osi-tools/pacman-choices

#!/usr/bin/env python3
# Copyright (C) 2023  Umorpha Systems
# SPDX-License-Identifier: AGPL-3.0-or-later

from typing import Callable, Literal, NamedTuple, Optional, TypeAlias, cast

import pyalpm
from pycman import config

__version__ = "20231024"

################################################################################

# pyalpm doesn't expose the alpm_find_dbs_satisfier() function, so we
# replicate it here.  Refer to deps.c in pacman.git.

alpm_depmod_t: TypeAlias = Literal[None, "<", "<=", "=", ">=", ">"]


class alpm_depend_t(NamedTuple):
    name: str
    version: Optional[str]
    desc: Optional[str]
    mod: alpm_depmod_t

    def vercmp(self, ver: str) -> bool:
        if self.mod is None:
            return True
        assert self.version
        if self.mod == "<":
            return pyalpm.vercmp(ver, self.version) < 0
        elif self.mod == "<=":
            return pyalpm.vercmp(ver, self.version) <= 0
        elif self.mod == "=":
            return pyalpm.vercmp(ver, self.version) == 0
        elif self.mod == ">=":
            return pyalpm.vercmp(ver, self.version) >= 0
        elif self.mod == ">":
            return pyalpm.vercmp(ver, self.version) > 0

    def _depcmp_literal(self, pkg: pyalpm.Package) -> bool:
        return pkg.name == self.name and self.vercmp(pkg.version)

    def _depcmp_provides(self, pkg: pyalpm.Package) -> bool:
        for pvdstring in pkg.provides:
            pvd = alpm_dep_from_string(pvdstring)
            if self.mod is None:
                if pvd.name == self.name:
                    return True
            else:
                if (
                    pvd.version is not None
                    and pvd.name == self.name
                    and self.vercmp(pvd.version)
                ):
                    return True
        return False

    def depcmp(self, pkg: pyalpm.Package) -> bool:
        return self._depcmp_literal(pkg) or self._depcmp_provides(pkg)


def alpm_dep_from_string(depstring: str) -> alpm_depend_t:
    desc: Optional[str] = None
    if (idx := depstring.find(": ")) >= 0:
        desc = depstring[idx + 2 :]
        depstring = depstring[:idx]

    mod: alpm_depmod_t = None
    ver: Optional[str] = None
    if (idx := depstring.find("<")) >= 0:
        if depstring[idx + 1 :].startswith("="):
            mod = cast(alpm_depmod_t, depstring[idx : idx + 2])
            ver = depstring[idx + 2 :]
        else:
            mod = cast(alpm_depmod_t, depstring[idx : idx + 1])
            ver = depstring[idx + 1 :]
        depstring = depstring[:idx]
    elif (idx := depstring.find(">")) >= 0:
        if depstring[idx + 1 :].startswith("="):
            mod = cast(alpm_depmod_t, depstring[idx : idx + 2])
            ver = depstring[idx + 2 :]
        else:
            mod = cast(alpm_depmod_t, depstring[idx : idx + 1])
            ver = depstring[idx + 1 :]
        depstring = depstring[:idx]
    elif (idx := depstring.find("=")) >= 0:
        mod = cast(alpm_depmod_t, depstring[idx : idx + 1])
        ver = depstring[idx + 1 :]
        depstring = depstring[:idx]

    return alpm_depend_t(
        name=depstring,
        version=ver,
        desc=desc,
        mod=mod,
    )


def alpm_find_dbs_satisfier(
    handle: pyalpm.Handle,
    dbs: list[pyalpm.DB],
    depstring: str,
    questioncb: Callable[[list[pyalpm.Package]], Optional[pyalpm.Package]],
) -> Optional[pyalpm.Package]:
    # BUG(lukeshu): alpm_find_dbs_satisfier doesn't bother to
    # replicate the 'nodepversion' transaction option nor the
    # 'ignorepkgs' and 'ignoregrps' config lists.
    dep = alpm_dep_from_string(depstring)

    # Literal
    for db in dbs:
        pkg = db.get_pkg(dep.name)
        if pkg and dep._depcmp_literal(pkg):
            return pkg

    # Provides
    providers: list[pyalpm.Package] = []
    for db in dbs:
        for pkg in db.pkgcache:
            if pkg.name != dep.name and dep._depcmp_provides(pkg):
                providers.append(pkg)

    if len(providers) == 0:
        return None
    if len(providers) == 1:
        return providers[0]
    return questioncb(providers)


################################################################################


def get_all_questions(handle: pyalpm.Handle) -> dict[str, list[pyalpm.Package]]:
    questions: dict[str, list[pyalpm.Package]] = dict()
    by_name: dict[str, list[pyalpm.Package]] = dict()

    def insert(name: str, pkg: pyalpm.Package) -> None:
        nonlocal by_name
        if name not in by_name:
            by_name[name] = []
        if pkg not in by_name[name]:
            by_name[name].append(pkg)

    for db in handle.get_syncdbs():
        for pkg in db.pkgcache:
            insert(pkg.name, pkg)
            for pvdstring in pkg.provides:
                pvd = alpm_dep_from_string(pvdstring)
                insert(pvd.name, pkg)

    for name, pkgs in by_name.items():
        if len(pkgs) < 2 or name.endswith(".so"):
            continue
        if not any(pkg.name == name for pkg in pkgs):
            questions[name] = pkgs
    return questions


def get_questions(
    handle: pyalpm.Handle, targets: list[str]
) -> dict[str, list[pyalpm.Package]]:
    questions: dict[str, list[pyalpm.Package]] = dict()
    done: set[str] = set()
    for target in targets:
        if target in done:
            continue

        providers: Optional[list[pyalpm.Package]] = None

        target_dep = alpm_dep_from_string(target)

        def questioncb(opts: list[pyalpm.Package]) -> Optional[pyalpm.Package]:
            nonlocal providers
            if target_dep.name.endswith(".so"):
                return opts[0]
            else:
                providers = opts
                return None

        satisfier = alpm_find_dbs_satisfier(
            handle, handle.get_syncdbs(), target, questioncb
        )

        if providers:
            questions[target] = providers
        if satisfier:
            targets += satisfier.depends
        done.add(target)

    return questions


def main() -> None:
    parser = config.make_parser(
        prog="pacman-choices",
        description="""Show package choices that pacman would consider
            when when asked to install `targets`.  This does NOT take
            in to account when pacman would automatically decide the
            answer based on other items in the package list or what's
            already installed; it presents these questions even though
            pacman would hide them.""",
    )
    parser.add_argument(
        "-V",
        "--version",
        action="version",
        version=f"%(prog)s (osi-tools) {__version__}",
    )

    parser.add_argument(
        "--all",
        action="store_true",
        help="show all possible questions, not just the ones in the target list",
    )
    parser.add_argument(
        "--oneline",
        action="store_true",
        help="show each question on one line, rather than in a multi-line format",
    )
    parser.add_argument("targets", nargs="*")

    args = parser.parse_args()
    handle = config.init_with_config_and_options(args)

    questions: dict[str, list[pyalpm.Package]]
    if args.all:
        questions = get_all_questions(handle)
    else:
        questions = get_questions(handle, args.targets)

    sep = " " if args.oneline else "\n\t"
    for target, options in sorted(questions.items()):
        text = target + ":"
        for option in options:
            assert option.db
            text += sep + option.db.name + "/" + option.name
        print(text)


if __name__ == "__main__":
    main()