#!/usr/bin/env python3
# -*- coding: utf-8 -*-

'''
Helper library with code needed for Adobe stuff.
'''

from uuid import getnode
import os, hashlib, base64
import urllib.request, ssl
from datetime import datetime, timedelta

from lxml import etree

try:
    from Crypto import Random
    from Crypto.Cipher import AES
    from Crypto.PublicKey import RSA
    from Crypto.Hash import SHA
except ImportError:
    # Debian (and Ubuntu) ship pycryptodome, but not in its compatible mode with pycrypto
    # If `Crypto` can't be found, try under pycryptodome's own namespace
    from Cryptodome import Random
    from Cryptodome.Cipher import AES
    from Cryptodome.PublicKey import RSA
    from Cryptodome.Hash import SHA

try: 
    from customRSA import CustomRSA
except: 
    from calibre_plugins.deacsm.customRSA import CustomRSA

from oscrypto import keys
from oscrypto.asymmetric import dump_certificate, dump_private_key


VAR_ACS_SERVER_HTTP = "http://adeactivate.adobe.com/adept"
VAR_ACS_SERVER_HTTPS = "https://adeactivate.adobe.com/adept"

FILE_DEVICEKEY = "devicesalt"
FILE_DEVICEXML = "device.xml"
FILE_ACTIVATIONXML = "activation.xml"


# Lists of different ADE "versions" we know about
VAR_VER_SUPP_CONFIG_NAMES = [ "ADE 1.7.2", "ADE 2.0.1", "ADE 3.0.1", "ADE 4.0.3", "ADE 4.5.10", "ADE 4.5.11" ]
VAR_VER_SUPP_VERSIONS = [ "ADE WIN 9,0,1131,27", "2.0.1.78765", "3.0.1.91394", "4.0.3.123281", 
                            "com.adobe.adobedigitaleditions.exe v4.5.10.186048", 
                            "com.adobe.adobedigitaleditions.exe v4.5.11.187303" ]
VAR_VER_HOBBES_VERSIONS = [ "9.0.1131.27", "9.3.58046", "10.0.85385", "12.0.123217", "12.5.4.186049", "12.5.4.187298" ]
VAR_VER_OS_IDENTIFIERS = [ "Windows Vista", "Windows Vista", "Windows 8", "Windows 8", "Windows 8", "Windows 8" ]


# "Missing" versions:
# 1.7.1, 2.0, 3.0, 4.0, 4.0.1, 4.0.2, 4.5 to 4.5.9

# This is a list of ALL versions we know (and can potentially use if present in a config file).
# Must have the same length / size as the four lists above.
VAR_VER_BUILD_IDS = [ 1131, 78765, 91394, 123281, 186048, 187303 ]
# Build ID 185749 also exists, that's a different (older) variant of 4.5.10. 

# This is a list of versions that can be used for new authorizations:
VAR_VER_ALLOWED_BUILD_IDS_AUTHORIZE = [ 78765, 91394, 123281, 187303 ]

# This is a list of versions to be displayed in the version changer.
VAR_VER_ALLOWED_BUILD_IDS_SWITCH_TO = [ 1131, 78765, 91394, 123281, 187303 ]

# Versions >= this one are using HTTPS
# According to changelogs, this is implemented as of ADE 4.0.1 - no idea what build ID that is.
VAR_VER_NEED_HTTPS_BUILD_ID_LIMIT = 123281

# Default build ID to use - ADE 2.0.1
VAR_VER_DEFAULT_BUILD_ID = 78765



def are_ade_version_lists_valid():
    # These five lists MUST all have the same amount of elements. 
    # Otherwise that will cause all kinds of issues. 

    fail = False
    if len(VAR_VER_SUPP_CONFIG_NAMES) != len(VAR_VER_SUPP_VERSIONS):
        fail = True
    if len(VAR_VER_SUPP_CONFIG_NAMES) != len(VAR_VER_HOBBES_VERSIONS):
        fail = True
    if len(VAR_VER_SUPP_CONFIG_NAMES) != len(VAR_VER_OS_IDENTIFIERS):
        fail = True
    if len(VAR_VER_SUPP_CONFIG_NAMES) != len(VAR_VER_BUILD_IDS):
        fail = True
    
    if fail:
        print("Internal error in DeACSM: Mismatched version list lenghts.")
        print("This should never happen, please open a bug report.")
        return False
    
    return True


devkey_bytes = None



def get_devkey_path():
    global FILE_DEVICEKEY
    return FILE_DEVICEKEY
def get_device_path():
    global FILE_DEVICEXML
    return FILE_DEVICEXML
def get_activation_xml_path():
    global FILE_ACTIVATIONXML
    return FILE_ACTIVATIONXML


def update_account_path(folder_path: str):
    global FILE_DEVICEKEY, FILE_DEVICEXML, FILE_ACTIVATIONXML

    FILE_DEVICEKEY = os.path.join(folder_path, "devicesalt")
    FILE_DEVICEXML = os.path.join(folder_path, "device.xml")
    FILE_ACTIVATIONXML = os.path.join(folder_path, "activation.xml")


def createDeviceKeyFile():
    # Original implementation: Device::createDeviceKeyFile()

    DEVICE_KEY_SIZE = 16
    global devkey_bytes
    devkey_bytes = Random.get_random_bytes(DEVICE_KEY_SIZE)

    f = open(FILE_DEVICEKEY, "wb")
    f.write(devkey_bytes)
    f.close()

def get_mac_address(): 
    mac1 = getnode()
    mac2 = getnode()
    if (mac1 != mac2) or ((mac1 >> 40) % 2):
        return bytes([1, 2, 3, 4, 5, 0])
    
    return mac1.to_bytes(6, byteorder='big')



def makeSerial(random: bool):
    # Original implementation: std::string Device::makeSerial(bool random)

    # It doesn't look like this implementation results in the same fingerprint Adobe is using in ADE.
    # Given that Adobe only ever sees the SHA1 hash of this value, that probably doesn't matter.

    sha_out = None

    if not random: 
        try:
            # Linux
            uid = os.getuid()
            import pwd
            username = pwd.getpwuid(uid).pw_name.encode("utf-8").decode("latin-1")
        except: 
            # Windows
            uid = 1000
            username = os.getlogin().encode("utf-8").decode("latin-1")

        mac_address = get_mac_address()

        dataToHash = "%d:%s:%02x:%02x:%02x:%02x:%02x:%02x\x00" % (uid, username, 
            mac_address[0], mac_address[1], mac_address[2], 
            mac_address[3], mac_address[4], mac_address[5])

        sha_out = hashlib.sha1(dataToHash.encode('latin-1')).hexdigest().lower()
    else: 
        sha_out = Random.get_random_bytes(20).hex().lower()

    return sha_out

def makeFingerprint(serial: str):
    # Original implementation: std::string Device::makeFingerprint(const std::string& serial)
    # base64(sha1(serial + privateKey))
    # Fingerprint must be 20 bytes or less.

    f = open(FILE_DEVICEKEY, "rb")
    devkey_bytes = f.read()
    f.close()

    str_to_hash = serial + devkey_bytes.decode('latin-1')
    hashed_str = hashlib.sha1(str_to_hash.encode('latin-1')).digest()
    b64str = base64.b64encode(hashed_str)

    return b64str


############################################## HTTP stuff:

def sendHTTPRequest_DL2FILE(URL: str, outputfile: str):
    headers = {
        "Accept": "*/*",
        "User-Agent": "book2png",
        # MacOS uses different User-Agent. Good thing we're emulating a Windows client.
    }
    req = urllib.request.Request(url=URL, headers=headers)
    handler = urllib.request.urlopen(req)

    chunksize = 16 * 1024

    ret_code = handler.getcode()


    loc = None
    try: 
        loc = req.headers.get("Location")
    except:
        pass

    if loc is not None: 
        return sendHTTPRequest_DL2FILE(loc)

    if ret_code != 200:
        return ret_code

    with open(outputfile, "wb") as f:
        while True: 
            chunk = handler.read(chunksize)
            if not chunk: 
                break
            f.write(chunk)

    return 200

def sendHTTPRequest_getSimple(URL: str):

    headers = {
        "Accept": "*/*",
        "User-Agent": "book2png",
        # MacOS uses different User-Agent. Good thing we're emulating a Windows client.
    }

    # Ignore SSL:
    # It appears as if lots of book distributors have either invalid or expired certs ...
    # No idea how Adobe handles that (pinning?), but we can just ignore SSL errors and continue anyways.
    # Not the best solution, but it works.
    ctx = ssl.create_default_context()
    ctx.check_hostname = False
    ctx.verify_mode = ssl.CERT_NONE

    req = urllib.request.Request(url=URL, headers=headers)
    handler = urllib.request.urlopen(req, context=ctx)

    content = handler.read()

    loc = None
    try: 
        loc = req.headers.get("Location")
    except:
        pass

    if loc is not None: 
        return sendHTTPRequest_getSimple(loc)

    return content

def sendPOSTHTTPRequest(URL: str, document: bytes, type: str, returnRC = False):

    headers = {
        "Accept": "*/*",
        "User-Agent": "book2png",
        # MacOS uses different User-Agent. Good thing we're emulating a Windows client.
        "Content-Type": type
    }

    # Ignore SSL:
    # It appears as if lots of book distributors have either invalid or expired certs ...
    # No idea how Adobe handles that (pinning?), but we can just ignore SSL errors and continue anyways.
    # Not the best solution, but it works.
    ctx = ssl.create_default_context()
    ctx.check_hostname = False
    ctx.verify_mode = ssl.CERT_NONE

    req = urllib.request.Request(url=URL, headers=headers, data=document)
    try: 
        handler = urllib.request.urlopen(req, context=ctx)
    except urllib.error.HTTPError as err: 
        # This happens with HTTP 500 and related errors.
        print("Post request caused HTTPError %d" % (err.code))
        return err.code, "Post request caused HTTPException"


    ret_code = handler.getcode()
    if (ret_code == 204 and returnRC):
        return 204, ""
    if (ret_code != 200):
        print("Post request returned something other than 200 - returned %d" % (ret_code))

    content = handler.read()

    loc = None
    try: 
        loc = req.headers.get("Location")
    except:
        pass

    if loc is not None: 
        return sendPOSTHTTPRequest(loc, document, type, returnRC)

    if returnRC:
        return ret_code, content

    return content


def sendHTTPRequest(URL: str):
    return sendHTTPRequest_getSimple(URL)


def sendRequestDocu(document: str, URL: str):
    return sendPOSTHTTPRequest(URL, document.encode("utf-8"), "application/vnd.adobe.adept+xml", False)

def sendRequestDocuRC(document: str, URL: str):
    return sendPOSTHTTPRequest(URL, document.encode("utf-8"), "application/vnd.adobe.adept+xml", True)



######### Encryption and signing ###################


def encrypt_with_device_key(data):

    global devkey_bytes
    if devkey_bytes is None: 
        f = open(FILE_DEVICEKEY, "rb")
        devkey_bytes = f.read()
        f.close()

    remain = 16
    if (len(data) % 16):
        remain = 16 - (len(data) % 16)

    data += bytes([remain])*remain

    iv = Random.get_random_bytes(16)
    cip = AES.new(devkey_bytes, AES.MODE_CBC, iv)
    encrypted = cip.encrypt(data)

    res = iv + encrypted
    return res

def decrypt_with_device_key(data): 
    global devkey_bytes
    if devkey_bytes is None: 
        f = open(FILE_DEVICEKEY, "rb")
        devkey_bytes = f.read()
        f.close()

    cip = AES.new(devkey_bytes, AES.MODE_CBC, data[:16])
    decrypted = cip.decrypt(data[16:])

    # Remove padding
    decrypted = decrypted[:-decrypted[-1]]

    return decrypted


def addNonce(): 

    # TODO: Update nonce calculation
    # Currently, the plugin always uses the current time, and the counter (tmp) is always 0. 
    # What Adobe does instead is save the current time on program start, then increase tmp
    # every time a Nonce is needed. 

    dt = datetime.utcnow()
    usec = dt.microsecond
    sec = (dt - datetime(1970,1,1)).total_seconds()


    Ntime = int(int(sec * 1000) + usec/1000)

    # Unixtime to gregorian timestamp
    Ntime += 62167219200000

    final = bytearray(Ntime.to_bytes(8, 'little'))

    # Something is fishy with this tmp value. It usually is 0 in ADE, but not always. 
    # I haven't yet figured out what it means ...
    tmp = 0
    final.extend(tmp.to_bytes(4, 'little'))

    ret = ""

    ret += "<adept:nonce>%s</adept:nonce>" % (base64.b64encode(final).decode("utf-8"))

    m10m = dt + timedelta(minutes=10)
    m10m_str = m10m.strftime("%Y-%m-%dT%H:%M:%SZ")

    ret += "<adept:expiration>%s</adept:expiration>" % (m10m_str)

    return ret


def get_cert_from_pkcs12(_pkcs12, _key):

    _, cert, _ = keys.parse_pkcs12(_pkcs12, _key)
    return dump_certificate(cert, encoding="der")




def sign_node(node):

    sha_hash = hash_node(node)
    sha_hash = sha_hash.digest()

    # print("Hash is " + sha_hash.hex())

    global devkey_bytes
    global pkcs12

    if devkey_bytes is None: 
        f = open(FILE_DEVICEKEY, "rb")
        devkey_bytes = f.read()
        f.close()

    try: 
        activationxml = etree.parse(FILE_ACTIVATIONXML)
        adNS = lambda tag: '{%s}%s' % ('http://ns.adobe.com/adept', tag)
        pkcs12 = activationxml.find("./%s/%s" % (adNS("credentials"), adNS("pkcs12"))).text
    except: 
        return None

    my_pkcs12 = base64.b64decode(pkcs12)

    my_priv_key, _, _ = keys.parse_pkcs12(my_pkcs12, base64.b64encode(devkey_bytes))
    my_priv_key = dump_private_key(my_priv_key, None, "der")


    key = RSA.importKey(my_priv_key)
    keylen = CustomRSA.byte_size(key.n)
    padded = CustomRSA.pad_message(sha_hash, keylen)
    payload = CustomRSA.transform_bytes2int(padded)
    encrypted = CustomRSA.normal_encrypt(key, payload)
    block = CustomRSA.transform_int2bytes(encrypted, keylen)
    signature = base64.b64encode(block).decode()

    # Debug
    # print("sig is %s\n" % block.hex())

    return signature


 

def hash_node(node):

    hash_ctx = SHA.new()
    hash_node_ctx(node, hash_ctx)
    return hash_ctx



ASN_NONE = 0
ASN_NS_TAG = 1      # aka "BEGIN_ELEMENT"
ASN_CHILD = 2       # aka "END_ATTRIBUTES"
ASN_END_TAG = 3     # aka "END_ELEMENT"
ASN_TEXT = 4        # aka "TEXT_NODE"
ASN_ATTRIBUTE = 5   # aka "ATTRIBUTE"

debug = False

def hash_node_ctx(node, hash_ctx):

    qtag = etree.QName(node.tag)

    if (qtag.localname == "hmac" or qtag.localname == "signature"):
        if (qtag.namespace == "http://ns.adobe.com/adept"):
            # Adobe HMAC and signature are not hashed
            return
        else: 
            print("Warning: Found hmac or signature node in unexpected namespace " + qtag.namespace)

    hash_do_append_tag(hash_ctx, ASN_NS_TAG)

    if qtag.namespace is None: 
        hash_do_append_string(hash_ctx, "")
    else:
        hash_do_append_string(hash_ctx, qtag.namespace)
    hash_do_append_string(hash_ctx, qtag.localname)


    attrKeys = node.keys()

    # Attributes need to be sorted
    attrKeys.sort()
    # TODO Implement UTF-8 bytewise sorting:
    # "Attributes are sorted first by their namespaces and
    # then by their names; sorting is done bytewise on UTF-8
    # representations."

    for attribute in attrKeys: 
        # Hash all the attributes
        hash_do_append_tag(hash_ctx, ASN_ATTRIBUTE)

        # Check for element namespace and hash that, if present:
        q_attribute = etree.QName(attribute)

        # Hash element namespace (usually "")
        # If namespace is none, use "". Else, use namespace.
        hash_do_append_string(hash_ctx, "" if q_attribute.namespace is None else q_attribute.namespace)

        # Hash (local) name and value
        hash_do_append_string(hash_ctx, q_attribute.localname)
        hash_do_append_string(hash_ctx, node.get(attribute))

    hash_do_append_tag(hash_ctx, ASN_CHILD)

    if (node.text is not None):
        # If there's raw text, hash that.

        # This code block used to just be the following:
        #   hash_do_append_tag(hash_ctx, ASN_TEXT)
        #   hash_do_append_string(hash_ctx, node.text.strip())
        # though that only works with text nodes < 0x7fff.
        # While I doubt we'll ever encounter text nodes larger than 32k in
        # this application, I want to implement the spec correctly.
        # So there's a loop going over the text, hashing 32k chunks.

        text = node.text.strip()
        textlen = len(text)
        if textlen > 0:
            done = 0
            remaining = 0
            while True: 
                remaining = textlen - done
                if remaining > 0x7fff:
                    print("Warning: Hashing text node larger than 32k.")
                    print("This usually doesn't happen, and I'm not sure if this is implemented correctly.")
                    print("If you run into issues, please open a bug report.")
                    remaining = 0x7fff

                hash_do_append_tag(hash_ctx, ASN_TEXT)
                hash_do_append_string(hash_ctx, text[done:done+remaining]) 

                done += remaining
                if done >= textlen:
                    break

    for child in node: 
        # If there's child nodes, hash these as well.
        hash_node_ctx(child, hash_ctx)



    hash_do_append_tag(hash_ctx, ASN_END_TAG)



def hash_do_append_string(hash_ctx, string: str):

    str_bytes = bytes(string, encoding="utf-8")

    length = len(str_bytes)
    len_upper = int(length / 256)
    len_lower = int(length & 0xFF)

    hash_do_append_raw_bytes(hash_ctx, [len_upper, len_lower])
    hash_do_append_raw_bytes(hash_ctx, str_bytes)

def hash_do_append_tag(hash_ctx, tag: int):

    if (tag > 5):
        return
    
    hash_do_append_raw_bytes(hash_ctx, [tag])

def hash_do_append_raw_bytes(hash_ctx, data: bytes):
    hash_ctx.update(bytearray(data))