from os.path import exists, join

from .exceptions import BundleError, NoSuchBundle, RepositoryError
from .metadata import DoNotRunAgain
from .utils import cached_property
from .utils.text import bold, mark_for_translation as _
from .utils.text import validate_name
from .utils.ui import io


FILENAME_BUNDLE = "bundle.py"
FILENAME_ITEMS = "items.py"
FILENAME_METADATA = "metadata.py"


def metadata_reactor_for_bundle(bundle_name):
    reactor_names = set()

    def metadata_reactor(func):
        """
        Decorator that tags metadata reactors.
        """
        if func.__name__ == "defaults":
            raise ValueError(_(
                "metadata reactor in bundle '{}' cannot be named 'defaults'"
            ).format(bundle_name))
        if func.__name__ in reactor_names:
            raise ValueError(_(
                "duplicate metadata reactor '{reactor}' in bundle '{bundle}'"
            ).format(bundle=bundle_name, reactor=func.__name__))
        reactor_names.add(func.__name__)
        func._is_metadata_reactor = True
        return func

    def metadata_reactor_provides(*args):
        def provides_inner(func):
            func._provides = set()
            for arg in args:
                if isinstance(arg, str):
                    arg = arg.split("/")
                func._provides.add(tuple(arg))
            return metadata_reactor(func)
        return provides_inner

    metadata_reactor.provides = metadata_reactor_provides

    return metadata_reactor


class Bundle:
    """
    A collection of config items, bound to a node.
    """
    def __init__(self, node, name):
        self.name = name
        self.node = node
        self.repo = node.repo

        if not validate_name(name):
            raise RepositoryError(_("invalid bundle name: {}").format(name))

        if name not in self.repo.bundle_names:
            raise NoSuchBundle(_("bundle not found: {}").format(name))

        self.bundle_dir = join(self.repo.bundles_dir, self.name)
        self.bundle_data_dir = join(self.repo.data_dir, self.name)
        self.bundle_file = join(self.bundle_dir, FILENAME_BUNDLE)
        self.items_file = join(self.bundle_dir, FILENAME_ITEMS)
        self.metadata_file = join(self.bundle_dir, FILENAME_METADATA)

    def __lt__(self, other):
        return self.name < other.name

    @cached_property
    @io.job_wrapper(_("{}  {}  parsing bundle attributes").format(bold("{0.node.name}"), bold("{0.name}")))
    def bundle_attrs(self):
        if not exists(self.bundle_file):
            return {}
        else:
            base_env = {
                'node': self.node,
                'repo': self.repo,
            }

            # TODO prevent access to node.metadata
            return self.repo.get_all_attrs_from_file(
                self.bundle_file,
                base_env=base_env,
            )

    @cached_property
    @io.job_wrapper(_("{}  {}  parsing bundle items").format(bold("{0.node.name}"), bold("{0.name}")))
    def bundle_item_attrs(self):
        if not exists(self.items_file):
            return {}
        else:
            base_env = {
                'node': self.node,
                'repo': self.repo,
            }
            for item_class in self.repo.item_classes:
                base_env[item_class.BUNDLE_ATTRIBUTE_NAME] = {}

            return self.repo.get_all_attrs_from_file(
                self.items_file,
                base_env=base_env,
            )

    @cached_property
    @io.job_wrapper(_("{}  {}  creating items").format(bold("{0.node.name}"), bold("{0.name}")))
    def items(self):
        for item_class in self.repo.item_classes:
            for item_name, item_attrs in self.bundle_item_attrs.get(
                item_class.BUNDLE_ATTRIBUTE_NAME,
                {},
            ).items():
                yield self.make_item(
                    item_class.BUNDLE_ATTRIBUTE_NAME,
                    item_name,
                    item_attrs,
                )

    def make_item(self, attribute_name, item_name, item_attrs):
        for item_class in self.repo.item_classes:
            if item_class.BUNDLE_ATTRIBUTE_NAME == attribute_name:
                return item_class(self, item_name, item_attrs)
        raise RuntimeError(
            _("bundle '{bundle}' tried to generate item '{item}' from "
              "unknown attribute '{attr}'").format(
                attr=attribute_name,
                bundle=self.name,
                item=item_name,
            )
        )

    @cached_property
    def _metadata_defaults_and_reactors(self):
        with io.job(_("{node}  {bundle}  collecting metadata reactors").format(
            node=bold(self.node.name),
            bundle=bold(self.name),
        )):
            if not exists(self.metadata_file):
                return {}, set()

            defaults = {}
            reactors = set()
            internal_names = set()
            for name, attr in self.repo.get_all_attrs_from_file(
                self.metadata_file,
                base_env={
                    'DoNotRunAgain': DoNotRunAgain,
                    'metadata_reactor': metadata_reactor_for_bundle(self.name),
                    'node': self.node,
                    'repo': self.repo,
                },
            ).items():
                if name == "defaults":
                    defaults = attr
                elif getattr(attr, '_is_metadata_reactor', False):
                    internal_name = getattr(attr, '__name__', name)
                    if internal_name in internal_names:
                        raise BundleError(_(
                            "Metadata reactor '{name}' in bundle {bundle} for node {node} has "
                            "__name__ '{internal_name}', which was previously used by another "
                            "metadata reactor in the same metadata.py. BundleWrap uses __name__ "
                            "internally to tell metadata reactors apart, so this is a problem. "
                            "Perhaps you used a decorator on your metadata reactors that "
                            "doesn't use functools.wraps? You should use that."
                        ).format(
                            bundle=self.name,
                            node=self.node.name,
                            internal_name=internal_name,
                            name=name,
                        ))
                    internal_names.add(internal_name)
                    reactors.add(attr)
            return defaults, reactors
