'''
Embeeding code
'''
import math



# Read Secret bits from file
file1 = open('Secrets.txt', 'r')

SecretCount = 0
Secret = []
while True:
    S = file1.read(1)
    if S  != "":
        SecretCount += 1
        Secret.append(int(S))
    else:
        break

#Add a redundant bit if number of secret bits is odd
if SecretCount % 2 == 1:
    Secret.append(0)
file1.close()


#Find the number of characters in the cover text including spaces
file2 = open('Cover.txt', 'r')
CoverLength = file2.read()
file2.close()

#Find the number of characters in the cover text excluding spaces and remove white spaces
file2 = open('Cover.txt', 'r')
file3 = open('NewCover.txt', 'w')
i = 0
CharacterCount = 0
SpaceCount = 0
while i < len(CoverLength):
    Char = file2.read(1)
    CharHex = (''.join([f'\\u{ord(Char):0>4x}']))
    if ((CharHex == '\\u061c') or (CharHex == '\\u200f') or (CharHex == '\\u200c') or (CharHex == '\\u034f')):
        None
    else:
        file3.write(Char)
        if Char == ' ':
            SpaceCount += 1
        else:
            CharacterCount += 1
    i += 1
file3.close()
file2.close()

file2 = open('NewCover.txt', 'a')
file2.write(' ')
file2.close()

print('# Characters = ', CharacterCount, ', # Spaces = ', SpaceCount, ', # Secret bits =', SecretCount)
print('# Characters before hiding = ', CharacterCount + SpaceCount)


if len(Secret) > CharacterCount*2:
    print('Secret bits cannot be embedded in the given cover text')
    print('Required number of Characters:', int(len(Secret)/2))
else:

    file2 = open('NewCover.txt', 'r')
    
    CharCount = 0
    CoverRead = 0
    i = 0
    T = []
    T2 = []
    Text = []
    D = 0
    C = 0
    DC = []
    j = 0
    
    #Find the XOR of the secret bits with the cover texts
    while i < len(Secret):
        
        Text.append(file2.read(1))
        CoverRead += 1
        T.append(''.join([f'\\u{ord(Text[j]):0>4x}']))
        while (Text[j] != " ") and (i < len(Secret)):

            CharCount += 1
            if Text[j] in ["ب" ,"ت" ,"ث","ج","خ","ذ","ز", "ش","ض","ظ","غ", "ف","ق", "ن","ي","ة"]:
                D = 1     # The letter is dotted
            else:
                D = 0     # The letter is undotted
            if Text[j] in ["ء" ,"أ" ,"ا" ,"آ","إ","د","ذ","ر", "ز","و","ؤ","ى","ة"]:
                C = 0       # The letter is disconnected
            else:
                C = 1       # The letter is connected
    
            DC.append(D ^ Secret[i])
            DC.append(C ^ Secret[i+1])
            j += 1
            i +=2
            Text.append(file2.read(1))
            CoverRead += 1
            T.append(''.join([f'\\u{ord(Text[j]):0>4x}']))

        j += 1
    
    
    i = 0
    j = 0
    CoverLimit = len(T)
    T_New = []
    CharCount = 0
    Embedded  = 0
    
    #Embed pseudo spaces to represent secret bits
    while i < len(DC):
        while j < CoverLimit: 

            if (T[j] == '\\u0020'):
                Count = 0
                while Count < CharCount:
                    if i < len(Secret):
                        if DC[i] == 0:
                            if DC[i+1] == 0:
                                T_New.append('\\u061C')
                            else:
                                T_New.append('\\u200F')
                        else:
                            if DC[i+1] == 0:
                                T_New.append('\\u200C')
                            else:
                                T_New.append('\\u034F ')
                        Count += 1
                        Embedded += 1
                        i += 2
                    else:
                        break
                T_New.append('\\u0020')
                CharCount = 0
            else:
                T_New.append(T[j])
                CharCount += 1

            j += 1
        i += 2
    
    

    T_len_before = len(T)
    
    #if there are still some secret bits not embedded
    if Embedded < len(DC)/2:
        k = len(Text)-1
        while (Text[k] != ' '): #read more characters tuntil the end of a word (a space)
            Text.append(file2.read(1))
            CoverRead += 1
            k += 1

        k = len(T)
        while k < len(Text):
            T.append(''.join([f'\\u{ord(Text[k]):0>4x}']))
            k += 1
    
    
        T_len_after = len(T)
        
        k1 = T_len_before
        k2 = T_len_after - 1       # until before the last read space
        
        while k1 < k2:
            
            T_New.append(T[k1])
            k1 += 1
        
    #Embed the remaining secret bits
        i = 2*Embedded
        j = Embedded
        CoverLimit = len(T)
    
        while j < CoverLimit: 
            
            if i < len(DC):
                if DC[i] == 0:
                    if DC[i+1] == 0:
                        T_New.append('\\u061C')
                    else:
                        T_New.append('\\u200F')
                else:
                    if DC[i+1] == 0:
                        T_New.append('\\u200C')
                    else:
                        T_New.append('\\u034F ')
                Embedded += 1
                i += 2
            else:
                break
            j += 1
    
        
    #indicate the end of secret bits
    if SecretCount % 2 == 1:
        T_New.append('\\uFE00') # number of secret bits is odd
    else:
        T_New.append('\\uFE01') # number of secret bits is even
                
    k1 = len(T) - 1
    T_New.append(T[k1])        # Embed the last space

    '''
    # Compute the capacity (method 1)     
    StegoSize = len(T_New) * 16
    print('# characters after hiding = ', len(T_New), ', StegoSize 2 = ', StegoSize)
    print(T_New)
    Capacity1 = (SecretCount / StegoSize) * 100
    print("Capacity 1 = ", Capacity1)
    '''    
    
    #convert the unicode to characters
    Character = []
    Count = 0
    while Count < len(T_New):
        T2.append(T_New[Count].replace('\\u','0x'))
        Char = chr(int(T2[Count], base = 16))
        Character.append(Char)
        Count += 1

    
    file3 = open('Stego.txt', 'w')
    
    # Write the characters to the output file
    i=0
    while i < len(Character):
        file3.write(Character[i])
        i += 1
    
    # Write the remaining characters of the cover text to the output file
    while CoverRead < len(CoverLength):
        file3.write(file2.read(1))
        CoverRead += 1
    

    file3.close()

    file2.close()