module MNC

# File lib/mnc.rb, line 7
def self.[](now: Time.now, crontab: `crontab -l`)
  Integer(
    crontab
    .lines
    .select { |l| l =~ /^(?:[-0-9,*]+\s+){5}\S+/ }
    .map { |l| l.split.zip %w[%M %H %d %m %w] }
    .map { |a| a[0..4].reject { |b| b[0] == '*' } }
    .map { |a|
      a.map { |b|
        b[0].split(',').map { |c| [c, b[1]] }
      }.map { |b|
        b.map { |c|
          d = c[0].split('-')
          (d[0]..(d[1] || d[0])).map { |e| [e, c[1]] }
        }.flatten(1)
      }
    }
    .map { |a|
      (a[0] || [nil]).map { |b|
        (a[1] || [nil]).map { |c|
          (a[2] || [nil]).map { |d|
            (a[3] || [nil]).map { |e|
              (a[4] || [nil]).map { |f|
                g = [b, c, d, e, f].compact
                t = g.map { |h| h[0] }.join(' ')
                f = g.map { |h| h[1] }.join(' ')
                n = now
                n += 60 while (r = (Time.strptime t, f, n)) < now
                r
              }
            }
          }
        }
      }
    }.flatten.min - now
  )
end