#!/usr/bin/ruby

require 'json'

def platform_for_runtime(runtime)
  runtime['identifier'].gsub(/com.apple.CoreSimulator.SimRuntime.([^-]+)-.*/, '\1')
end

def platform_for_device_type(device_type)
  case device_type['identifier']
  when /Watch/
    'watchOS'
  when /TV/
    'tvOS'
  else
    'iOS'
  end
end

def wait_for_core_simulator_service
  # Run until we get a result since switching simulator versions often causes CoreSimulatorService to throw an exception.
  while `xcrun simctl list devices`.empty?
  end
end

def running_devices(devices)
  devices.select { |device| device['state'] != 'Shutdown' }
end

def shutdown_simulator_devices(devices)
  # Shut down any simulators that need it.
  running_devices(devices).each do |device|
    puts "Shutting down simulator #{device['udid']}"
    system("xcrun simctl shutdown #{device['udid']}") or puts "    Failed to shut down simulator #{device['udid']}"
  end
end

attempts = 0
begin
  # Kill all the current simulator processes as they may be from a different Xcode version
  print 'Killing running Simulator processes...'
  while system('pgrep -q Simulator')
    system('pkill Simulator 2>/dev/null')
    # CoreSimulatorService doesn't exit when sent SIGTERM
    system('pkill -9 Simulator 2>/dev/null')
  end
  wait_for_core_simulator_service
  puts ' done!'

  print 'Shut down existing simulator devices...'
  # Shut down any running simulator devices. This may take multiple attempts if some
  # simulators are currently in the process of booting or being created.
  all_available_devices = []
  (0..5).each do |shutdown_attempt|
    begin
      devices_json = `xcrun simctl list devices -j`
      all_devices = JSON.parse(devices_json)['devices'].flat_map { |_, devices| devices }
    rescue JSON::ParserError
      sleep shutdown_attempt if shutdown_attempt > 0
      next
    end

    # Exclude devices marked as unavailable as they're from a different version of Xcode.
    all_available_devices = all_devices.reject { |device| device['availability'] =~ /unavailable/ }

    break if running_devices(all_available_devices).empty?

    shutdown_simulator_devices all_available_devices
    sleep shutdown_attempt if shutdown_attempt > 0
  end
  puts ' done!'

  # Delete all simulators.
  print 'Deleting all simulators...'
  all_available_devices.each do |device|
    system("xcrun simctl delete #{device['udid']}") or raise "Failed to delete simulator #{device['udid']}"
  end
  puts ' done!'

  # Recreate all simulators.
  runtimes = JSON.parse(`xcrun simctl list runtimes -j`)['runtimes']
  device_types = JSON.parse(`xcrun simctl list devicetypes -j`)['devicetypes']

  runtimes_by_platform = Hash.new { |hash, key| hash[key] = [] }
  runtimes.each do |runtime|
    next unless runtime['availability'] == '(available)' || runtime['isAvailable'] == true
    runtimes_by_platform[platform_for_runtime(runtime)] << runtime
  end

  print 'Creating fresh simulators...'
  device_types.each do |device_type|
    platform = platform_for_device_type(device_type)
    runtimes_by_platform[platform].each do |runtime|
      output = `xcrun simctl create '#{device_type['name']}' '#{device_type['identifier']}' '#{runtime['identifier']}' 2>&1`
      next if $? == 0

      # Error code 161 and 162 indicate that the given device is not supported by the runtime, such as the iPad 2 and
      # iPhone 4s not being supported by the iOS 10 simulator runtime.
      next if output =~ /(domain=com.apple.CoreSimulator.SimError, code=16[12])/

      puts "Failed to create device of type #{device_type['identifier']} with runtime #{runtime['identifier']}:"
      output.each_line do |line|
        puts "    #{line}"
      end
    end
  end
  puts ' done!'

  print 'Booting iPhone 8 simulator...'
  system("xcrun simctl boot 'iPhone 8'") or raise "Failed to boot iPhone 8 simulator"
  puts ' done!'

rescue => e
  if (attempts += 1) < 5
    puts ''
    puts e.message
    e.backtrace.each { |line| puts line }
    puts ''
    puts 'Retrying...'
    retry
  end
  system('ps auxwww')
  system('xcrun simctl list')
  raise
end