/**
 * Validate aadhaar number using verhoeff algorithm
 * Created by Frozenex
 */
class AadhaarUtil {

    companion object {

        private val d by lazy {
            arrayOf(intArrayOf(0, 1, 2, 3, 4, 5, 6, 7, 8, 9),
                    intArrayOf(1, 2, 3, 4, 0, 6, 7, 8, 9, 5),
                    intArrayOf(2, 3, 4, 0, 1, 7, 8, 9, 5, 6),
                    intArrayOf(3, 4, 0, 1, 2, 8, 9, 5, 6, 7),
                    intArrayOf(4, 0, 1, 2, 3, 9, 5, 6, 7, 8),
                    intArrayOf(5, 9, 8, 7, 6, 0, 4, 3, 2, 1),
                    intArrayOf(6, 5, 9, 8, 7, 1, 0, 4, 3, 2),
                    intArrayOf(7, 6, 5, 9, 8, 2, 1, 0, 4, 3),
                    intArrayOf(8, 7, 6, 5, 9, 3, 2, 1, 0, 4),
                    intArrayOf(9, 8, 7, 6, 5, 4, 3, 2, 1, 0))
        }

        private val p by lazy {
            arrayOf(intArrayOf(0, 1, 2, 3, 4, 5, 6, 7, 8, 9),
                    intArrayOf(1, 5, 7, 6, 2, 8, 3, 0, 9, 4),
                    intArrayOf(5, 8, 0, 3, 7, 9, 6, 1, 4, 2),
                    intArrayOf(8, 9, 1, 6, 0, 4, 3, 5, 2, 7),
                    intArrayOf(9, 4, 5, 3, 1, 2, 6, 8, 7, 0),
                    intArrayOf(4, 2, 8, 6, 5, 7, 3, 9, 0, 1),
                    intArrayOf(2, 7, 9, 3, 8, 0, 6, 4, 1, 5),
                    intArrayOf(7, 0, 4, 6, 9, 1, 3, 2, 5, 8))
        }

        private val TRIM_SPACE_REGEX by lazy { "\\s".toRegex() }


        /**
         * Check if aadhaar number is valid or not
         * @param aadhaarNo
         * @return Boolean
         */
        fun isAadhaarNumberValid(aadhaarNo: String): Boolean {

            // Remove extra spaces
            val mAadhaarNo = aadhaarNo.replace(TRIM_SPACE_REGEX, "")

            // Check if aadhaar no has 12 digits
            // Check if aadhaar no consists only of digits
            // Check if aadhaar no first digit is not 0 or 1
            if (mAadhaarNo.length != 12 || mAadhaarNo.toBigIntegerOrNull() == null || mAadhaarNo.first().toString().toInt() in 0..1) return false

            // Check using verhoeff algorithm
            var c = 0
            val reversedIntArray = mAadhaarNo.chunked(1).map({ it.toInt() }).toIntArray().reversedArray()
            for (i in reversedIntArray.indices) {
                c = d[c][p[i % 8][reversedIntArray[i]]]
            }

            return c == 0
        }
    }
}