#!/usr/bin/env python3
import sys
import os
import time
import serial
import threading
import argparse
from serial.tools.miniterm import console, character, LF

sfl_magic_len = 14
sfl_magic_req = "sL5DdSMmkekro\n"
sfl_magic_ack = "z6IHG7cYDID6o\n"

# General commands
sfl_cmd_abort = 0x00
sfl_cmd_load = 0x01
sfl_cmd_jump = 0x02

# Replies
sfl_ack_success = 'K'
sfl_ack_crcerror = 'C'
sfl_ack_unknown = 'U'
sfl_ack_error = 'E'

# XXX : can we get CRC16 from a standard Python library as it's done
# for CRC32 with binascii?
crc16_table = [
    0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7,
    0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF,
    0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294, 0x72F7, 0x62D6,
    0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE,
    0x2462, 0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7, 0x44A4, 0x5485,
    0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D,
    0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4,
    0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC,
    0x48C4, 0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823,
    0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948, 0x9969, 0xA90A, 0xB92B,
    0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12,
    0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A,
    0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41,
    0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49,
    0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70,
    0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78,
    0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E, 0xE16F,
    0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067,
    0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E,
    0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256,
    0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D,
    0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
    0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C,
    0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676, 0x4615, 0x5634,
    0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB,
    0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3,
    0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A,
    0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92,
    0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9,
    0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1,
    0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8,
    0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0
]


def crc16(l):
    crc = 0
    for d in l:
        crc = crc16_table[((crc >> 8) ^ d) & 0xff] ^ (crc << 8)
    return crc


class SFLFrame:
    def __init__(self):
        self.length = None
        self.cmd = None
        self.payload = []
        self.crc = None
        self.raw = []

    def compute_crc(self):
        crc_data = []
        crc_data.append(self.cmd)
        for d in self.payload:
            crc_data.append(d)
        self.crc = crc16(crc_data)
        return self.crc

    def encode(self):
        self.raw = []
        self.raw.append(self.length)
        self.compute_crc()
        self.raw.append((self.crc & 0xff00) >> 8)
        self.raw.append(self.crc & 0x00ff)
        self.raw.append(self.cmd)
        for d in self.payload:
            self.raw.append(d)


def get_file_data(filename):
    with open(filename, "rb") as f:
        data = []
        while True:
            w = f.read(1)
            if not w:
                break
            data.append(int.from_bytes(w, "big"))
    return data


class Flterm:
    def __init__(self, kernel_image, kernel_address):
        self.kernel_image = kernel_image
        self.kernel_address = kernel_address

        self.reader_alive = False
        self.writer_alive = False

        self.detect_magic_str = " "*len(sfl_magic_req)

    def open(self, port, speed):
        port = port if not port.isdigit() else int(port)
        self.serial = serial.Serial(port, speed, timeout=0.25)
        self.serial.flushOutput()
        self.serial.flushInput()
        self.serial.close()  # in case port was not correctly closed
        self.serial.open()

    def close(self):
        self.serial.close()

    def write_exact(self, data):
        if isinstance(data, str):
            self.serial.write(bytes(data, "utf-8"))
        else:
            self.serial.write(serial.to_bytes(data))

    def send_frame(self, frame):
        frame.encode()
        retry = 1
        while retry:
            self.write_exact(frame.raw)
            # Get the reply from the device
            reply = character(self.serial.read())
            if reply == sfl_ack_success:
                retry = 0
            elif reply == sfl_ack_crcerror:
                retry = 1
            else:
                print("[FLTERM] Got unknown reply '{}' from the device, aborting.".format(reply))
                return 0
        return 1

    def upload(self, filename, address):
        data = get_file_data(filename)
        print("[FLTERM] Uploading {} ({} bytes)...".format(filename, len(data)))
        current_address = address
        position = 0
        length = len(data)
        start = time.time()
        while len(data) != 0:
            print("{}%\r".format(100*position//length), end="")
            frame = SFLFrame()
            if len(data) > 251:
                frame_data = data[:251]
            frame.length = len(frame_data)+4
            frame.cmd = sfl_cmd_load
            frame.payload.append((current_address & 0xff000000) >> 24)
            frame.payload.append((current_address & 0x00ff0000) >> 16)
            frame.payload.append((current_address & 0x0000ff00) >> 8)
            frame.payload.append((current_address & 0x000000ff) >> 0)
            for d in frame_data:
                frame.payload.append(d)
            if self.send_frame(frame) == 0:
                return
            current_address += len(frame_data)
            position += len(frame_data)
            try:
                data = data[251:]
            except:
                data = []
        end = time.time()
        elapsed = end - start
        print("[FLTERM] Upload complete ({0:.1f}KB/s).".format(length/(elapsed*1024)))
        return length

    def boot(self):
        print("[FLTERM] Booting the device.")
        frame = SFLFrame()
        frame.length = 4
        frame.cmd = sfl_cmd_jump
        frame.payload.append((self.kernel_address & 0xff000000) >> 24)
        frame.payload.append((self.kernel_address & 0x00ff0000) >> 16)
        frame.payload.append((self.kernel_address & 0x0000ff00) >> 8)
        frame.payload.append((self.kernel_address & 0x000000ff) >> 0)
        self.send_frame(frame)

    def detect_magic(self, data):
        if data is not "":
            self.detect_magic_str = self.detect_magic_str[1:] + data
            return self.detect_magic_str == sfl_magic_req
        else:
            return False

    def answer_magic(self):
        print("[FLTERM] Received firmware download request from the device.")
        if os.path.exists(self.kernel_image):
            self.write_exact(sfl_magic_ack)
            self.upload(self.kernel_image, self.kernel_address)
            self.boot()
        print("[FLTERM] Done.");

    def reader(self):
        try:
            while self.reader_alive:
                c = character(self.serial.read())
                if c == '\r':
                    sys.stdout.write('\n')
                else:
                    sys.stdout.write(c)
                sys.stdout.flush()

                if self.kernel_image is not None:
                    if self.detect_magic(c):
                        self.answer_magic()

        except serial.SerialException:
            self.reader_alive = False
            raise

    def start_reader(self):
        self.reader_alive = True
        self.reader_thread = threading.Thread(target=self.reader)
        self.reader_thread.setDaemon(True)
        self.reader_thread.start()

    def stop_reader(self):
        self.reader_alive = False
        self.reader_thread.join()

    def writer(self):
        try:
            while self.writer_alive:
                try:
                    b = console.getkey()
                except KeyboardInterrupt:
                    b = serial.to_bytes([3])
                c = character(b)
                if c == chr(0x03):
                    self.stop()
                elif c == '\n':
                    self.serial.write(LF)
                else:
                    self.serial.write(b)
        except:
            self.writer_alive = False
            raise

    def start_writer(self):
        self.writer_alive = True
        self.writer_thread = threading.Thread(target=self.writer)
        self.writer_thread.setDaemon(True)
        self.writer_thread.start()

    def stop_writer(self):
        self.writer_alive = False
        self.writer_thread.join()

    def start(self):
        print("[FLTERM] Starting....")
        self.start_reader()
        self.start_writer()

    def stop(self):
        self.reader_alive = False
        self.writer_alive = False

    def join(self, writer_only=False):
        self.writer_thread.join()
        if not writer_only:
            self.reader_thread.join()


def _get_args():
    parser = argparse.ArgumentParser()
    parser.add_argument("--port", default="2", help="serial port")
    parser.add_argument("--speed", default=115200, help="serial baudrate")
    parser.add_argument("--kernel", default=None, help="kernel image")
    parser.add_argument("--kernel_adr", default=0x40000000, help="kernel address")
    return parser.parse_args()

if __name__ == "__main__":
    args = _get_args()
    flterm = Flterm(args.kernel, args.kernel_adr)
    flterm.open(args.port, args.speed)
    flterm.start()
    try:
        flterm.join(True)
    except KeyboardInterrupt:
        pass
    flterm.join()