//
//  ReusableTableViewController.swift
//  LoginApp
//
//  Created by Matheus Oliveira Costa on 05/10/19.
//  Copyright © 2019 mathocosta. All rights reserved.
//

import UIKit

fileprivate enum UserProfileSection: Int, CaseIterable {
    case personal
    case sizing

    var title: String {
        switch self {
        case .personal:
            return "Personal info"
        case .sizing:
            return "Sizing info"
        }
    }

    var rows: [UserProfileRow] {
        switch self {
        case .personal:
            return [.firstName, .lastName]
        case .sizing:
            return [.height, .weight]
        }
    }

    static var allRows: [UserProfileRow] {
        return UserProfileSection.allCases.flatMap { $0.rows }
    }

    static func tag(for row: UserProfileRow) -> Int {
        return allRows.firstIndex(of: row)!
    }

    static func row(for tag: Int) -> UserProfileRow {
        return allRows[tag]
    }
}

fileprivate enum UserProfileRow: String {
    case firstName = "First Name"
    case lastName = "Last Name"
    case height = "Height"
    case weight = "Weight (lbs)"

    func isValid(for value: String?) -> Bool {
        // make some validation
        return true
    }
}

class UserProfileCache {
    var firstName: String?
    var lastName: String?
    var height: String?
    var weight: String?

    private func value(for row: UserProfileRow) -> String? {
        switch row {
        case .firstName: return firstName
        case .lastName: return lastName
        case .height: return height
        case .weight: return weight
        }
    }

    private func set(value: String?, for row: UserProfileRow) {
        switch row {
        case .firstName: firstName = value
        case .lastName: lastName = value
        case .height: height = value
        case .weight: weight = value
        }
    }

    fileprivate subscript(row: UserProfileRow) -> String? {
        get { return value(for: row) }
        set(newValue) { set(value: newValue, for: row) }
    }
}

protocol Reusable {}
extension UITableViewCell: Reusable {}

extension Reusable where Self: UITableViewCell {
    static var reuseID: String {
        return String(describing: self)
    }
}

extension UITableView {
    func registerCell<Cell: UITableViewCell>(_ cellClass: Cell.Type) {
        register(cellClass, forCellReuseIdentifier: cellClass.reuseID)
    }

    func dequeueReusableCell<Cell: UITableViewCell>(forIndexPath indexPath: IndexPath) -> Cell {
        guard let cell = self.dequeueReusableCell(
            withIdentifier: Cell.reuseID, for: indexPath
        ) as? Cell else { fatalError("Fatal error for cell at \(indexPath)") }

        return cell
    }
}

class ReusableTableViewCell: UITableViewCell {
    let textField: UITextField = {
        return UITextField()
    }()
}

class ReusableTableViewController: UITableViewController, UITextFieldDelegate {

    var user = UserProfileCache()

    override func viewDidLoad() {
        super.viewDidLoad()

        tableView.registerCell(ReusableTableViewCell.self)
    }

    // MARK: - Table view data source
    override func numberOfSections(in tableView: UITableView) -> Int {
        return UserProfileSection.allCases.count
    }

    override func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
        guard let section = UserProfileSection(rawValue: section) else { return nil }
        return section.title
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        let section = UserProfileSection(rawValue: section)!
        return section.rows.count
    }

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(forIndexPath: indexPath) as ReusableTableViewCell

        let section = UserProfileSection(rawValue: indexPath.section)!
        let row = section.rows[indexPath.row]

        let value = user[row]
        cell.textLabel?.textColor = row.isValid(for: value) ? .black : .red

        let tag = UserProfileSection.tag(for: row)
        cell.textLabel?.text = row.rawValue

        cell.textField.tag = tag
        cell.textField.text = value
        cell.textField.delegate = self

        return cell
    }

    // MARK: - Text field delegate
    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        textField.resignFirstResponder()
        let row = UserProfileSection.row(for: textField.tag)
        user[row] = textField.text

        return false
    }

}