Attractor/SBrowser/Browser View/BrowserViewController.swift

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

import UIKit

class BrowserViewController: UIViewController,
                             SBRProcessBundleBridgeDelegate, WKNavigationDelegate,
                             UITextFieldDelegate, ScriptPolicyViewControllerDelegate
{
    let bridge = SBRProcessBundleBridge()
    let browserView = BrowserView()
    
    var javaScriptEnabledForTab: Bool = false
    
    private let policyManager = ResourcePolicyManager()
    private let toolbarController = ToolbarViewController()
    private var allowedScriptOrigins = Set<String>()
    private var blockedScriptOrigins = Set<String>()
    override var canBecomeFirstResponder: Bool { true }
    
    private var titleObservation: NSKeyValueObservation?
    private var loadingObservation: NSKeyValueObservation?
    
    override var preferredStatusBarStyle: UIStatusBarStyle { .lightContent }
    
    init() {
        super.init(nibName: nil, bundle: nil)
    }
    
    required init?(coder: NSCoder) { fatalError("init(coder:) has not been implemented") }
    
    override func loadView() {
        bridge.delegate = self
        bridge.policyDataSource = policyManager
        
        let webView = bridge.webView
        webView.allowsBackForwardNavigationGestures = true
        webView.navigationDelegate = self
        
        browserView.webView = webView
        browserView.toolbarView = toolbarController.toolbarView
        
        // Refresh button
        toolbarController.urlBar.refreshButton.addAction(UIAction(handler: { action in
            if webView.isLoading {
                webView.stopLoading()
            } else {
                webView.reload()
            }
        }), for: .touchUpInside)
        
        // Script button
        toolbarController.scriptControllerIconView.addAction(UIAction(handler: { action in
            let hostOrigin = webView.url?.host ?? ""
            let loadedScripts = self.allowedScriptOrigins.union(self.blockedScriptOrigins)
            let scriptViewController = ScriptPolicyViewController(policyManager: self.policyManager,
                                                                  hostOrigin: hostOrigin,
                                                                  loadedScripts: loadedScripts,
                                                                  scriptsAllowedForTab: self.javaScriptEnabledForTab)
            scriptViewController.delegate = self
            
            let navController = UINavigationController(rootViewController: scriptViewController)
            navController.modalPresentationStyle = .popover
            navController.popoverPresentationController?.sourceView = self.toolbarController.scriptControllerIconView
            
            self.present(navController, animated: true, completion: nil)
        }), for: .touchUpInside)
        
        // Dark mode button
        toolbarController.darkModeButton.addAction(UIAction(handler: { _ in
            self.bridge.darkModeEnabled = !self.bridge.darkModeEnabled
            self.toolbarController.darkModeEnabled = self.bridge.darkModeEnabled
        }), for: .touchUpInside)
        
        // TextField delegate
        toolbarController.urlBar.textField.delegate = self
        
        // Load progress
        loadingObservation = webView.observe(\.estimatedProgress) { (webView, observedChange) in
            if webView.estimatedProgress == 1.0 {
                self.toolbarController.urlBar.loadProgress = .complete
            } else {
                self.toolbarController.urlBar.loadProgress = .loading(progress: webView.estimatedProgress)
            }
        }
        
        // Title observer
        titleObservation = webView.observe(\.title, changeHandler: { (webView, observedChange) in
            self.browserView.titlebarView.titleLabelView.text = webView.title
        })
        
        self.view = browserView
    }
    
    override func viewDidLoad() {
        beginLoadingURL(URL(string: "https://news.ycombinator.com")!)
    }
    
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        becomeFirstResponder()
    }
    
    private func updateScriptBlockerButton() {
        toolbarController.scriptControllerIconView.setBlockedScriptsNumber(blockedScriptOrigins.count)
    }
    
    func beginLoadingURL(_ url: URL) {
        let request = URLRequest(url: url)
        bridge.webView.load(request)
    }
    
    // MARK: SBRProcessBundleBridgeDelegate
    
    func webProcess(_ bridge: SBRProcessBundleBridge, didAllowScriptResourceFromOrigin origin: String) {
        print("Allowed script resource from origin: \(origin)")
        allowedScriptOrigins.formUnion([ origin ])
        updateScriptBlockerButton()
    }
    
    func webProcess(_ bridge: SBRProcessBundleBridge, didBlockScriptResourceFromOrigin origin: String) {
        print("Blocked script resource from origin: \(origin)")
        blockedScriptOrigins.formUnion([ origin ])
        updateScriptBlockerButton()
    }
    
    // MARK: Navigation Delegate
    
    func webView(_ webView: WKWebView, didStartProvisionalNavigation navigation: WKNavigation!) {
        // Reset tracking this
        blockedScriptOrigins.removeAll()
        
        if let urlString = webView.url?.absoluteString {
            toolbarController.urlBar.textField.text = urlString
        }
    }
    
    func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
        toolbarController.urlBar.loadProgress = .complete
    }
    
    func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, preferences: WKWebpagePreferences, decisionHandler: @escaping (WKNavigationActionPolicy, WKWebpagePreferences) -> Void)
    {
        var allowJavaScript = javaScriptEnabledForTab
        if !allowJavaScript, let host = navigationAction.request.url?.host {
            // Check origin policy
            allowJavaScript = policyManager.allowedOriginsForScriptResources().contains(host)
        }
        
        preferences.allowsContentJavaScript = allowJavaScript
        decisionHandler(.allow, preferences)
    }
    
    // MARK: UITextField Delegate
    
    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        if let text = textField.text, let url = URL(string: text) {
            if url.scheme == nil {
                let urlString = "https://\(text)"
                if let url = URL(string: urlString) {
                    beginLoadingURL(url)
                }
            }
        }
        
        textField.resignFirstResponder()
        return false
    }
    
    // MARK: Script Policy View Controller Delegate
    
    func didChangeScriptPolicy() {
        bridge.policyDataSourceDidChange()
        bridge.webView.reload()
    }
    
    func setScriptsEnabledForTab(_ enabled: Bool) {
        javaScriptEnabledForTab = enabled
        bridge.allowAllScripts = enabled
    }
    
}