#!/usr/bin/env ruby
#
# $ progress dump.sql.gz
# gzip (68010): 56.13%, 27m52s left (1804580 bytes/sec)
#

DIFFS_COUNT = 20

if !(file = ARGV[0])
  puts "usage: #{$0} <file>"
  exit 1
end

diffs = []

last_off = -1
loop do
  fs = `fstat -o #{file}`.split("\n")
  if fs.count == 1
    if last_off > -1
      exit
    end
    puts "nothing has #{file} open"
    exit 1
  end
	fields = fs.last.split(" ")
  cmd = fields[1]
  pid = fields[2]
  size, off = fields[8].split(":")

  if off == "*"
    puts "no access to read status of pid #{pid}"
    exit 1
  end
  off = off.to_i

  if last_off > -1
    diffs.push (off - last_off)
    if diffs.count == DIFFS_COUNT
      diffs.shift
    end
  end
  last_off = off

  if diffs.any?
    avg = diffs.sum / diffs.count.to_f
    secs = ((size.to_i - off.to_i) / avg.to_f).floor
    rem = ""
    if secs > (60 * 60)
      h = (secs / (60 * 60).to_f).floor
      rem = "#{sprintf("%02d", h)}h"
      secs -= (h * 60 * 60)
    end
    if secs > 60 || rem.length > 0
      m = (secs / 60.0).floor
      rem += "#{sprintf("%02d", m)}m"
      secs -= (m * 60)
    end
    rem += "#{sprintf("%02d", secs)}s left"
  else
    avg = 0
    rem = "-"
  end

  perc = sprintf("%0.2f%%", (off / size.to_f) * 100.0)
  print "\r\e[K#{cmd} (#{pid}): #{perc}, #{rem} (#{avg.floor} bytes/sec)"

  sleep 1
rescue Interrupt
  puts ""
  exit
end