Port hashing stuff to Kotlin

src/main/kotlin/link/infra/packwiz/installer/metadata/hash/GeneralHashingSource.kt

@@ -0,0 +1,10 @@
+package link.infra.packwiz.installer.metadata.hash
+
+import okio.ForwardingSource
+import okio.Source
+
+abstract class GeneralHashingSource(delegate: Source) : ForwardingSource(delegate) {
+	abstract val hash: Hash
+
+	fun hashIsEqual(compareTo: Any) = compareTo == hash
+}

src/main/kotlin/link/infra/packwiz/installer/metadata/hash/Hash.kt

@@ -0,0 +1,34 @@
+package link.infra.packwiz.installer.metadata.hash
+
+import com.google.gson.*
+import java.lang.reflect.Type
+
+abstract class Hash {
+	protected abstract val stringValue: String
+	protected abstract val type: String
+
+	class TypeHandler : JsonDeserializer<Hash>, JsonSerializer<Hash> {
+		override fun serialize(src: Hash, typeOfSrc: Type, context: JsonSerializationContext): JsonElement = JsonObject().apply {
+			add("type", JsonPrimitive(src.type))
+			add("value", JsonPrimitive(src.stringValue))
+		}
+
+		@Throws(JsonParseException::class)
+		override fun deserialize(json: JsonElement, typeOfT: Type, context: JsonDeserializationContext): Hash {
+			val obj = json.asJsonObject
+			val type: String
+			val value: String
+			try {
+				type = obj["type"].asString
+				value = obj["value"].asString
+			} catch (e: NullPointerException) {
+				throw JsonParseException("Invalid hash JSON data")
+			}
+			return try {
+				HashUtils.getHash(type, value)
+			} catch (e: Exception) {
+				throw JsonParseException("Failed to create hash object", e)
+			}
+		}
+	}
+}

src/main/kotlin/link/infra/packwiz/installer/metadata/hash/HashUtils.kt

@@ -0,0 +1,21 @@
+package link.infra.packwiz.installer.metadata.hash
+
+object HashUtils {
+	private val hashTypeConversion: Map<String, IHasher> = mapOf(
+			"sha256" to HashingSourceHasher("sha256"),
+			"sha512" to HashingSourceHasher("sha512"),
+			"murmur2" to Murmur2Hasher()
+	)
+
+	@JvmStatic
+	@Throws(Exception::class)
+	fun getHasher(type: String): IHasher {
+		return hashTypeConversion[type] ?: throw Exception("Hash type not supported: $type")
+	}
+
+	@JvmStatic
+	@Throws(Exception::class)
+	fun getHash(type: String, value: String): Hash {
+		return hashTypeConversion[type]?.getHash(value) ?: throw Exception("Hash type not supported: $type")
+	}
+}

src/main/kotlin/link/infra/packwiz/installer/metadata/hash/HashingSourceHasher.kt

@@ -0,0 +1,45 @@
+package link.infra.packwiz.installer.metadata.hash
+
+import okio.HashingSource
+import okio.Source
+
+class HashingSourceHasher internal constructor(private val type: String) : IHasher {
+	// i love naming things
+	private inner class HashingSourceGeneralHashingSource internal constructor(val delegateHashing: HashingSource) : GeneralHashingSource(delegateHashing) {
+		override val hash: Hash by lazy(LazyThreadSafetyMode.NONE) {
+			HashingSourceHash(delegateHashing.hash.hex())
+		}
+	}
+
+	// this some funky inner class stuff
+	// each of these classes is specific to the instance of the HasherHashingSource
+	// therefore HashingSourceHashes from different parent instances will be not instanceof each other
+	private inner class HashingSourceHash(val value: String) : Hash() {
+		override val stringValue get() = value
+
+		override fun equals(other: Any?): Boolean {
+			if (other !is HashingSourceHash) {
+				return false
+			}
+			return stringValue.equals(other.stringValue, ignoreCase = true)
+		}
+
+		override fun toString(): String = "$type: $stringValue"
+		override fun hashCode(): Int = value.hashCode()
+
+		override val type: String get() = this@HashingSourceHasher.type
+	}
+
+	override fun getHashingSource(delegate: Source): GeneralHashingSource {
+		when (type) {
+			"md5" -> return HashingSourceGeneralHashingSource(HashingSource.md5(delegate))
+			"sha256" -> return HashingSourceGeneralHashingSource(HashingSource.sha256(delegate))
+			"sha512" -> return HashingSourceGeneralHashingSource(HashingSource.sha512(delegate))
+		}
+		throw RuntimeException("Invalid hash type provided")
+	}
+
+	override fun getHash(value: String): Hash {
+		return HashingSourceHash(value)
+	}
+}

src/main/kotlin/link/infra/packwiz/installer/metadata/hash/IHasher.kt

@@ -0,0 +1,8 @@
+package link.infra.packwiz.installer.metadata.hash
+
+import okio.Source
+
+interface IHasher {
+	fun getHashingSource(delegate: Source): GeneralHashingSource
+	fun getHash(value: String): Hash
+}

src/main/kotlin/link/infra/packwiz/installer/metadata/hash/Murmur2Hasher.kt

@@ -0,0 +1,76 @@
+package link.infra.packwiz.installer.metadata.hash
+
+import okio.Buffer
+import okio.Source
+import java.io.IOException
+
+class Murmur2Hasher : IHasher {
+	private inner class Murmur2GeneralHashingSource(delegate: Source) : GeneralHashingSource(delegate) {
+		val internalBuffer = Buffer()
+		val tempBuffer = Buffer()
+
+		override val hash: Hash by lazy(LazyThreadSafetyMode.NONE) {
+			val data = computeNormalizedArray(internalBuffer.readByteArray())
+			Murmur2Hash(Murmur2Lib.hash32(data, data.size, 1))
+		}
+
+		@Throws(IOException::class)
+		override fun read(sink: Buffer, byteCount: Long): Long {
+			val out = delegate.read(tempBuffer, byteCount)
+			if (out > -1) {
+				sink.write(tempBuffer.clone(), out)
+				internalBuffer.write(tempBuffer, out)
+			}
+			return out
+		}
+
+		// Credit to https://github.com/modmuss50/CAV2/blob/master/murmur.go
+		private fun computeNormalizedArray(input: ByteArray): ByteArray {
+			val output = ByteArray(input.size)
+			var index = 0
+			for (b in input) {
+				when (b.toInt()) {
+					9, 10, 13, 32 -> {}
+					else -> {
+						output[index] = b
+						index++
+					}
+				}
+			}
+			val outputTrimmed = ByteArray(index)
+			System.arraycopy(output, 0, outputTrimmed, 0, index)
+			return outputTrimmed
+		}
+
+	}
+
+	private class Murmur2Hash : Hash {
+		val value: Int
+
+		constructor(value: String) {
+			// Parsing as long then casting to int converts values gt int max value but lt uint max value
+			// into negatives. I presume this is how the murmur2 code handles this.
+			this.value = value.toLong().toInt()
+		}
+
+		constructor(value: Int) {
+			this.value = value
+		}
+
+		override val stringValue get() = value.toString()
+		override val type get() = "murmur2"
+
+		override fun equals(other: Any?): Boolean {
+			if (other !is Murmur2Hash) {
+				return false
+			}
+			return value == other.value
+		}
+
+		override fun toString(): String = "murmur2: $value"
+		override fun hashCode(): Int = value
+	}
+
+	override fun getHashingSource(delegate: Source): GeneralHashingSource = Murmur2GeneralHashingSource(delegate)
+	override fun getHash(value: String): Hash = Murmur2Hash(value)
+}