#!/usr/bin/env bash
#
# Recover an Android wireless-debugging connection when `adb connect` reports
# "No route to host" even though the device's TCP port is reachable.
#
# Usage:
#   scripts/fix_adb_connection.sh [PORT]
#   scripts/fix_adb_connection.sh [HOST:PORT]
#
# The defaults below are the most recently used development device.

set -u

DEFAULT_HOST="10.99.0.213"
DEFAULT_PORT="34483"
MAX_ATTEMPTS=3

usage() {
  sed -n '2,10p' "$0"
}

case "${1:-}" in
  -h|--help)
    usage
    exit 0
    ;;
esac

HOST="$DEFAULT_HOST"
PORT="$DEFAULT_PORT"

if [ "$#" -gt 2 ]; then
  usage >&2
  exit 2
fi

if [ "$#" -eq 2 ]; then
  HOST="$1"
  PORT="$2"
elif [ "$#" -eq 1 ]; then
  case "$1" in
    *:*)
      HOST="${1%:*}"
      PORT="${1##*:}"
      ;;
    *[!0-9]*) HOST="$1" ;;
    *) PORT="$1" ;;
  esac
fi

case "$PORT" in
  ''|*[!0-9]*)
    echo "invalid port: $PORT" >&2
    exit 2
    ;;
esac

if [ "$PORT" -lt 1 ] || [ "$PORT" -gt 65535 ]; then
  echo "port must be between 1 and 65535" >&2
  exit 2
fi

for bin in adb nc; do
  command -v "$bin" >/dev/null || {
    echo "missing required tool: $bin" >&2
    exit 1
  }
done

ENDPOINT="$HOST:$PORT"

echo "Checking $ENDPOINT directly..."
if [ "$(uname -s)" = "Darwin" ]; then
  NC_ARGS=(-G 3 -z)
else
  NC_ARGS=(-w 3 -z)
fi

if ! nc "${NC_ARGS[@]}" "$HOST" "$PORT" >/dev/null 2>&1; then
  echo "The TCP port is not reachable, so restarting ADB cannot fix it." >&2
  echo "Check that Wireless debugging is enabled and that $PORT is the current connection port." >&2
  exit 1
fi
echo "TCP port is reachable."

# Prevent Bonjour/mDNS from adding a second transport for the same device while
# this script establishes the explicit host:port connection.
export ADB_MDNS_AUTO_CONNECT=0

LAST_OUTPUT=""
attempt=1
while [ "$attempt" -le "$MAX_ATTEMPTS" ]; do
  echo "ADB reconnect attempt $attempt/$MAX_ATTEMPTS..."

  # `adb kill-server` sometimes leaves the macOS daemon alive. Killing only
  # this user's exact `adb` processes clears that stale network-permission
  # state without requiring sudo or affecting other users.
  adb kill-server >/dev/null 2>&1 || true
  pkill -x -u "$(id -u)" adb >/dev/null 2>&1 || true

  adb start-server >/dev/null 2>&1
  adb disconnect "$ENDPOINT" >/dev/null 2>&1 || true

  LAST_OUTPUT="$(adb connect "$ENDPOINT" 2>&1)"
  echo "$LAST_OUTPUT"

  if adb -s "$ENDPOINT" get-state 2>/dev/null | grep -qx device; then
    echo
    echo "Connected successfully: $ENDPOINT"
    adb -s "$ENDPOINT" shell getprop ro.product.model 2>/dev/null \
      | sed 's/^/Device: /'
    exit 0
  fi

  attempt=$((attempt + 1))
  [ "$attempt" -le "$MAX_ATTEMPTS" ] && sleep 1
done

echo >&2
echo "ADB could not connect after $MAX_ATTEMPTS clean restarts." >&2
if printf '%s' "$LAST_OUTPUT" | grep -q "No route to host"; then
  echo "The port is reachable, but the ADB daemon is being denied local-network access." >&2
  if [ "$(uname -s)" = "Darwin" ]; then
    echo "Toggle your terminal app under System Settings > Privacy & Security > Local Network," >&2
    echo "then run this script again." >&2
  fi
fi
exit 1