//
//  Loader.swift
//  VDS
//
//  Created by Matt Bruce on 7/5/23.
//

import Foundation
import UIKit
import VDSColorTokens


@objc(VDSLoader)
/// A loader is an indicator that uses animation to show customers that there is an indefinite amount of wait time while a task is ongoing, e.g. a page is loading, a form is being submitted. The component disappears when the task is complete.
open class Loader: View {
    //--------------------------------------------------
    // MARK: - Private Properties
    //--------------------------------------------------
    private var icon = Icon().with { $0.name = .loader }
    private var opacity: CGFloat = 0.8
    private var iconColorConfiguration = SurfaceColorConfiguration(VDSColor.elementsPrimaryOnlight, VDSColor.elementsPrimaryOndark)

    //--------------------------------------------------
    // MARK: - Public Properties
    //--------------------------------------------------    
    /// Loader will be active if 'active' prop is passed.
    open var isActive: Bool = true { didSet { setNeedsUpdate() } }
    
    /// The Int used to determine the height and width of the Loader
    open var size: Int = 40 {
        didSet {
            setNeedsUpdate();
            invalidateIntrinsicContentSize()
        }
    }
    
    /// The natural size for the receiving view, considering only properties of the view itself.
    open override var intrinsicContentSize: CGSize { .init(width: size, height: size) }
    
    //--------------------------------------------------
    // MARK: - Lifecycle
    //--------------------------------------------------
    open override func setup() {
        super.setup()
        addSubview(icon)        
        
        icon
            .pinTopGreaterThanOrEqualTo()
            .pinLeadingGreaterThanOrEqualTo()
            .pinTrailingLessThanOrEqualTo()
            .pinBottomLessThanOrEqualTo()
        
        NSLayoutConstraint.activate([
            icon.centerXAnchor.constraint(equalTo: centerXAnchor),
            icon.centerYAnchor.constraint(equalTo: centerYAnchor)
        ])
    }
    
    /// Used to make changes to the View based off a change events or from local properties.
    open override func updateView() {
        super.updateView()
        icon.color = iconColorConfiguration.getColor(self)
        icon.customSize = size
        if isActive {
            startAnimating()
        } else {
            stopAnimating()
        }
    }
        
    //--------------------------------------------------
    // MARK: - Animation
    //--------------------------------------------------
    private let rotationLayerName = "rotationAnimation"
    func startAnimating() {
        icon.layer.remove(layerName: rotationLayerName)
        let rotation : CABasicAnimation = CABasicAnimation(keyPath: "transform.rotation.z")
        rotation.toValue = NSNumber(value: Double.pi * 2)
        rotation.duration = 0.5 // the speed of the rotation
        rotation.isCumulative = true
        rotation.repeatCount = Float.greatestFiniteMagnitude
        icon.layer.add(rotation, forKey: rotationLayerName)
    }

    func stopAnimating() {
        icon.layer.removeAnimation(forKey: rotationLayerName)
    }
}

extension Icon.Name {
    static let loader = Icon.Name(name: "loader")
}