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

import UIKit
import Combine

protocol TabDelegate: class
{
    func didBlockScriptOrigin(_ origin: String, forTab: Tab)
}

class Tab: NSObject, SBRProcessBundleBridgeDelegate
{
    public weak var delegate: TabDelegate?
    
    public let homeURL: URL?
    public let bridge = SBRProcessBundleBridge()
    public var webView: WKWebView {
        if self.loadedWebView == nil {
            self.loadedWebView = bridge.webView
            
            if let homeURL = homeURL {
                beginLoadingURL(homeURL)
            }
        }
        
        return bridge.webView
    }
    public var policyManager: ResourcePolicyManager
    
    private var loadedWebView: WKWebView? = nil
    public var title: String? { loadedWebView?.title }
    public var url: URL?      { loadedWebView?.url ?? self.homeURL }
    
    public var javaScriptEnabled: Bool = false {
        didSet { bridge.allowAllScripts = javaScriptEnabled }
    }
    
    public var identifier = UUID()
    
    public var favicon: UIImage?
    private var faviconHost: String?
    private var faviconRequest: AnyCancellable?
    
    public var allowedScriptOrigins = Set<String>()
    public var blockedScriptOrigins = Set<String>()
    
    private var titleObservation: NSKeyValueObservation?
    private var urlObservation: NSKeyValueObservation?
    
    convenience init(policyManager: ResourcePolicyManager) {
        self.init(url: nil, policyManager: policyManager)
    }
    
    convenience init(urlString: String, policyManager: ResourcePolicyManager) {
        self.init(url: URL(string: urlString), policyManager: policyManager)
    }
    
    init(url: URL?, policyManager: ResourcePolicyManager) {
        self.homeURL = url
        self.policyManager = policyManager
        bridge.policyDataSource = policyManager
        
        super.init()
        
        bridge.delegate = self
    }
    
    deinit {
        bridge.tearDown()
    }
    
    func beginLoadingURL(_ url: URL) {
        let request = URLRequest(url: url)
        webView.load(request)
    }
    
    // MARK: SBRProcessBundleBridgeDelegate
    
    func webProcess(_ bridge: SBRProcessBundleBridge, didAllowScriptResourceFromOrigin origin: String) {
        print("Allowed script resource from origin: \(origin)")
        allowedScriptOrigins.formUnion([ origin ])
    }
    
    func webProcess(_ bridge: SBRProcessBundleBridge, didBlockScriptResourceFromOrigin origin: String) {
        print("Blocked script resource from origin: \(origin)")
        blockedScriptOrigins.formUnion([ origin ])
        delegate?.didBlockScriptOrigin(origin, forTab: self)
    }
    
    func updateFaviconForURL(_ url: URL) {
        if let faviconHost = faviconHost, url.host == faviconHost {} else {
            guard var faviconURLComponents = URLComponents(url: url, resolvingAgainstBaseURL: false) else { return }
            faviconURLComponents.path = "/favicon.ico"
                
            let defaultImage = UIImage(systemName: "globe")
            guard let faviconURL = faviconURLComponents.url else { return }
            faviconRequest = URLSession.shared.dataTaskPublisher(for: faviconURL)
                .map { (data: Data, response: URLResponse) -> UIImage? in
                    UIImage(data: data)
                }
                .replaceError(with: defaultImage)
                .replaceNil(with: defaultImage)
                .assign(to: \.favicon, on: self)
        }
    }
}