//
//  EnhancedTableViewController.swift
//  Tusker
//
//  Created by Shadowfacts on 11/10/18.
//  Copyright © 2018 Shadowfacts. All rights reserved.
//

import UIKit

class EnhancedTableViewController: UITableViewController {

    var prevScrollToTopOffset: CGPoint? = nil

    private var topOffset: CGPoint {
        // when scrolled to top, the content offset is negative the height of the UI above the scroll view (i.e. the nav and status bars)
        let windowScene = UIApplication.shared.keyWindow!.windowScene!
        let barOffset = -1 * (navigationController!.navigationBar.frame.height + windowScene.statusBarManager!.statusBarFrame.height)
        // add one so it's not technically all the way at the top, and scrollViewWShouldScrollToTop is still called to trigger undo
        return CGPoint(x: 0, y: barOffset + 1)
    }

    override func scrollViewShouldScrollToTop(_ scrollView: UIScrollView) -> Bool {
        if let offset = prevScrollToTopOffset {
            tableView.setContentOffset(offset, animated: true)
            prevScrollToTopOffset = nil
        } else {
            prevScrollToTopOffset = tableView.contentOffset
            tableView.setContentOffset(topOffset, animated: true)
        }
        return false
    }

    override func scrollViewWillBeginDragging(_ scrollView: UIScrollView) {
        prevScrollToTopOffset = nil
    }

}