Adds support for ChatGPT (gpt-3.5-turbo and gpt-3.5-turbo-0301) (#10)

* Adds support for gpt-3.5-turbo and gpt-3.5-turbo-0301

* Adds a test for the chat API.

Sources/OpenAIKit/Chat/Chat.swift

@@ -0,0 +1,38 @@
+import Foundation
+
+/**
+ Given a prompt, the model will return one or more predicted chat completions, and can also return the probabilities of alternative tokens at each position.
+ */
+public struct Chat {
+    public let id: String
+    public let object: String
+    public let created: Date
+    public let model: String
+    public let choices: [Choice]
+    public let usage: Usage
+}
+
+extension Chat: Codable {}
+
+extension Chat {
+    public struct Choice {
+        public let index: Int
+        public let message: Message
+        public let finishReason: String?
+    }
+}
+
+extension Chat.Choice: Codable {}
+
+extension Chat {
+    public struct Message {
+        public let role: String
+        public let content: String
+        public init(role: String, content: String) {
+            self.role = role
+            self.content = content
+        }
+    }
+}
+
+extension Chat.Message: Codable {}

Sources/OpenAIKit/Chat/ChatProvider.swift

@@ -0,0 +1,49 @@
+public struct ChatProvider {
+
+    private let requestHandler: RequestHandler
+
+    init(requestHandler: RequestHandler) {
+        self.requestHandler = requestHandler
+    }
+
+    /**
+     Create chat completion
+     POST
+      
+     https://api.openai.com/v1/chat/completions
+
+     Creates a chat completion for the provided prompt and parameters
+     */
+    public func create(
+        model: ModelID,
+        messages: [Chat.Message] = [],
+        temperature: Double = 1.0,
+        topP: Double = 1.0,
+        n: Int = 1,
+        stream: Bool = false,
+        stops: [String] = [],
+        presencePenalty: Double = 0.0,
+        frequencyPenalty: Double = 0.0,
+        logitBias: [String : Int] = [:],
+        user: String? = nil
+    ) async throws -> Chat {
+
+        let request = try CreateChatRequest(
+            model: model.id,
+            messages: messages,
+            temperature: temperature,
+            topP: topP,
+            n: n,
+            stream: stream,
+            stops: stops,
+            presencePenalty: presencePenalty,
+            frequencyPenalty: frequencyPenalty,
+            logitBias: logitBias,
+            user: user
+        )
+        let chat: Chat = try await requestHandler.perform(request: request)
+
+        return chat
+
+    }
+}

Sources/OpenAIKit/Chat/CreateChatRequest.swift

@@ -0,0 +1,97 @@
+import AsyncHTTPClient
+import NIOHTTP1
+import Foundation
+
+struct CreateChatRequest: Request {
+    let method: HTTPMethod = .POST
+    let path = "/v1/chat/completions"
+    let body: HTTPClient.Body?
+
+    init(
+        model: String,
+        messages: [Chat.Message],
+        temperature: Double,
+        topP: Double,
+        n: Int,
+        stream: Bool,
+        stops: [String],
+        presencePenalty: Double,
+        frequencyPenalty: Double,
+        logitBias: [String: Int],
+        user: String?
+    ) throws {
+
+        let body = Body(
+            model: model,
+            messages: messages,
+            temperature: temperature,
+            topP: topP,
+            n: n,
+            stream: stream,
+            stops: stops,
+            presencePenalty: presencePenalty,
+            frequencyPenalty: frequencyPenalty,
+            logitBias: logitBias,
+            user: user
+        )
+
+        self.body = .data(try Self.encoder.encode(body))
+    }
+}
+
+extension CreateChatRequest {
+    struct Body: Encodable {
+        let model: String
+        let messages: [Chat.Message]
+        let temperature: Double
+        let topP: Double
+        let n: Int
+        let stream: Bool
+        let stops: [String]
+        let presencePenalty: Double
+        let frequencyPenalty: Double
+        let logitBias: [String: Int]
+        let user: String?
+
+        enum CodingKeys: CodingKey {
+            case model
+            case messages
+            case temperature
+            case topP
+            case n
+            case stream
+            case stop
+            case presencePenalty
+            case frequencyPenalty
+            case logitBias
+            case user
+        }
+
+        func encode(to encoder: Encoder) throws {
+            var container = encoder.container(keyedBy: CodingKeys.self)
+            try container.encode(model, forKey: .model)
+
+            if !messages.isEmpty {
+                try container.encode(messages, forKey: .messages)
+            }
+
+            try container.encode(temperature, forKey: .temperature)
+            try container.encode(topP, forKey: .topP)
+            try container.encode(n, forKey: .n)
+            try container.encode(stream, forKey: .stream)
+
+            if !stops.isEmpty {
+                try container.encode(stops, forKey: .stop)
+            }
+
+            try container.encode(presencePenalty, forKey: .presencePenalty)
+            try container.encode(frequencyPenalty, forKey: .frequencyPenalty)
+
+            if !logitBias.isEmpty {
+                try container.encode(logitBias, forKey: .logitBias)
+            }
+
+            try container.encodeIfPresent(user, forKey: .user)
+        }
+    }
+}

Sources/OpenAIKit/Client/Client.swift

@@ -7,6 +7,7 @@ public struct Client {
 
     public let models: ModelProvider
     public let completions: CompletionProvider
+    public let chats: ChatProvider
     public let edits: EditProvider
     public let images: ImageProvider
     public let embeddings: EmbeddingProvider
@@ -25,6 +26,7 @@ public struct Client {
 
         self.models = ModelProvider(requestHandler: requestHandler)
         self.completions = CompletionProvider(requestHandler: requestHandler)
+        self.chats = ChatProvider(requestHandler: requestHandler)
         self.edits = EditProvider(requestHandler: requestHandler)
         self.images = ImageProvider(requestHandler: requestHandler)
         self.embeddings = EmbeddingProvider(requestHandler: requestHandler)

Sources/OpenAIKit/Model/Model.swift

@@ -36,6 +36,8 @@ public protocol ModelID {
 
 extension Model {
     public enum GPT3: String, ModelID {
+        case gpt3_5Turbo = "gpt-3.5-turbo"
+        case gpt3_5Turbo0301 = "gpt-3.5-turbo-0301"
         case textDavinci003 = "text-davinci-003"
         case textDavinci002 = "text-davinci-002"
         case textCurie001 = "text-curie-001"

Tests/OpenAIKitTests/OpenAIKitTests.swift

@@ -50,6 +50,20 @@ final class OpenAIKitTests: XCTestCase {
         print(completion)
     }
 
+    func test_createChat() async throws {
+        let completion = try await client.chats.create(
+            model: Model.GPT3.gpt3_5Turbo,
+            messages: [
+                Chat.Message(
+                    role: "user",
+                    content: "Write a haiku"
+                )
+            ]
+        )
+
+        print(completion)
+    }
+
     func test_createEdit() async throws {
         let edit = try await client.edits.create(
             input: "Whay day of the wek is it?",