#!/usr/bin/python
# Copyright 2021 The ANGLE Project Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
#
# create_mtl_internal_shaders.py:
#   Script to compile a metalLib into NSData, for including the compilded
#       library in the ANGLE dylib.

import os
import sys
import json
from datetime import datetime

sys.path.append('../..')

template_header_boilerplate = """// GENERATED FILE - DO NOT EDIT.
// Generated by {script_name}
//
// Copyright {copyright_year} The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
"""


# Convert content of a file to byte array and store in a header file.
# variable_name: name of C++ variable that will hold the file content as byte array.
# filename: the file whose content will be converted to C++ byte array.
# dest_src_file: destination header file that will contain the byte array.
def append_file_as_byte_array_string(variable_name, filename, dest_src_file):
    string = '// Generated from {0}:\n'.format(filename)
    string += 'constexpr uint8_t {0}[]={{\n'.format(variable_name)
    bytes_ = open(filename, "rb").read()
    for byte in bytes_:
        string += '0x{:02x}'.format(ord(byte)) + ", "
    string += "\n};\n"
    with open(dest_src_file, "a") as out_file:
        out_file.write(string)
        


# Compile metal shader.
# compiled_file: The compiled metallib
# variable_name: name of C++ variable that will hold the compiled binary data as a C array.
# additional_flags: additional shader compiler flags
# src_files: metal source files
def gen_precompiled_shaders(compiled_file, variable_name, output_file):
    append_file_as_byte_array_string(variable_name,
                                     compiled_file,
                                     output_file)
    os.system('echo "constexpr size_t {0}_len=sizeof({0});" >> \"{1}\"'
              .format(variable_name, output_file))

def main():
    input_file = sys.argv[1]
    output_file = sys.argv[2]
    os.chdir(sys.path[0])
    
    boilerplate_code = template_header_boilerplate.format(
        script_name=sys.argv[0], copyright_year=datetime.today().year)

    # -------- Compile shaders -----------
    # boiler plate code
    os.system("echo \"{0}\" > \"{1}\"".format(boilerplate_code, output_file))
    os.system(
        'echo "// Compiled binary for Metal default shaders.\n\n" >>  \"{0}\"'.format(output_file)
    )
    os.system('echo "#include <TargetConditionals.h>\n\n" >>  \"{0}\"'.format(output_file))

    os.system('echo "// clang-format off" >> \"{0}\"'.format(output_file))
    
    gen_precompiled_shaders(input_file, 'gMetalBinaryShaders', output_file)

    os.system('echo "// clang-format on" >> \"{0}\"'.format(output_file))


if __name__ == '__main__':
    sys.exit(main())
