# Copyright 2007-2020 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2

from portage.dep import Atom, ExtendedAtomDict, best_match_to_list, match_from_list
from portage.exception import InvalidAtom
from portage.versions import cpv_getkey


OPERATIONS = ["merge", "unmerge"]


class PackageSet:
    # Set this to operations that are supported by your subclass. While
    # technically there is no difference between "merge" and "unmerge" regarding
    # package sets, the latter doesn't make sense for some sets like "system"
    # or "security" and therefore isn't supported by them.
    _operations = ["merge"]
    description = "generic package set"

    def __init__(self, allow_wildcard=False, allow_repo=False):
        self._atoms = set()
        self._atommap = ExtendedAtomDict(set)
        self._loaded = False
        self._loading = False
        self.errors = []
        self._nonatoms = set()
        self.world_candidate = False
        self._allow_wildcard = allow_wildcard
        self._allow_repo = allow_repo

    def __contains__(self, atom):
        self._load()
        return atom in self._atoms or atom in self._nonatoms

    def __iter__(self):
        self._load()
        yield from self._atoms
        yield from self._nonatoms

    def __bool__(self):
        self._load()
        return bool(self._atoms or self._nonatoms)

    def supportsOperation(self, op):
        if not op in OPERATIONS:
            raise ValueError(op)
        return op in self._operations

    def _load(self):
        if not (self._loaded or self._loading):
            self._loading = True
            self.load()
            self._loaded = True
            self._loading = False

    def getAtoms(self):
        self._load()
        return self._atoms.copy()

    def getNonAtoms(self):
        self._load()
        return self._nonatoms.copy()

    def _setAtoms(self, atoms):
        self._atoms.clear()
        self._nonatoms.clear()
        for a in atoms:
            if not isinstance(a, Atom):
                if isinstance(a, str):
                    a = a.strip()
                if not a:
                    continue
                try:
                    a = Atom(a, allow_wildcard=True, allow_repo=True)
                except InvalidAtom:
                    self._nonatoms.add(a)
                    continue
            if not self._allow_wildcard and a.extended_syntax:
                raise InvalidAtom("extended atom syntax not allowed here")
            if not self._allow_repo and a.repo:
                raise InvalidAtom("repository specification not allowed here")
            self._atoms.add(a)

        self._updateAtomMap()

    def load(self):
        # This method must be overwritten by subclasses
        # Editable sets should use the value of self._mtime to determine if they
        # need to reload themselves
        raise NotImplementedError()

    def containsCPV(self, cpv):
        self._load()
        for a in self._atoms:
            if match_from_list(a, [cpv]):
                return True
        return False

    def getMetadata(self, key):
        if hasattr(self, key.lower()):
            return getattr(self, key.lower())
        return ""

    def _updateAtomMap(self, atoms=None):
        """Update self._atommap for specific atoms or all atoms."""
        if not atoms:
            self._atommap.clear()
            atoms = self._atoms
        for a in atoms:
            self._atommap.setdefault(a.cp, set()).add(a)

    # Not sure if this one should really be in PackageSet
    def findAtomForPackage(self, pkg, modified_use=None):
        """Return the best match for a given package from the arguments, or
        None if there are no matches.  This matches virtual arguments against
        the PROVIDE metadata.  This can raise an InvalidDependString exception
        if an error occurs while parsing PROVIDE."""

        if modified_use is not None and modified_use is not pkg.use.enabled:
            pkg = pkg.copy()
            pkg._metadata["USE"] = " ".join(modified_use)

        # Atoms matched via PROVIDE must be temporarily transformed since
        # match_from_list() only works correctly when atom.cp == pkg.cp.
        rev_transform = {}
        for atom in self.iterAtomsForPackage(pkg):
            if atom.cp == pkg.cp:
                rev_transform[atom] = atom
            else:
                rev_transform[
                    Atom(
                        atom.replace(atom.cp, pkg.cp, 1),
                        allow_wildcard=True,
                        allow_repo=True,
                    )
                ] = atom
        best_match = best_match_to_list(pkg, iter(rev_transform))
        if best_match:
            return rev_transform[best_match]
        return None

    def iterAtomsForPackage(self, pkg):
        """
        Find all matching atoms for a given package. This matches virtual
        arguments against the PROVIDE metadata.  This will raise an
        InvalidDependString exception if PROVIDE is invalid.
        """
        cpv_slot_list = [pkg]
        cp = cpv_getkey(pkg.cpv)
        self._load()  # make sure the atoms are loaded

        atoms = self._atommap.get(cp)
        if atoms:
            for atom in atoms:
                if match_from_list(atom, cpv_slot_list):
                    yield atom


class EditablePackageSet(PackageSet):
    def __init__(self, allow_wildcard=False, allow_repo=False):
        super().__init__(allow_wildcard=allow_wildcard, allow_repo=allow_repo)

    def update(self, atoms):
        self._load()
        modified = False
        normal_atoms = []
        for a in atoms:
            if not isinstance(a, Atom):
                try:
                    a = Atom(a, allow_wildcard=True, allow_repo=True)
                except InvalidAtom:
                    modified = True
                    self._nonatoms.add(a)
                    continue
            if not self._allow_wildcard and a.extended_syntax:
                raise InvalidAtom("extended atom syntax not allowed here")
            if not self._allow_repo and a.repo:
                raise InvalidAtom("repository specification not allowed here")
            normal_atoms.append(a)

        if normal_atoms:
            modified = True
            self._atoms.update(normal_atoms)
            self._updateAtomMap(atoms=normal_atoms)
        if modified:
            self.write()

    def add(self, atom):
        self.update([atom])

    def replace(self, atoms):
        self._setAtoms(atoms)
        self.write()

    def remove(self, atom):
        self._load()
        self._atoms.discard(atom)
        self._nonatoms.discard(atom)
        self._updateAtomMap()
        self.write()

    def removePackageAtoms(self, cp):
        self._load()
        for a in list(self._atoms):
            if a.cp == cp:
                self.remove(a)
        self.write()

    def write(self):
        # This method must be overwritten in subclasses that should be editable
        raise NotImplementedError()


class InternalPackageSet(EditablePackageSet):
    def __init__(self, initial_atoms=None, allow_wildcard=False, allow_repo=True):
        """
        Repo atoms are allowed more often than not, so it makes sense for this
        class to allow them by default. The Atom constructor and isvalidatom()
        functions default to allow_repo=False, which is sufficient to ensure
        that repo atoms are prohibited when necessary.
        """
        super().__init__(allow_wildcard=allow_wildcard, allow_repo=allow_repo)
        if initial_atoms is not None:
            self.update(initial_atoms)

    def clear(self):
        self._atoms.clear()
        self._updateAtomMap()

    def load(self):
        pass

    def write(self):
        pass


class DummyPackageSet(PackageSet):
    def __init__(self, atoms=None):
        super().__init__()
        if atoms:
            self._setAtoms(atoms)

    def load(self):
        pass

    def singleBuilder(cls, options, settings, trees):
        atoms = options.get("packages", "").split()
        return DummyPackageSet(atoms=atoms)

    singleBuilder = classmethod(singleBuilder)
