Number only

TestMoney

//
//  TestMoney.swift
//  FormButtonTest
//
//  Created by Justin Allen on 10/10/22.
//

import SwiftUI

extension String {
  public func removingCharacters(in set: CharacterSet) -> String {
    let filtered = unicodeScalars.filter { !set.contains($0) }
    return String(String.UnicodeScalarView(filtered))
  }
}

class NumberOnly: ObservableObject {
    let invalidCharacters = CharacterSet(charactersIn: "0123456789.").inverted
    let decimalPlaces: Int
    
    init(decimalPlaces: Int) {
        
        self.decimalPlaces = max(0, decimalPlaces)
    }
    
    @Published var characters: [Character] = []
    @Published var decimalValue: Decimal = 0
    @Published var value: String = "" {
        didSet {
            
            if value.count == 0 {
                characters = []
                return
            }
            
            var chars : [Character] = Array(value.removingCharacters(in: invalidCharacters))
            if chars.count == 0 {
                value = ""
                characters = []
                return
            }
            
            
            while chars.filter({$0 == "."}).count > 1 {
                let periodIndex = chars.lastIndex(of: ".")!
                print(chars)
                
                chars.removeSubrange(periodIndex..<chars.count)
            }
            
            if chars.filter({$0 == "."}).count == 1 {
                let periodIndex = chars.lastIndex(of: ".")! + (decimalPlaces + 1)
                print(chars)
                
                if chars.count > periodIndex {
                    chars.removeSubrange(periodIndex..<chars.count)
                }
                
                if decimalPlaces == 0 {
                    chars.removeLast()
                }
            }
            
            if decimalPlaces != 0 && chars[0] == "." {
                chars.insert("0", at: 0)
            }
               
            print(chars)

            let possibleString = chars.compactMap { "\($0)" }.joined()
            print(possibleString)
            
            if value != possibleString {
                value = possibleString
            }
            
            decimalValue = Decimal(string: value) ?? 0
        }
    }
    
}

struct TestMoney: View {
    @ObservedObject var stringAmount = NumberOnly(decimalPlaces: 2)
    
    var body: some View {
        TextField("0.00", text: $stringAmount.value)
            .keyboardType(.decimalPad)
            .padding()
        
    }
}

struct TestMoney_Previews: PreviewProvider {
    static var previews: some View {
        TestMoney()
    }
}