#!/bin/bash
# Copyright 2016 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

# The purpose of this script is to help user setup SSH/ADB connection to
# the Android apps on their Chromebook. It performs the following steps:
# 1. Download SSH RSA key for devmode Chromebook.
# 2. Add an entry in .ssh/config, then ssh to the Chromebook via RSA key.
# 3. Copy local ADB key to Chromebook so that ADB would accept request from
#    this workstation.

# Configurable constants
KEY_URL="https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/3b1b89803279f3f21b6b95b88cdaae22efe56c63/chromeos-base/chromeos-test-testauthkeys/files/testing_rsa?format=TEXT"

# Environment checks
if [ $# -ne 2 ]; then
  echo "Usage: $0 <ip address> <chromebook host name>"
  exit 1
fi

IP=$1
CHROMEBOOK=$2

if ! ping -c1 -W1 ${IP} &> /dev/null; then
  echo "ERROR: ${IP} is not reachable"
  exit 1
fi

# Download SSH key file
mkdir --mode=700 -p ~/.ssh
TESTING_RSA=$(readlink -f ~/.ssh/chromebook_testing_rsa)
if [ ! -f ${TESTING_RSA} ]; then
  curl -s ${KEY_URL} | base64 --decode > ${TESTING_RSA}
  chmod 600 ${TESTING_RSA}
fi

# Check if the SSH config already had the host
SSH_CONFIG=$(readlink -f ~/.ssh/config)
if [[ -z "$(grep "Host ${CHROMEBOOK}" ${SSH_CONFIG} 2> /dev/null)" ]]; then
  # Alter .ssh/config
  cat << EOF >> ${SSH_CONFIG}

Host ${CHROMEBOOK}
  Hostname ${IP}
  User root
  IdentityFile ${TESTING_RSA}
  UserKnownHostsFile /dev/null
  StrictHostKeyChecking no
  LogLevel ERROR
EOF
fi

# Connect to Chromebook
function ssh_exec() {
  ssh ${CHROMEBOOK} $1 || (echo "ERROR: failed to execute command: $1" && exit 1)
}

ssh_exec "exit"
echo "INFO: SSH connectivity established."

# Copy ADB key
adb kill-server &> /dev/null
adb start-server &> /dev/null
ADB_KEY=$(readlink -f ~/.android/adbkey.pub)
if [ -z ${ADB_KEY} ]; then
  echo "ERROR: cannot locate ADB public key."
  exit 1
fi

ssh_exec "android-sh -c 'cat > /data/misc/adb/adb_keys'" < ${ADB_KEY}
ssh_exec "android-sh -c 'restorecon /data/misc/adb/adb_keys'"
ssh_exec "android-sh -c 'setprop persist.sys.usb.config mtp,adb'"

SDK_VERSION=`ssh_exec "android-sh -c 'getprop ro.build.version.sdk'"`
# 25: Android N SDK version.
if [ "${SDK_VERSION}" -ge 25 ]; then
  # In N or later, init.usb.rc is updated so that persist.sys.usb.config
  # is propagated to sys.usb.config only on booting.
  # So, here manually propagate it so that adbd is triggered to start.
  ssh_exec "android-sh -c 'setprop sys.usb.config mtp,adb'"
fi

echo "INFO: ADB set up complete."