class RomanNumeralGenerator  {

	constructor(number = null){

		this.state = {
			romanNumericalMapping: {
				units: {
					1: 'I',
					2: 'II',
					3: 'III',
					4: 'IV',
					5: 'V',
					6: 'VI',
					7: 'VII',
					8: 'VIII',
					9: 'IX',
				},
				tens: {
					10: 'X',
					20: 'XX',
					30: 'XXX',
					40: 'XL',
					50: 'L',
					60: 'LX',
					70: 'LXX',
					80: 'LXXX',
					90: 'XC',
				},
				hundreds: {
					100: 'C',
					200: 'CC',
					300: 'CCC',
					400: 'CD',
					500: 'D',
					600: 'DC',
					700: 'DCC',
					800: 'DCCC',
					900: 'CM',
				},
				thousands:{
					1000: 'M',
					2000: 'MM',
					3000: 'MMM',
					4000: 'MMMM'
				}
			},
			inputNumber: number,
			outputNumber:''
		}

		if(this.state.inputNumber >= 1 && this.state.inputNumber <= 3999){
			this.state.outputNumber = this.generate(this.state.inputNumber);
			return console.log(this.state.outputNumber);
		}

		return 0;
	}

	generate(num){
		if(!Number.isInteger(num)){
			return 'Generate Function only accepts an integer value';
		}
		let numsArray = num.toString().split('');
		if(numsArray.length === 4){
			numsArray.map( (a,b) => {
				if(a > 0){
					if(b === 0) this.state.outputNumber = this.state.outputNumber.concat('', this.state.romanNumericalMapping.thousands[parseInt(a.concat('000'))]);
					else if(b === 1) this.state.outputNumber = this.state.outputNumber.concat('', this.state.romanNumericalMapping.hundreds[parseInt(a.concat('00'))]);
					else if(b === 2) this.state.outputNumber = this.state.outputNumber.concat('', this.state.romanNumericalMapping.tens[parseInt(a.concat('0'))]);
					else if(b === 3) this.state.outputNumber = this.state.outputNumber.concat('', this.state.romanNumericalMapping.units[parseInt(a)]);
				}
			});
		}else if(numsArray.length === 3){
			numsArray.map( (a,b) => {
				if(a > 0){
					if(b === 0) this.state.outputNumber = this.state.outputNumber.concat('', this.state.romanNumericalMapping.hundreds[parseInt(a.concat('00'))]);
					else if(b === 1) this.state.outputNumber = this.state.outputNumber.concat('', this.state.romanNumericalMapping.tens[parseInt(a.concat('0'))]);
					else if(b === 2) this.state.outputNumber = this.state.outputNumber.concat('', this.state.romanNumericalMapping.units[parseInt(a)]);
				}
			});
		}else if(numsArray.length === 2){
			numsArray.map( (a,b) => {
				if(a > 0){
					if(b === 0) this.state.outputNumber = this.state.outputNumber.concat('', this.state.romanNumericalMapping.tens[parseInt(a.concat('0'))]);
					else if(b === 1) this.state.outputNumber = this.state.outputNumber.concat('', this.state.romanNumericalMapping.units[parseInt(a)]);
				}
			});
		}else if(numsArray.length === 1){
			this.state.outputNumber = this.state.outputNumber.concat('', this.state.romanNumericalMapping.units[parseInt(numsArray[0])]);
		}
		return this.state.outputNumber;
	}
}

//tests
t1 = new RomanNumeralGenerator(1);
t2 = new RomanNumeralGenerator(5);
t3 = new RomanNumeralGenerator(10);
t4 = new RomanNumeralGenerator(20);
t5 = new RomanNumeralGenerator(3999);