Attractor/SBrowser/Browser View/URLBar.swift

//
//  URLBar.swift
//  SBrowser
//
//  Created by James Magahern on 7/23/20.
//

import UIKit

class URLBar: UIView
{
    let textField = UITextField(frame: .zero)
    let refreshButton = UIButton(frame: .zero)
    
    public enum LoadProgress {
        case complete
        case loading(progress: Double)
    }
    
    public var loadProgress: LoadProgress = .complete {
        didSet { updateProgressIndicator() }
    }
    
    private let backgroundView = UIVisualEffectView(effect: UIBlurEffect(style: .systemThickMaterial))
    private let progressIndicatorView = ProgressIndicatorView()
    private let fadeMaskView = UIImageView(frame: .zero)
    
    private let refreshImage = UIImage(systemName: "arrow.clockwise")
    private let stopImage = UIImage(systemName: "xmark")
    
    private let backgroundCornerRadius: CGFloat = 8
    
    convenience init() {
        self.init(frame: .zero)
        
        backgroundColor = .clear
        
        backgroundView.layer.masksToBounds = true
        backgroundView.layer.cornerRadius = backgroundCornerRadius
        backgroundView.layer.borderWidth = 1
        backgroundView.layer.borderColor = UIColor.systemFill.cgColor
        backgroundView.isUserInteractionEnabled = false
        addSubview(backgroundView)
        
        backgroundView.contentView.addSubview(progressIndicatorView)
        
        textField.backgroundColor = .clear
        textField.textContentType = .URL
        textField.keyboardType = .webSearch
        textField.autocorrectionType = .no
        textField.autocapitalizationType = .none
        textField.font = .systemFont(ofSize: 14.0)
        textField.clearingBehavior = .clearOnInsertionAndShowSelectionTint
        textField.clearButtonMode = .whileEditing
        addSubview(textField)
        
        textField.addAction(.init(handler: { _ in
            self.refreshButton.isHidden = self.textField.isFirstResponder
        }), for: [ .editingDidBegin, .editingDidEnd ])
        
        refreshButton.tintColor = .secondaryLabel
        refreshButton.setImage(refreshImage, for: .normal)
        addSubview(refreshButton)
    }
    
    private func updateProgressIndicator() {
        UIView.animate(withDuration: 0.4) {
            switch self.loadProgress {
            case .complete:
                self.refreshButton.setImage(self.refreshImage, for: .normal)
                self.progressIndicatorView.progress = 1.0
                UIView.animate(withDuration: 0.5, delay: 0.5, options: AnimationOptions()) {
                    self.progressIndicatorView.alpha = 0.0
                } completion: { _ in
                    // Reset back to zero
                    self.progressIndicatorView.progress = 0.0
                }
            case .loading(let progress):
                self.refreshButton.setImage(self.stopImage, for: .normal)
                self.progressIndicatorView.progress = progress
                self.progressIndicatorView.alpha = 1.0
            }
        }
    }
    
    override var intrinsicContentSize: CGSize {
        let preferredHeight = CGFloat(34)
        return CGSize(width: 1000.0, height: preferredHeight)
    }
    
    private func fadeBackgroundImageForSize(_ size: CGSize) -> UIImage? {
        var image: UIImage? = nil
        
        UIGraphicsBeginImageContext(CGSize(width: size.width, height: 1.0))
        if let context = UIGraphicsGetCurrentContext() {
            let gradientColorsArray = [
                UIColor(white: 1.0, alpha: 1.0).cgColor,
                UIColor(white: 1.0, alpha: 1.0).cgColor,
                UIColor(white: 1.0, alpha: 0.08).cgColor,
                UIColor(white: 1.0, alpha: 0.08).cgColor
            ]
            
            let locations: [CGFloat] = [
                0.0, 0.80, 0.90, 1.0
            ]
            
            if let gradient = CGGradient(colorsSpace: nil, colors: gradientColorsArray as CFArray, locations: locations) {
                context.drawLinearGradient(gradient, start: .zero, end: CGPoint(x: size.width, y: 0.0), options: CGGradientDrawingOptions())
            }
            
            image = UIGraphicsGetImageFromCurrentImageContext()
            UIGraphicsEndImageContext();
        }
        
        return image
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
        backgroundView.frame = bounds
        progressIndicatorView.frame = backgroundView.contentView.bounds
        textField.frame = bounds.insetBy(dx: 6.0, dy: 0)
        
        fadeMaskView.frame = textField.bounds
        fadeMaskView.image = fadeBackgroundImageForSize(fadeMaskView.frame.size)
        if !textField.isFirstResponder {
            textField.mask = fadeMaskView
        } else {
            textField.mask = nil
        }
        
        let refreshButtonSize = CGSize(width: textField.frame.height, height: textField.frame.height)
        refreshButton.frame = CGRect(origin: CGPoint(x: bounds.width - refreshButtonSize.width, y: 0), size: refreshButtonSize)
    }
}

class ProgressIndicatorView: UIView
{
    public var progress: Double = 0.0 {
        didSet { layoutSubviews() }
    }
    
    private let progressFillView = UIView(frame: .zero)
    
    convenience init() {
        self.init(frame: .zero)
        
        progressFillView.backgroundColor = .systemBlue
        progressFillView.alpha = 0.3
        addSubview(progressFillView)
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
        
        let width = CGFloat(progress) * bounds.width
        progressFillView.frame = CGRect(origin: .zero, size: CGSize(width: width, height: bounds.height))
    }
}