Start porting to Kotlin

src/main/kotlin/link/infra/packwiz/installer/request/IRequestHandler.kt

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+package link.infra.packwiz.installer.request
+
+import link.infra.packwiz.installer.metadata.SpaceSafeURI
+import okio.Source
+
+/**
+ * IRequestHandler handles requests for locations specified in modpack metadata.
+ */
+interface IRequestHandler {
+	fun matchesHandler(loc: SpaceSafeURI): Boolean
+
+	fun getNewLoc(loc: SpaceSafeURI): SpaceSafeURI {
+		return loc
+	}
+
+	/**
+	 * Gets the Source for a location. Must be threadsafe.
+	 * It is assumed that each location is read only once for the duration of an IRequestHandler.
+	 * @param loc The location to be read
+	 * @return The Source containing the data of the file
+	 * @throws Exception Exception if it failed to download a file!!!
+	 */
+	fun getFileSource(loc: SpaceSafeURI): Source?
+}

src/main/kotlin/link/infra/packwiz/installer/request/handlers/RequestHandlerGithub.kt

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+package link.infra.packwiz.installer.request.handlers
+
+import link.infra.packwiz.installer.metadata.SpaceSafeURI
+import java.util.*
+import java.util.concurrent.locks.ReentrantReadWriteLock
+import java.util.regex.Pattern
+import kotlin.concurrent.read
+import kotlin.concurrent.write
+
+class RequestHandlerGithub : RequestHandlerZip(true) {
+	override fun getNewLoc(loc: SpaceSafeURI): SpaceSafeURI {
+		return loc
+	}
+
+	companion object {
+		private val repoMatcherPattern = Pattern.compile("/([\\w.-]+/[\\w.-]+).*")
+		private val branchMatcherPattern = Pattern.compile("/[\\w.-]+/[\\w.-]+/blob/([\\w.-]+).*")
+	}
+
+	// TODO: is caching really needed, if HTTPURLConnection follows redirects correctly?
+	private val zipUriMap: MutableMap<String, SpaceSafeURI> = HashMap()
+	private val zipUriLock = ReentrantReadWriteLock()
+	private fun getRepoName(loc: SpaceSafeURI): String? {
+		val matcher = repoMatcherPattern.matcher(loc.path)
+		return if (matcher.matches()) {
+			matcher.group(1)
+		} else {
+			null
+		}
+	}
+
+	override fun getZipUri(loc: SpaceSafeURI): SpaceSafeURI {
+		val repoName = getRepoName(loc)
+		val branchName = getBranch(loc)
+
+		zipUriLock.read {
+			zipUriMap["$repoName/$branchName"]
+		}?.let { return it }
+
+		var zipUri = SpaceSafeURI("https://api.github.com/repos/$repoName/zipball/$branchName")
+		zipUriLock.write {
+			// If another thread sets the value concurrently, use the existing value from the
+			// thread that first acquired the lock.
+			zipUri = zipUriMap.putIfAbsent("$repoName/$branchName", zipUri) ?: zipUri
+		}
+		return zipUri
+	}
+
+	private fun getBranch(loc: SpaceSafeURI): String? {
+		val matcher = branchMatcherPattern.matcher(loc.path)
+		return if (matcher.matches()) {
+			matcher.group(1)
+		} else {
+			null
+		}
+	}
+
+	override fun getLocationInZip(loc: SpaceSafeURI): SpaceSafeURI {
+		val path = "/" + getRepoName(loc) + "/blob/" + getBranch(loc)
+		return SpaceSafeURI(loc.scheme, loc.authority, path, null, null).relativize(loc)
+	}
+
+	override fun matchesHandler(loc: SpaceSafeURI): Boolean {
+		val scheme = loc.scheme
+		if (!("http" == scheme || "https" == scheme)) {
+			return false
+		}
+		return "github.com" == loc.host
+		// TODO: sanity checks, support for more github urls
+	}
+}

src/main/kotlin/link/infra/packwiz/installer/request/handlers/RequestHandlerHTTP.kt

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+package link.infra.packwiz.installer.request.handlers
+
+import link.infra.packwiz.installer.metadata.SpaceSafeURI
+import link.infra.packwiz.installer.request.IRequestHandler
+import okio.Source
+import okio.source
+
+open class RequestHandlerHTTP : IRequestHandler {
+	override fun matchesHandler(loc: SpaceSafeURI): Boolean {
+		val scheme = loc.scheme
+		return "http" == scheme || "https" == scheme
+	}
+
+	override fun getFileSource(loc: SpaceSafeURI): Source? {
+		val conn = loc.toURL().openConnection()
+		// TODO: when do we send specific headers??? should there be a way to signal this?
+		// github *sometimes* requires it, sometimes not!
+		//conn.addRequestProperty("Accept", "application/octet-stream");
+		conn.apply {
+			// 30 second read timeout
+			readTimeout = 30 * 1000
+		}
+		return conn.getInputStream().source()
+	}
+}

src/main/kotlin/link/infra/packwiz/installer/request/handlers/RequestHandlerZip.kt

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+package link.infra.packwiz.installer.request.handlers
+
+import link.infra.packwiz.installer.metadata.SpaceSafeURI
+import okio.Buffer
+import okio.Source
+import okio.buffer
+import okio.source
+import java.util.*
+import java.util.concurrent.locks.ReentrantLock
+import java.util.concurrent.locks.ReentrantReadWriteLock
+import java.util.function.Predicate
+import java.util.zip.ZipEntry
+import java.util.zip.ZipInputStream
+import kotlin.concurrent.read
+import kotlin.concurrent.withLock
+import kotlin.concurrent.write
+
+abstract class RequestHandlerZip(private val modeHasFolder: Boolean) : RequestHandlerHTTP() {
+	private fun removeFolder(name: String): String {
+		return if (modeHasFolder) {
+			// TODO: replace with proper path checks once switched to Path??
+			name.substring(name.indexOf("/") + 1)
+		} else {
+			name
+		}
+	}
+
+	private inner class ZipReader internal constructor(zip: Source) {
+		private val zis = ZipInputStream(zip.buffer().inputStream())
+		private val readFiles: MutableMap<SpaceSafeURI, Buffer> = HashMap()
+		// Write lock implies access to ZipInputStream - only 1 thread must read at a time!
+		val filesLock = ReentrantLock()
+		private var entry: ZipEntry? = null
+
+		private val zipSource = zis.source().buffer()
+
+		// File lock must be obtained before calling this function
+		private fun readCurrFile(): Buffer {
+			val fileBuffer = Buffer()
+			zipSource.readFully(fileBuffer, entry!!.size)
+			return fileBuffer
+		}
+
+		// File lock must be obtained before calling this function
+		private fun findFile(loc: SpaceSafeURI): Buffer? {
+			while (true) {
+				entry = zis.nextEntry
+				entry?.also {
+					val data = readCurrFile()
+					val fileLoc = SpaceSafeURI(removeFolder(it.name))
+					if (loc == fileLoc) {
+						return data
+					} else {
+						readFiles[fileLoc] = data
+					}
+				} ?: return null
+			}
+		}
+
+		fun getFileSource(loc: SpaceSafeURI): Source? {
+			filesLock.withLock {
+				// Assume files are only read once, allow GC by removing
+				readFiles.remove(loc)?.also { return it }
+				return findFile(loc)
+			}
+		}
+
+		fun findInZip(matches: Predicate<SpaceSafeURI>): SpaceSafeURI? {
+			filesLock.withLock {
+				readFiles.keys.find { matches.test(it) }?.let { return it }
+
+				do {
+					val entry = zis.nextEntry?.also {
+						val data = readCurrFile()
+						val fileLoc = SpaceSafeURI(removeFolder(it.name))
+						readFiles[fileLoc] = data
+						if (matches.test(fileLoc)) {
+							return fileLoc
+						}
+					}
+				} while (entry != null)
+				return null
+			}
+		}
+	}
+
+	private val cache: MutableMap<SpaceSafeURI, ZipReader> = HashMap()
+	private val cacheLock = ReentrantReadWriteLock()
+
+	protected abstract fun getZipUri(loc: SpaceSafeURI): SpaceSafeURI
+	protected abstract fun getLocationInZip(loc: SpaceSafeURI): SpaceSafeURI
+	abstract override fun matchesHandler(loc: SpaceSafeURI): Boolean
+
+	override fun getFileSource(loc: SpaceSafeURI): Source? {
+		val zipUri = getZipUri(loc)
+		var zr = cacheLock.read { cache[zipUri] }
+		if (zr == null) {
+			cacheLock.write {
+				// Recheck, because unlocking read lock allows another thread to modify it
+				zr = cache[zipUri]
+
+				if (zr == null) {
+					val src = super.getFileSource(zipUri) ?: return null
+					zr = ZipReader(src).also { cache[zipUri] = it }
+				}
+			}
+		}
+		return zr?.getFileSource(getLocationInZip(loc))
+	}
+
+	protected fun findInZip(loc: SpaceSafeURI, matches: Predicate<SpaceSafeURI>): SpaceSafeURI? {
+		val zipUri = getZipUri(loc)
+		return (cacheLock.read { cache[zipUri] } ?: cacheLock.write {
+			// Recheck, because unlocking read lock allows another thread to modify it
+			cache[zipUri] ?: run {
+				// Create the ZipReader if it doesn't exist, return null if getFileSource returns null
+				super.getFileSource(zipUri)?.let { ZipReader(it) }
+						?.also { cache[zipUri] = it }
+			}
+		})?.findInZip(matches)
+	}
+
+}