Attractor/SBrowser/Browser View/BrowserView.swift

//
//  BrowserView.swift
//  SBrowser
//
//  Created by James Magahern on 7/21/20.
//

import Combine
import UIKit
import WebKit

class BrowserView: UIView
{
    let titlebarView = TitlebarView()
    
    var toolbarView: ToolbarView? {
        didSet { addSubview(toolbarView!) }
    }
    
    var webView: WKWebView? {
        didSet {
            oldValue?.removeFromSuperview()
            
            if let toolbarView = toolbarView {
                insertSubview(webView!, belowSubview: toolbarView)
            } else {
                addSubview(webView!)
            }
        }
    }
    
    var keyboardWillShowObserver: AnyCancellable?
    var keyboardWillHideObserver: AnyCancellable?
    var keyboardLayoutOffset: CGFloat = 0 { didSet { setNeedsLayout() } }
    
    convenience init() {
        self.init(frame: .zero)
        
        addSubview(titlebarView)
        
        keyboardWillShowObserver = NotificationCenter.default.publisher(for: UIWindow.keyboardWillShowNotification).sink { [weak self] notification in
            self?.adjustOffsetForKeyboardNotification(userInfo: notification.userInfo!)
        }
        
        keyboardWillHideObserver = NotificationCenter.default.publisher(for: UIWindow.keyboardWillHideNotification).sink { [weak self] notification in
            self?.adjustOffsetForKeyboardNotification(userInfo: notification.userInfo!)
        }
    }
    
    private func adjustOffsetForKeyboardNotification(userInfo: [AnyHashable : Any]) {
        guard let keyboardEndFrame = userInfo[UIWindow.keyboardFrameEndUserInfoKey] as? CGRect else { return }
        guard let animationDuration = userInfo[UIWindow.keyboardAnimationDurationUserInfoKey] as? TimeInterval else { return }
        guard let animationCurve = userInfo[UIWindow.keyboardAnimationCurveUserInfoKey] as? Int else { return }
        
        let animationOptions: UIView.AnimationOptions = { curve -> UIView.AnimationOptions in
            switch UIView.AnimationCurve(rawValue: curve) {
                case .easeIn: return .curveEaseIn
                case .easeOut: return .curveEaseOut
                case .easeInOut: return .curveEaseInOut
                default: return .init()
            }
        }(animationCurve)
        
        keyboardLayoutOffset = bounds.height - keyboardEndFrame.minY
        UIView.animate(withDuration: animationDuration, delay: 0.0, options: animationOptions, animations: { self.layoutIfNeeded() }, completion: nil)
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
        webView?.frame = bounds
        
        var webViewContentInset = UIEdgeInsets()
        
        bringSubviewToFront(titlebarView)
        
        var titlebarHeight: CGFloat = 24.0
        titlebarHeight += safeAreaInsets.top
        titlebarView.frame = CGRect(origin: .zero, size: CGSize(width: bounds.width, height: titlebarHeight))
        webViewContentInset.top += titlebarView.frame.height
        
        if let toolbarView = toolbarView {
            var toolbarSize = toolbarView.sizeThatFits(bounds.size)
            
            // Compact: toolbar is at the bottom
            if traitCollection.horizontalSizeClass == .compact {
                var bottomOffset: CGFloat = 0.0
                if keyboardLayoutOffset == 0 {
                    toolbarSize.height += safeAreaInsets.bottom
                } else if toolbarView.urlBar?.textField.isFirstResponder ?? false {
                    bottomOffset = keyboardLayoutOffset
                }
                
                toolbarView.bounds = CGRect(origin: .zero, size: toolbarSize)
                toolbarView.center = CGPoint(x: bounds.center.x, y: bounds.maxY - (toolbarView.bounds.height / 2) - bottomOffset)
                webViewContentInset.bottom += toolbarView.frame.height
            } else {
                // Regular: toolbar is at the top
                toolbarView.frame = CGRect(origin: CGPoint(x: 0.0, y: titlebarView.frame.maxY), size: toolbarSize)
                webViewContentInset.top += toolbarView.frame.height
            }
        }
        
        // Fix web view content insets
        webView?.scrollView.automaticallyAdjustsScrollIndicatorInsets = false
        
        webView?.scrollView.contentInset = webViewContentInset.subtracting(safeAreaInsets)
        webView?.scrollView.scrollIndicatorInsets = webViewContentInset
    }
}