swift API for chat, started chat UI (#228)

* started swift API for chat

* skeleton UI

* show all chat responses in Terminal view

* show chat list in UI

* refactor swift API

apps/ios/Shared/Model/SimpleXAPI.swift

@@ -0,0 +1,220 @@
+//
+//  ChatAPI.swift
+//  SimpleX
+//
+//  Created by Evgeny Poberezkin on 27/01/2022.
+//  Copyright © 2022 SimpleX Chat. All rights reserved.
+//
+
+import Foundation
+
+private var chatStore: chat_store?
+private var chatController: chat_ctrl?
+private let jsonDecoder = JSONDecoder()
+private let jsonEncoder = JSONEncoder()
+
+enum ChatCommand {
+    case apiGetChats
+    case apiGetChatItems(type: String, id: Int64)
+    case string(String)
+    case help
+
+    var cmdString: String {
+        get {
+            switch self {
+            case .apiGetChats:
+                return "/api/v1/chats"
+            case let .apiGetChatItems(type, id):
+                return "/api/v1/chat/items/\(type)/\(id)"
+            case let .string(str):
+                return str
+            case .help: return "/help"
+            }
+        }
+    }
+}
+
+struct APIResponse: Identifiable {
+    var resp: ChatResponse
+    var id: Int64
+}
+
+struct APIResponseJSON: Decodable {
+    var resp: ChatResponse
+}
+
+enum ChatResponse: Codable {
+    case response(type: String, json: String)
+    case apiChats(chats: [ChatPreview])
+    case apiDirectChat(chat: Chat) // direct/<id> or group/<id>, same as ChatPreview.id
+//    case chatHelp(String)
+//    case newSentInvitation
+    case contactConnected(contact: Contact)
+
+    var responseType: String {
+        get {
+            switch self {
+            case let .response(type, _): return "* \(type)"
+            case .apiChats(_): return "apiChats"
+            case .apiDirectChat(_): return "apiDirectChat"
+            case .contactConnected(_): return "contactConnected"
+            }
+        }
+    }
+    
+    var details: String {
+        get {
+            switch self {
+            case let .response(_, json): return json
+            case let .apiChats(chats): return String(describing: chats)
+            case let .apiDirectChat(chat): return String(describing: chat)
+            case let .contactConnected(contact): return String(describing: contact)
+            }
+        }
+    }
+}
+
+func chatGetUser() -> User? {
+    let store = getStore()
+    print("chatGetUser")
+    let r: UserResponse? = decodeCJSON(chat_get_user(store))
+    let user = r?.user
+    if user != nil { initChatCtrl(store) }
+    print("user", user as Any)
+    return user
+}
+
+func chatCreateUser(_ p: Profile) -> User? {
+    let store = getStore()
+    print("chatCreateUser")
+    var str = encodeCJSON(p)
+    chat_create_user(store, &str)
+    let user = chatGetUser()
+    if user != nil { initChatCtrl(store) }
+    print("user", user as Any)
+    return user
+}
+
+func chatSendCmd(_ chatModel: ChatModel, _ cmd: ChatCommand) {
+    var c = cmd.cmdString.cString(using: .utf8)!
+    processAPIResponse(chatModel,
+        apiResponse(
+            chat_send_cmd(getChatCtrl(), &c)!))
+}
+
+func chatRecvMsg(_ chatModel: ChatModel) {
+    processAPIResponse(chatModel,
+        apiResponse(
+            chat_recv_msg(getChatCtrl())!))
+}
+
+private func processAPIResponse(_ chatModel: ChatModel, _ res: APIResponse?) {
+    if let r = res {
+        DispatchQueue.main.async {
+            chatModel.apiResponses.append(r)
+            switch r.resp {
+            case let .apiChats(chats):
+                chatModel.chatPreviews = chats
+            case let .apiDirectChat(chat):
+                chatModel.chats[chat.chatInfo.id] = chat
+            case let .contactConnected(contact):
+                chatModel.chatPreviews.insert(
+                    ChatPreview(chatInfo: .direct(contact: contact)),
+                    at: 0
+                )
+            default: return
+
+//            case let .response(type, _):
+//                chatModel.chatItems.append(ChatItem(
+//                    ts: Date.now,
+//                    content: .text(type)
+//                ))
+            }
+        }
+    }
+}
+
+private struct UserResponse: Decodable {
+    var user: User?
+    var error: String?
+}
+
+private var respId: Int64 = 0
+
+private func apiResponse(_ cjson: UnsafePointer<CChar>) -> APIResponse? {
+    let s = String.init(cString: cjson)
+    print("apiResponse", s)
+    let d = s.data(using: .utf8)!
+//  TODO is there a way to do it without copying the data? e.g:
+//    let p = UnsafeMutableRawPointer.init(mutating: UnsafeRawPointer(cjson))
+//    let d = Data.init(bytesNoCopy: p, count: strlen(cjson), deallocator: .free)
+
+    do {
+        let r = try jsonDecoder.decode(APIResponseJSON.self, from: d)
+        return APIResponse(resp: r.resp, id: respId)
+    } catch {
+        print (error)
+    }
+        
+    var type: String?
+    var json: String?
+    if let j = try? JSONSerialization.jsonObject(with: d) as? NSDictionary {
+        if let j1 = j["resp"] as? NSDictionary, j1.count == 1 {
+            type = j1.allKeys[0] as? String
+        }
+        json = prettyJSON(j)
+    }
+    respId += 1
+    return APIResponse(
+        resp: ChatResponse.response(type: type ?? "invalid", json: json ?? s),
+        id: respId
+    )
+}
+
+func prettyJSON(_ obj: NSDictionary) -> String? {
+    if let d = try? JSONSerialization.data(withJSONObject: obj, options: .prettyPrinted) {
+        return String(decoding: d, as: UTF8.self)
+    }
+    return nil
+}
+
+private func getStore() -> chat_store {
+    if let store = chatStore { return store }
+    let dataDir = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!.path + "/mobile_v1"
+    var cstr = dataDir.cString(using: .utf8)!
+    chatStore = chat_init_store(&cstr)
+    return chatStore!
+}
+
+private func initChatCtrl(_ store: chat_store) {
+    if chatController == nil {
+        chatController = chat_start(store)        
+    }
+}
+
+private func getChatCtrl() -> chat_ctrl {
+    if let controller = chatController { return controller }
+    fatalError("Chat controller was not started!")
+}
+
+private func decodeCJSON<T: Decodable>(_ cjson: UnsafePointer<CChar>) -> T? {
+    let s = String.init(cString: cjson)
+    print("decodeCJSON", s)
+    let d = s.data(using: .utf8)!
+//    let p = UnsafeMutableRawPointer.init(mutating: UnsafeRawPointer(cjson))
+//    let d = Data.init(bytesNoCopy: p, count: strlen(cjson), deallocator: .free)
+    return try? jsonDecoder.decode(T.self, from: d)
+}
+
+private func getJSONObject(_ cjson: UnsafePointer<CChar>) -> NSDictionary? {
+    let s = String.init(cString: cjson)
+    let d = s.data(using: .utf8)!
+    return try? JSONSerialization.jsonObject(with: d) as? NSDictionary
+}
+
+private func encodeCJSON<T: Encodable>(_ value: T) -> [CChar] {
+    let data = try! jsonEncoder.encode(value)
+    let str = String(decoding: data, as: UTF8.self)
+    print("encodeCJSON", str)
+    return str.cString(using: .utf8)!
+}