feat: Algolia Answers (#701)

* Implement Answers structures, endpoint and tests
* Add Find Answers snippet

Author: VladislavFitz

Dockerfile

@@ -9,11 +9,3 @@ COPY ./Package.* ./
 RUN swift package resolve
 
 COPY . .
-
-RUN swift build \
-    --enable-test-discovery \
-    -c release \
-    -Xswiftc -g \
-    -j 4
-
-# RUN swift test --enable-test-discovery

Sources/AlgoliaSearchClient/Command/Command+Answers.swift

@@ -0,0 +1,35 @@
+//
+//  Command+Answers.swift
+//  
+//
+//  Created by Vladislav Fitc on 19/11/2020.
+//
+
+import Foundation
+#if canImport(FoundationNetworking)
+import FoundationNetworking
+#endif
+
+extension Command {
+
+  enum Answers {
+
+    struct Find: AlgoliaCommand {
+
+      let callType: CallType = .read
+      let urlRequest: URLRequest
+      let requestOptions: RequestOptions?
+
+      init(indexName: IndexName,
+           query: AnswersQuery,
+           requestOptions: RequestOptions?) {
+        self.requestOptions = requestOptions
+        let path: IndexCompletion = .answers >>> .index(indexName) >>> .prediction
+        urlRequest = .init(method: .post, path: path, body: query.httpBody, requestOptions: self.requestOptions)
+      }
+
+    }
+
+  }
+
+}

Sources/AlgoliaSearchClient/Helpers/AssertionTestHelper.swift

@@ -0,0 +1,20 @@
+//
+//  AssertionTestHelper.swift
+//  
+//
+//  Created by Vladislav Fitc on 20/11/2020.
+//
+
+import Foundation
+
+/// Our custom drop-in replacement `assertionFailure`.
+///
+/// This will call Swift's `assertionFailure` by default (and terminate the program).
+/// But it can be changed at runtime to be tested instead of terminating.
+func assertionFailure(_ message: @autoclosure () -> String = String(), file: StaticString = #file, line: UInt = #line) {
+  assertionClosure(message(), file, line)
+}
+
+/// The actual function called by our custom `precondition`.
+var assertionClosure: (String, StaticString, UInt) -> Void = defaultAssertionClosure
+let defaultAssertionClosure = { Swift.assertionFailure($0, file: $1, line: $2) }

Sources/AlgoliaSearchClient/Index/Index+Answers.swift

@@ -0,0 +1,40 @@
+//
+//  Index+Answers.swift
+//  
+//
+//  Created by Vladislav Fitc on 20/11/2020.
+//
+
+import Foundation
+
+public extension Index {
+
+  /**
+   Returns answers that match the query.
+   
+   - Parameter query: The AnswersQuery used to search.
+   - Parameter requestOptions: Configure request locally with RequestOptions.
+   - Parameter completion: Result completion
+   - Returns: Launched asynchronous operation
+   */
+  @discardableResult func findAnswers(for query: AnswersQuery,
+                                      requestOptions: RequestOptions? = nil,
+                                      completion: @escaping ResultCallback<SearchResponse>) -> Operation & TransportTask {
+    let command = Command.Answers.Find(indexName: name, query: query, requestOptions: requestOptions)
+    return execute(command, completion: completion)
+  }
+
+  /**
+   Returns answers that match the query.
+   
+   - Parameter query: The AnswersQuery used to search.
+   - Parameter requestOptions: Configure request locally with RequestOptions.
+   - Returns: SearchResponse object
+   */
+  @discardableResult func findAnswers(for query: AnswersQuery,
+                                      requestOptions: RequestOptions? = nil) throws -> SearchResponse {
+    let command = Command.Answers.Find(indexName: name, query: query, requestOptions: requestOptions)
+    return try execute(command)
+  }
+
+}

Sources/AlgoliaSearchClient/Models/Answers/AnswersQuery+Language.swift

@@ -0,0 +1,46 @@
+//
+//  AnswersQuery+Language.swift
+//  
+//
+//  Created by Vladislav Fitc on 20/11/2020.
+//
+
+import Foundation
+
+extension AnswersQuery {
+
+  public enum Language: RawRepresentable, Codable {
+
+    case english
+    case custom(String)
+
+    public var rawValue: AlgoliaSearchClient.Language {
+      switch self {
+      case .english:
+        return .english
+      case .custom(let rawValue):
+        return .init(rawValue: rawValue)
+      }
+    }
+
+    public init(rawValue: AlgoliaSearchClient.Language) {
+      switch rawValue {
+      case .english:
+        self = .english
+      default:
+        self = .custom(rawValue.rawValue)
+      }
+    }
+
+    public init(from decoder: Decoder) throws {
+      let rawLanguage = try AlgoliaSearchClient.Language(from: decoder)
+      self.init(rawValue: rawLanguage)
+    }
+
+    public func encode(to encoder: Encoder) throws {
+      try rawValue.encode(to: encoder)
+    }
+
+  }
+
+}

Sources/AlgoliaSearchClient/Models/Answers/AnswersQuery.swift

@@ -0,0 +1,102 @@
+//
+//  AnswersQuery.swift
+//  
+//
+//  Created by Vladislav Fitc on 19/11/2020.
+//
+
+import Foundation
+
+public struct AnswersQuery: SearchParameters, Codable {
+
+  /// The query for which to retrieve results.
+  public var query: String
+  
+  /// The languages in the query.
+  ///
+  /// Default value: [.english]
+  public var queryLanguages: [Language]
+
+  /// Attributes to use for predictions.
+  ///
+  /// Default value: ["*"]  (all searchable attributes)
+  /// - Warning: All your attributesForPrediction must be part of your searchableAttributes.
+  public var attributesForPrediction: [Attribute]?
+
+  /// Maximum number of answers to retrieve from the Answers Engine.
+  ///
+  /// Default value: 10
+  ///
+  /// Cannot be greater than 1000.
+  public var nbHits: Int?
+
+  /// Threshold for the answers’ confidence score: only answers with extracts that score above this threshold are returned.
+  ///
+  /// Default value: 0.0
+  public var threshold: Double?
+
+  /// Not supported by Answers
+  public var attributesToSnippet: [Snippet]? {
+    get {
+      return nil
+    }
+    // swiftlint:disable:next unused_setter_value
+    set {
+      assertionFailure("attributesToSnippet is not supported by answers")
+    }
+  }
+
+  /// Not supported by Answers
+  public var hitsPerPage: Int? {
+    get {
+      return nil
+    }
+    // swiftlint:disable:next unused_setter_value
+    set {
+      assertionFailure("hitsPerPage is not supported by answers")
+    }
+  }
+
+  /// Not supported by Answers
+  public var restrictSearchableAttributes: [Attribute]? {
+    get {
+      return nil
+    }
+    // swiftlint:disable:next unused_setter_value
+    set {
+      assertionFailure("restrictSearchableAttributes is not supported by answers")
+    }
+  }
+
+  internal var params: SearchParametersStorage?
+
+  public init(query: String, queryLanguages: [Language]) {
+    self.query = query
+    self.queryLanguages = queryLanguages
+  }
+
+}
+
+extension AnswersQuery: ExpressibleByStringLiteral {
+
+  public init(stringLiteral value: String) {
+    self.init(query: value, queryLanguages: [.english])
+  }
+
+}
+
+extension AnswersQuery: SearchParametersStorageContainer {
+
+  var searchParametersStorage: SearchParametersStorage {
+    get {
+      return params ?? .init()
+    }
+
+    set {
+      params = newValue
+    }
+  }
+
+}
+
+extension AnswersQuery: Builder {}