// Spark IM HTTP + TCP demo against production (iOS 13+ / macOS).
// Drop into a Swift command-line target or iOS app and call SparkImClient.run().
import Foundation
import Network

enum SparkImClient {
	static let api = URL(string: "https://sparkapi.wyrs365.com")!
	static let imHost = NWEndpoint.Host("sparkim.wyrs365.com")
	static let imPort = NWEndpoint.Port(443)!
	static let deviceID: UInt64 = 7

	struct LoginEnv: Decodable {
		struct Data: Decodable { let access_token: String }
		let code: String
		let data: Data
	}

	static func run() {
		do {
			let token = try login()
			connect(token: token)
			RunLoop.main.run(until: Date().addingTimeInterval(15))
		} catch {
			fputs("login failed: \(error)\n", stderr)
		}
	}

	static func login() throws -> String {
		var req = URLRequest(url: api.appendingPathComponent("/v1/auth/login"))
		req.httpMethod = "POST"
		req.setValue("application/json", forHTTPHeaderField: "Content-Type")
		req.setValue("zh-CN", forHTTPHeaderField: "X-Language")
		req.setValue("1.0.0", forHTTPHeaderField: "X-App-Version")
		req.httpBody = """
		{"email":"test01@spark.com","verify_code":"000000","device_id":\(deviceID),"device_type":"ios","device_name":"demo"}
		""".data(using: .utf8)
		let sem = DispatchSemaphore(value: 0)
		var result: Result<String, Error> = .failure(URLError(.unknown))
		URLSession.shared.dataTask(with: req) { data, _, err in
			defer { sem.signal() }
			if let err {
				result = .failure(err)
				return
			}
			guard let data else {
				result = .failure(URLError(.badServerResponse))
				return
			}
			do {
				let env = try JSONDecoder().decode(LoginEnv.self, from: data)
				guard env.code == "0" else {
					result = .failure(URLError(.userAuthenticationRequired))
					return
				}
				result = .success(env.data.access_token)
			} catch {
				result = .failure(error)
			}
		}.resume()
		sem.wait()
		return try result.get()
	}

	static func connect(token: String) {
		let conn = NWConnection(host: imHost, port: imPort, using: .tls)
		conn.stateUpdateHandler = { state in
			guard case .ready = state else { return }
			let auth = #"{"token":"\#(token)","device_id":\#(deviceID),"app_version":"1.0.0","language":"zh-CN"}"#
			send(conn, cmd: 1, seq: 1, body: Data(auth.utf8)) {
				recv(conn) { authResp in
					print("AUTH", authResp)
					send(conn, cmd: 2, seq: 2, body: Data()) {
						recv(conn) { hb in
							print("HB", hb)
							let sendBody = #"{"peer_id":1,"client_msg_id":"demo-1","content":{"t":1,"text":{"body":"hi"}}}"#
							send(conn, cmd: 4, seq: 3, body: Data(sendBody.utf8)) {
								recv(conn) { ack in
									print("SEND", ack)
								}
							}
						}
					}
				}
			}
		}
		conn.start(queue: .main)
	}

	static func frame(cmd: UInt16, seq: UInt32, body: Data) -> Data {
		var d = Data(capacity: 23 + body.count)
		func u16(_ v: UInt16) { d.append(UInt8(v >> 8)); d.append(UInt8(v & 0xff)) }
		func u32(_ v: UInt32) {
			d.append(UInt8((v >> 24) & 0xff)); d.append(UInt8((v >> 16) & 0xff))
			d.append(UInt8((v >> 8) & 0xff)); d.append(UInt8(v & 0xff))
		}
		u16(0x5350); d.append(1); u16(cmd); u16(0)
		d.append(contentsOf: [UInt8](repeating: 0, count: 8))
		u32(seq); u32(UInt32(body.count)); d.append(body)
		return d
	}

	static func send(_ conn: NWConnection, cmd: UInt16, seq: UInt32, body: Data, done: @escaping () -> Void) {
		conn.send(content: frame(cmd: cmd, seq: seq, body: body), completion: .contentProcessed { _ in done() })
	}

	static func recv(_ conn: NWConnection, done: @escaping (String) -> Void) {
		conn.receive(minimumIncompleteLength: 23, maximumLength: 23) { header, _, _, err in
			guard let header, header.count == 23, err == nil else { return }
			let n = Int(header[19]) << 24 | Int(header[20]) << 16 | Int(header[21]) << 8 | Int(header[22])
			let cmd = Int(header[3]) << 8 | Int(header[4])
			if n == 0 {
				done("cmd=\(cmd) {}")
				return
			}
			conn.receive(minimumIncompleteLength: n, maximumLength: max(n, 1)) { body, _, _, _ in
				let payload = body ?? Data()
				done("cmd=\(cmd) " + (String(data: payload, encoding: .utf8) ?? "<gzip \(payload.count)B>"))
			}
		}
	}
}