#!/usr/bin/env python3

import os
import re
import sys
import glob
import json
import time
import fcntl
import struct
import socket
import subprocess
import numpy as np


def eprint(*args, **kargs):
    print(*args, file=sys.stderr, **kargs)


class DeviceUnderTest:
    def __init__(self):
        pass

    def flash(self):
        """
        This method should be overridden to flash the DUT.
        """
        pass

    def dump_ram(self):
        """
        This should be overridden to return the RAM dump as a bytes string.
        """
        return None


class DeviceUnderTestAeadUARTP(DeviceUnderTest):
    def __init__(self, ser=None):
        self.ser = ser
        self.firmware_path = None

    def prepare(self):
        exp_hello = b"Hello, World!"
        hello = self.ser.read(13)

        if hello[-13:] != exp_hello:
            time.sleep(2)
            hello += self.ser.read(self.ser.in_waiting)

        if hello[-13:] != exp_hello:
            raise Exception(
                "Improper board initialization message: %s" % hello)
        self.uartp = UARTP(self.ser)

    def send_var(self, key, value):
        self.uartp.send(struct.pack("B", key) + value)
        ack = self.uartp.recv()
        if len(ack) != 1 or ack[0] != key:
            raise Exception("Unacknowledged variable transfer")

    def obtain_var(self, key):
        c = struct.pack("B", key)
        self.uartp.send(c)
        v = self.uartp.recv()
        if len(v) < 1 or v[0] != key:
            raise Exception("Could not obtain variable from board")
        return v[1:]

    def do_cmd(self, action):
        c = struct.pack("B", action)
        self.uartp.send(c)
        ack = self.uartp.recv()
        if len(ack) != 1 or ack[0] != action:
            raise Exception("Unacknowledged command")


class UARTP:
    def __init__(self, ser):
        UARTP.SYN = 0xf9
        UARTP.FIN = 0xf3
        self.ser = ser

    def uart_read(self):
        r = self.ser.read(1)
        if len(r) != 1:
            raise Exception("Serial read error")
        return r[0]

    def uart_write(self, c):
        b = struct.pack("B", c)
        r = self.ser.write(b)
        if r != len(b):
            raise Exception("Serial write error")
        return r

    def send(self, buf):
        self.uart_write(UARTP.SYN)
        len_ind_0 = 0xff & len(buf)
        len_ind_1 = 0xff & (len(buf) >> 7)
        if len(buf) < 128:
            self.uart_write(len_ind_0)
        else:
            self.uart_write(len_ind_0 | 0x80)
            self.uart_write(len_ind_1)
        fcs = 0
        for i in range(len(buf)):
            info = buf[i]
            fcs = (fcs + info) & 0xff
            self.uart_write(buf[i])
        fcs = (0xff - fcs) & 0xff
        self.uart_write(fcs)
        self.uart_write(UARTP.FIN)
        # eprint("sent frame '%s'" % buf.hex())

    def recv(self):
        tag_old = UARTP.FIN
        while 1:
            tag = tag_old
            while 1:
                if tag_old == UARTP.FIN:
                    if tag == UARTP.SYN:
                        break
                tag_old = tag
                tag = self.uart_read()
            tag_old = tag

            pkt = self.uart_read()
            if pkt & 0x80:
                pkt &= 0x7f
                pkt |= self.uart_read() << 7

            fcs = 0
            buf = []
            for i in range(pkt):
                info = self.uart_read()
                buf.append(info)
                fcs = (fcs + info) & 0xff
            fcs = (fcs + self.uart_read()) & 0xff

            tag = self.uart_read()
            if fcs == 0xff:
                if tag == UARTP.FIN:
                    buf = bytes(buf)
                    # eprint("rcvd frame '%s'" % buf.hex())
                    if len(buf) >= 1 and buf[0] == 0xde:
                        sys.stderr.buffer.write(buf[1:])
                        sys.stderr.flush()
                    else:
                        return buf


def run_nist_aead_test_line(dut, i, m, ad, k, npub, c):
    eprint()
    eprint("Count = %d" % i)
    eprint("   m = %s" % m.hex())
    eprint("  ad = %s" % ad.hex())
    eprint("npub = %s" % npub.hex())
    eprint("   k = %s" % k.hex())
    eprint("   c = %s" % c.hex())

    dut.send_var(ord('c'), b"\0" * (len(m) + 32))
    dut.send_var(ord('s'), b"")

    dut.send_var(ord('m'), m)
    dut.send_var(ord('a'), ad)
    dut.send_var(ord('k'), k)
    dut.send_var(ord('p'), npub)

    dut.do_cmd(ord('e'))
    output = dut.obtain_var(ord('C'))
    print("   c = %s" % output.hex())
    if c != output:
        raise Exception("output of encryption is different from " +
                        "expected ciphertext")

    dut.send_var(ord('m'), b"\0" * len(c))
    dut.send_var(ord('s'), b"")

    dut.send_var(ord('c'), c)
    dut.send_var(ord('a'), ad)
    dut.send_var(ord('k'), k)
    dut.send_var(ord('p'), npub)

    dut.do_cmd(ord('d'))
    output = dut.obtain_var(ord('M'))
    print("   m = %s" % output.hex())
    if m != output:
        raise Exception("output of encryption is different from " +
                        "expected ciphertext")


def parse_nist_aead_test_vectors(test_file_path):
    with open(test_file_path, 'r') as test_file:
        lineprog = re.compile(
            r"^\s*([A-Z]+)\s*=\s*(([0-9a-f])*)\s*$",
            re.IGNORECASE)
        m = b""
        ad = b""
        k = b""
        npub = b""
        c = b""
        i = -1
        for line in test_file.readlines():
            line = line.strip()
            res = lineprog.match(line)
            if line == "":
                yield i, m, ad, k, npub, c
                i = -1
                m = b""
                ad = b""
                k = b""
                npub = b""
                c = b""
            elif res is not None:
                if res[1].lower() == 'count':
                    i = int(res[2], 10)
                elif res[1].lower() == 'key':
                    k = bytes.fromhex(res[2])
                elif res[1].lower() == 'nonce':
                    npub = bytes.fromhex(res[2])
                elif res[1].lower() == 'pt':
                    m = bytes.fromhex(res[2])
                elif res[1].lower() == 'ad':
                    ad = bytes.fromhex(res[2])
                elif res[1].lower() == 'ct':
                    c = bytes.fromhex(res[2])
                else:
                    raise Exception(
                        "ERROR: unparsed line in test vectors file: '%s'"
                        % res)
            else:
                raise Exception(
                    "ERROR: unparsed line in test vectors file: '%s'" % line)

        if i >= 0:
            yield i, m, ad, k, npub, c


class TimeMeasurementTool:
    def begin_measurement(self):
        pass

    def arm(self):
        pass

    def unarm(self):
        pass

    def end_measurement(self):
        pass


class LogicMultiplexerTimeMeasurements(TimeMeasurementTool):

    def __init__(self, mask=0xffffffffffffffff):
        self.mask = mask
        self.sock = None
        self.capture = []

    def recv_samples(self):
        import socket

        capture = []
        while 1:
            try:
                rcvd = self.sock.recv(16)
            except socket.timeout:
                break
            except BlockingIOError:
                break
            if len(rcvd) != 16:
                raise Exception("Could not receive 16 bytes of logic sample!")

            time, value = struct.unpack("<dQ", rcvd)
            eprint("%16.10f: %016x" % (time, value))
            capture.append((time, value))
        return capture

    def begin_measurement(self):
        import socket

        server_addr = os.path.expandvars('$XDG_RUNTIME_DIR/lwc-logic-socket')
        self.sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
        self.sock.settimeout(0)
        self.server_addr = server_addr
        self.sock.connect(self.server_addr)
        self.sock.send(struct.pack("<Q", self.mask))

    def arm(self):
        self.capture.extend(self.recv_samples())

    def unarm(self):
        self.capture.extend(self.recv_samples())

    def end_measurement(self):
        time.sleep(1)
        self.capture.extend(self.recv_samples())
        self.sock.close()


class SaleaeTimeMeasurements(TimeMeasurementTool):
    __slots__ = ['sal']

    def __init__(self, channels=[0, 1]):
        import saleae
        sal = saleae.Saleae()
        sal.set_active_channels(self.channels, [])
        sal.set_sample_rate(sal.get_all_sample_rates()[0])
        sal.set_capture_seconds(6000)
        self.sal = sal

    def begin_measurement(self):
        # Channel 0 is reset
        # Channel 1 is crypto_busy
        import time
        sal = self.sal

        sal.capture_start()
        time.sleep(1)
        if sal.is_processing_complete():
            raise Exception("Capture didn't start successfully")

    def end_measurement(self):
        import time
        sal = self.sal

        if sal.is_processing_complete():
            raise Exception("Capture finished before expected")
        time.sleep(1)
        sal.capture_stop()
        time.sleep(.1)
        for attempt in range(3):
            if not sal.is_processing_complete():
                print("Waiting for capture to complete...")
                time.sleep(1)
                continue
            outfile = "measurement_%s.csv" % time.strftime("%Y%m%d-%H%M%S")
            outfile = os.path.join("measurements", outfile)
            if os.path.isfile(outfile):
                os.unlink(outfile)
            sal.export_data2(os.path.abspath(outfile))
            print("Measurements written to '%s'" % outfile)
            mdbfile = os.path.join("measurements", "measurements.txt")
            mdbfile = open(mdbfile, "a")
            mdbfile.write("%s > %s\n" % (' '.join(sys.argv), outfile))
            mdbfile.close()
            return 0
        raise Exception("Capture didn't complete successfully")


class FileMutex:
    def __init__(self, lock_path):
        self.lock_path = lock_path
        self.locked = False
        self.lock_fd = None
        eprint("Locking %s mutex" % lock_path)
        self.lock_fd = open(lock_path, 'w')
        fcntl.lockf(self.lock_fd, fcntl.LOCK_EX)
        self.locked = True
        print('%d' % os.getpid(), file=self.lock_fd)
        self.lock_fd.flush()
        eprint("%s mutex locked." % lock_path)

    def __del__(self):
        if not self.locked:
            return
        eprint("Releasing %s mutex" % self.lock_path)
        self.lock_fd.close()
        self.locked = False
        eprint("%s mutex released." % self.lock_path)


class OpenOcd:
    def __init__(self, config_file, tcl_port=6666, verbose=False):
        self.verbose = verbose
        self.tclRpcIp = "127.0.0.1"
        self.tclRpcPort = tcl_port
        self.bufferSize = 4096

        self.process = subprocess.Popen([
            'openocd',
            '-f', config_file,
            '-c', 'tcl_port %d' % tcl_port,
            '-c', 'gdb_port disabled',
            '-c', 'telnet_port disabled',
            ], stderr=sys.stderr, stdout=sys.stderr)
        self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        while 1:
            try:
                self.sock.connect((self.tclRpcIp, self.tclRpcPort))
                break
            except Exception:
                time.sleep(.1)

    def __del__(self):
        self.send('exit')
        self.sock.close()
        self.process.kill()
        time.sleep(.1)
        self.process.send_signal(9)

    def send(self, cmd):
        """
        Send a command string to TCL RPC. Return the result that was read.
        """
        data = cmd.encode('ascii')
        if self.verbose:
            print("<- ", data)

        self.sock.send(data + b"\x1a")
        res = self._recv()
        return res

    def _recv(self):
        """
        Read from the stream until the token (\x1a) was received.
        """
        data = b''
        while len(data) < 1 or data[-1] != 0x1a:
            chunk = self.sock.recv(self.bufferSize)
            data += chunk
        data = data[:-1]  # strip trailing \x1a

        if self.verbose:
            print("-> ", data)

        return data.decode('ascii')


def pack_results(job, platform):
    build_dir = job.path

    subprocess.call(
        ['rm', 'results.zip', 'results.json'],
        cwd=build_dir)

    logic_path = os.path.join(build_dir, 'logic_trace.csv')
    logic_trace = []
    with open(logic_path, 'rt') as f:
        f.readline()  # skip header
        for line in f.readlines():
            parts = line.split(',')
            t = float(parts[0].strip())
            v = int(parts[1].strip(), 0)
            logic_trace.append((t, v))

    dips = find_dips(logic_trace)
    dips_durations = [rais-fall for fall, rais in dips]

    ram_dumps = {}
    for dump_path in glob.glob(os.path.join(build_dir, "ram_dump.*.bin")):
        dump_name = os.path.basename(dump_path)
        m = re.match(r"ram_dump.(\d+).bin", dump_name)
        if not m:
            raise Exception("RAM dump has an unexpected name %s" % dump_name)
        idx = int(m[1], 0)
        with open(dump_path, 'rb') as f:
            ram_dumps[idx] = f.read()
    print(list(ram_dumps.keys()))
    if 0 in ram_dumps and 1 in ram_dumps:
        total_memory = len(ram_dumps[0])
        untouched_memory = compare_dumps(ram_dumps[0], ram_dumps[1])
        print("  longest chunk of untouched memory = %d" % untouched_memory)
        memory_utilization = total_memory - untouched_memory
    else:
        memory_utilization = None

    with open(os.path.join(build_dir, 'firmware_size.txt'), 'rt') as f:
        firmware_size = int(f.readline(), 0)

    cipher_family, cipher_variant, cipher_impl = tuple(
        job.cipher.split('.', 2)
    )

    test_vectors_path = os.path.join(build_dir, 'LWC_AEAD_KAT.txt')
    test_vector = identify_test_vector(test_vectors_path)

    results = {
        'format_version': '1.0',
        'test_timestamp': job.time_started,
        'avg_enc_time': np.mean(dips_durations[0::2]),
        'avg_dec_time': np.mean(dips_durations[1::2]),
        'firmware_size': firmware_size,
        'memory_utilization': memory_utilization,
        'cipher': {
            'family': cipher_family,
            'variant': cipher_variant,
            'implementation': cipher_impl,
            'timestamp': job.cipher_timestamp,
        },
        'template': {
            'name': job.template,
            'timestamp': job.template_timestamp,
            'commit': job.template_commit,
        },
        'platform': {
            'name': platform,
        },
        'test_vector': test_vector,
        'dips': dips_durations,
    }

    json_path = os.path.join(build_dir, 'results.json')
    with open(json_path, 'wt') as f:
        json.dump(results, f)

    subprocess.check_call(
        ['zip', '-r', 'results.zip', '.'],
        cwd=build_dir)


def find_dips(logic_trace):
    # There should be an even number of edges (2 edges for each dip)
    assert 0 != len(logic_trace)
    assert 0 == len(logic_trace) % 2
    # First record should be a negative edge, last should be a positive one
    assert 0 == logic_trace[0][1]
    assert 0 != logic_trace[-1][1]
    # Record the start and end times of every dip
    dips = []
    for i in range(0, len(logic_trace), 2):
        assert 0 == logic_trace[i][1]
        assert 0 != logic_trace[i+1][1]
        dips.append((logic_trace[i][0], logic_trace[i+1][0]))

    # Debounce dips by assuming that a data transfer
    # between two dips takes at least 1 microsecond
    THERESHOLD = 1e-6
    debounced = []
    i = 0
    while i < len(dips)-1:
        fall, rais = dips[i]
        next_fall, next_rais = dips[i+1]
        xfer_time = next_fall - rais
        if xfer_time < THERESHOLD:
            # Merge current dip with the next
            dips[i] = (fall, next_rais)
            dips.pop(i+1)
        else:
            # Save current dip
            debounced.append((fall, rais))
            i += 1

    # Add the last dip
    debounced.append((dips[i][0], dips[i][1]))
    dips = debounced

    # There should be an even number of dips (encryption and decryption)
    assert 0 == len(dips) % 2

    return dips


def compare_dumps(dump_a, dump_b):
    """
    Gets the length of the longes streaks of equal bytes in two RAM dumps
    """
    streaks = []
    streak_beg = 0
    streak_end = 0
    for i in range(len(dump_a)):
        if dump_a[i] == dump_b[i]:
            streak_end = i
        else:
            if streak_end != streak_beg:
                streaks.append((streak_beg, streak_end))
            streak_beg = i
            streak_end = i

    for b, e in streaks:
        print(
            "equal bytes from 0x%x to 0x%x (length: %d)" % (b, e, e-b))

    b, e = max(streaks, key=lambda a: a[1]-a[0])
    print(
        "longest equal bytes streak from 0x%x to 0x%x (length: %d)" %
        (b, e, e-b))
    return e-b


def identify_test_vector(kat_path):
    # Check if a provided test vector is the official NIST LWC or not
    kat = list(parse_nist_aead_test_vectors(kat_path))

    def is_nist_aead_kat(kat):
        if len(kat) != 1089:
            return False

        def genstr(length):
            return bytes([b % 256 for b in range(length)])
        expected_k = genstr(len(kat[0][3]))
        expected_npub = genstr(len(kat[0][4]))
        expected_i = 0
        for i, m, ad, k, npub, c in kat:
            expected_m = genstr((i-1) // 33)
            expected_ad = genstr((i-1) % 33)
            expected_i += 1
            if not (expected_i == i and expected_m == m and
                    expected_k == k and expected_ad == ad and
                    expected_npub == npub):
                return False
        return True

    if is_nist_aead_kat(kat):
        return "NIST AEAD KAT"
    return None


def run_nist_lws_aead_test(dut, vectors_file, build_dir,
                           logic_mask=0xffff):
    kat = list(parse_nist_aead_test_vectors(vectors_file))

    firmware_size = dut.firmware_size()
    path = os.path.join(build_dir, 'firmware_size.txt')
    with open(path, 'wt') as f:
        print(firmware_size, file=f)

    dut.flash()
    dut.prepare()
    sys.stdout.write("Board prepared\n")
    sys.stdout.flush()

    ram_dumps = [dut.dump_ram()]

    tool = LogicMultiplexerTimeMeasurements(logic_mask)
    try:
        tool.begin_measurement()

        for i, m, ad, k, npub, c in kat:
            tool.arm()
            run_nist_aead_test_line(dut, i, m, ad, k, npub, c)
            tool.unarm()

            if i == 1 and ram_dumps[0] is not None:
                ram_dumps.append(dut.dump_ram())

    except Exception as ex:
        print("TEST FAILED")
        raise ex

    finally:
        tool.end_measurement()

    for i, d in enumerate(ram_dumps):
        path = os.path.join(build_dir, 'ram_dump.%d.bin' % i)
        if d is not None:
            with open(path, 'wb') as f:
                f.write(d)

    logic_trace = tool.capture
    path = os.path.join(build_dir, 'logic_trace.csv')
    with open(path, 'wt') as f:
        print("TIME,VALUE", file=f)
        for t, v in logic_trace:
            print("%f,0x%x" % (t, v), file=f)