// Copyright 2021 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 XCTest
@testable import FirebaseCore
@testable import FirebaseInstallations
@testable import FirebaseMLModelDownloader

extension UserDefaults {
  /// Returns a new cleared instance of user defaults.
  static func createTestInstance(testName: String) -> UserDefaults {
    let suiteName = "com.google.firebase.ml.test.\(testName)"
    let defaults = UserDefaults(suiteName: suiteName)!
    defaults.removePersistentDomain(forName: suiteName)
    return defaults
  }

  /// Returns the existing user defaults instance.
  static func getTestInstance(testName: String) -> UserDefaults {
    let suiteName = "com.google.firebase.ml.test.\(testName)"
    return UserDefaults(suiteName: suiteName)!
  }
}

final class ModelDownloaderIntegrationTests: XCTestCase {
  override class func setUp() {
    super.setUp()
    // TODO: Use FirebaseApp internal for test app.
    let bundle = Bundle(for: self)
    if let plistPath = bundle.path(forResource: "GoogleService-Info", ofType: "plist"),
       let options = FirebaseOptions(contentsOfFile: plistPath) {
      FirebaseApp.configure(options: options)
    } else {
      XCTFail("Could not locate GoogleService-Info.plist.")
    }
    FirebaseConfiguration.shared.setLoggerLevel(.debug)
  }

  override func setUp() {
    do {
      try ModelFileManager.emptyModelsDirectory()
    } catch {
      XCTFail("Could not empty models directory.")
    }
  }

  /// Test to download model info - makes an actual network call.
  func testDownloadModelInfo() {
    guard let testApp = FirebaseApp.app() else {
      XCTFail("Default app was not configured.")
      return
    }
    testApp.isDataCollectionDefaultEnabled = false

    let testName = String(#function.dropLast(2))
    let testModelName = "pose-detection"

    let modelInfoRetriever = ModelInfoRetriever(
      modelName: testModelName,
      projectID: testApp.options.projectID!,
      apiKey: testApp.options.apiKey!,
      appName: testApp.name, installations: Installations.installations(app: testApp)
    )

    let modelInfoDownloadExpectation = expectation(description: "Wait for model info to download.")
    modelInfoRetriever.downloadModelInfo(completion: { result in
      switch result {
      case let .success(modelInfoResult):
        switch modelInfoResult {
        case let .modelInfo(modelInfo):
          XCTAssertNotNil(modelInfo.urlExpiryTime)
          XCTAssertGreaterThan(modelInfo.downloadURL.absoluteString.count, 0)
          XCTAssertGreaterThan(modelInfo.modelHash.count, 0)
          XCTAssertGreaterThan(modelInfo.size, 0)
          let localModelInfo = LocalModelInfo(from: modelInfo)
          localModelInfo.writeToDefaults(
            .createTestInstance(testName: testName),
            appName: testApp.name
          )
        case .notModified:
          XCTFail("Failed to retrieve model info.")
        }
      case let .failure(error):
        XCTAssertNotNil(error)
        XCTFail("Failed to retrieve model info - \(error)")
      }
      modelInfoDownloadExpectation.fulfill()
    })

    wait(for: [modelInfoDownloadExpectation], timeout: 5)

    if let localInfo = LocalModelInfo(
      fromDefaults: .getTestInstance(testName: testName),
      name: testModelName,
      appName: testApp.name
    ) {
      XCTAssertNotNil(localInfo)
      testRetrieveModelInfo(localInfo: localInfo)
    } else {
      XCTFail("Could not save model info locally.")
    }
  }

  func testRetrieveModelInfo(localInfo: LocalModelInfo) {
    guard let testApp = FirebaseApp.app() else {
      XCTFail("Default app was not configured.")
      return
    }
    let testModelName = "pose-detection"

    let modelInfoRetriever = ModelInfoRetriever(
      modelName: testModelName,
      projectID: testApp.options.projectID!,
      apiKey: testApp.options.apiKey!,
      appName: testApp.name, installations: Installations.installations(app: testApp),
      localModelInfo: localInfo
    )

    let modelInfoRetrieveExpectation =
      expectation(description: "Wait for model info to be retrieved.")
    modelInfoRetriever.downloadModelInfo(completion: { result in
      switch result {
      case let .success(modelInfoResult):
        switch modelInfoResult {
        case .modelInfo:
          XCTFail("Local model info is already the latest and should not be set again.")
        case .notModified: break
        }
      case let .failure(error):
        XCTAssertNotNil(error)
        XCTFail("Failed to retrieve model info - \(error)")
      }
      modelInfoRetrieveExpectation.fulfill()
    })

    wait(for: [modelInfoRetrieveExpectation], timeout: 5)
  }

  /// Test to download model file - makes an actual network call.
  func testModelDownload() throws {
    guard let testApp = FirebaseApp.app() else {
      XCTFail("Default app was not configured.")
      return
    }
    testApp.isDataCollectionDefaultEnabled = false

    let testName = String(#function.dropLast(2))
    let testModelName = "\(testName)-test-model"
    let urlString =
      "https://tfhub.dev/tensorflow/lite-model/ssd_mobilenet_v1/1/metadata/1?lite-format=tflite"
    let url = URL(string: urlString)!

    let remoteModelInfo = RemoteModelInfo(
      name: testModelName,
      downloadURL: url,
      modelHash: "mock-valid-hash",
      size: 10,
      urlExpiryTime: Date()
    )

    let conditions = ModelDownloadConditions()
    let downloadExpectation = expectation(description: "Wait for model to download.")
    let downloader = ModelFileDownloader(conditions: conditions)
    let taskProgressHandler: ModelDownloadTask.ProgressHandler = { progress in
      XCTAssertLessThanOrEqual(progress, 1)
      XCTAssertGreaterThanOrEqual(progress, 0)
    }
    let taskCompletion: ModelDownloadTask.Completion = { result in
      switch result {
      case let .success(model):
        let modelURL = URL(fileURLWithPath: model.path)
        XCTAssertTrue(ModelFileManager.isFileReachable(at: modelURL))
        // Remove downloaded model file.
        do {
          try ModelFileManager.removeFile(at: modelURL)
        } catch {
          XCTFail("Model removal failed - \(error)")
        }
      case let .failure(error):
        XCTFail("Error: \(error)")
      }
      downloadExpectation.fulfill()
    }
    let modelDownloadManager = ModelDownloadTask(
      remoteModelInfo: remoteModelInfo,
      appName: testApp.name,
      defaults: .createTestInstance(testName: testName),
      downloader: downloader,
      progressHandler: taskProgressHandler,
      completion: taskCompletion
    )

    modelDownloadManager.resume()
    wait(for: [downloadExpectation], timeout: 5)
    XCTAssertEqual(modelDownloadManager.downloadStatus, .complete)
  }

  func testGetModel() {
    guard let testApp = FirebaseApp.app() else {
      XCTFail("Default app was not configured.")
      return
    }
    testApp.isDataCollectionDefaultEnabled = false

    let testName = String(#function.dropLast(2))
    let testModelName = "image-classification"

    let conditions = ModelDownloadConditions()
    let modelDownloader = ModelDownloader.modelDownloaderWithDefaults(
      .createTestInstance(testName: testName),
      app: testApp
    )

    /// Test download type - latest model.
    var downloadType: ModelDownloadType = .latestModel
    let latestModelExpectation = expectation(description: "Get latest model.")

    modelDownloader.getModel(
      name: testModelName,
      downloadType: downloadType,
      conditions: conditions,
      progressHandler: { progress in
        XCTAssertTrue(Thread.isMainThread, "Completion must be called on the main thread.")

        XCTAssertLessThanOrEqual(progress, 1)
        XCTAssertGreaterThanOrEqual(progress, 0)
      }
    ) { result in
      XCTAssertTrue(Thread.isMainThread, "Completion must be called on the main thread.")

      switch result {
      case let .success(model):
        XCTAssertNotNil(model.path)
        let modelURL = URL(fileURLWithPath: model.path)
        XCTAssertTrue(ModelFileManager.isFileReachable(at: modelURL))
      case let .failure(error):
        XCTFail("Failed to download model - \(error)")
      }
      latestModelExpectation.fulfill()
    }

    wait(for: [latestModelExpectation], timeout: 5)

    /// Test download type - local model update in background.
    downloadType = .localModelUpdateInBackground
    let backgroundModelExpectation =
      expectation(description: "Get local model and update in background.")

    modelDownloader.getModel(
      name: testModelName,
      downloadType: downloadType,
      conditions: conditions,
      progressHandler: { progress in
        XCTFail("Model is already available on device.")
      }
    ) { result in
      switch result {
      case let .success(model):
        XCTAssertNotNil(model.path)
        let modelURL = URL(fileURLWithPath: model.path)
        XCTAssertTrue(ModelFileManager.isFileReachable(at: modelURL))
      case let .failure(error):
        XCTFail("Failed to download model - \(error)")
      }
      backgroundModelExpectation.fulfill()
    }
    wait(for: [backgroundModelExpectation], timeout: 5)

    /// Test download type - local model.
    downloadType = .localModel
    let localModelExpectation = expectation(description: "Get local model.")

    modelDownloader.getModel(
      name: testModelName,
      downloadType: downloadType,
      conditions: conditions,
      progressHandler: { progress in
        XCTFail("Model is already available on device.")
      }
    ) { result in
      switch result {
      case let .success(model):
        XCTAssertNotNil(model.path)
        let modelURL = URL(fileURLWithPath: model.path)
        XCTAssertTrue(ModelFileManager.isFileReachable(at: modelURL))
        // Remove downloaded model file.
        do {
          try ModelFileManager.removeFile(at: modelURL)
        } catch {
          XCTFail("Model removal failed - \(error)")
        }
      case let .failure(error):
        XCTFail("Failed to download model - \(error)")
      }
      localModelExpectation.fulfill()
    }
    wait(for: [localModelExpectation], timeout: 5)
  }

  func testGetModelWhenNameIsEmpty() {
    guard let testApp = FirebaseApp.app() else {
      XCTFail("Default app was not configured.")
      return
    }
    testApp.isDataCollectionDefaultEnabled = false

    let testName = String(#function.dropLast(2))
    let emptyModelName = ""

    let conditions = ModelDownloadConditions()
    let modelDownloader = ModelDownloader.modelDownloaderWithDefaults(
      .createTestInstance(testName: testName),
      app: testApp
    )

    let completionExpectation = expectation(description: "getModel")
    let progressExpectation = expectation(description: "progressHandler")
    progressExpectation.isInverted = true

    modelDownloader.getModel(
      name: emptyModelName,
      downloadType: .latestModel,
      conditions: conditions,
      progressHandler: { progress in
        progressExpectation.fulfill()
      }
    ) { result in
      XCTAssertTrue(Thread.isMainThread, "Completion must be called on the main thread.")

      switch result {
      case .failure(.emptyModelName):
        // The expected error.
        break

      default:
        XCTFail("Unexpected result: \(result)")
      }
      completionExpectation.fulfill()
    }

    wait(for: [completionExpectation, progressExpectation], timeout: 5)
  }

  /// Delete previously downloaded model.
  func testDeleteModel() {
    guard let testApp = FirebaseApp.app() else {
      XCTFail("Default app was not configured.")
      return
    }
    testApp.isDataCollectionDefaultEnabled = false

    let testName = String(#function.dropLast(2))
    let testModelName = "pose-detection"

    let conditions = ModelDownloadConditions()
    let modelDownloader = ModelDownloader.modelDownloaderWithDefaults(
      .createTestInstance(testName: testName),
      app: testApp
    )

    let downloadType: ModelDownloadType = .latestModel
    let latestModelExpectation = expectation(description: "Get latest model for deletion.")

    modelDownloader.getModel(
      name: testModelName,
      downloadType: downloadType,
      conditions: conditions,
      progressHandler: { progress in
        XCTAssertTrue(Thread.isMainThread, "Completion must be called on the main thread.")
        XCTAssertLessThanOrEqual(progress, 1)
        XCTAssertGreaterThanOrEqual(progress, 0)
      }
    ) { result in
      XCTAssertTrue(Thread.isMainThread, "Completion must be called on the main thread.")

      switch result {
      case let .success(model):
        XCTAssertNotNil(model.path)
        let filePath = URL(fileURLWithPath: model.path)
        XCTAssertTrue(ModelFileManager.isFileReachable(at: filePath))
      case let .failure(error):
        XCTFail("Failed to download model - \(error)")
      }
      latestModelExpectation.fulfill()
    }

    wait(for: [latestModelExpectation], timeout: 5)

    let deleteExpectation = expectation(description: "Wait for model deletion.")
    modelDownloader.deleteDownloadedModel(name: testModelName) { result in
      deleteExpectation.fulfill()
      XCTAssertTrue(Thread.isMainThread, "Completion must be called on the main thread.")

      switch result {
      case .success: break
      case let .failure(error):
        XCTFail("Failed to delete model - \(error)")
      }
    }

    wait(for: [deleteExpectation], timeout: 5)
  }

  /// Test listing models in model directory.
  func testListModels() {
    guard let testApp = FirebaseApp.app() else {
      XCTFail("Default app was not configured.")
      return
    }
    testApp.isDataCollectionDefaultEnabled = false

    let testName = String(#function.dropLast(2))
    let testModelName = "pose-detection"

    let conditions = ModelDownloadConditions()
    let modelDownloader = ModelDownloader.modelDownloaderWithDefaults(
      .createTestInstance(testName: testName),
      app: testApp
    )

    let downloadType: ModelDownloadType = .latestModel
    let latestModelExpectation = expectation(description: "Get latest model.")

    modelDownloader.getModel(
      name: testModelName,
      downloadType: downloadType,
      conditions: conditions,
      progressHandler: { progress in
        XCTAssertLessThanOrEqual(progress, 1)
        XCTAssertGreaterThanOrEqual(progress, 0)
      }
    ) { result in
      switch result {
      case let .success(model):
        XCTAssertNotNil(model.path)
        let filePath = URL(fileURLWithPath: model.path)
        XCTAssertTrue(ModelFileManager.isFileReachable(at: filePath))
      case let .failure(error):
        XCTFail("Failed to download model - \(error)")
      }
      latestModelExpectation.fulfill()
    }

    wait(for: [latestModelExpectation], timeout: 5)

    let listExpectation = expectation(description: "Wait for list models.")
    modelDownloader.listDownloadedModels { result in
      listExpectation.fulfill()
      switch result {
      case let .success(models):
        XCTAssertGreaterThan(models.count, 0)
      case let .failure(error):
        XCTFail("Failed to list models - \(error)")
      }
    }

    wait(for: [listExpectation], timeout: 5)
  }

  /// Test logging telemetry event.
  func testLogTelemetryEvent() {
    guard let testApp = FirebaseApp.app() else {
      XCTFail("Default app was not configured.")
      return
    }
    // Flip this to `true` to test logging.
    testApp.isDataCollectionDefaultEnabled = false

    let testModelName = "digit-classification"
    let testName = String(#function.dropLast(2))

    let conditions = ModelDownloadConditions()
    let modelDownloader = ModelDownloader.modelDownloaderWithDefaults(
      .createTestInstance(testName: testName),
      app: testApp
    )

    let latestModelExpectation = expectation(description: "Test get model telemetry.")

    modelDownloader.getModel(
      name: testModelName,
      downloadType: .latestModel,
      conditions: conditions
    ) { result in
      switch result {
      case .success: break
      case let .failure(error):
        XCTFail("Failed to download model - \(error)")
      }
      latestModelExpectation.fulfill()
    }
    wait(for: [latestModelExpectation], timeout: 5)

    let deleteModelExpectation = expectation(description: "Test delete model telemetry.")
    modelDownloader.deleteDownloadedModel(name: testModelName) { result in
      switch result {
      case .success(()): break
      case let .failure(error):
        XCTFail("Failed to delete model - \(error)")
      }
      deleteModelExpectation.fulfill()
    }

    wait(for: [deleteModelExpectation], timeout: 5)

    let notFoundModelName = "fakeModelName"
    let notFoundModelExpectation =
      expectation(description: "Test get model telemetry with unknown model.")

    modelDownloader.getModel(
      name: notFoundModelName,
      downloadType: .latestModel,
      conditions: conditions
    ) { result in
      switch result {
      case .success: XCTFail("Unexpected model success.")
      case let .failure(error):
        XCTAssertEqual(error, .notFound)
      }
      notFoundModelExpectation.fulfill()
    }
    wait(for: [notFoundModelExpectation], timeout: 5)
  }

  func testGetModelWithConditions() {
    guard let testApp = FirebaseApp.app() else {
      XCTFail("Default app was not configured.")
      return
    }
    testApp.isDataCollectionDefaultEnabled = false

    let testModelName = "pose-detection"
    let testName = String(#function.dropLast(2))

    let conditions = ModelDownloadConditions(allowsCellularAccess: false)

    let modelDownloader = ModelDownloader.modelDownloaderWithDefaults(
      .createTestInstance(testName: testName),
      app: testApp
    )

    let latestModelExpectation = expectation(description: "Get latest model with conditions.")

    modelDownloader.getModel(
      name: testModelName,
      downloadType: .latestModel,
      conditions: conditions,
      progressHandler: { progress in
        XCTAssertTrue(Thread.isMainThread, "Completion must be called on the main thread.")
        XCTAssertLessThanOrEqual(progress, 1)
        XCTAssertGreaterThanOrEqual(progress, 0)
      }
    ) { result in
      XCTAssertTrue(Thread.isMainThread, "Completion must be called on the main thread.")

      switch result {
      case let .success(model):
        XCTAssertNotNil(model.path)
        let filePath = URL(fileURLWithPath: model.path)
        XCTAssertTrue(ModelFileManager.isFileReachable(at: filePath))
      case let .failure(error):
        XCTFail("Failed to download model - \(error)")
      }
      latestModelExpectation.fulfill()
    }
    wait(for: [latestModelExpectation], timeout: 5)
  }
}