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

# The MIT License (MIT)
#
# Copyright (c) 2016 Peter Hinch
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

import argparse
import sys
import os

# UTILITIES FOR WRITING PYTHON SOURCECODE TO A FILE

# ByteWriter takes as input a variable name and data values and writes
# Python source to an output stream of the form
# my_variable = b'\x01\x02\x03\x04\x05\x06\x07\x08'\

# Lines are broken with \ for readability.


class ByteWriter(object):
    bytes_per_line = 16

    def __init__(self, stream, varname):
        self.stream = stream
        self.stream.write("{} =\\\n".format(varname))
        self.bytecount = 0  # For line breaks

    def _eol(self):
        self.stream.write("'\\\n")

    def _eot(self):
        self.stream.write("'\n")

    def _bol(self):
        self.stream.write("b'")

    # Output a single byte
    def obyte(self, data):
        if not self.bytecount:
            self._bol()
        self.stream.write("\\x{:02x}".format(data))
        self.bytecount += 1
        self.bytecount %= self.bytes_per_line
        if not self.bytecount:
            self._eol()

    # Output from a sequence
    def odata(self, bytelist):
        for byt in bytelist:
            self.obyte(byt)

    # ensure a correct final line
    def eot(self):  # User force EOL if one hasn't occurred
        if self.bytecount:
            self._eot()
        self.stream.write("\n")


# PYTHON FILE WRITING

STR01 = """# Code generated by data_to_py.py.
version = '0.1'
"""

STR02 = """_mvdata = memoryview(_data)

def data():
    return _mvdata

"""


def write_func(stream, name, arg):
    stream.write("def {}():\n    return {}\n\n".format(name, arg))


def write_data(op_path, ip_path):
    try:
        with open(ip_path, "rb") as ip_stream:
            try:
                with open(op_path, "w") as op_stream:
                    write_stream(ip_stream, op_stream)
            except OSError:
                print("Can't open", op_path, "for writing")
                return False
    except OSError:
        print("Can't open", ip_path)
        return False
    return True


def write_stream(ip_stream, op_stream):
    op_stream.write(STR01)
    op_stream.write("\n")
    data = ip_stream.read()
    bw_data = ByteWriter(op_stream, "_data")
    bw_data.odata(data)
    bw_data.eot()
    op_stream.write(STR02)


# PARSE COMMAND LINE ARGUMENTS

def quit(msg):
    print(msg)
    sys.exit(1)


DESC = """data_to_py.py
Utility to convert an arbitrary binary file to Python source.
Sample usage:
data_to_py.py image.jpg image.py

"""

if __name__ == "__main__":
    parser = argparse.ArgumentParser(__file__, description=DESC,
                                     formatter_class=argparse.RawDescriptionHelpFormatter)
    parser.add_argument("infile", type=str, help="Input file path")
    parser.add_argument("outfile", type=str,
                        help="Path and name of output file. Must have .py extension.")

    args = parser.parse_args()

    if not os.path.isfile(args.infile):
        quit("Data filename does not exist")

    if not os.path.splitext(args.outfile)[1].upper() == ".PY":
        quit("Output filename must have a .py extension.")

    print("Writing Python file.")
    if not write_data(args.outfile, args.infile):
        sys.exit(1)

    print(args.outfile, "written successfully.")