class SimpleCov::ExitCodes::MaximumCoverageDropCheck

def compute_coverage_drop_data
  maximum_coverage_drop.map do |criterion, percent|
    {
      criterion: criterion,
      max_drop: percent,
      drop_percent: drop_percent(criterion)
    }
  end
end

def coverage_drop_violations
  @coverage_drop_violations ||=
    compute_coverage_drop_data.select do |achieved|
      achieved.fetch(:max_drop) < achieved.fetch(:drop_percent)
    end
end

def drop_percent(criterion)
  drop = last_coverage(criterion) -
         SimpleCov.round_coverage(
           result.coverage_statistics.fetch(criterion).percent
         )
  # floats, I tell ya.
  # irb(main):001:0* 80.01 - 80.0
  # => 0.010000000000005116
  drop.floor(MAX_DROP_ACCURACY)
end

def exit_code
  SimpleCov::ExitCodes::MAXIMUM_COVERAGE_DROP
end

def failing?
  return false unless maximum_coverage_drop && last_run
  coverage_drop_violations.any?
end

def initialize(result, maximum_coverage_drop)
  @result = result
  @maximum_coverage_drop = maximum_coverage_drop
end

def last_coverage(criterion)
  last_coverage_percent = last_run[:result][criterion]
  # fallback for old file format
  last_coverage_percent = last_run[:result][:covered_percent] if !last_coverage_percent && criterion == :line
  last_coverage_percent || 0
end

def last_run
  return @last_run if defined?(@last_run)
  @last_run = SimpleCov::LastRun.read
end

def report
  coverage_drop_violations.each do |violation|
    $stderr.printf(
      "%<criterion>s coverage has dropped by %<drop_percent>.2f%% since the last time (maximum allowed: %<max_drop>.2f%%).\n",
      criterion: violation[:criterion].capitalize,
      drop_percent: SimpleCov.round_coverage(violation[:drop_percent]),
      max_drop: violation[:max_drop]
    )
  end
end