    //--------------------------------------------------
    // MARK: - Initializers
    //--------------------------------------------------
    required public init() {
        super.init(frame: .zero)
    }
    
    public override init(frame: CGRect) {
        super.init(frame: .zero)
    }
    
    public required init?(coder: NSCoder) {
        super.init(coder: coder)
    }

    //--------------------------------------------------
    // MARK: - Private Properties
    //--------------------------------------------------
    private var dimensions: CGSize {
        guard let customSize else { return size.dimensions }
        return .init(width: customSize, height: customSize)
    }
    
    //--------------------------------------------------
    // MARK: - Public Properties
    //--------------------------------------------------
    /// UIImageView used to render the icon.
    open var imageView = UIImageView().with {
        $0.translatesAutoresizingMaskIntoConstraints = false
        $0.contentMode = .scaleAspectFill
        $0.clipsToBounds = true
    }
    
    /// Color of the icon.
    open var color: UIColor = VDSColor.paletteBlack {
        didSet {
            if let hex = color.hexString, !UIColor.isVDSColor(color: color) {
                print("icon.color is not a VDSColor. Hex: \(hex) is not a supported color")
            }
            setNeedsUpdate()
        }
    }
    
    /// Size of the icon.
    open var size: Size = .medium { didSet { setNeedsUpdate() }}
    
    /// This will be used to render the icon with corresponding name.
    open var name: Name? { didSet { setNeedsUpdate() }}
    
    /// A custom size of the icon.
    open var customSize: Int? { didSet { setNeedsUpdate() }}
    
    /// The natural size for the receiving view, considering only properties of the view itself.
    open override var intrinsicContentSize: CGSize {
        dimensions
    }

    //functions
    //--------------------------------------------------
    // MARK: - Overrides
    //--------------------------------------------------
    /// Called once when a view is initialized and is used to Setup additional UI or other constants and configurations.
    open override func setup() {
        super.setup()

        setContentCompressionResistancePriority(.required, for: .vertical)
        setContentHuggingPriority(.required, for: .vertical)
        setContentCompressionResistancePriority(.required, for: .horizontal)
        setContentHuggingPriority(.required, for: .horizontal)

        addSubview(imageView)
        imageView.pinToSuperView()
        
        backgroundColor = .clear
        
        isAccessibilityElement = true
        accessibilityTraits = .image
    }
    
    /// Used to make changes to the View based off a change events or from local properties.
    open override func updateView() {
        super.updateView()
        //get the color for the image
        var imageColor = color
        
        //ensure the correct color for white/black colors
        if surface == .dark && color == VDSColor.paletteBlack {
            imageColor = VDSColor.elementsPrimaryOndark
        } else if surface == .light && color == VDSColor.paletteBlack {
            imageColor = VDSColor.elementsPrimaryOnlight
        }
                
        //get the image name
        //set the image
        if let name, let image = getImage(for: name.rawValue) {
            setImage(image: image, imageColor: imageColor)
        } else {
            imageView.image = nil
        }
        
        invalidateIntrinsicContentSize()
    }
        
    /// Resets to default settings.
    open override func reset() {
        super.reset()
        color = VDSColor.paletteBlack
        imageView.image = nil
    }
               
    //--------------------------------------------------
    // MARK: - Private Methods
    //--------------------------------------------------
    private func getImage(for imageName: String) -> UIImage? {
        
        return BundleManager.shared.image(for: imageName)
    }
    
    private func setImage(image: UIImage, imageColor: UIColor) {
        imageView.image = image.withTintColor(imageColor)
    }
}