/*
 * Copyright 2016, gRPC Authors All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#if SWIFT_PACKAGE
  import CgRPC
#endif
import Foundation // for String.Encoding

public final class gRPC {
  private init() { }  // Static members only.
  
  /// Initializes gRPC system
  public static func initialize() {
    grpc_init()
  }
  
  /// Shuts down gRPC system
  public static func shutdown() {
    grpc_shutdown()
  }
  
  /// Returns version of underlying gRPC library
  ///
  /// Returns: gRPC version string
  public static var version: String {
    // These two should always be valid UTF-8 strings, so we can forcibly unwrap them.
    return String(cString: grpc_version_string(), encoding: String.Encoding.utf8)!
  }
  
  /// Returns name associated with gRPC version
  ///
  /// Returns: gRPC version name
  public static var gStandsFor: String {
    return String(cString: grpc_g_stands_for(), encoding: String.Encoding.utf8)!
  }
}

/// Status codes for gRPC operations (replicated from status_code_enum.h)
public enum StatusCode: Int {
  /// Not an error; returned on success.
  case ok = 0

  /// The operation was cancelled (typically by the caller).
  case cancelled = 1

  /// Unknown error. An example of where this error may be returned is if a
  /// Status value received from another address space belongs to an error-space
  /// that is not known in this address space. Also errors raised by APIs that
  /// do not return enough error information may be converted to this error.
  case unknown = 2

  /// Client specified an invalid argument. Note that this differs from
  /// FAILED_PRECONDITION. INVALID_ARGUMENT indicates arguments that are
  /// problematic regardless of the state of the system (e.g., a malformed file
  /// name).
  case invalidArgument = 3

  /// Deadline expired before operation could complete. For operations that
  /// change the state of the system, this error may be returned even if the
  /// operation has completed successfully. For example, a successful response
  /// from a server could have been delayed long enough for the deadline to
  /// expire.
  case deadlineExceeded = 4

  /// Some requested entity (e.g., file or directory) was not found.
  case notFound = 5

  /// Some entity that we attempted to create (e.g., file or directory) already
  /// exists.
  case alreadyExists = 6

  /// The caller does not have permission to execute the specified operation.
  /// PERMISSION_DENIED must not be used for rejections caused by exhausting
  /// some resource (use RESOURCE_EXHAUSTED instead for those errors).
  /// PERMISSION_DENIED must not be used if the caller can not be identified
  /// (use UNAUTHENTICATED instead for those errors).
  case permissionDenied = 7

  /// The request does not have valid authentication credentials for the
  /// operation.
  case unauthenticated = 16

  /// Some resource has been exhausted, perhaps a per-user quota, or perhaps the
  /// entire file system is out of space.
  case resourceExhausted = 8

  /// Operation was rejected because the system is not in a state required for
  /// the operation's execution. For example, directory to be deleted may be
  /// non-empty, an rmdir operation is applied to a non-directory, etc.
  ///
  /// A litmus test that may help a service implementor in deciding
  /// between FAILED_PRECONDITION, ABORTED, and UNAVAILABLE:
  ///  (a) Use UNAVAILABLE if the client can retry just the failing call.
  ///  (b) Use ABORTED if the client should retry at a higher-level
  ///      (e.g., restarting a read-modify-write sequence).
  ///  (c) Use FAILED_PRECONDITION if the client should not retry until
  ///      the system state has been explicitly fixed. E.g., if an "rmdir"
  ///      fails because the directory is non-empty, FAILED_PRECONDITION
  ///      should be returned since the client should not retry unless
  ///      they have first fixed up the directory by deleting files from it.
  ///  (d) Use FAILED_PRECONDITION if the client performs conditional
  ///      REST Get/Update/Delete on a resource and the resource on the
  ///      server does not match the condition. E.g., conflicting
  ///      read-modify-write on the same resource.
  case failedPrecondition = 9

  /// The operation was aborted, typically due to a concurrency issue like
  /// sequencer check failures, transaction aborts, etc.
  ///
  /// See litmus test above for deciding between FAILED_PRECONDITION, ABORTED,
  /// and UNAVAILABLE.
  case aborted = 10

  /// Operation was attempted past the valid range. E.g., seeking or reading
  /// past end of file.
  ///
  /// Unlike INVALID_ARGUMENT, this error indicates a problem that may be fixed
  /// if the system state changes. For example, a 32-bit file system will
  /// generate INVALID_ARGUMENT if asked to read at an offset that is not in the
  /// range [0,2^32-1], but it will generate OUT_OF_RANGE if asked to read from
  /// an offset past the current file size.
  ///
  /// There is a fair bit of overlap between FAILED_PRECONDITION and
  /// OUT_OF_RANGE. We recommend using OUT_OF_RANGE (the more specific error)
  /// when it applies so that callers who are iterating through a space can
  /// easily look for an OUT_OF_RANGE error to detect when they are done.
  case outOfRange = 11

  /// Operation is not implemented or not supported/enabled in this service.
  case unimplemented = 12

  /// Internal errors. Means some invariants expected by underlying System has
  /// been broken. If you see one of these errors, Something is very broken.
  case internalError = 13

  /// The service is currently unavailable. This is a most likely a transient
  /// condition and may be corrected by retrying with a backoff.
  ///
  /// See litmus test above for deciding between FAILED_PRECONDITION, ABORTED,
  /// and UNAVAILABLE.
  case unavailable = 14

  /// Unrecoverable data loss or corruption.
  case dataLoss = 15

  /// Force users to include a default branch:
  case doNotUse = -1
}