#!/usr/bin/python3

import os, re, sys, random, hashlib
import sys
import lib_xit

""" Contains the commands available through the command line """

def xorFiles(keyStrings, inFileNames, outFileNames, outSha1Files, size):
    """ XOR(inFileNames) == XOR(outFileNames) 
    
    The size is the size of all output files. If necessary it pads or truncate files.
    """

    keyStrings = [bytearray(k, 'utf8') for k in keyStrings]
    try:
        inFiles = [open(fileName, 'rb') for fileName in inFileNames]
        inSizes = [len(k) for k in keyStrings] + [os.fstat(f.fileno()).st_size for f in inFiles]
        if size =="min":     size = min(inSizes)
        elif size =="max":   size = -1
        elif size =="first": size = inSizes[0]
        elif size == "last": size = inSizes[-1]
        elif size == "even":
            if len(set(inSizes))!=1:
                # Security check, better stop here than truncating data!
                raise IndexError('ERROR: check --size and file sizes!')
            size = -1

        assert(type(size) is int)

        # The smaller data will be looped in XorData
        inContents = keyStrings + [bytearray(f.read(size)) for f in inFiles]
        outContents = lib_xit.xorData(inContents, len(outFileNames) + (1 if outSha1Files else 0), size)

        for fileName in outFileNames:
            with open(fileName, "wb") as f:
                f.write(outContents.pop())

        assert(len(outContents) == bool(outSha1Files)) # There must be a last one to build the sha1

        if outSha1Files:
            allSha1Xor = outContents.pop() # All sha1 sequences share the same XOR
            assert(not outContents) # It was the last one, added to get the XOR of sha1 sets

            for outSha1File in outSha1Files: # One XOR set for each sha1 file name
                outContents = lib_xit.xorData(allSha1Xor, int(outSha1File), size)

                filesAndContents = []
                for _ in range(int(outSha1File)):
                    content = outContents.pop()
                    sha1 = hashlib.sha1(content).hexdigest()
                    filesAndContents.append((outSha1File.nameWithSha1(sha1), content))

                assert(not outContents) # All the contents to be written, no more no less

                for fileName, content in filesAndContents:
                    with open(fileName, 'wb') as f:
                        f.write(content)

    finally:
        for i in inFiles: i.close()