#!/usr/bin/env python3

class RNG:
    def __init__(self):
        self.rng = [0xe3, 0x34, 0xad, 0x30]

    def next(self):
        self.rng[0] += 1
        self.rng[0] &= 0xff

        self.rng[1] ^= self.rng[0]
        self.rng[1] ^= self.rng[3]
        self.rng[2] += self.rng[1]
        self.rng[2] &= 0xff
        self.rng[3] += (self.rng[2] >> 1) ^ self.rng[1]
        self.rng[3] &= 0xff
        return self.rng[3]

class FunnyCode:
    def __init__(self):
        self.code = self.gencode()
        self.cache = {}

    def __str__(self):
        return " ".join(map(lambda x: "%02x" % x, self.code))

    def gencode(self):
        rng = RNG()
        code = []
        for x in range(0x400):
            val1 = rng.next()
            while val1 == 0:
                val1 = rng.next()

            val2 = rng.next()
            while True:
                val2 &= 0xf8
                if val2 in [0x00, 0x08, 0xf8]:
                    val2 = rng.next()
                    continue
                break

            code.append(0x0e)  # ld c, n8
            code.append(val1)
            code.append(0x09)  # add hl, bc
            code.append(0x15)  # dec d
            code.append(0xc8)  # ret z
            code.append(0x1d)  # dec e

            if x < 0x14:
                code.append(0x20)  # jr nz, o8
                code.append(val2 & 0x7f)
            elif x >= 0x400 - 0x14:
                code.append(0x18)  # jr o8
                code.append((val2 & 0x7f) + 0x80)
            else:
                code.append(0x20)  # jr nz, o8
                code.append(val2)

        return code

    def runcode(self, offset, de):
        key = offset << 16 | de
        if key in self.cache:
            return self.cache[key]

        hl = 0
        bc = 0
        d = de >> 8
        e = de & 0xff
        while True:
            # de = d << 8 | e
            # print("0x%04x"%offset, "bc=0x%04x"%bc, "de=0x%04x"%de, "hl=0x%04x"%hl)
            c = self.code[offset + 1]
            bc = (bc & 0xff00) | c
            hl = (hl + bc) & 0xffff
            d -= 1
            d &= 0xff
            if d == 0: break
            e -= 1
            e &= 0xff
            if self.code[offset + 6] == 0x20 and e == 0:
                offset += 8
            else:
                jr = self.code[offset + 7]
                if jr >= 0x80: jr -= 0x100
                offset = (offset + 8) + jr

        self.cache[key] = hl
        return hl

class PasswordHash:
    def __init__(self, password):
        self.hash = self.hashpass(password)
        self.valid = True
        if (self.hash[0] & 0xe000) != 0:
            self.valid = False
        if (self.hash[0] & 0x0007) != 0:
            self.valid = False

    def swap(self, val):
        vl = (val & 0xf0) >> 4
        vh = (val & 0x0f) << 4
        return vh | vl

    def hashpass(self, password):
        c = password[0] & 0xf
        b = self.swap(password[0]) & 0x03
        c = ((password[1] & 0xf) + self.swap(c)) & 0xff
        b = ((self.swap(password[1]) & 0x03) + ((b << 2) & 0xff)) & 0xff
        c1 = c
        c = password[2] & 0xf
        b = ((self.swap(password[2]) & 0x03) + ((b << 2) & 0xff)) & 0xff
        c = ((password[3] & 0xf) + self.swap(c)) & 0xff
        b = ((self.swap(password[3]) & 0x03) + ((b << 2) & 0xff)) & 0xff

        return (password[4] << 8) | b, (c << 8) | c1

passchars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789?!"
def convpass(password):
    return bytearray(passchars.index(x) for x in password)

if __name__ == "__main__":
    wanted = [
        0xadaa,
        0xac39,
        0x002f
    ]

    from sys import argv
    if len(argv) > 1 and argv[1] == "valid":
        for x in argv[2:]:
            pwd = convpass(x)
            password = PasswordHash(pwd)
            print(*map(hex, password.hash))
            if password.valid:
                print(x)
        exit()
    if len(argv) > 1 and argv[1] == "run":
        code = FunnyCode()
        for x in argv[2:]:
            pwd = convpass(x)
            password = PasswordHash(pwd)
            result = code.runcode(*password.hash)
            if result in wanted:
                print(hex(result), x)
        exit()

    code = FunnyCode()

    pwd = convpass("BEPISBEPISBEPIS")
    password = PasswordHash(pwd)
    print(password.hash)
    if not password.valid:
        print("Password invalid!")
        exit(1)
    print(hex(code.runcode(*password.hash)))

    # val = code.runcode(0, 0)
    # print(hex(val))
    # if val != 0x1a51:
        # exit(1)

    # val = code.runcode(0x1200, 0xf814)
    # print(hex(val))
    # if val != 0x4031:
        # exit(1)

    # print("success")