# Copyright 2023 The Dawn & Tint Authors
#
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# Adapted from https://source.chromium.org/chromium/chromium/src/+/main:build/win/message_compiler.py;l=7?q=message_compiler.py&ss=chromium

# Runs the Microsoft Message Compiler (mc.exe).
#
# Usage: message_compiler.py <environment_file> [<args to mc.exe>*]

import difflib
import filecmp
import os
import re
import shutil
import subprocess
import sys
import tempfile


def main():
    env_file, rest = sys.argv[1], sys.argv[2:]

    # Parse some argument flags.
    header_dir = None
    resource_dir = None
    input_file = None
    for i, arg in enumerate(rest):
        if arg == '-h' and len(rest) > i + 1:
            assert header_dir == None
            header_dir = rest[i + 1]
        elif arg == '-r' and len(rest) > i + 1:
            assert resource_dir == None
            resource_dir = rest[i + 1]
        elif arg.endswith('.mc') or arg.endswith('.man'):
            assert input_file == None
            input_file = arg

    # Copy checked-in outputs to final location.
    THIS_DIR = os.path.abspath(os.path.dirname(__file__))
    assert header_dir == resource_dir
    # Final destination is in ../win_build_output/mc/<header_dir>.
    source = os.path.join(THIS_DIR, "..", "win_build_output",
                          re.sub(r'.*gn/dxc/', 'mc/', header_dir))
    # If these are new files, create the source directory. The diff will fail later to let
    # the user know what files to copy.
    os.makedirs(source, exist_ok=True)
    # Set copy_function to shutil.copy to update the timestamp on the destination.
    shutil.copytree(source,
                    header_dir,
                    copy_function=shutil.copy,
                    dirs_exist_ok=True)

    # On non-Windows, that's all we can do.
    if sys.platform != 'win32':
        return

    # On Windows, run mc.exe on the input and check that its outputs are
    # identical to the checked-in outputs.

    # Read the environment block from the file. This is stored in the format used
    # by CreateProcess. Drop last 2 NULs, one for list terminator, one for
    # trailing vs. separator.
    env_pairs = open(env_file).read()[:-2].split('\0')
    env_dict = dict([item.split('=', 1) for item in env_pairs])

    extension = os.path.splitext(input_file)[1]

    # mc writes to stderr, so this explicitly redirects to stdout and eats it.
    try:
        tmp_dir = tempfile.mkdtemp()
        delete_tmp_dir = True
        if header_dir:
            rest[rest.index('-h') + 1] = tmp_dir
            header_dir = tmp_dir
        if resource_dir:
            rest[rest.index('-r') + 1] = tmp_dir
            resource_dir = tmp_dir

        # This needs shell=True to search the path in env_dict for the mc
        # executable.
        subprocess.check_output(['mc.exe'] + rest,
                                env=env_dict,
                                stderr=subprocess.STDOUT,
                                shell=True)
        # We require all source code (in particular, the header generated here) to
        # be UTF-8. jinja can output the intermediate .mc file in UTF-8 or UTF-16LE.
        # However, mc.exe only supports Unicode via the -u flag, and it assumes when
        # that is specified that the input is UTF-16LE (and errors out on UTF-8
        # files, assuming they're ANSI). Even with -u specified and UTF16-LE input,
        # it generates an ANSI header, and includes broken versions of the message
        # text in the comment before the value. To work around this, for any invalid
        # // comment lines, we simply drop the line in the header after building it.
        # Also, mc.exe apparently doesn't always write #define lines in
        # deterministic order, so manually sort each block of #defines.
        if header_dir:
            header_file = os.path.join(
                header_dir,
                os.path.splitext(os.path.basename(input_file))[0] + '.h')
            header_contents = []
            with open(header_file, 'r') as f:
                define_block = []  # The current contiguous block of #defines.
                for line in f.readlines():
                    if line.startswith('//') and '?' in line:
                        continue
                    if line.startswith('#define '):
                        define_block.append(line)
                        continue
                    # On the first non-#define line, emit the sorted preceding #define
                    # block.
                    header_contents += sorted(define_block,
                                              key=lambda s: s.split()[-1])
                    define_block = []
                    header_contents.append(line)
                # If the .h file ends with a #define block, flush the final block.
                header_contents += sorted(define_block,
                                          key=lambda s: s.split()[-1])
            with open(header_file, 'w') as f:
                f.write(''.join(header_contents))

        # mc.exe invocation and post-processing are complete, now compare the output
        # in tmp_dir to the checked-in outputs.
        diff = filecmp.dircmp(tmp_dir, source)
        if diff.diff_files or set(diff.left_list) != set(diff.right_list):
            print('mc.exe output different from files in %s, see %s' %
                  (source, tmp_dir))
            diff.report()
            for f in diff.diff_files:
                if f.endswith('.bin'): continue
                fromfile = os.path.join(source, f)
                tofile = os.path.join(tmp_dir, f)
                print(''.join(
                    difflib.unified_diff(
                        open(fromfile).readlines(),
                        open(tofile).readlines(), fromfile, tofile)))
            delete_tmp_dir = False
            sys.exit(1)
    except subprocess.CalledProcessError as e:
        print(e.output)
        sys.exit(e.returncode)
    finally:
        if os.path.exists(tmp_dir) and delete_tmp_dir:
            shutil.rmtree(tmp_dir)


if __name__ == '__main__':
    main()