#!/usr/bin/env bash
# emu.sh — headless Android emulator helper on .27.
#
# The physical Pixel 8a is normally attached to .27 (USB and/or wireless) at the
# same time as the emulator. adb therefore refuses bare commands with
# "error: more than one device/emulator". Every device-specific adb call below
# is given an explicit serial.
#
# Serial selection order:
#   1. $ANDROID_SERIAL, when set (a serial or an emulator port).
#   2. The first emulator-* entry in "adb devices".
# Commands that need a device fail with a clear message when no emulator runs.
#
# Called from .13, e.g.:
#     ssh 192.168.20.27 '~/android/emu.sh start'
#     ssh 192.168.20.27 '~/android/emu.sh wait'
#     ssh 192.168.20.27 '~/android/emu.sh install /home/sam/app-debug.apk'
#     ssh 192.168.20.27 '~/android/emu.sh screenshot /tmp/shot.png'
#     ssh 192.168.20.27 '~/android/emu.sh status'
#     ssh 192.168.20.27 '~/android/emu.sh stop'
#
# Source of truth for this copy: sam/kotlin_phone_app_admin, android/tooling/emu.sh
set -euo pipefail

export ANDROID_HOME="${ANDROID_HOME:-$HOME/Android/Sdk}"
export PATH="$ANDROID_HOME/platform-tools:$ANDROID_HOME/emulator:$ANDROID_HOME/cmdline-tools/latest/bin:$PATH"
AVD="${AVD_NAME:-pixel35}"
LOG="/tmp/emu-$AVD.log"

# Serial of the emulator this script acts on. Prints nothing when no emulator
# entry is present. Matches any state (device, offline) so that "wait" can pick
# up an emulator that is still booting.
select_serial() {
  if [ -n "${ANDROID_SERIAL:-}" ]; then
    printf '%s\n' "$ANDROID_SERIAL"
    return 0
  fi
  adb devices 2>/dev/null | awk '$1 ~ /^emulator-/ { print $1; exit }'
}

# State column of one serial in "adb devices": device, offline, unauthorized,
# or empty when the serial is not listed.
device_state() {
  adb devices 2>/dev/null | awk -v s="$1" '$1 == s { print $2; exit }'
}

# Echo the selected serial, or exit 1 with a clear message. Used by every
# command that must talk to a specific device.
require_serial() {
  local serial state
  serial="$(select_serial)"
  if [ -z "$serial" ]; then
    echo "ERROR: no emulator is running (no emulator-* device, and ANDROID_SERIAL is unset)." >&2
    echo "       Start one with: $0 start" >&2
    echo "       'adb devices' says:" >&2
    adb devices >&2
    exit 1
  fi
  state="$(device_state "$serial")"
  if [ -z "$state" ]; then
    echo "ERROR: serial '$serial' is not attached. 'adb devices' says:" >&2
    adb devices >&2
    exit 1
  fi
  if [ "$state" != "device" ]; then
    echo "ERROR: '$serial' is '$state', not ready." >&2
    echo "       Wait for it with: $0 wait" >&2
    exit 1
  fi
  printf '%s\n' "$serial"
}

case "${1:-status}" in
  start)
    if adb devices 2>/dev/null | awk '$1 ~ /^emulator-/ { found = 1 } END { exit !found }'; then
      echo "already running ($(select_serial))"
      exit 0
    fi
    setsid nohup "$ANDROID_HOME/emulator/emulator" -avd "$AVD" \
      -no-window -no-audio -no-snapshot -no-boot-anim -gpu swiftshader_indirect \
      > "$LOG" 2>&1 &
    echo "starting $AVD (log: $LOG)"
    ;;

  wait)
    boot_timeout="${2:-420}"
    deadline=$(( $(date +%s) + boot_timeout ))
    # Poll for a serial instead of using bare "adb wait-for-device": with the
    # Pixel 8a attached, bare adb fails at once with
    # "error: more than one device/emulator", even before the emulator appears.
    serial="$(select_serial)"
    while [ -z "$serial" ]; do
      if [ "$(date +%s)" -ge "$deadline" ]; then
        echo "ERROR: no emulator-* device appeared within ${boot_timeout}s. 'adb devices' says:" >&2
        adb devices >&2
        echo "       Start one with: $0 start" >&2
        exit 1
      fi
      sleep 2
      serial="$(select_serial)"
    done
    remaining=$(( deadline - $(date +%s) ))
    [ "$remaining" -gt 0 ] || remaining=1
    timeout "$remaining" adb -s "$serial" wait-for-device \
      || { echo "ERROR: emulator $serial did not come online within ${boot_timeout}s"; exit 1; }
    n=0
    while [ "$n" -lt 72 ]; do
      if [ "$(adb -s "$serial" shell getprop sys.boot_completed 2>/dev/null | tr -d '\r')" = "1" ]; then
        echo "booted ($serial)"
        exit 0
      fi
      n=$((n + 1))
      sleep 5
    done
    echo "ERROR: boot timeout (6 minutes) waiting for $serial"
    exit 1
    ;;

  install)
    apk="${2:?usage: emu.sh install <apk>}"
    if [ ! -f "$apk" ]; then echo "ERROR: no such apk: $apk"; exit 1; fi
    serial="$(require_serial)"
    adb -s "$serial" install -r "$apk"
    ;;

  screenshot)
    out="${2:-/tmp/emulator-screen.png}"
    serial="$(require_serial)"
    adb -s "$serial" exec-out screencap -p > "$out"
    size="$(stat -c%s "$out")"
    if [ "$size" -eq 0 ]; then
      echo "ERROR: screencap from $serial produced an empty file: $out" >&2
      exit 1
    fi
    echo "wrote $out ($size bytes) from $serial"
    ;;

  stop)
    serial="$(select_serial)"
    if [ -n "$serial" ]; then
      adb -s "$serial" emu kill >/dev/null 2>&1 || true
    fi
    sleep 2
    pkill -f qemu-system-x86_64 >/dev/null 2>&1 || true
    echo "stopped"
    ;;

  status)
    serial="$(select_serial)"
    adb devices
    if [ -z "$serial" ]; then
      echo "ERROR: no emulator is running (no emulator-* device, and ANDROID_SERIAL is unset)." >&2
      echo "       Start one with: $0 start" >&2
      exit 1
    fi
    state="$(device_state "$serial")"
    printf "emulator=%s state=%s android=" "$serial" "$state"
    adb -s "$serial" shell getprop ro.build.version.release 2>/dev/null | tr -d '\r'
    [ "$state" = "device" ] || exit 1
    ;;

  *)
    echo "usage: $0 start|wait|install <apk>|screenshot [out]|stop|status"
    exit 2
    ;;
esac