#!/usr/bin/env python
# -*- coding: utf-8 -*-
#====================================================
#          FILE: sdat2img.py
#       AUTHORS: xpirt - luxi78 - howellzhu
#          DATE: 2015-10-11 16:33:32 CST
#====================================================

import sys, os

try:
    TRANSFER_LIST_FILE = str(sys.argv[1])
    NEW_DATA_FILE = str(sys.argv[2])
    OUTPUT_IMAGE_FILE = str(sys.argv[3])
except IndexError:
   print ("\nsdat2img - usage is: \n\n      sdat2img <transfer_list> <system_new_file> <system_img>\n\n")
   print ("Visit xda thread for more information.\n")
   try:
       input = raw_input
   except NameError: pass
   input ("Press ENTER to exit...\n")
   sys.exit()

BLOCK_SIZE = 4096

def rangeset(src):
    src_set = src.split(',')
    num_set =  [int(item) for item in src_set]
    if len(num_set) != num_set[0]+1:
        print ('Error on parsing following data to rangeset:\n%s' % src)
        sys.exit(1)

    return tuple ([ (num_set[i], num_set[i+1]) for i in range(1, len(num_set), 2) ])

def parse_transfer_list_file(path):
    trans_list = open(TRANSFER_LIST_FILE, 'r')
    version = int(trans_list.readline())    # 1st line = transfer list version
    new_blocks = int(trans_list.readline()) # 2nd line = total number of blocks

    # system.transfer.list:
    #   - version 1: android-5.0.0_r1
    #   - version 2: android-5.1.0_r1
    #   - version 3: android-6.0.0_r1

    # skip next 2 lines. we don't need this stuff now
    if version >= 2:
        trans_list.readline()               # 3rd line = stash entries needed simultaneously
        trans_list.readline()               # 4th line = number of blocks that will be stashed

    commands = []
    for line in trans_list:
        line = line.split(' ')              # 5th & next lines should be only commands
        cmd = line[0]
        if cmd in ['erase', 'new', 'zero']:
            commands.append([cmd, rangeset(line[1])])
        else:
            # skip lines starting with numbers, they're not commands anyway.
            if not cmd[0].isdigit():
                print ('No valid command: %s.' % cmd)
                trans_list.close()
                sys.exit(1)

    trans_list.close()
    return version, new_blocks, commands

def init_output_file_size(output_file_obj, commands):
    all_block_sets = [i for command in commands for i in command[1]]
    max_block_num = max(pair[1] for pair in all_block_sets)
    output_file_obj.seek(max_block_num*BLOCK_SIZE - 1)
    output_file_obj.write('\0'.encode('utf-8'))
    output_file_obj.flush()

def main(argv):
    version, new_blocks, commands = parse_transfer_list_file(TRANSFER_LIST_FILE)
    output_img = open(OUTPUT_IMAGE_FILE, 'wb')
    init_output_file_size(output_img, commands)
    new_data_file = open(NEW_DATA_FILE, 'rb')

    for command in commands:
        if command[0] == 'new':
            for block in command[1]:
                begin = block[0]
                end = block[1]
                block_count = end - begin
                data = new_data_file.read(block_count*BLOCK_SIZE)
                print('Copying {} blocks into position {}...'.format(block_count, begin))
                output_img.seek(begin*BLOCK_SIZE)
                output_img.write(data)
        else:
            print('Skipping command %s' % command[0])

    output_img.close()
    new_data_file.close()
    print ('\nDone! Output image: %s' % os.path.realpath(output_img.name))

if __name__ == "__main__":
    main(sys.argv)