/*
 * Copyright 2019 Google
 *
 * 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

let JAR_URL = "https://storage.googleapis.com/firebase-engprod-metrics/upload_tool.jar"
let JAR_LOCAL_PATH = "upload.jar"
let DATABASE_CONFIG = "database.config"
let JSON_PATH = "database.json"

/// Uploads metrics to the Cloud SQL database.
public class Uploader {
  /// Uploads the provided metrics to the Cloud SQL database.
  public class func upload(metrics: UploadMetrics) throws {
    let jar = try downloadJar()
    let json = try writeJson(metrics: metrics)

    let returnCode = runJar(jar: jar, json: json, config: DATABASE_CONFIG)
    if returnCode == 0 {
      print("Successfully uploaded metrics!")
    } else {
      print("Failed to upload metrics... return code is \(returnCode).")
    }

    try FileManager.default.removeItem(atPath: jar)
    try FileManager.default.removeItem(atPath: json)
  }

  /// Writes the metrics to a local file in a JSON format and returns that path.
  private class func writeJson(metrics: UploadMetrics) throws -> String {
    try metrics.json().write(to: NSURL(fileURLWithPath: JSON_PATH) as URL,
                             atomically: false,
                             encoding: .utf8)
    return JSON_PATH
  }

  /// Downloads the uploader JAR and returns the path to it.
  private class func downloadJar() throws -> String {
    let jarData = try Data(contentsOf: URL(string: JAR_URL)!)
    try jarData.write(to: NSURL(fileURLWithPath: JAR_LOCAL_PATH) as URL)
    return JAR_LOCAL_PATH
  }

  /// Executes the uploader jar and returns the exit code.
  private class func runJar(jar: String, json: String, config: String) -> Int32 {
    let task = Process()
    task.launchPath = "/usr/bin/java"
    task.arguments = ["-jar", jar, "--json_path=\(json)", "--config_path=\(config)"]
    task.launch()
    task.waitUntilExit()
    return task.terminationStatus
  }
}