Improve comments in code

src/main/kotlin/backup/BackupClient.kt

@@ -24,11 +24,18 @@ import java.util.zip.ZipInputStream
 import java.util.zip.ZipOutputStream
 import kotlin.io.path.createDirectory
 
+/**
+ * AWS S3 backup client.
+ */
 class BackupClient(
     private val s3: S3Client,
     private val bucketName: String,
     private val bufSize: Int = 1024 * 1024 * 100
 ) {
+    /**
+     * Upload a file/directory backup to AWS S3.
+     * @param file The File object for the file or directory.
+     */
     suspend fun upload(file: File) = coroutineScope {
         val backupKey = "${file.name}/${Instant.now()}.zip"
         PipedInputStream().use { inputStream ->
@@ -58,7 +65,7 @@ class BackupClient(
                             partNumber = number
                             uploadId = upload.uploadId
                             body = ByteStream.fromBytes(data.take(bytesRead))
-                        }.asCompletedPart(number)
+                        }.toCompletedPart(number)
                         uploadParts.add(part)
                         number++
                         bytesRead = inputStream.readNBytes(data, 0, bufSize)
@@ -92,6 +99,11 @@ class BackupClient(
         backupKey
     }
 
+    /**
+     * Restore a backup from AWS S3.
+     * @param destination The destination directory path for the backup contents.
+     * @param backupKey The S3 key of the backup.
+     */
     suspend fun restore(destination: Path, backupKey: String) = coroutineScope {
         val req = GetObjectRequest {
             bucket = bucketName
@@ -107,6 +119,12 @@ class BackupClient(
         }
     }
 
+    /**
+     * Restore a single file from a backup from AWS S3.
+     * @param destination The destination directory path for the file from the backup.
+     * @param backupKey The S3 key of the backup.
+     * @param fileName The full name of the file to restore (including directories if it was under a subdirectory).
+     */
     suspend fun restoreFile(destination: Path, backupKey: String, fileName: String) = coroutineScope {
         // For byte ranges refer to https://pkware.cachefly.net/webdocs/APPNOTE/APPNOTE-6.3.9.TXT
         val eocdReq = GetObjectRequest {
@@ -187,7 +205,12 @@ class BackupClient(
     }
 }
 
-private fun UploadPartResponse.asCompletedPart(number: Int): CompletedPart {
+/**
+ * Convert an UploadPartResponse to a CompletedPart.
+ * @param number The part number that was used for this part upload.
+ * @return The CompletedPart object.
+ */
+private fun UploadPartResponse.toCompletedPart(number: Int): CompletedPart {
     val part = this
     return CompletedPart {
         partNumber = number
@@ -199,10 +222,19 @@ private fun UploadPartResponse.asCompletedPart(number: Int): CompletedPart {
     }
 }
 
+/**
+ * Take first `n` items from the beginning of a ByteArray.
+ * @param n The number of items to take.
+ * @return A ByteArray of the first `n` items.
+ */
 private fun ByteArray.take(n: Int) =
     if (n == size) this // No copy
     else asList().subList(0, n).toByteArray() // TODO: One copy (toByteArray()), not sure how to do 0 copies here
 
+/**
+ * Compress a file or directory as a ZIP file to an `OutputStream`.
+ * @param outputStream The `OutputStream` to write the ZIP file contents to.
+ */
 private fun File.compressToZip(outputStream: OutputStream) = ZipOutputStream(outputStream).use { zipStream ->
     val parentDir = this.absoluteFile.parent + "/"
     val fileQueue = ArrayDeque<File>()
@@ -226,6 +258,11 @@ private fun File.compressToZip(outputStream: OutputStream) = ZipOutputStream(out
     }
 }
 
+/**
+ * Decompress `ZipInputStream` contents to specified destination paths.
+ * @param bufSize The buffer size to use for writing the decompressed files.
+ * @param entryNameToPath A function to convert ZIP entry names to destination `Path`s.
+ */
 private fun ZipInputStream.decompress(
     bufSize: Int = 1024 * 1024,
     entryNameToPath: (String) -> Path
@@ -250,6 +287,11 @@ private fun ZipInputStream.decompress(
     }
 }
 
+/**
+ * Set a `ZipEntry`'s attributes given a file's path.
+ * @param entry The `ZipEntry` to set attributes of.
+ * @param path The `Path` of the file to get the attributes from.
+ */
 private fun setZipAttributes(entry: ZipEntry, path: Path) {
     try {
         val attrs = Files.getFileAttributeView(path, BasicFileAttributeView::class.java).readAttributes()
@@ -260,6 +302,11 @@ private fun setZipAttributes(entry: ZipEntry, path: Path) {
     }
 }
 
+/**
+ * Set a file's attributes given a `ZipEntry`.
+ * @param entry The `ZipEntry` to get the attributes from.
+ * @param path The `Path` of the file to set the attributes of.
+ */
 private fun applyZipAttributes(entry: ZipEntry, path: Path) {
     try {
         val attrs = Files.getFileAttributeView(path, BasicFileAttributeView::class.java)

src/main/kotlin/backup/main.kt

@@ -1,11 +1,7 @@
 package backup
 
 import aws.sdk.kotlin.services.s3.S3Client
-import aws.sdk.kotlin.services.s3.model.ListBucketsRequest
-import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.runBlocking
-import java.io.File
-import kotlin.io.path.Path
 
 fun main() = runBlocking {
     S3Client.fromEnvironment().use { s3 ->

src/main/kotlin/ziputils/CentralDirectoryFileHeader.kt

@@ -3,6 +3,9 @@ package ziputils
 import java.nio.ByteBuffer
 import java.nio.ByteOrder
 
+/**
+ * Represents a partial ZIP central directory file header.
+ */
 internal class CentralDirectoryFileHeader(
     val compressedSize: UInt,
     val uncompressedSize: UInt,
@@ -22,8 +25,11 @@ internal class CentralDirectoryFileHeader(
         const val SIZE = 46
 
         /**
-         * Create CentralDirectoryFileHeader from raw byte data.
-         * @throws InvalidDataException provided ByteArray is not a supported CEN.
+         * Create `CentralDirectoryFileHeader` from raw byte data.
+         * @throws InvalidDataException provided `ByteArray` is not a supported CEN.
+         * @param data Raw byte data.
+         * @param offset Skip first <offset> bytes in data array.
+         * @return A `CentralDirectoryFileHeader`.
          */
         @Throws(InvalidDataException::class)
         fun fromByteArray(data: ByteArray, offset: Int): CentralDirectoryFileHeader {

src/main/kotlin/ziputils/EndOfCentralDirectoryLocator.kt

@@ -3,12 +3,22 @@ package ziputils
 import java.nio.ByteBuffer
 import java.nio.ByteOrder
 
+/**
+ * Represents a partial ZIP64 end of central directory locator.
+ */
 internal class EndOfCentralDirectoryLocator(
     val endOfCentralDirectory64Offset: ULong
 ) {
     companion object {
         const val SIGNATURE = 0x07064b50U
         const val SIZE = 20
+        /**
+         * Create `EndOfCentralDirectoryLocator` from raw byte data.
+         * @throws InvalidDataException Provided `ByteArray` is not a supported EOCD locator.
+         * @param data Raw byte data.
+         * @param offset Skip first <offset> bytes in data array.
+         * @return A `EndOfCentralDirectoryLocator`.
+         */
         @Throws(InvalidDataException::class)
         fun fromByteArray(data: ByteArray, offset: Int): EndOfCentralDirectoryLocator {
             if (data.size - offset < SIZE) {

src/main/kotlin/ziputils/EndOfCentralDirectoryRecord.kt

@@ -4,8 +4,7 @@ import java.nio.ByteBuffer
 import java.nio.ByteOrder
 
 /**
- * Partial End of Central Directory record class.
- * Only supports data required by the backup tool.
+ * Represents a partial ZIP end of central directory record.
  */
 internal class EndOfCentralDirectoryRecord(
     val centralDirectoryOffset: UInt
@@ -17,8 +16,11 @@ internal class EndOfCentralDirectoryRecord(
         const val SIGNATURE = 0x06054b50U
         const val SIZE = 22
         /**
-         * Create EndOfCentralDirectoryRecord from raw byte data.
-         * @throws InvalidDataException provided ByteArray is not a supported EOCD64.
+         * Create `EndOfCentralDirectoryRecord` from raw byte data.
+         * @throws InvalidDataException Provided `ByteArray` is not a supported EOCD64.
+         * @param data Raw byte data.
+         * @param offset Skip first <offset> bytes in data array.
+         * @return A `EndOfCentralDirectoryRecord`.
          */
         @Throws(InvalidDataException::class)
         fun fromByteArray(data: ByteArray, offset: Int): EndOfCentralDirectoryRecord {

src/main/kotlin/ziputils/EndOfCentralDirectoryRecord64.kt

@@ -4,8 +4,7 @@ import java.nio.ByteBuffer
 import java.nio.ByteOrder
 
 /**
- * Partial End of Central Directory record (ZIP64) class.
- * Only supports data required by the backup tool.
+ * Represents a partial ZIP64 end of central directory record.
  */
 internal class EndOfCentralDirectoryRecord64(
     val centralDirectoryOffset: ULong
@@ -14,8 +13,11 @@ internal class EndOfCentralDirectoryRecord64(
         const val SIGNATURE = 0x06064b50U
         const val SIZE = 56
         /**
-         * Create EndOfCentralDirectoryRecord64 from raw byte data.
-         * @throws InvalidDataException provided ByteArray is not a supported EOCD.
+         * Create `EndOfCentralDirectoryRecord64` from raw byte data.
+         * @throws InvalidDataException Provided `ByteArray` is not a supported EOCD.
+         * @param data Raw byte data.
+         * @param offset Skip first <offset> bytes in data array.
+         * @return A `EndOfCentralDirectoryRecord64`.
          */
         @Throws(InvalidDataException::class)
         fun fromByteArray(data: ByteArray, offset: Int): EndOfCentralDirectoryRecord64 {

src/main/kotlin/ziputils/Exceptions.kt

@@ -1,4 +1,11 @@
 package ziputils
 
+/**
+ * Represents an invalid raw byte data exception.
+ */
 class InvalidDataException(message: String): Exception(message)
+
+/**
+ * Represents an invalid raw byte signature exception.
+ */
 class InvalidSignatureException(message: String): Exception(message)

src/main/kotlin/ziputils/ExtraFieldRecord.kt

@@ -1,5 +1,8 @@
 package ziputils
 
+/**
+ * Represents a partial ZIP extra field record.
+ */
 internal open class ExtraFieldRecord(
     val id: UShort,
     val size: UShort

src/main/kotlin/ziputils/Zip64ExtraFieldRecord.kt

@@ -1,5 +1,8 @@
 package ziputils
 
+/**
+ * Represents a ZIP ZIP64 extra field record (ID 0x0001).
+ */
 internal class Zip64ExtraFieldRecord(
     size: UShort,
     val uncompressedSize: ULong?,