write bill class. closes #17

src/main/kotlin/dev/persianTools/feature/bill/Bill.kt

@@ -0,0 +1,106 @@
+package dev.persianTools.feature.bill
+
+/**
+ * Bill class
+ */
+data class Bill(
+    var barcode: String? = null,
+    val currency: BillCurrency,
+    val billId: Int?,
+    val paymentId: Int?
+): BillResult {
+
+    companion object {
+        /**
+         * Find bill ID and payment ID using barcode
+         * @sample
+         *   val (billID,paymentID) = Bill.findByBarcode(barcode)
+         */
+        fun findByBarcode(barcode: String): Pair<Int?,Int?> {
+            return Pair(
+                barcode.substring(0,13).toIntOrNull(),
+                barcode.substring(16).toIntOrNull()
+            )
+        }
+    }
+
+    override fun amount(): Int? {
+        if (paymentId == null) return null
+
+        val currencyAmount = if (currency == BillCurrency.RIAL) 1000 else 100
+
+        return (paymentId / 100000) * currencyAmount
+    }
+
+    override fun type(): BillType {
+        val billIdStr = billId.toString()
+
+        return billIdStr.substring(billIdStr.length - 2,
+            billIdStr.length -1).toIntOrNull()?.billType() ?: BillType.UNKNOWN
+    }
+
+    override fun barcode(): String? {
+        if (billId == null || paymentId == null) return null
+
+        val br = "${billId}000${paymentId}"
+
+        if (barcode == null) barcode = br
+
+        return br
+    }
+
+    override fun isValid(): Boolean = isValidBillId() && isValidBillPayment()
+
+    override fun isValidBillId(): Boolean {
+        var billIdStr = billId.toString()
+
+        if (billIdStr.length < 6) return false
+
+        val firstControlBit = billIdStr[billIdStr.length - 1]
+
+        billIdStr = billIdStr.substring(0,billIdStr.length - 1)
+
+        return calTheBit(billIdStr) == firstControlBit.toInt() && type() != BillType.UNKNOWN
+    }
+
+    override fun isValidBillPayment(): Boolean {
+        val billIdStr = billId.toString()
+        var paymentIdStr = paymentId.toString()
+
+        if (paymentIdStr.length < 6) return false
+
+        val firstControlBit = paymentIdStr[paymentIdStr.length - 2]
+        val secondControlBit = paymentIdStr[paymentIdStr.length - 1]
+
+        paymentIdStr = paymentIdStr.substring(0,paymentIdStr.length - 2)
+
+        return calTheBit(paymentIdStr) == firstControlBit.toInt() &&
+                calTheBit(billIdStr + paymentIdStr + firstControlBit) ==
+                secondControlBit.toInt()
+    }
+
+    private fun calTheBit(number: String): Int {
+        var sum = 0
+        var base = 2
+        number.forEachIndexed { index, _ ->
+            if (base == 8) base = 2
+
+            val subString = number.substring(
+                number.length - 1 - index,
+                number.length - index
+            ).toInt()
+
+            sum += subString * base
+
+            base++
+        }
+        sum %= 11
+
+        sum = if (sum < 2) {
+            0
+        } else {
+            11 - sum
+        }
+        return sum
+    }
+}