import sys
import hashlib


print("  Note: Must be run in Terminal")
print("  e.g. python md5_IX_v01.py -r filename hashTotal")
#by D@CC
#on 2023ISep25
progName="md5_IX_v01.py"
print("progName:",progName)

#Hash Source: https://stackoverflow.com/questions/22058048/hashing-a-file-in-python
# compare to:
# $ md5-console -f bigfile
# $ shasum bigfile

#Snap Source:https://snapcraft.io/install/md5-console/raspbian
# $ sudo apt update
# $ sudo apt install snapd
# then reboot
# $ sudo snap install core
# $ sudo snap install snapcraft --classic
# $ sudo snap install md5-console
#  the last step took several minutes
import time; now=int(time.time());print ("UnixEpochTime:",now)

# BUF_SIZE is totally arbitrary, change for your app!
BUF_SIZE = 65536  # lets read stuff in 64kb chunks!

subjectFile=sys.argv[2]
print("subjectFile:",subjectFile)

md5 = hashlib.md5()
#sha1 = hashlib.sha1()
controlString=sys.argv[1]
controlString=controlString[1:2]
print("controlString:",controlString)

if "aefru".find(controlString) :
    print("controlString is valid")
else:
    print("Error 01: Invalid Control String:",controlString)
    exit
#if end
if controlString=="r":
    md5old=sys.argv[3]
    print(md5old,":md5")
    #get first record only

    with open(subjectFile, 'r') as t:
        rec=t.readline().strip()
        lenPrefix=17
        prefix=rec[0:17]
        if prefix=="#########_MD5_IX ":
            suffix=rec[17:len(rec)]
            #print("prefix:"+prefix+":")
            #print("suffix:"+suffix+":")
            r1h=suffix  #get real MD5 from rec 1
        else:
            r1h="bad"
        #if end
        print(r1h,":r1h")
    #with end
    t.close()
    
    # chop off rec1, write out file as "temp.txt"
    temp=open("temp.txt", 'w')
    with open(subjectFile, 'r') as t:
        rec=t.readline()
        n=1
        while True:
            n+=1
            rec=t.readline()
            #print(n,rec)
            if rec=="": break
            temp.write(rec)
        #while end
        #print("eof")
    #with end
    #print("temp written:",n," records")
    with open("temp.txt", 'rb') as f:             
        #with open(sys.argv[2], 'rb') as f:
        while True:
            data = f.read(BUF_SIZE)
            if not data:
                break
            md5.update(data)
            #sha1.update(data)
    # with end
    f.close()
    print("{0} :MD5".format(md5.hexdigest()))
    if md5old==md5.hexdigest() and md5old==r1h:
        print("This is a valid md5_IX file. The 3 md5 agree.")
    else:
        print("Bad md5 hashes.")
    #if end
    #print("SHA1: {0}".format(sha1.hexdigest()))
#if end r