# -*- coding: utf-8 -*-
#
# Source: https://forum.openwrt.org/viewtopic.php?pid=183315#p183315

from __future__ import division #1/2 = float, 1//2 = integer, python 3.0 behaviour in 2.6, to make future port to 3 easier.
from __future__ import print_function
from optparse import OptionParser
import os
import struct
import sys
import zlib

debug = False
if not debug:
	import serial

# The maximum size to transfer if we can determinate the size of the file (if input data comes from stdin).
MAX_SIZE = 2 ** 30
LINE_FEED = "\n"

# Wait for the prompt
def getprompt(ser, addr, verbose):
	# Send a command who does not produce a result so when receiving the next line feed, only show the prompt will be returned
	prompt = "mw {0:08x} 0".format(addr) + LINE_FEED
	ser.write(prompt.encode())
	# Flushing read buffer
	while ser.read(256).decode():
		pass
	if verbose:
		print("Waiting for a prompt...", file = sys.stderr)
	while True:
		# Write carriage return and wait for a response
		ser.write(LINE_FEED.encode())
		# Read the response
		buf = ser.read(256).decode()
		if (buf.endswith("# ") or buf.endswith("=> ")):
			if verbose:
				print("Ok, prompt is '", buf, "'", sep='', file = sys.stderr)
			# The prompt returned starts with a line feed. This is the echo of the line feed we send to get the prompt.
			# We keep this linefeed
			return buf
		else:
			# Flush read buffer
			while ser.read(256).decode():
				pass

# Wait for the prompt and return True if received or False otherwise
def writecommand(ser, command, prompt, verbose):
	# Write the command and a line feed, so we must get back the command and the prompt
	ser.write(command.encode())
	ser.write(LINE_FEED.encode())

	buf = ser.read(len(command)).decode()
	if (buf != command):
		if verbose:
			print("Echo command not received. Instead received '", buf, "'", sep='', file = sys.stderr)
		return False

	if verbose:
		print("Waiting for prompt...", file = sys.stderr)

	buf = ser.read(len(prompt)).decode()
	if (buf == prompt):
		if verbose:
			print("Ok, prompt received", file = sys.stderr)
		return True
	else:
		if verbose:
			print("Prompt not received. Instead received '", buf, "'", sep='', file = sys.stderr)
		return False

def memwrite(ser, path, size, start_addr, verbose, debug):
	if not debug:
		prompt = getprompt(ser, start_addr, verbose)

	if (path == "-"):
		fd = sys.stdin
		if (size <= 0):
			size = MAX_SIZE
	else:
		fd = open(path,"rb")
		if (size <= 0):
			# Get the size of the file
			fd.seek(0, os.SEEK_END)
			size = fd.tell()
			fd.seek(0, os.SEEK_SET)

	addr = start_addr
	bytes_read = 0
	crc32_checksum = 0
	while (bytes_read < size):
		if ((size - bytes_read) > 4):
			read_bytes = fd.read(4)
		else:
			read_bytes = fd.read(size - bytes_read)

		if (len(read_bytes) == 0):
			if (path == "-"):
				size = bytes_read
			break

		bytes_read += len(read_bytes)
		crc32_checksum = zlib.crc32(read_bytes, crc32_checksum) & 0xFFFFFFFF

		while (len(read_bytes) < 4):
			read_bytes += b'\x00'

		(val, ) = struct.unpack(">L", read_bytes)
		read_bytes = "".format(val)

		str_to_write = "mw {0:08x} {1:08x}".format(addr, val)
		if verbose:
			print("Writing:", str_to_write, "at:", "0x{0:08x}".format(addr), file = sys.stderr)

		if debug:
			str_to_write = struct.pack(">L", int("{0:08x}".format(val), 16))
		else:
			if not writecommand(ser, str_to_write, prompt, verbose):
				print("Found an error, so aborting", file = sys.stderr)
				return

		# Increment address
		addr += 4

	if (bytes_read != size):
		print("Error while reading file '", fd.name, "' at offset ", bytes_read, sep='', file = sys.stderr)
	else:
		print("File successfully written. You should run command 'crc32", " {0:08x}".format(start_addr), " {0:08x}".format(bytes_read), "' on the modem and the result must be", " {0:08x}".format(crc32_checksum), ".", sep='', file = sys.stderr)

	fd.close()
	return

def main():
	optparser = OptionParser("usage: %prog [options]", version = "%prog 0.1")
	optparser.add_option("--verbose", action = "store_true", dest = "verbose", help = "be verbose", default = False)
	optparser.add_option("--serial", dest = "serial", help = "specify serial port", default = "/dev/ttyUSB0", metavar = "dev")
	optparser.add_option("--write", dest = "write", help = "write mem from file", metavar = "path")
	optparser.add_option("--addr", dest = "addr", help = "mem address", default = "0x81000000", metavar = "addr")
	optparser.add_option("--size", dest = "size", help = "# bytes to write", default = "0", metavar = "size")
	(options, args) = optparser.parse_args()
	if (len(args) != 0):
		optparser.error("incorrect number of arguments")

	if not debug:
		ser = serial.Serial(options.serial, 115200, timeout=1)
	else:
		ser = open(options.write + ".out", "wb")

	if debug:
		prompt = getprompt(ser, options.verbose)
		command = "mw {0:08x} 01234567".format(options.addr)
		writecommand(ser, command, prompt, options.verbose)
		buf = ser.read(256).decode()
		print("buf = '", buf, "'", sep = "")
		return

	if options.write:
		memwrite(ser, options.write, int(options.size, 0), int(options.addr, 0), options.verbose, debug)
	return

if __name__ == '__main__':
	main()