usb-devices/src/com/android/tools/usb/UsbDeviceCollector.kt

/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * 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.
 */

package com.android.tools.usb

import java.io.InputStream
import java.util.*
import java.util.concurrent.CompletableFuture

/**
 * Interface to hide the implementation class.
 * Also allows consumers of this library to easily test since [UsbDeviceCollectorImpl]
 * is final.
 */
interface UsbDeviceCollector {
  /**
   * returns list of [UsbDevice]
   */
  fun listUsbDevices(): CompletableFuture<List<UsbDevice>>

  /**
   * returns if the given platform is supported.
   */
  fun isSupported(platform: String): Boolean

  /**
   * Returns an enum representing the platform OS
   */
  fun getPlatform(): Platform
}

/**
 * Returns [UsbDevice] by parsing usb devices command output.
 */
class UsbDeviceCollectorImpl : UsbDeviceCollector {
  override fun listUsbDevices(): CompletableFuture<List<UsbDevice>> {
    val currentOS = Platform.currentOS()
    if (!currentOS.supported) return CompletableFuture.completedFuture(Collections.emptyList())

    return execute(currentOS.command!!).thenApply { it -> currentOS.parser().parse(it) }
  }


  override fun isSupported(platform: String) = Platform.currentOS(platform).supported

  override fun getPlatform() = Platform.currentOS()

  private fun execute(command: String): CompletableFuture<InputStream> {
    return CompletableFuture.supplyAsync {
      ProcessBuilder(command.split(" ")).redirectErrorStream(true).start().inputStream
    }
  }
}