#!/usr/bin/python3

# adapted from Trung's create_trustcache.py

import sys
import struct
import urllib

def create_tc(hashes):
    tc = b""

    #write the header
    #version
    tc += struct.pack("<I", 1)

    #unknown header properties
    #tc += struct.pack("<I", 0)
    #tc += struct.pack("<I", 0)
    #tc += struct.pack("<I", 0)
    #tc += struct.pack("<I", 0)
    #uuid
    tc += bytes.fromhex(sys.argv[3]).ljust(16, b'\x00')

    #number of hashes in the trust cache
    tc += struct.pack("<I", len(hashes))

    for hash_txt in hashes:
        if len(hash_txt) == 0:
            continue

        assert(len(hash_txt) >= 40)
        
        cdhash = bytes.fromhex(hash_txt.decode('ascii'))[:20]
        #write the hash itself
        tc += cdhash
        # for i in range(5):
        #     four_bytes = hash_txt[i * 8 : (i + 1) * 8]
        #     number = int(four_bytes, 16)
        #     tc += struct.pack(">I", number)

        #hash type
        tc += struct.pack("B", 2)
        #hash flags
        tc += struct.pack("B", 0)
    return tc

if __name__ == "__main__":
    hashes_txt = open(sys.argv[1], "rb").read()
    hashes = hashes_txt.splitlines()
    hashes = [hash.strip() for hash in hashes]
    #the kernel does a binary search for the hash so they must be sorted
    hashes = sorted(hashes)
    tc = create_tc(hashes)
    open(sys.argv[2], "wb").write(tc)