// Copyright 2022 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import Foundation

/// A `HTTPSCallableResult` contains the result of calling a `HTTPSCallable`.
@objc(FIRHTTPSCallableResult)
open class HTTPSCallableResult: NSObject {
  /// The data that was returned from the Callable HTTPS trigger.
  ///
  /// The data is in the form of native objects. For example, if your trigger returned an
  /// array, this object would be an `Array<Any>`. If your trigger returned a JavaScript object with
  /// keys and values, this object would be an instance of `[String: Any]`.
  @objc public let data: Any

  init(data: Any) {
    self.data = data
  }
}

/**
 * A `HTTPSCallable` is a reference to a particular Callable HTTPS trigger in Cloud Functions.
 */
@objc(FIRHTTPSCallable)
open class HTTPSCallable: NSObject {
  // MARK: - Private Properties

  // The functions client to use for making calls.
  private let functions: Functions

  private let url: URL

  private let options: HTTPSCallableOptions?

  // MARK: - Public Properties

  /// The timeout to use when calling the function. Defaults to 70 seconds.
  @objc open var timeoutInterval: TimeInterval = 70

  init(functions: Functions, url: URL, options: HTTPSCallableOptions? = nil) {
    self.functions = functions
    self.url = url
    self.options = options
  }

  /// Executes this Callable HTTPS trigger asynchronously.
  ///
  /// The data passed into the trigger can be any of the following types:
  /// - `nil` or `NSNull`
  /// - `String`
  /// - `NSNumber`, or any Swift numeric type bridgeable to `NSNumber`
  /// - `[Any]`, where the contained objects are also one of these types.
  /// - `[String: Any]` where the values are also one of these types.
  ///
  /// The request to the Cloud Functions backend made by this method automatically includes a
  /// Firebase Installations ID token to identify the app instance. If a user is logged in with
  /// Firebase Auth, an auth ID token for the user is also automatically included.
  ///
  /// Firebase Cloud Messaging sends data to the Firebase backend periodically to collect
  /// information
  /// regarding the app instance. To stop this, see `Messaging.deleteData()`. It
  /// resumes with a new FCM Token the next time you call this method.
  ///
  /// - Parameters:
  ///   - data: Parameters to pass to the trigger.
  ///   - completion: The block to call when the HTTPS request has completed.
  @objc(callWithObject:completion:) open func call(_ data: Any? = nil,
                                                   completion: @escaping (HTTPSCallableResult?,
                                                                          Error?) -> Void) {
    let callback: ((Result<HTTPSCallableResult, Error>) -> Void) = { result in
      switch result {
      case let .success(callableResult):
        completion(callableResult, nil)
      case let .failure(error):
        completion(nil, error)
      }
    }

    functions.callFunction(
      at: url,
      withObject: data,
      options: options,
      timeout: timeoutInterval,
      completion: callback
    )
  }

  /// Executes this Callable HTTPS trigger asynchronously. This API should only be used from
  /// Objective-C.
  ///
  /// The request to the Cloud Functions backend made by this method automatically includes a
  /// Firebase Installations ID token to identify the app instance. If a user is logged in with
  /// Firebase Auth, an auth ID token for the user is also automatically included.
  ///
  /// Firebase Cloud Messaging sends data to the Firebase backend periodically to collect
  /// information
  /// regarding the app instance. To stop this, see `Messaging.deleteData()`. It
  /// resumes with a new FCM Token the next time you call this method.
  ///
  /// - Parameter completion: The block to call when the HTTPS request has completed.
  @objc(callWithCompletion:) public func __call(completion: @escaping (HTTPSCallableResult?,
                                                                       Error?) -> Void) {
    call(nil, completion: completion)
  }

  /// Executes this Callable HTTPS trigger asynchronously.
  ///
  /// The request to the Cloud Functions backend made by this method automatically includes a
  /// FCM token to identify the app instance. If a user is logged in with Firebase
  /// Auth, an auth ID token for the user is also automatically included.
  ///
  /// Firebase Cloud Messaging sends data to the Firebase backend periodically to collect
  /// information
  /// regarding the app instance. To stop this, see `Messaging.deleteData()`. It
  /// resumes with a new FCM Token the next time you call this method.
  ///
  /// - Parameter data: Parameters to pass to the trigger.
  /// - Throws: An error if the Cloud Functions invocation failed.
  /// - Returns: The result of the call.
  @available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
  open func call(_ data: Any? = nil) async throws -> HTTPSCallableResult {
    return try await withCheckedThrowingContinuation { continuation in
      // TODO(bonus): Use task to handle and cancellation.
      self.call(data) { callableResult, error in
        if let callableResult {
          continuation.resume(returning: callableResult)
        } else {
          continuation.resume(throwing: error!)
        }
      }
    }
  }
}