ABI.Record.swift

//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2024 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for Swift project authors
//

extension ABI {
  /// A type implementing the JSON encoding of records for the ABI entry point
  /// and event stream output.
  ///
  /// This type is not part of the public interface of the testing library. It
  /// assists in converting values to JSON; clients that consume this JSON are
  /// expected to write their own decoders.
  struct Record<V>: Sendable where V: ABI.Version {
    /// An enumeration describing the various kinds of record.
    enum Kind: Sendable {
      /// A test record.
      case test(EncodedTest<V>)

      /// An event record.
      case event(EncodedEvent<V>)
    }

    /// The kind of record.
    var kind: Kind

    init(encoding test: borrowing Test) {
      kind = .test(EncodedTest(encoding: test))
    }

    init?(encoding event: borrowing Event, in eventContext: borrowing Event.Context, messages: borrowing [Event.HumanReadableOutputRecorder.Message]) {
      guard let event = EncodedEvent<V>(encoding: event, in: eventContext, messages: messages) else {
        return nil
      }
      kind = .event(event)
    }
  }
}

// MARK: - Decodable

extension ABI.Record: Decodable {
  private enum CodingKeys: String, CodingKey {
    case version
    case kind
    case payload
  }

  init(from decoder: any Decoder) throws {
    let container = try decoder.container(keyedBy: CodingKeys.self)

    let versionNumber = try container.decode(Int.self, forKey: .version)
    if versionNumber != V.versionNumber {
      throw DecodingError.dataCorrupted(
        DecodingError.Context(
          codingPath: decoder.codingPath + CollectionOfOne(CodingKeys.version as any CodingKey),
          debugDescription: "Unexpected record version \(versionNumber) (expected \(V.versionNumber))."
        )
      )
    }

    switch try container.decode(String.self, forKey: .kind) {
    case "test":
      let test = try container.decode(ABI.EncodedTest<V>.self, forKey: .payload)
      kind = .test(test)
    case "event":
      let event = try container.decode(ABI.EncodedEvent<V>.self, forKey: .payload)
      kind = .event(event)
    case let kind:
      throw DecodingError.dataCorrupted(
        DecodingError.Context(
          codingPath: decoder.codingPath + CollectionOfOne(CodingKeys.kind as any CodingKey),
          debugDescription: "Unrecognized record kind '\(kind)'"
        )
      )
    }
  }
}

extension ABI.Record: JSON.Serializable {
  func makeJSONValue() -> JSON.Value {
    var dict = [
      "version": V.versionNumber.makeJSONValue()
    ]

    switch kind {
    case let .test(test):
      dict["kind"] = "test".makeJSONValue()
      dict["payload"] = test.makeJSONValue()
    case let .event(event):
      dict["kind"] = "event".makeJSONValue()
      dict["payload"] = event.makeJSONValue()
    }

    return dict.makeJSONValue()
  }
}