class VCR::VersionChecker

def check_version!
  raise_too_low_error if too_low?
end

def compare_version
  case
    when @major < @min_major then :too_low
    when @major > @min_major then :ok
    when @minor < @min_minor then :too_low
    when @minor > @min_minor then :ok
    when @patch < @min_patch then :too_low
  end
end

def initialize(library_name, library_version, min_version)
  @library_name    = library_name
  @library_version = library_version
  @min_version     = min_version
  @major,     @minor,     @patch     = parse_version(library_version)
  @min_major, @min_minor, @min_patch = parse_version(min_version)
end

def parse_version(version)
  version.split('.').map { |v| v.to_i }
end

def raise_too_low_error
  raise Errors::LibraryVersionTooLowError,
    "You are using #{@library_name} #{@library_version}. " +
    "VCR requires version #{version_requirement}."
end

def too_low?
  compare_version == :too_low
end

def version_requirement
  ">= #{@min_version}"
end