import Foundation

public class PlateNumber {
    private var number: String = ""
    private var numberEnglish: String = ""
    
    private let maxLength = 9
    private let mainPartLength = 6
    private let isDigitMask = [false, true, true, true, false, false, true, true, true]
    
    public init(_ string: String) {
        setNumber(string)
    }
    
    public func setNumber(_ number: String) {
        self.number = number
        self.numberEnglish = String(self.number.map { Constants.pnLettersMap[$0] ?? $0 })
    }
    
    public func asString() -> String {
        return self.number
    }
    
    public func mainPart() -> String {
        return String(self.numberEnglish.prefix(mainPartLength))
    }
    
    public func region() -> String {
        guard numberEnglish.count > mainPartLength else {
            return ""
        }
        
        return String(self.numberEnglish.dropFirst(mainPartLength))
    }
    
    public var isValid: Bool {
        number.count >= 8
    }
    
    // MARK: - UIKeyInput
    
    public var hasText: Bool {
        return !number.isEmpty
    }
    
    // Returns true if number was changed
    public func insertText(_ text: String) -> Bool {
        guard number.count < maxLength, text.count == 1 else {
            return false
        }
        
        if text.first?.isNumber == isDigitMask[number.count] {
            setNumber(number + text)
            return true
        } else {
            return false
        }
    }
    
    public func deleteBackward() -> Bool {
        guard !number.isEmpty else {
            return false
        }
        
        setNumber(String(number.dropLast()))
        return true
    }
}