//
//  TitlebarView.swift
//  SBrowser
//
//  Created by James Magahern on 7/29/20.
//

import UIKit

class TitlebarView: UIView
{
    public let titleLabelView = UILabel(frame: .zero)
    private let backgroundImageView = UIImageView(frame: .zero)
    
    convenience init() {
        self.init(frame: .zero)
        addSubview(backgroundImageView)
        addSubview(titleLabelView)
        
        titleLabelView.textColor = .white
        titleLabelView.layer.shadowColor = UIColor.black.cgColor
        titleLabelView.layer.shadowRadius = 0.0
        titleLabelView.layer.shadowOffset = CGSize(width: 0.0, height: 2.0)
        titleLabelView.font = UIFont.boldSystemFont(ofSize: 12.0)
        
        backgroundImageView.alpha = 0.98
    }
        
    private func backgroundImageForSize(_ size: CGSize) -> UIImage? {
        var image: UIImage? = nil
        
        UIGraphicsBeginImageContext(CGSize(width: size.width, height: 1.0))
        if let context = UIGraphicsGetCurrentContext() {
            let gradientColorsArray = [
                UIColor(red: 0.101, green: 0.176, blue: 0.415, alpha: 1.0).cgColor,
                UIColor(red: 0.153, green: 0.000, blue: 0.153, alpha: 1.0).cgColor
            ]
            
            if let gradient = CGGradient(colorsSpace: nil, colors: gradientColorsArray as CFArray, locations: nil) {
                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()
        
        backgroundImageView.frame = bounds
        titleLabelView.frame = bounds.avoiding(verticalInsets: safeAreaInsets).insetBy(dx: 8.0 + layoutMargins.left, dy: 0.0)
        
        if let image = backgroundImageView.image, image.size == bounds.size {
            // No op
        } else {
            backgroundImageView.image = backgroundImageForSize(bounds.size)
        }
    }
}