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

import UIKit

class ToolbarButtonView: UIView
{
    private var buttonPadding = CGFloat(24.0)
    private var buttonViews: [UIView] = []
    
    public var numberOfButtonViews: Int { buttonViews.count }
    
    func addButtonView(_ button: UIView) {
        buttonViews.append(button)
        addSubview(button)
        setNeedsLayout()
    }
    
    func removeAllButtonViews() {
        buttonViews.forEach { $0.removeFromSuperview() }
        buttonViews.removeAll()
        setNeedsLayout()
    }
    
    override func sizeThatFits(_ size: CGSize) -> CGSize {
        let width: CGFloat = buttonViews.reduce(0.0) { (result, button) -> CGFloat in
            return result + button.sizeThatFits(size).width + buttonPadding
        }
        
        return CGSize(width: width, height: size.height)
    }
    
    override func layoutSubviews() {
        var buttonRect = CGRect(origin: .zero, size: CGSize(width: 0, height: bounds.height))
        buttonRect.origin.x = layoutMargins.left
        
        for button in buttonViews {
            let buttonSize = button.sizeThatFits(bounds.size)
            buttonRect.size = CGSize(width: buttonSize.width, height: bounds.height)
            button.frame = buttonRect
            
            buttonRect.origin.x += buttonRect.width + buttonPadding
        }
    }
}

class ToolbarView: UIView
{
    var urlBar: URLBar? { didSet { containerView.addSubview(urlBar!) } }
    
    var cancelButtonVisible: Bool = false { didSet { layoutSubviews() } }
    
    let containerView = UIView(frame: .zero)
    let backgroundView = UIVisualEffectView(effect: UIBlurEffect(style: .systemThickMaterial))
    let cancelButton = UIButton(type: .system)
    
    let leadingButtonsView = ToolbarButtonView(frame: .zero)
    let trailingButtonsView = ToolbarButtonView(frame: .zero)
    
    convenience init()
    {
        self.init(frame: .zero)
        addSubview(backgroundView)
        addSubview(containerView)
        
        containerView.addSubview(leadingButtonsView)
        containerView.addSubview(trailingButtonsView)
        
        cancelButton.setTitle("Cancel", for: .normal)
        containerView.addSubview(cancelButton)
        
        layer.masksToBounds = false
        layer.shadowColor = UIColor.black.cgColor
        layer.shadowOpacity = 0.2
        layer.shadowOffset = CGSize(width: 0.0, height: 1.0)
        layer.shadowRadius = 1.5
    }
    
    override func sizeThatFits(_ size: CGSize) -> CGSize
    {
        return CGSize(width: size.width, height: 44.0)
    }
    
    override func layoutSubviews()
    {
        super.layoutSubviews()

        backgroundView.frame = bounds
        
        var containerBounds = bounds
        containerBounds.size.height -= safeAreaInsets.bottom
        containerView.frame = containerBounds
        containerView.frame = containerView.frame.insetBy(dx: 8.0, dy: 4.0)
        
        // Cancel button
        let urlBarPadding: CGFloat = 8.0
        var cancelButtonSize = cancelButton.sizeThatFits(containerView.bounds.size)
        cancelButtonSize.width += (urlBarPadding * 2)
        cancelButton.frame = CGRect(origin: CGPoint(x: (containerView.bounds.maxX - cancelButtonSize.width), y: 0),
                                    size: CGSize(width: cancelButtonSize.width + urlBarPadding, height: containerView.bounds.height))
        
        // Leading toolbar buttons
        if leadingButtonsView.numberOfButtonViews > 0 {
            let leadingContainerSize = leadingButtonsView.sizeThatFits(containerView.bounds.size)
            leadingButtonsView.frame = CGRect(origin: .zero, size: leadingContainerSize)
        } else {
            leadingButtonsView.frame = .zero
        }
        
        // Trailing toolbar buttons
        let trailingContainerSize = trailingButtonsView.sizeThatFits(containerView.bounds.size)
        trailingButtonsView.frame = CGRect(origin: CGPoint(x: (containerView.bounds.maxX - trailingContainerSize.width) + urlBarPadding, y: 0), size: trailingContainerSize)
        
        var avoidingSize: CGSize = .zero
        if cancelButtonVisible {
            cancelButton.alpha = 1.0
            trailingButtonsView.alpha = 0.0
            
            avoidingSize = cancelButtonSize
        } else {
            cancelButton.alpha = 0.0
            trailingButtonsView.alpha = 1.0
            
            avoidingSize = trailingContainerSize
        }
        
        if let urlBar = urlBar {
            let origin = CGPoint(
                x: leadingButtonsView.frame.maxX,
                y: 0.0
            )
            
            urlBar.frame = CGRect(
                origin: origin,
                size: CGSize(
                    width: containerView.bounds.width - avoidingSize.width - origin.x,
                    height: containerView.bounds.height
                )
            )
        }
    }
}

class ToolbarViewController: UIViewController
{
    let urlBar = URLBar()
    let toolbarView = ToolbarView()
    let scriptControllerIconView = ScriptControllerIconView()
    let shareButton = UIButton(frame: .zero)
    let darkModeButton = UIButton(frame: .zero)
    let windowButton = UIButton(frame: .zero)
    let backButton = UIButton(frame: .zero)
    let forwardButton = UIButton(frame: .zero)
    let newTabButton = UIButton(frame: .zero)
    
    var darkModeEnabled: Bool = false {
        didSet {
            if darkModeEnabled {
                darkModeButton.setImage(darkModeEnabledImage, for: .normal)
            } else {
                darkModeButton.setImage(darkModeDisabledImage, for: .normal)
            }
        }
    }
    
    private let darkModeDisabledImage = UIImage(systemName: "moon.circle")
    private let darkModeEnabledImage = UIImage(systemName: "moon.circle.fill")
    
    init() {
        super.init(nibName: nil, bundle: nil)
        
        toolbarView.urlBar = urlBar
        
        // Dark mode button
        darkModeButton.setImage(darkModeDisabledImage, for: .normal)
        
        // Share button
        shareButton.setImage(UIImage(systemName: "square.and.arrow.up"), for: .normal)
        
        // Window button
        windowButton.setImage(UIImage(systemName: "rectangle.on.rectangle"), for: .normal)
        
        // Back button
        backButton.setImage(UIImage(systemName: "chevron.left"), for: .normal)
        
        // Forward button
        forwardButton.setImage(UIImage(systemName: "chevron.right"), for: .normal)
        
        // New tab button
        newTabButton.setImage(UIImage(systemName: "plus"), for: .normal)
        
        let toolbarAnimationDuration: TimeInterval = 0.3
        urlBar.textField.addAction(.init(handler: { [traitCollection, toolbarView, urlBar] _ in
            if traitCollection.horizontalSizeClass == .compact {
                UIView.animate(withDuration: toolbarAnimationDuration) {
                    toolbarView.cancelButtonVisible = urlBar.textField.isFirstResponder
                }
            }
        }), for: [ .editingDidBegin, .editingDidEnd ])
        
        toolbarView.cancelButton.addAction(.init(handler: { [urlBar] action in
            urlBar.textField.resignFirstResponder()
        }), for: .touchUpInside)
        
        traitCollectionDidChange(nil)
    }
    
    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
        super.traitCollectionDidChange(previousTraitCollection)
        
        toolbarView.leadingButtonsView.removeAllButtonViews()
        toolbarView.trailingButtonsView.removeAllButtonViews()
        
        // Setup toolbar based on trait collection
        if traitCollection.horizontalSizeClass == .compact {
            toolbarView.trailingButtonsView.addButtonView(darkModeButton)
            toolbarView.trailingButtonsView.addButtonView(scriptControllerIconView)
            toolbarView.trailingButtonsView.addButtonView(windowButton)
        } else {
            toolbarView.leadingButtonsView.addButtonView(backButton)
            toolbarView.leadingButtonsView.addButtonView(forwardButton)
            
            toolbarView.trailingButtonsView.addButtonView(darkModeButton)
            toolbarView.trailingButtonsView.addButtonView(shareButton)
            toolbarView.trailingButtonsView.addButtonView(scriptControllerIconView)
            toolbarView.trailingButtonsView.addButtonView(newTabButton)
            toolbarView.trailingButtonsView.addButtonView(windowButton)
        }
    }
    
    override func loadView() {
        self.view = toolbarView
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}