ENH Use dist-info + `importlib.metadata` to store and retrieve package metadata. This switches to using the file system to store the information about packages
and using `importlib.metadata` to retrieve it.
This has two related benefits:

1. We don't have to separately maintain our own separate state about what
we've installed.

2. We are guaranteed to agree with the Python stdlib about whether or not a
package is installed, and if so which version is installed. Since the state is 
maintained in only one place, there is no chance of it diverging.

According to the packaging specs, if the package is from a url we should put 
that into a file here:
https://packaging.python.org/en/latest/specifications/direct-url/#direct-url
Other than that, we should set the `INSTALLER` to `pyodide.loadPackage` 
if the package was loaded with `pyodide.loadPackage` either directly or 
indirectly via `micropip`. Otherwise set `INSTALLER` to `micropip`. That
way we can maintain the current behavior of `micropip.list`:
1. if `direct_url.json` is present, then `source` is the url in `direct_url.json`
2. otherwise, set `source` to `pyodide` if `INSTALLER` is `pyodide.loadPackage`
and set it to `micropip` if `INSTALLER` is `micropip`.

Oddly enough, the packaging specs suggest no place to put the source
index, so it seems that according to the specs if a package was installed
by name from some custom index, this info should not be recorded.

### Checklists

- [x] Add a [CHANGELOG](https://github.com/pyodide/pyodide/blob/main/docs/project/changelog.md) entry
- [x] Add / update tests

from dataclasses import dataclass

import pytest

from pyodide_build.pywasmcross import handle_command_generate_args  # noqa: E402
from pyodide_build.pywasmcross import replay_f2c  # noqa: E402
from pyodide_build.pywasmcross import environment_substitute_args


@dataclass
class BuildArgs:
    """An object to hold build arguments"""

    cflags: str = ""
    cxxflags: str = ""
    ldflags: str = ""
    replace_libs: str = ""
    host_install_dir: str = ""
    target_install_dir: str = ""
    pythoninclude: str = "python/include"


def _args_wrapper(func):
    """Convert function to take as input / return a string instead of a
    list of arguments

    Also sets dryrun=True
    """

    def _inner(line, *pargs):
        args = line.split()
        res = func(args, *pargs, dryrun=True)
        if hasattr(res, "__len__"):
            return " ".join(res)
        else:
            return res

    return _inner


f2c_wrap = _args_wrapper(replay_f2c)


def generate_args(line: str, args, is_link_cmd=False) -> str:
    splitline = line.split()
    res = handle_command_generate_args(splitline, args, is_link_cmd)
    for arg in [
        "-Werror=implicit-function-declaration",
        "-Werror=mismatched-parameter-types",
        "-Werror=return-type",
    ]:
        assert arg in res
        res.remove(arg)
    if "-c" in splitline:
        include_index = res.index("python/include")
        del res[include_index]
        del res[include_index - 1]

    if is_link_cmd:
        arg = "-Wl,--fatal-warnings"
        assert arg in res
        res.remove(arg)
    return " ".join(res)


def test_handle_command():
    args = BuildArgs()
    assert handle_command_generate_args(["gcc", "-print-multiarch"], args, True) == [  # type: ignore[arg-type]
        "echo",
        "wasm32-emscripten",
    ]
    assert generate_args("gcc test.c", args) == "emcc test.c"
    assert (
        generate_args("gcc -shared -c test.o -o test.so", args, True)
        == "emcc -c test.o -o test.so"
    )

    # check cxxflags injection and cpp detection
    args = BuildArgs(
        cflags="-I./lib2",
        cxxflags="-std=c++11",
        ldflags="-lm",
    )
    assert (
        generate_args("gcc -I./lib1 -c test.cpp -o test.o", args)
        == "em++ -I./lib2 -std=c++11 -I./lib1 -c test.cpp -o test.o"
    )

    # check ldflags injection
    args = BuildArgs(
        cflags="",
        cxxflags="",
        ldflags="-lm",
        host_install_dir="",
        replace_libs="",
        target_install_dir="",
    )
    assert (
        generate_args("gcc -shared -c test.o -o test.so", args, True)
        == "emcc -lm -c test.o -o test.so"
    )

    # check library replacement and removal of double libraries
    args = BuildArgs(
        replace_libs="bob=fred",
    )
    assert (
        generate_args("gcc -shared test.o -lbob -ljim -ljim -o test.so", args)
        == "emcc test.o -lfred -ljim -o test.so"
    )


def test_handle_command_ldflags():
    # Make sure to remove unsupported link flags for wasm-ld

    args = BuildArgs()
    assert (
        generate_args(
            "gcc -Wl,--strip-all,--as-needed -Wl,--sort-common,-z,now,-Bsymbolic-functions -shared -c test.o -o test.so",
            args,
            True,
        )
        == "emcc -Wl,-z,now -c test.o -o test.so"
    )


@pytest.mark.parametrize(
    "in_ext, out_ext, executable, flag_name",
    [
        (".c", ".o", "emcc", "cflags"),
        (".cpp", ".o", "em++", "cxxflags"),
        (".c", ".so", "emcc", "ldflags"),
    ],
)
def test_handle_command_optflags(in_ext, out_ext, executable, flag_name):
    # Make sure that when multiple optflags are present those in cflags,
    # cxxflags, or ldflags has priority

    args = BuildArgs(**{flag_name: "-Oz"})
    assert (
        generate_args(f"gcc -O3 -c test.{in_ext} -o test.{out_ext}", args, True)
        == f"{executable} -Oz -c test.{in_ext} -o test.{out_ext}"
    )


def test_f2c():
    assert f2c_wrap("gfortran test.f") == "gcc test.c"
    assert f2c_wrap("gcc test.c") is None
    assert f2c_wrap("gfortran --version") is None
    assert (
        f2c_wrap("gfortran --shared -c test.o -o test.so")
        == "gcc --shared -c test.o -o test.so"
    )


def test_conda_unsupported_args():
    # Check that compile arguments that are not supported by emcc and are sometimes
    # used in conda are removed.
    args = BuildArgs()
    assert generate_args(
        "gcc -shared -c test.o -B /compiler_compat -o test.so", args
    ) == ("emcc -c test.o -o test.so")

    assert generate_args("gcc -shared -c test.o -Wl,--sysroot=/ -o test.so", args) == (
        "emcc -c test.o -o test.so"
    )


def test_environment_var_substitution(monkeypatch):
    monkeypatch.setenv("PYODIDE_BASE", "pyodide_build_dir")
    monkeypatch.setenv("BOB", "Robert Mc Roberts")
    monkeypatch.setenv("FRED", "Frederick F. Freddertson Esq.")
    monkeypatch.setenv("JIM", "James Ignatius Morrison:Jimmy")
    args = environment_substitute_args(
        {
            "ldflags": '"-l$(PYODIDE_BASE)"',
            "cxxflags": "$(BOB)",
            "cflags": "$(FRED)",
            "replace_libs": "$(JIM)",
        }
    )
    assert (
        args["cflags"] == "Frederick F. Freddertson Esq."
        and args["cxxflags"] == "Robert Mc Roberts"
        and args["ldflags"] == '"-lpyodide_build_dir"'
        and args["replace_libs"] == "James Ignatius Morrison:Jimmy"
    )

from dataclasses import dataclass

import pytest

from pyodide_build.pywasmcross import handle_command_generate_args  # noqa: E402
from pyodide_build.pywasmcross import replay_f2c  # noqa: E402
from pyodide_build.pywasmcross import environment_substitute_args


@dataclass
class BuildArgs:
    """An object to hold build arguments"""

    cflags: str = ""
    cxxflags: str = ""
    ldflags: str = ""
    replace_libs: str = ""
    host_install_dir: str = ""
    target_install_dir: str = ""
    pythoninclude: str = "python/include"


def _args_wrapper(func):
    """Convert function to take as input / return a string instead of a
    list of arguments

    Also sets dryrun=True
    """

    def _inner(line, *pargs):
        args = line.split()
        res = func(args, *pargs, dryrun=True)
        if hasattr(res, "__len__"):
            return " ".join(res)
        else:
            return res

    return _inner


f2c_wrap = _args_wrapper(replay_f2c)


def generate_args(line: str, args, is_link_cmd=False) -> str:
    splitline = line.split()
    res = handle_command_generate_args(splitline, args, is_link_cmd)
    for arg in [
        "-Werror=implicit-function-declaration",
        "-Werror=mismatched-parameter-types",
        "-Werror=return-type",
    ]:
        assert arg in res
        res.remove(arg)
    if "-c" in splitline:
        include_index = res.index("python/include")
        del res[include_index]
        del res[include_index - 1]

    if is_link_cmd:
        arg = "-Wl,--fatal-warnings"
        assert arg in res
        res.remove(arg)
    return " ".join(res)


def test_handle_command():
    args = BuildArgs()
    assert handle_command_generate_args(["gcc", "-print-multiarch"], args, True) == [  # type: ignore[arg-type]
        "echo",
        "wasm32-emscripten",
    ]
    assert generate_args("gcc test.c", args) == "emcc test.c"
    assert (
        generate_args("gcc -shared -c test.o -o test.so", args, True)
        == "emcc -c test.o -o test.so"
    )

    # check cxxflags injection and cpp detection
    args = BuildArgs(
        cflags="-I./lib2",
        cxxflags="-std=c++11",
        ldflags="-lm",
    )
    assert (
        generate_args("gcc -I./lib1 -c test.cpp -o test.o", args)
        == "em++ -I./lib2 -std=c++11 -I./lib1 -c test.cpp -o test.o"
    )

    # check ldflags injection
    args = BuildArgs(
        cflags="",
        cxxflags="",
        ldflags="-lm",
        host_install_dir="",
        replace_libs="",
        target_install_dir="",
    )
    assert (
        generate_args("gcc -shared -c test.o -o test.so", args, True)
        == "emcc -lm -c test.o -o test.so"
    )

    # check library replacement and removal of double libraries
    args = BuildArgs(
        replace_libs="bob=fred",
    )
    assert (
        generate_args("gcc -shared test.o -lbob -ljim -ljim -o test.so", args)
        == "emcc test.o -lfred -ljim -o test.so"
    )


def test_handle_command_ldflags():
    # Make sure to remove unsupported link flags for wasm-ld

    args = BuildArgs()
    assert (
        generate_args(
            "gcc -Wl,--strip-all,--as-needed -Wl,--sort-common,-z,now,-Bsymbolic-functions -shared -c test.o -o test.so",
            args,
            True,
        )
        == "emcc -Wl,-z,now -c test.o -o test.so"
    )


@pytest.mark.parametrize(
    "in_ext, out_ext, executable, flag_name",
    [
        (".c", ".o", "emcc", "cflags"),
        (".cpp", ".o", "em++", "cxxflags"),
        (".c", ".so", "emcc", "ldflags"),
    ],
)
def test_handle_command_optflags(in_ext, out_ext, executable, flag_name):
    # Make sure that when multiple optflags are present those in cflags,
    # cxxflags, or ldflags has priority

    args = BuildArgs(**{flag_name: "-Oz"})
    assert (
        generate_args(f"gcc -O3 -c test.{in_ext} -o test.{out_ext}", args, True)
        == f"{executable} -Oz -c test.{in_ext} -o test.{out_ext}"
    )


def test_f2c():
    assert f2c_wrap("gfortran test.f") == "gcc test.c"
    assert f2c_wrap("gcc test.c") is None
    assert f2c_wrap("gfortran --version") is None
    assert (
        f2c_wrap("gfortran --shared -c test.o -o test.so")
        == "gcc --shared -c test.o -o test.so"
    )


def test_conda_unsupported_args():
    # Check that compile arguments that are not supported by emcc and are sometimes
    # used in conda are removed.
    args = BuildArgs()
    assert generate_args(
        "gcc -shared -c test.o -B /compiler_compat -o test.so", args
    ) == ("emcc -c test.o -o test.so")

    assert generate_args("gcc -shared -c test.o -Wl,--sysroot=/ -o test.so", args) == (
        "emcc -c test.o -o test.so"
    )


def test_environment_var_substitution(monkeypatch):
    monkeypatch.setenv("PYODIDE_BASE", "pyodide_build_dir")
    monkeypatch.setenv("BOB", "Robert Mc Roberts")
    monkeypatch.setenv("FRED", "Frederick F. Freddertson Esq.")
    monkeypatch.setenv("JIM", "James Ignatius Morrison:Jimmy")
    args = environment_substitute_args(
        {
            "ldflags": '"-l$(PYODIDE_BASE)"',
            "cxxflags": "$(BOB)",
            "cflags": "$(FRED)",
            "replace_libs": "$(JIM)",
        }
    )
    assert (
        args["cflags"] == "Frederick F. Freddertson Esq."
        and args["cxxflags"] == "Robert Mc Roberts"
        and args["ldflags"] == '"-lpyodide_build_dir"'
        and args["replace_libs"] == "James Ignatius Morrison:Jimmy"
    )
