yaotp/app/src/test/java/com/chameth/yaotp/algos/HotpTest.kt

package com.chameth.yaotp.algos

import com.natpryce.hamkrest.assertion.assert
import com.natpryce.hamkrest.equalTo
import org.junit.Test

class HotpTest {

    private val rfcByteArray = byteArrayOfInts(0x1f, 0x86, 0x98, 0x69, 0x0e, 0x02, 0xca, 0x16, 0x61, 0x85, 0x50, 0xef, 0x7f, 0x19, 0xda, 0x8e, 0x94, 0x5b, 0x55, 0x5a)

    @Test
    fun testOffsetValue_returnsLastFourBitsAsInt() {
        assert.that(offsetValue(rfcByteArray), equalTo(10))
    }

    @Test
    fun testOffset_returnsFourBytesAtOffsetValue() {
        assert.that(offset(rfcByteArray).toHexString(), equalTo("50ef7f19"))
    }

    @Test
    fun testMask_returnsValueUnchanged_ifMsbIsZero() {
        assert.that(mask(byteArrayOfInts(0x50, 0xef, 0x7f, 0x19)).toHexString(), equalTo("50ef7f19"))
    }

    @Test
    fun testMask_returnsMaskedValue_ifMsbIsNotZero() {
        assert.that(mask(byteArrayOfInts(0xA0, 0xef, 0x7f, 0x19)).toHexString(), equalTo("20ef7f19"))
    }

    @Test
    fun testHmacToHotp_withDefaultLength() {
        assert.that(hmacToHotp(rfcByteArray), equalTo(872921))
    }

    @Test
    fun testHotp_withRfcTestData() {
        val key = "12345678901234567890".toByteArray()
        val expected = listOf(755224, 287082, 359152, 969429, 338314, 254676, 287922, 162583, 399871, 520489)

        expected.forEachIndexed { index, i -> assert.that(hotp(key, byteArrayOfInts(0, 0, 0, 0, 0, 0, 0, index)), equalTo(i)) }
    }

    private fun byteArrayOfInts(vararg ints: Int) = ByteArray(ints.size) { pos -> ints[pos].toByte() }
}