dat.py

""" Copyright 2015-2017  sta256+mpskit at gmail.com
    
    This file is part of mpskit.

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License as
    published by the Free Software Foundation, either version 3 of the
    License, or (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY.

    See LICENSE file for more details.
"""
from common import *
from fab import *



def save_mdat_messages(mdat_name, h):
	oname = "{}.msg.json".format(mdat_name)
	with open(oname, 'w') as f:
		json.dump(h, f, indent=2, ensure_ascii=False)
	output(oname)
	
def save_mdat_metainfo(mdat_name, h):
	oname = "{}.id.json".format(mdat_name)
	with open(oname, 'w') as f:
		json.dump(h, f, indent=2)
	output(oname)

def load_mdat_messages(mdat_name):
	with open("{}.msg.json".format(mdat_name), 'r') as f:
		return json.load(f)

def load_mdat_metainfo(mdat_name):
	with open("{}.id.json".format(mdat_name), 'r') as f:
		return json.load(f)


def read_mdat(fname, verbose = 0):
	if fname != 'MESSAGES.DAT':
		warning('mdat decoder: only MESSAGES.DAT allowed')
	
	entries = []
	metas = []

	with open(fname, 'rb') as f:
	
		# number of entries
		num = read_uint16(f)
		
		if verbose:
			print('mdat: count={}'.format(num))
		
		
		curr_header = f.tell()
			
		for _ in range(num):
			# entry header
			f.seek(curr_header)
			sid,offset,length = read_struct(f, "<IIH")
			curr_header = f.tell()
						
			# entry content
			f.seek(offset)
			
			
			dest = read_fab(f, length, verbose = 0)
			
			clength = f.tell() - offset
			if verbose:
				print("sid = {}; length = {}; clength = {};".format(sid, length, clength))
				
			
			
			entry = decode_string(dest.read())
			entries.append(entry)
			
			metas.append({"id": sid})
		
		
	save_mdat_messages(fname, entries)
	save_mdat_metainfo(fname, metas)


def write_mdat(fname, verbose = 0):
	if fname != 'MESSAGES.DAT':
		warning('mdat decoder: only MESSAGES.DAT allowed')
	
	messages = load_mdat_messages(fname)
	metas = load_mdat_metainfo(fname)
	
	
	
	#
	msgs = [encode_string(s, null_term=True) for s in messages]
	num = len(msgs)
	
	
	with open(fname, 'wb') as f:
		write_uint16(f, num)
		if verbose:
			print('mdat: count={}'.format(num))
			
		curr_header = f.tell()
		curr_offset = f.tell() + num * struct.calcsize("<IIH")
		
		#sid = 1
		for meta,data in zip(metas, msgs):
			
			assert data[-1] == 0
			
			
			
			length = len(data)
			
			#if verbose:
			#	print("sid = {}; offset = {}; msg = {};".format(sid, curr_offset, data))
			
			
			sid = meta['id']
			
			# head
			f.seek(curr_header)
			write_struct(f, "<IIH", (sid,curr_offset,length))
			curr_header = f.tell()
			
			# body
			f.seek(curr_offset)
			write_fab(f, data)
			clength = f.tell() - curr_offset
			curr_offset = f.tell()
			
			if verbose:
				print("sid = {}; length = {}; clength = {};".format(sid, length, clength))
			
			#sid += 1
		
	
	output(fname)	
		

'''
return struct.pack("<3sBH15sH1cBBB",
		b'FAB',
		0x0C,
		0xFFFF,
		b'1234567890abcde',
		0xFFFE,
		b'f',
		0x00,
		0x00,
		0x00,
	)
'''