Gemini/BrowserCore/NavigationManager.swift

//
//  NavigationManager.swift
//  Gemini
//
//  Created by Shadowfacts on 7/14/20.
//

import Foundation

public protocol NavigationManagerDelegate: class {
    func loadNonGeminiURL(_ url: URL)
}

public class NavigationManager: NSObject, ObservableObject {
    
    public weak var delegate: NavigationManagerDelegate?
    
    @Published public var currentURL: URL
    @Published public var backStack = [URL]()
    @Published public var forwardStack = [URL]()
    
    public init(url: URL) {
        self.currentURL = url
    }
    
    public func changeURL(_ url: URL) {
        guard url.scheme == "gemini" else {
            delegate?.loadNonGeminiURL(url)
            return
        }
        
        backStack.append(currentURL)
        currentURL = cannonicalizeURL(url)
        forwardStack = []
    }
    
    public func reload() {
        let url = currentURL
        currentURL = url
    }
    
    private func cannonicalizeURL(_ url: URL) -> URL {
        var components = URLComponents(url: url, resolvingAgainstBaseURL: false)!
        if components.scheme == "gemini" && components.port == 1965 {
            components.port = nil
        }
        return components.url!
    }
    
    @objc public func back() {
        guard !backStack.isEmpty else { return }
        forwardStack.insert(currentURL, at: 0)
        currentURL = backStack.removeLast()
    }
    
    @objc public func forward() {
        guard !forwardStack.isEmpty else { return }
        backStack.append(currentURL)
        currentURL = forwardStack.removeFirst()
    }
    
}