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/*
TODO:
- add arguments to methods
- switch from returned strings to exceptions
*/
/**
* The [ProtocolTranslator] interface provides methods that coincide 1:1 with each request type in the 9P protocol.
* Every method that can fail, that is, every request that can receive a response with `Rerror` type instead of the same
* type as itself, returns a non-null `String` that contains the error message received in the response.
*
* Tags, FIDs, QIDs, and the `msize` value are supposed to be managed internally by the implementing class.
*
* When compared to 9P's formal message descriptions, like those which can be read in Plan 9's manual pages, some of the
* methods might lack parameters. Those which can be inferred from the existing parameters are purposefully omitted. An
* example is [walk], which omits `nwname` because it can be obtained by calculating the size of `wname`.
*
* Trivia: comments for each method are taken from each message type's manual page in section 5.
*/
interface ProtocolTranslator {
/**
* Negotiate protocol version.
*
* This must be the first message sent on the 9P connection and no other requests can be issued until a response has
* been received.
*
* @param msize The maximum length, in bytes, that the client will ever generate or expect to receive in a single
* 9P message.
* @param version Should be "9P2000", which is the only defined value.
* @throws except.InvalidMessageException if the received message is invalid.
* @throws except.RErrorException if the received message is an R-error message.
* @throws except.MsizeValueTooBigException if the received `msize` value is bigger than what the client requested.
* @throws except.UnknownVersionException if the version negotiation failed.
*/
fun version(msize: UInt, version: String)
/**
* Perform authentication.
*/
fun auth(afid: UInt, uname: String, aname: String)
/**
* Abort a message.
*
* @param oldtag The tag of the message that needs to be purged.
* @throws except.InvalidMessageException if the received message is invalid.
* @throws except.RErrorException if the received message is an R-error message.
*/
fun flush(oldtag: UShort)
/**
* Establish a connection.
*
* @param fid FID that represents the root directory of the desired file tree.
* @param afid A FID previously established by an auth message.
* @param uname A user identifier.
* @param aname The desired file tree to access.
* @throws except.InvalidMessageException if the received message is invalid.
* @throws except.RErrorException if the received message is an R-error message.
*/
fun attach(fid: UInt, afid: UInt, uname: String, aname: String)
/**
* Descend a directory hierarchy.
*
* @param fid The existing FID. It must represent a directory.
* @param newfid The proposed FID, which is going to be associated with the result of walking the hierarchy. It must
* be not in use, unless it is the same as [fid].
* @param wname The successive path name elements which describe the file to walk to.
* @return a possible error.
*/
fun walk(fid: UInt, newfid: UInt, wname: List<String>): String?
/**
* Prepare an FID for I/O on an existing file.
*/
fun open(path: String)
/**
* Prepare an FID for I/O on a new file.
*/
fun create(path: String)
/**
* Transfer data from file. Due to the negotiated maximum size of 9P messages, called `msize`, one is supposed to
* call this method multiple times, unless the content is smaller than `msize`.
*
* @return A pair of: (1) an optional error message and (2) the content read with the call just made. If the string
* is not null, an error occurred and the array is going to be empty.
*/
fun read(fid: UInt, offset: ULong, count: UInt): Pair<String?, Array<UByte>>
/**
* Transfer data to file. Due to the negotiated maximum size of 9P messages, called `msize`, one is supposed to
* call this method multiple times, unless the content is smaller than `msize`.
*
* @param fid The FID to write to.
* @param offset The distance between the beginning of the file and the first written byte.
* @param data The raw bytes that are going to be written.
* @return A pair of: (1) an optional error message and (2) the amount of bytes written with the call just made. If
* the string is not null, an error occurred and the amount of written bytes is going to be zero.
*/
fun write(fid: UInt, offset: ULong, count: UInt, data: Iterable<UByte>): Pair<String?, UInt>
/**
* Forget about an FID.
*/
fun clunk(path: String)
/**
* Remove a file from a server.
*/
fun remove(path: String)
/**
* Inquire file attributes.
*/
fun stat(path: String)
/**
* Change file attributes.
*/
fun wstat(path: String)
}
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