#!/usr/bin/env python

import sys, os, readsnap, argparse

# read parameters
parser = argparse.ArgumentParser(description="find blocks of gadget file and print its information")
parser.add_argument("filename",help="gadget file name")
args = parser.parse_args();  filename = args.filename

# find actual file
if os.path.exists(filename):	     curfilename = filename
elif os.path.exists(filename+".0"):  curfilename = filename+".0"
else:                                raise Exception("file not found")

  
head = readsnap.snapshot_header(curfilename)
format = head.format;  swap = head.swap;  del head
  
print('\nGADGET FORMAT : %d'%format)
if (format != 2):
   print("#   OFFSET   SIZE")
else:            
   print("#   BLOCK   OFFSET   SIZE")
print("-------------------------")
  
readsnap.find_block(curfilename, format, swap, "XXXX", 0, only_list_blocks=True)
  
print("-------------------------\n")
