module CloudwatchCommon

# File lib/sensu-plugins-aws/cloudwatch-common.rb, line 61
def self.parse_dimensions(dimension_string)
  dimension_string.split(',')
                  .collect { |d| d.split '=' }
                  .collect { |a| { name: a[0], value: a[1] } }
end

# File lib/sensu-plugins-aws/cloudwatch-common.rb, line 71
def check(config)
  resp = client.get_metric_statistics(metrics_request(config))

  no_data = resp_has_no_data(resp, config[:statistics])
  if no_data && config[:no_data_ok]
    ok "#{metric_desc} returned no data but that's ok"
  elsif no_data && !config[:no_data_ok]
    unknown "#{metric_desc} could not be retrieved"
  end

  value = read_value(resp, config[:statistics])
  base_msg = "#{metric_desc} is #{value}: comparison=#{config[:compare]}"

  if compare value, config[:critical], config[:compare]
    critical "#{base_msg} threshold=#{config[:critical]}"
  elsif config[:warning] && compare(value, config[:warning], config[:compare])
    warning "#{base_msg} threshold=#{config[:warning]}"
  else
    ok "#{base_msg}, will alarm at #{!config[:warning].nil? ? config[:warning] : config[:critical]}"
  end
end

# File lib/sensu-plugins-aws/cloudwatch-common.rb, line 4
def client
  @client ||= Aws::CloudWatch::Client.new
end

# File lib/sensu-plugins-aws/cloudwatch-common.rb, line 20
def compare(value, threshold, compare_method)
  case compare_method
  when 'greater'
    value > threshold
  when 'less'
    value < threshold
  when 'not'
    value != threshold
  else
    value == threshold
  end
end

# File lib/sensu-plugins-aws/cloudwatch-common.rb, line 56
def composite_metrics_request(metric)
  ## config is a class variable but don't want to change signature
  metrics_request(config).merge(metric_name: metric)
end

# File lib/sensu-plugins-aws/cloudwatch-common.rb, line 67
def dimension_string
  config[:dimensions].map { |d| "#{d[:name]}=#{d[:value]}" }.join('&')
end

# File lib/sensu-plugins-aws/cloudwatch-common.rb, line 33
def extended_stats?(stats)
  stats[/p\d+\.\d+|p\d+/] # Check for percentile format
end

# File lib/sensu-plugins-aws/cloudwatch-common.rb, line 52
def get_metric(metric)
  client.get_metric_statistics(composite_metrics_request(metric))
end

# File lib/sensu-plugins-aws/cloudwatch-common.rb, line 37
def metrics_request(config)
  request = {
    namespace: config[:namespace],
    metric_name: config[:metric_name],
    dimensions: config[:dimensions],
    start_time: Time.now - config[:period] * 10,
    end_time: Time.now,
    period: config[:period],
    unit: config[:unit]
  }
  stats_key = extended_stats?(config[:statistics]) ? :extended_statistics : :statistics
  request[stats_key] = [config[:statistics]]
  request
end

# File lib/sensu-plugins-aws/cloudwatch-common.rb, line 8
def read_value(resp, stats)
  if extended_stats? stats
    resp.datapoints.sort_by(&:timestamp).last.extended_statistics[stats]
  else
    resp.datapoints.sort_by(&:timestamp).last.send(stats.downcase)
  end
end

# File lib/sensu-plugins-aws/cloudwatch-common.rb, line 16
def resp_has_no_data(resp, stats)
  resp.datapoints.nil? || resp.datapoints.empty? || resp.datapoints.first.nil? || read_value(resp, stats).nil?
end