Attractor/App/Settings/RedirectRulesSettingsViewController.swift

//
//  RedirectRulesSettingsViewController.swift
//  RedirectRulesSettingsViewController
//
//  Created by James Magahern on 6/25/21.
//

import UIKit
import MachO

class RedirectRulesSettingsViewController: UICollectionViewController
{
    private enum Section {
        case rules
        case addButton
    }
    
    private enum Items: String {
        case addButton
    }
    
    private lazy var dataSource: UICollectionViewDiffableDataSource<Section, String> = {
        let registry = UICollectionView.CellRegistration<UICollectionViewListCell, String> { [unowned self] cell, indexPath, item in
            var config = cell.defaultContentConfiguration()
            if item == Items.addButton.rawValue {
                config.text = "Add Redirect Rule"
                config.textProperties.font = .preferredFont(forTextStyle: .subheadline)
                config.textProperties.alignment = .center
                config.image = .init(systemName: "plus.circle")
                
                cell.accessories = []
            } else {
                if let rule = Settings.shared.redirectRules[item] {
                    config.text = "\(item) → \(rule)"
                }
                
                let deleteOptions = UICellAccessory.DeleteOptions(isHidden: false, reservedLayoutWidth: nil, tintColor: .red, backgroundColor: nil)
                cell.accessories = [
                    .delete(displayed: .always, options: deleteOptions, actionHandler: { [unowned self] in
                        deleteRedirectRule(fromHost: item)
                    })
                ]
            }
            
            cell.contentConfiguration = config
        }
        
        return UICollectionViewDiffableDataSource<Section, String>(collectionView: collectionView) { (collectionView, indexPath, itemIdentifier) in
            collectionView.dequeueConfiguredReusableCell(using: registry, for: indexPath, item: itemIdentifier)
        }
    }()
    
    init() {
        let config = UICollectionLayoutListConfiguration(appearance: .insetGrouped)
        let layout = UICollectionViewCompositionalLayout { section, layoutEnvironment in
            let listSection = NSCollectionLayoutSection.list(using: config, layoutEnvironment: layoutEnvironment)
            
            #if targetEnvironment(macCatalyst)
            listSection.contentInsets = NSDirectionalEdgeInsets(top: 24.0, leading: 164.0, bottom: 24.0, trailing: 164.0)
            #endif
            
            return listSection
        }
        
        super.init(collectionViewLayout: layout)
        
        tabBarItem.title = "Redirect Rules"
        tabBarItem.image = UIImage(systemName: "arrowshape.zigzag.forward")
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func viewDidLoad() {
        var snapshot = dataSource.snapshot()
        snapshot.appendSections([ .rules, .addButton ])
        snapshot.appendItems(Settings.shared.redirectRules.keys.sorted(), toSection: .rules)
        snapshot.appendItems([ Items.addButton.rawValue ], toSection: .addButton)
        dataSource.applySnapshotUsingReloadData(snapshot)
    }
    
    override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        collectionView.deselectItem(at: indexPath, animated: true)
        
        let item = dataSource.itemIdentifier(for: indexPath)
        if item == Items.addButton.rawValue {
            let createRuleViewController = CreateRedirectRuleViewController()
            createRuleViewController.finishedCreatingRule = { [unowned self] (fromHost, toHost) in
                if fromHost.count > 0 && toHost.count > 0 {
                    addRedirectRule(fromHost: fromHost, toHost: toHost)
                }
            }
            
            let navController = UINavigationController(rootViewController: createRuleViewController)
            present(navController, animated: true, completion: nil)
        }
    }
    
    private func addRedirectRule(fromHost: String, toHost: String) {
        Settings.shared.redirectRules[fromHost] = toHost
        
        var snapshot = dataSource.snapshot()
        snapshot.appendItems([ fromHost ], toSection: .rules)
        dataSource.apply(snapshot, animatingDifferences: true)
    }
    
    private func deleteRedirectRule(fromHost: String) {
        Settings.shared.redirectRules.removeValue(forKey: fromHost)
        
        var snapshot = dataSource.snapshot()
        snapshot.deleteItems([ fromHost ])
        dataSource.apply(snapshot, animatingDifferences: true)
    }
}

class CreateRedirectRuleViewController: UICollectionViewController
{
    enum Section {
        case hosts
    }
    
    enum Item: String {
        case fromHost
        case toHost
    }
    
    struct TextFieldCellConfiguration: UIContentConfiguration {
        var textField: UITextField
        
        func makeContentView() -> UIView & UIContentView {
            return GenericContentView<UITextField, TextFieldCellConfiguration>(configuration: self, view: textField) { _,_ in }
        }
        
        func updated(for state: UIConfigurationState) -> TextFieldCellConfiguration {
            self
        }
    }
    
    public var finishedCreatingRule: ((_ fromHost: String, _ toHost: String) -> Void)?
    
    private let fromHostField = UITextField(frame: .zero)
    private let toHostField = UITextField(frame: .zero)
    
    private let doneButton = UIBarButtonItem(systemItem: .done, primaryAction: nil, menu: nil)
    
    private lazy var dataSource: UICollectionViewDiffableDataSource<Section, Item> = {
        let registry = UICollectionView.CellRegistration<UICollectionViewListCell, Item> { [unowned self] cell, indexPath, item in
            if item == Item.fromHost {
                cell.contentConfiguration = TextFieldCellConfiguration(textField: fromHostField)
            } else if item == Item.toHost {
                cell.contentConfiguration = TextFieldCellConfiguration(textField: toHostField)
            }
        }
        
        return UICollectionViewDiffableDataSource<Section, Item>(collectionView: collectionView) { (collectionView, indexPath, itemIdentifier) in
            collectionView.dequeueConfiguredReusableCell(using: registry, for: indexPath, item: itemIdentifier)
        }
    }()
    
    init() {
        let config = UICollectionLayoutListConfiguration(appearance: .insetGrouped)
        let layout = UICollectionViewCompositionalLayout.list(using: config)
        super.init(collectionViewLayout: layout)
        
        preferredContentSize = CGSize(width: -1, height: 320.0)
        
        self.title = "Add Redirect Rule"
        
        navigationItem.leftBarButtonItem = UIBarButtonItem(systemItem: .cancel, primaryAction: UIAction { [unowned self] _ in
            dismiss(animated: true, completion: nil)
        }, menu: nil)
        
        doneButton.primaryAction = UIAction { [unowned self] _ in
            finishedCreatingRule?(fromHostField.text!, toHostField.text!)
            dismiss(animated: true, completion: nil)
        }
        
        navigationItem.rightBarButtonItem = doneButton
        
        fromHostField.placeholder = "From Host"
        toHostField.placeholder = "To Host"
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func viewDidLoad() {
        var snapshot = dataSource.snapshot()
        snapshot.appendSections([ Section.hosts ])
        snapshot.appendItems([ Item.fromHost, Item.toHost ], toSection: .hosts)
        dataSource.applySnapshotUsingReloadData(snapshot)
    }
    
    override func collectionView(_ collectionView: UICollectionView, shouldSelectItemAt indexPath: IndexPath) -> Bool {
        false
    }
}