#!/usr/bin/env fuchsia-vendored-python
# Copyright 2019 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Preprocess and clang-format a single GLSL shader script."""

import argparse
import os
import subprocess
import sys


def _Panic(msg):
    sys.stderr.write("ERROR: %s\n" % msg)
    sys.exit(1)


def main(argv):
    parser = argparse.ArgumentParser(description=__doc__)

    parser.add_argument(
        "--glslangValidator-tool",
        default="glslangValidator",
        help="Use specific glslangValidator tool path.",
    )

    parser.add_argument(
        "--clang-format-tool",
        default="clang-format",
        help="Use specific clang-format tool path.",
    )

    parser.add_argument(
        "-I",
        "--include-dir",
        action="append",
        default=[],
        help="Include directory used during pre-processing",
    )

    parser.add_argument(
        "-D", "--defines", action="append", default=[], help="GLSL defines"
    )

    parser.add_argument(
        "-o", "--output", default="-", help="Output path, use - for stdout."
    )

    parser.add_argument("input", help="Input GLSL shader script path.")

    args = parser.parse_args()

    cmd_args = [args.glslangValidator_tool, "-E", args.input]

    # For some reason, this is defined when compiling, but not pre-processing!
    cmd_args += ["-DVULKAN"]

    for include_dir in args.include_dir:
        cmd_args.append("-I%s" % include_dir)

    for define in args.defines:
        cmd_args.append("-D%s" % define)

    try:
        preprocessed_script = subprocess.check_output(cmd_args)
    except subprocess.CalledProcessError as e:
        _Panic("Preprocessing error: %s" % e)

    try:
        p = subprocess.Popen(
            [args.clang_format_tool, "--style=Chromium"],
            stdin=subprocess.PIPE,
            stdout=subprocess.PIPE,
        )
        formatted_script, _ = p.communicate(preprocessed_script)
    except subprocess.CalledProcessError as e:
        _Panic("Formatting error: %s" % e)

    out = sys.stdout if args.output == "-" else open(args.output, "wb")
    out.write(formatted_script)
    out.close()

    sys.exit(0)


if __name__ == "__main__":
    main(sys.argv)