file system rework

1 files changed, 86 insertions, 0 deletions

diff --git a/src/main/kotlin/files.kt b/src/main/kotlin/files.kt
new file mode 100644
index 0000000..990ae7e
--- /dev/null
+++ b/src/main/kotlin/files.kt
@@ -0,0 +1,86 @@
+class IOHandler {
+	val mounts = mutableListOf<Mount>()
+	fun mount(absolutePath: Path.Absolute, fileSystem: FileSystem) {
+		if (mounts.any { it.mountPoint == absolutePath })
+			return // TODO sensible error message handling
+		mounts += Mount(absolutePath, fileSystem)
+	}
+
+	fun unmount(mountPoint: Path.Absolute) {
+		mounts.removeAll { it.mountPoint == mountPoint }
+	}
+
+	fun <T> findMountFor(
+		workingDirectory: Path.Absolute,
+		path: Path,
+		operation: FileSystem.(relativePath: Path) -> T
+	): T {
+		val absolutPath = path.toAbsolutePath(workingDirectory)
+		val mount = mounts.filter {
+			it.mountPoint.parts.zip(absolutPath.parts).all { (a, b) -> a == b }
+		}.maxByOrNull { it.mountPoint.parts.size } ?: throw IllegalStateException("No mount present")
+		return mount.fileSystem.operation(
+			Path.Absolute(
+				absolutPath.parts.subList(
+					mount.mountPoint.parts.size,
+					absolutPath.parts.size
+				)
+			) // TODO: unangenehm
+		)
+	}
+
+	fun findINode(absolutePath: Path.Absolute): INode {
+		val mount = mounts.filter {
+			it.mountPoint.parts.zip(absolutePath.parts).all { (a, b) -> a == b }
+		}.maxByOrNull { it.mountPoint.parts.size } ?: throw IllegalStateException("No mount present")
+		val iNode = mount.fileSystem.getINode(absolutePath.relativize(mount.mountPoint))
+		return when (iNode) {
+			is INodeResult.File -> iNode.op
+			is INodeResult.ResolveAgain -> findINode(absolutePath.resolve(iNode.relativeToOriginal))
+		}
+	}
+
+	fun read(workingDirectory: Path.Absolute, path: Path): ReadResult =
+		findMountFor(workingDirectory, path) { read(it) }
+
+	fun write(workingDirectory: Path.Absolute, path: Path, data: ByteArray): Unit =
+		findMountFor(workingDirectory, path) { write(it, data) }
+
+	fun stat(workingDirectory: Path.Absolute, path: Path): Unit =
+		findMountFor(workingDirectory, path) { stat(it) }
+}
+
+interface INode {
+	val fs: FileSystem
+}
+
+sealed interface INodeResult {
+	class File(val op: INode) : INodeResult
+	class ResolveAgain(val relativeToOriginal: Path): INodeResult
+}
+
+interface FileSystem {
+	fun getINode(relativePath: Path.Relative): INodeResult
+	fun read(relativePath: Path): ReadResult
+	fun write(path: Path, data: ByteArray): Unit // Write result
+	fun stat(path: Path): Unit // TODO Stat result
+}
+
+sealed class ReadResult {
+	class Success(val text: String) : ReadResult()
+	object NotFound : ReadResult()
+	object NoAccess : ReadResult()
+}
+
+data class Mount(
+	val mountPoint: Path.Absolute,
+	val fileSystem: FileSystem
+)
+
+data class Stat(
+	val exists: Boolean,
+	var owner: User,
+	val created: Long,
+	val edited: Long,
+	val size: Long
+)