class Upstreamstatus

# File lib/upstreamstatus.rb, line 28
def initialize
  @conf = OpenStruct.new load_conf

  return unless opts[:notify]

  %w(
    sentry_dsn
    pagerduty_api_key
    pagerduty_rest_api_key
    pagerduty_api_url
    pagerduty_service_id
  ).each do |key|
    fail "Config missing #{key}" unless conf[key]
  end

  Unirest.default_header 'Authorization',
                         "Token token=#{pagerduty_rest_api_key}"
  Unirest.default_header 'Content-type', 'application/json'
  Unirest.default_header 'Accept', 'application/vnd.pagerduty+json;version=2'

  Raven.configure do |config|
    config.dsn = sentry_dsn
    config.logger = logger
  end
end

# File lib/upstreamstatus.rb, line 91
def current_status
  @current_status ||= begin
    return fake_response if opts[:simulate]

    r = Unirest.get status_check_url

    unless (200..299).include?(r.code)
      fail "Error code: #{r.code}\n" \
           "Headers: #{r.headers}" \
           "Body: #{r.body}"
    end

    r.body
  end
end

# File lib/upstreamstatus.rb, line 54
def down_hosts
  current_status['servers']['server'].select { |s| s['status'] != 'up' }
end

# File lib/upstreamstatus.rb, line 58
def run
  clear_active_alerts

  exit 0 if down_hosts.empty?

  puts "Detected down hosts:\n"
  print_hosts down_hosts
  logger.info "Detected down hosts: #{down_hosts.to_json}"

  if opts[:notify]
    down_hosts.each do |host|
      notify(
        "Upstream host #{host['upstream']} listed as down",
        host
      )
    end
  end
  exit 1
rescue Interrupt => e
  puts "Received #{e.class}"
  exit 99
rescue SignalException => e
  logger.info "Received: #{e.signm} (#{e.signo})"
  exit 2
rescue SystemExit => e
  exit e.status
rescue Exception => e # Need to rescue "Exception" so that Sentry gets it
  Raven.capture_exception(e) if sentry_dsn
  logger.fatal e.message
  logger.fatal e.backtrace.join("\n")
  raise e
end

# File lib/upstreamstatus.rb, line 123
def active_alert?(host)
  active_alerts.find do |a|
    a['incident_key'] == "upstreamstatus #{Socket.gethostname} #{host['upstream']}"
  end
end

# File lib/upstreamstatus.rb, line 129
def active_alerts
  @active_alerts ||= active_alerts_paged.select do |a|
    a['incident_key'] =~ /^upstreamstatus #{Socket.gethostname} .*/
  end
end

# File lib/upstreamstatus.rb, line 135
def active_alerts_paged(offset = 0)
  r = Unirest.get(
    "#{pagerduty_api_url}/incidents?service_ids[]=#{pagerduty_service_id}&statuses[]=triggered&statuses[]=acknowledged&offset=#{offset}"
  )
  fail "Result: #{r.inspect}" unless (200..299).include?(r.code)
  return [] if r.body['total'].nil?

  pointer = r.body['limit'] + offset
  r.body['incidents'] + (pointer < r.body['total'] ? active_alerts_paged(pointer) : [])
end

# File lib/upstreamstatus.rb, line 146
def clear_active_alerts
  return unless opts[:notify]
  active_alerts.reject { |a| down_hosts_incident_keys.include? a['incident_key'] }.each do |a|
    puts "Resolving incident: #{a['incident_key']}"
    pagerduty.get_incident(a['incident_key']).resolve
  end
end

# File lib/upstreamstatus.rb, line 192
def defaults
  { 'status_check_url' => 'http://localhost:8069/status?format=json' }
end

# File lib/upstreamstatus.rb, line 154
def down_hosts_incident_keys
  down_hosts.map { |host| "upstreamstatus #{Socket.gethostname} #{host['upstream']}" }
end

# File lib/upstreamstatus.rb, line 196
def fake_response
  {
    'servers' => {
      'total' => 2,
      'generation' => 99,
      'server' => [
        {
          'index' => 0,
          'upstream' => 'testupstream0',
          'name' => '10.0.0.1 =>8080',
          'status' => 'up',
          'rise' => 10_459,
          'fall' => 0,
          'type' => 'http',
          'port' => 0
        },
        {
          'index' => 1,
          'upstream' => 'testupstream1',
          'name' => '10.0.0.2 =>8080',
          'status' => 'down',
          'rise' => 10_029,
          'fall' => 0,
          'type' => 'http',
          'port' => 0
        },
        {
          'index' => 2,
          'upstream' => 'testupstream2',
          'name' => '10.0.0.2 =>8080',
          'status' => 'down',
          'rise' => 10_029,
          'fall' => 0,
          'type' => 'http',
          'port' => 0
        }
      ]
    }
  }
end

# File lib/upstreamstatus.rb, line 186
def load_conf
  conf_file = '/etc/upstreamstatus.yml'
  yaml_conf = File.exist?(conf_file) ? YAML.load_file(conf_file) : {}
  defaults.merge(yaml_conf)
end

# File lib/upstreamstatus.rb, line 158
def logger
  @logger ||= Logger.new(conf['log']).tap { |l| l.progname = 'upstreamstatus' }
end

# File lib/upstreamstatus.rb, line 109
def notify(msg, host)
  if active_alert?(host['upstream'])
    puts "Already an active alert. Not sending anything (message: #{msg})"
  else
    puts "Notifying PagerDuty (message: #{msg})"
    pagerduty.trigger(
      msg,
      incident_key: "upstreamstatus #{Socket.gethostname} #{host['upstream']}",
      client: Socket.gethostname,
      details: host
    )
  end
end

# File lib/upstreamstatus.rb, line 166
def opts
  @opts ||= Optimist.options do
    opt :notify,
        'Notify alert service on failure',
        short: '-n',
        default: false
    opt :simulate,
        'Simulate a failed server',
        short: '-s',
        default: false
  end
end

# File lib/upstreamstatus.rb, line 162
def pagerduty
  @pagerduty ||= Pagerduty.new pagerduty_api_key
end

# File lib/upstreamstatus.rb, line 179
def print_hosts(hosts)
  hosts.each do |host|
    host.each { |k, v| puts "#{k}: #{v}" }
    puts
  end
end