# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

import argparse
import os
import re
import sys

import mozpack.path as mozpath
from buildconfig import topobjdir, topsrcdir

from mozbuild.backend.configenvironment import PartialConfigEnvironment


def process_define_file(output, input):
    """Creates the given config header. A config header is generated by
    taking the corresponding source file and replacing some *#define/#undef*
    occurences:

      - "#undef NAME" is turned into "#define NAME VALUE"
      - "#define NAME" is unchanged
      - "#define NAME ORIGINAL_VALUE" is turned into "#define NAME VALUE"
      - "#undef UNKNOWN_NAME" is turned into "/* #undef UNKNOWN_NAME */"
      -  Whitespaces are preserved.

    As a special rule, "#undef ALLDEFINES" is turned into "#define NAME
    VALUE" for all the defined variables.
    """

    path = os.path.abspath(input)

    config = PartialConfigEnvironment(topobjdir)

    if mozpath.basedir(
        path, [mozpath.join(topsrcdir, "js/src")]
    ) and not config.substs.get("JS_STANDALONE"):
        config = PartialConfigEnvironment(mozpath.join(topobjdir, "js", "src"))

    with open(path) as input:
        r = re.compile(
            r"^\s*#\s*(?P<cmd>[a-z]+)(?:\s+(?P<name>\S+)(?:\s+(?P<value>\S+))?)?", re.U
        )
        for l in input:
            m = r.match(l)
            if m:
                cmd = m.group("cmd")
                name = m.group("name")
                value = m.group("value")
                if name:
                    if name == "ALLDEFINES":
                        if cmd == "define":
                            raise Exception(
                                "`#define ALLDEFINES` is not allowed in a "
                                "CONFIGURE_DEFINE_FILE"
                            )

                        def define_for_name(name, val):
                            """WebRTC files like to define WINVER and _WIN32_WINNT
                            via the command line, which raises a mass of macro
                            redefinition warnings.  Just handle those macros
                            specially here."""
                            define = f"#define {name} {val}"
                            if name in ("_WIN32_IE", "_WIN32_WINNT", "WIN32", "WINVER"):
                                return f"#if !defined({name})\n{define}\n#endif"
                            return define

                        defines = "\n".join(
                            sorted(
                                define_for_name(name, val)
                                for name, val in config.defines["ALLDEFINES"].items()
                            )
                        )
                        l = l[: m.start("cmd") - 1] + defines + l[m.end("name") :]
                    elif cmd == "define":
                        if value and name in config.defines:
                            l = (
                                l[: m.start("value")]
                                + str(config.defines[name])
                                + l[m.end("value") :]
                            )
                    elif cmd == "undef":
                        if name in config.defines:
                            l = (
                                l[: m.start("cmd")]
                                + "define"
                                + l[m.end("cmd") : m.end("name")]
                                + " "
                                + str(config.defines[name])
                                + l[m.end("name") :]
                            )
                        else:
                            l = "/* " + l[: m.end("name")] + " */" + l[m.end("name") :]

            output.write(l)

    deps = {path}
    deps.update(config.get_dependencies())
    return deps


def main(argv):
    parser = argparse.ArgumentParser(description="Process define files.")

    parser.add_argument("input", help="Input define file.")

    args = parser.parse_args(argv)

    return process_define_file(sys.stdout, args.input)


if __name__ == "__main__":
    sys.exit(main(sys.argv[1:]))
