#!/usr/bin/python
#
# Copyright (c) 2016, NORDUnet A/S All rights reserved.
#
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#   this list of conditions and the following disclaimer.
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# - Redistributions in binary form must reproduce the above copyright
#   notice, this list of conditions and the following disclaimer in the
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
# IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
# TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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# TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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"""
Utility to test file upload (or FPGA bitstream upload.
"""
import os
import sys
import time
import struct
import serial
import argparse

from binascii import crc32

CHUNK_SIZE = 256
DFU_CHUNK_SIZE = 256
FPGA_CHUNK_SIZE = 4096


def parse_args():
    """
    Parse the command line arguments
    """
    parser = argparse.ArgumentParser(description = "File uploader",
                                     add_help = True,
                                     formatter_class = argparse.ArgumentDefaultsHelpFormatter,
                                     )

    parser.add_argument('--fpga',
                        dest='fpga',
                        action='store_true', default=False,
                        help='Perform FPGA bitstream upload',
                        )
    parser.add_argument('--dfu',
                        dest='dfu',
                        action='store_true', default=False,
                        help='Perform DFU application upload',
                        )

    parser.add_argument('--device',
                        dest='device',
                        default='/dev/ttyUSB0',
                        help='Name of management port USB serial device',
                        )

    # positional argument(s)
    parser.add_argument('filename')

    return parser.parse_args()


def _write(dst, data):
    dst.write(data)
    if len(data) == 4:
        print("Wrote 0x{!s}".format(data.encode('hex')))
    else:
        print("Wrote {!r}".format(data))


def _read(dst):
    res = ''
    while True:
        x = dst.read(1)
        if not x:
            break
        res += x
    print ("Read {!r}".format(res))
    return res


def _execute(dst, cmd):
    _write(dst, '\r')
    prompt = _read(dst)
    if prompt.endswith('Username: '):
        _write(dst, 'ct\r')
        prompt = _read(dst)
    if prompt.endswith('Password: '):
        _write(dst, 'ct\r')
        prompt = _read(dst)
    if not prompt.endswith('> '):
        sys.stderr.write('Device does not seem to be ready for a file transfer (got {!r})\n'.format(prompt))
        return False
    _write(dst, cmd + '\r')
    response = _read(dst)
    return response

def send_file(filename, args, dst):
    s = os.stat(filename)
    size = s.st_size
    src = open(filename, 'rb')
    if args.fpga:
        # Skip header in FPGA bitstream file
        size -= 0x64
        src.read(0x64)
        chunk_size = FPGA_CHUNK_SIZE
        response = _execute(dst, 'fpga bitstream upload')
    elif args.dfu:
        chunk_size = DFU_CHUNK_SIZE
        response = _execute(dst, 'dfu upload')
    else:
        chunk_size = CHUNK_SIZE
        response = _execute(dst, 'filetransfer')
    if 'OK' not in response:
        sys.stderr.write('Device did not accept the upload command (got {!r})\n'.format(response))
        return False

    crc = 0
    counter = 0
    # 1. Write size of file (4 bytes)
    _write(dst, struct.pack('<I', size))
    _read(dst)
    # 2. Write file contents while calculating CRC-32
    while True:
        data = src.read(chunk_size)
        if not data:
            break
        dst.write(data)
        print("Wrote {!s} bytes (chunk {!s}/{!s})".format(len(data), counter, int(size / chunk_size)))
        # read ACK (a counter of number of 4k chunks received)
        while True:
            ack_bytes = dst.read(4)
            if len(ack_bytes) == 4:
                break
            print('ERROR: Did not receive an ACK, got {!r}'.format(ack_bytes))
            dst.write('\r')  # eventually get back to the CLI prompt
        ack = struct.unpack('<I', ack_bytes)[0]
        if ack != counter + 1:
            print('ERROR: Did not receive the expected counter as ACK (got {!r}/{!r}, not {!r})'.format(ack, ack_bytes, counter))
            flush = dst.read(100)
            print('FLUSH data: {!r}'.format(flush))
            return False
        counter += 1

        crc = crc32(data, crc) & 0xffffffff

    _read(dst)

    # 3. Write CRC-32 (4 bytes)
    _write(dst, struct.pack('<I', crc))
    _read(dst)

    src.close()
    return True


def main(args):
    dst = serial.Serial(args.device, 921600, timeout=2)
    send_file(args.filename, args, dst)
    dst.close()
    return True

if __name__ == '__main__':
    try:
        args = parse_args()
        if main(args):
            sys.exit(0)
        sys.exit(1)
    except KeyboardInterrupt:
        pass