class Sentry::Utils::SampleRand

def self.format(value)
  return unless value
  truncated = (value * PRECISION).floor / PRECISION
  "%.#{FORMAT_PRECISION}f" % truncated
end

def self.valid?(value)
  return false unless value
  value >= 0.0 && value < 1.0
end

def fallback_generation
  if @trace_id
    (random_from_trace_id * PRECISION).floor / PRECISION
  else
    format_random(Random.rand(1.0))
  end
end

def format_random(value)
  truncated = (value * PRECISION).floor / PRECISION
  ("%.#{FORMAT_PRECISION}f" % truncated).to_f
end

def generate_based_on_sampling(sampled, sample_rate)
  random = random_from_trace_id
  result = if sampled
    random * sample_rate
  elsif sample_rate == 1.0
    random
  else
    sample_rate + random * (1.0 - sample_rate)
  end
  format_random(result)
end

def generate_from_sampling_decision(sampled, sample_rate)
  if invalid_sample_rate?(sample_rate)
    fallback_generation
  else
    generate_based_on_sampling(sampled, sample_rate)
  end
end

def generate_from_trace_id
  (random_from_trace_id * PRECISION).floor / PRECISION
end

def generate_from_value(sample_rand_value)
  parsed_value = parse_value(sample_rand_value)
  if self.class.valid?(parsed_value)
    parsed_value
  else
    fallback_generation
  end
end

def initialize(trace_id: nil)
  @trace_id = trace_id
end

def invalid_sample_rate?(sample_rate)
  sample_rate.nil? || sample_rate <= 0.0 || sample_rate > 1.0
end

def parse_value(sample_rand_value)
  Float(sample_rand_value)
rescue ArgumentError
  nil
end

def random_from_trace_id
  if @trace_id
    Random.new(@trace_id[0, 16].to_i(16))
  else
    Random.new
  end.rand(1.0)
end