Rework target into interface; add overwrite mode and validity/identity tokens

src/main/kotlin/link/infra/packwiz/installer/target/OverwriteMode.kt

@@ -0,0 +1,13 @@
+package link.infra.packwiz.installer.target
+
+enum class OverwriteMode {
+	/**
+	 * Overwrite the destination with the source file, if the source file has changed.
+	 */
+	IF_SRC_CHANGED,
+
+	/**
+	 * Never overwrite the destination; if it exists, it should not be written to.
+	 */
+	NEVER
+}

src/main/kotlin/link/infra/packwiz/installer/target/Target.kt

@@ -1,32 +1,45 @@
 package link.infra.packwiz.installer.target
 
-import link.infra.packwiz.installer.metadata.SpaceSafeURI
-import link.infra.packwiz.installer.metadata.hash.Hash
-import java.nio.file.Path
+import link.infra.packwiz.installer.target.path.PackwizPath
+
+// TODO: rename to avoid conflicting with @Target
+interface Target {
+	val src: PackwizPath
+	val dest: PackwizPath
+	val validityToken: ValidityToken
 
-data class Target(
 	/**
-	 * The name that uniquely identifies this target.
-	 * Often equal to the name of the metadata file for this target, and can be displayed to the user in progress UI.
+	 * Token interface for types used to compare Target identity. Implementations should use equals to indicate that
+	 * these tokens represent the same file; used to preserve optional target choices between file renames.
 	 */
-	val name: String,
+	interface IdentityToken
+
 	/**
-	 * An optional user-friendly name.
+	 * Default implementation of IdentityToken that assumes files are not renamed; so optional choices do not need to
+	 * be preserved across renames.
 	 */
-	val userFriendlyName: String?,
-	val src: SpaceSafeURI,
-	val dest: Path,
-	val hash: Hash,
-	val side: Side,
-	val optional: Boolean,
-	val optionalDefaultValue: Boolean,
-	val optionalDescription: String,
+	@JvmInline
+	value class PathIdentityToken(val path: String): IdentityToken
+
+	val ident: IdentityToken
+		get() = PathIdentityToken(dest.path)
+
 	/**
-	 * If this is true, don't update a target when the file already exists.
+	 * A user-friendly name; defaults to the destination path of the file.
 	 */
-	val noOverwrite: Boolean
-) {
-	fun Iterable<Target>.filterForSide(side: Side) = this.filter {
-		it.side.hasSide(side)
+	val name: String
+		get() = dest.path
+	val side: Side
+		get() = Side.BOTH
+	val overwriteMode: OverwriteMode
+		get() = OverwriteMode.IF_SRC_CHANGED
+
+	interface Optional: Target {
+		val optional: Boolean
+		val optionalDefaultValue: Boolean
+	}
+
+	interface OptionalDescribed: Optional {
+		val optionalDescription: String
 	}
 }

src/main/kotlin/link/infra/packwiz/installer/target/ValidityToken.kt

@@ -0,0 +1,16 @@
+package link.infra.packwiz.installer.target
+
+import link.infra.packwiz.installer.metadata.hash.Hash
+
+/**
+ * A token used to determine if the source or destination file is changed, and ensure that the destination file is valid.
+ */
+interface ValidityToken {
+	// TODO: functions to allow validating this from file metadata, from file, or during the download process
+
+	/**
+	 * Default implementation of ValidityToken based on a single hash.
+	 */
+	@JvmInline
+	value class HashValidityToken(val hash: Hash): ValidityToken
+}