Scratchpad for file DSC functions.

ensure-file.kt

// Should hash on file write, then save date written, hash value, etc.
// Source files should also have this data written on first read, so it can be quickly compared later.
// Only rehash if the date-written metadata field is before the last-modified.'
// https://docs.oracle.com/javase/tutorial/essential/io/fileAttr.html

fun ensureFile(source: Path, target: Path) {
	when {
		source.toFile().exists && target.toFile().exists -> {
			
			val source_hash = Files.newInputStream(source).use { stream ->
				val digest = MessageDigest.getInstance("MD5")
				DigestInputStream(stream, digest).use {}
				return@use digest.digest()
			}
			
			val target_hash = Files.newInputStream(target).use { stream ->
				val digest = MessageDigest.getInstance("MD5")
				DigestInputStream(stream, digest).use {}
				return@use digest.digest()
			}
			
			if (source_hash == target_hash) {
				// files are identical, no worries.
				return
			}
			
			// 
			
		}
		source.toFile().exists -> // only source exists. Create target.
		else -> // only target exists. delete.
	}
}


// Not only does this have to grab the list of files on both sides and compare them to determine
//   needed changes, but it also needs to detect renames, etc. almost certainly by preserving a manifest of what
//   the expected source and target metadata was at the time of the last write/sync.
fun ensureFiles(source: List<Path>, target: List<Path>) {
	//
}