#!/bin/bash
# Copyright 2020 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

#### CATEGORY=Other
### Remotely run emulator

## usage: fx emu-remote [--no-build] [--stream [--no-emu] [--no-turn] [--no-open] [--display DPY] [--port PORT]] HOST [DIR] [-- ARGS]
##
## Connect to HOST, run a build using fx from DIR, fetch the artifacts and
## start the emulator. Alternatively, start the emulator on HOST,
## and open an WebRTC connection to it using local browser.
##
##  --no-build    do not build, just pull artifacts already present
##  --stream      stream output from remote emulator using WebRTC instead of fetching artifacts
##  --no-emu      only tunnel, do not start remote emulator
##  --no-turn     do not use turn configuration for remote emulator
##  --no-open     do not open https://web-femu.appspot.com, just run remote emulator
##  --display DPY do not start remote virtual display, use DPY instead
##  --port PORT   port used on local machine to connect with remote emulator over HTTP (default: 8080)
##
##  HOST          the hostname to connect to
##  DIR           defaults to ~/fuchsia, the path to the FUCHSIA_DIR on HOST
##  ARGS          arguments to pass to emulator
##
## HOST and DIR are persisted in the file //.fx-remote-config and are reused as
## defaults in future invocations of any 'fx *-remote' tools.

source "$(cd "$(dirname "${BASH_SOURCE[0]}")" >/dev/null 2>&1 && pwd)"/lib/vars.sh || exit $?
source "$(cd "$(dirname "${BASH_SOURCE[0]}")" >/dev/null 2>&1 && pwd)"/lib/fx-remote.sh || exit $?
fx-config-read

build=true
stream=false
emu=true
turn=true
open=true
display="xvfb-run"
host=""
dir=""
local_port="8080"
remote_port="8080"
while [[ $# -ne 0 ]]; do
  case "$1" in
  --help|-h)
    fx-command-help
    exit 0
    ;;
  --no-build)
    build=false
    ;;
  --stream)
    stream=true
    ;;
  --no-emu)
    emu=false
    ;;
  --no-turn)
    turn=false
    ;;
  --no-open)
    open=false
    ;;
  --display)
    shift
    display="DISPLAY=$1"
    ;;
  --port)
    shift
    local_port=$1
    ;;
  --)
    shift
    break
    ;;
  *)
    if [[ -z "${host}" ]]; then
      host="$1"
    elif [[ -z "${dir}" ]]; then
      dir="$1"
    else
      fx-error "unexpected argument: '$1'"
      exit 1
    fi
    ;;
  esac
  shift
done

if cached=( $(load_remote_info "$host") ); then
  host="${cached[0]}"
  dir="${cached[1]}"
fi

if [[ -z "${host}" ]]; then
  fx-error "HOST must be specified"
  fx-command-help
  exit 1
fi

# Use a dedicated ControlPath so script can manage a connection separately from the user's. We
# intentionally do not use %h/%p in the control path because there can only be one forwarding
# session at a time (due to the local forward of 8083).
ssh_base_args=(
  "${host}"
  -S "~/.ssh/control-fuchsia-fx-remote"
  -o ControlMaster=auto
)
ssh_exit() {
  ssh "${ssh_base_args[@]}" -O exit > /dev/null 2>&1
  wait # for ssh to exit
}
# If there is already control master then exit it. We can't be sure its to the right host and it
# also could be stale.
ssh_exit
# When we exit the script, close the background ssh connection.
trap_exit() {
  ssh_exit
  exit
}
trap trap_exit EXIT

if [[ -z "${dir}" ]]; then
  echo ssh "${ssh_base_args[@]}" ls \~/fuchsia/.jiri_root/bin/fx
  if ssh "${ssh_base_args[@]}" ls \~/fuchsia/.jiri_root/bin/fx > /dev/null; then
    dir="~/fuchsia"
  else
    fx-error "failed to find ~/fuchsia on $host, please specify DIR"
    fx-command-help
    exit 1
  fi
fi

emu_targets=(multiboot.bin fuchsia.zbi obj/build/images/fuchsia/fuchsia/fvm.blk)

if "${build}"; then
  ssh "${ssh_base_args[@]}" "cd ${dir} && ./.jiri_root/bin/fx build ${emu_targets[@]}" || exit $?
fi
build_dir=$(ssh "${ssh_base_args[@]}" "cd ${dir} && ./.jiri_root/bin/fx get-build-dir")

save_remote_info "$host" "$dir"

# Fetch artifacts and run local emulator when streaming is disabled.
if [[ "${stream}" == "false" ]]; then
  build_arch=$(ssh "${ssh_base_args[@]}" "cd ${dir} && ./.jiri_root/bin/fx exec sh -c 'echo \${FUCHSIA_ARCH}'")

  mkdir -p out/fetched
  printf -v files '%s,' "${emu_targets[@]}"
  rsync -z -P "${host}":"${build_dir}/{${files%,}}" out/fetched/
  echo >&2 "Build images fetched into out/fetched"

  fx-command-exec emu \
      -K out/fetched/multiboot.bin \
      -z out/fetched/fuchsia.zbi \
      -f out/fetched/fvm.blk \
      -A "${build_arch}" "$@"
fi

#
# The code below handles the case where output from a remote emulator
# is streamed using WebRTC to a local browser instance.
#

# Check if the port given in argument "$1" is listened by other processes.
#
# Returns true if other process is already listening to this port; otherwise
# returns false.
is_port_used() {
  # Print all listening ports and check if $1 is listed.
  if [[ "$(uname -s)" == "Darwin" ]]; then
    # On macOS we parse output from `netstat`.
    netstat -anp tcp 2>/dev/null |
    awk '$1 ~ /tcp4/ && $6 == "LISTEN" { \
      sub(/.*\./, "", $4); print $4 \
    }'
  else
    # On Linux we parse output from `ss`.
    ss -lpn4 2>/dev/null | awk '$1 == "tcp" { \
      if (match($5, /^[0-9.]+:[0-9]+$/)) { \
        sub(/^.*:/, "", $5); print $5 \
      } \
    }'
  fi | grep -q "^$1$"
}

if is_port_used ${local_port}; then
  fx-error "Local port ${local_port} is not available. Please try specifying"\
           "a different port using --port flag."
  exit 1
fi

echo "Using remote ${host}:${dir}"

wait_and_open() {
  timeout=10
  waited=0

  # Loop until connection is live or timeout expires.
  while true
  do
    # Check if we can connect to the forwarded port.
    if curl -sI "http://localhost:${local_port}" > /dev/null; then
      open_args=("https://web-femu.appspot.com/?port=${local_port}")

      # Launch Chrome browser tab for emulator feed.
      if [[ "$(uname -s)" == "Darwin" ]]; then
        exec open -a "/Applications/Google Chrome.app" "${open_args[@]}"
      else
        exec google-chrome "${open_args[@]}"
      fi
    fi

    # Continue waiting if we have not reached our timeout.
    if [ $waited -gt 0 ]; then
      if [ $waited -ge $timeout ]; then
        echo "No emulator after waiting $waited seconds, giving up."
        break
      fi
      echo "Waiting for emulator ($(($timeout-$waited)) seconds left).."
    fi
    sleep 1
    waited=$(($waited+1))
  done
}

ssh_args=(
  -6 # We want ipv6 binds for the port forwards.
  # Requests to the WebRTC service address locally go to the workstation.
  -L "${local_port}:localhost:${remote_port}"
  -o ExitOnForwardFailure=yes
)

if "${emu}"; then
  # If the user requested emulator, then we'll check to see if there's a
  # emulator already running and kill it, this prevents most cases where
  # signal propagation not make it to "qemu-system".
  if ssh "${ssh_base_args[@]}" 'pgrep -u $USER goldfish-webrtc' > /dev/null; then
    ssh "${ssh_base_args[@]}" 'pkill -u $USER qemu-system; pkill -u $USER goldfish-webrtc'
  fi

  emu_args=(-x ${remote_port})

  # Add turn configuration if enabled.
  if "${turn}"; then
    apikey="AIzaSyBl6TgfdN6FKAQ3nK2GvKNcKNjWLeRGVYQ"
    emu_args+=(-t "\"curl -s -X POST https://networktraversal.googleapis.com/v1alpha/iceconfig?key=${apikey}\"")
  fi

  # Starts emulator.
  ssh_args+=("cd ${dir} && ${display} ./.jiri_root/bin/fx emu ${emu_args[@]} $@")

  # Wait and open page for emulator when ready.
  if "${open}"; then
    wait_and_open &
  fi
else
  # Starts nothing, just goes to sleep.
  ssh_args+=("-nNT")
fi

# Cleanup after ssh command ends:
# - Terminate all child processes;
# - Close port forwarding if we use ssh multiplexing.
cleanup_processes_and_ports() {
  child_pids=$(jobs -p)
  if [[ -n "${child_pids}" ]]; then
    # Note: child_pids must be expanded to args here.
    kill ${child_pids} 2> /dev/null
    wait 2> /dev/null
  fi

  # Cancel port forwarding.
  if ssh -O check "${host}" > /dev/null 2>&1; then
    ssh -O cancel -L "${local_port}:localhost:${remote_port}" "${host}"
  fi
}
trap cleanup_processes_and_ports EXIT

ssh "${ssh_base_args[@]}" "${ssh_args[@]}"