"""
Orange Canvas Resource Loader

"""
import os
import glob
import pkgutil

from typing import Tuple, Dict, Optional, List, IO

from AnyQt.QtCore import QObject
from AnyQt.QtGui import QIcon

from orangecanvas.gui.svgiconengine import StyledSvgIconEngine


def package_dirname(package):
    """Return the directory path where package is located.

    """
    if isinstance(package, str):
        package = __import__(package, fromlist=[""])
    filename = package.__file__
    dirname = os.path.dirname(filename)
    return dirname


def package(qualified_name):
    """Return the enclosing package name where qualified_name is located.

    `qualified_name` can be a module inside the package or even an object
    inside the module. If a package name itself is provided it is returned.

    """
    try:
        module = __import__(qualified_name, fromlist=[""])
    except ImportError:
        # qualified_name could name an object inside a module/package
        if "." in qualified_name:
            qualified_name, attr_name = qualified_name.rsplit(".", 1)
            module = __import__(qualified_name, fromlist=[attr_name])
        else:
            raise

    if module.__package__:
        # the module's enclosing package
        return module.__package__
    else:
        # 'qualified_name' is itself the package
        assert module.__name__ == qualified_name
        return qualified_name


dirname = os.path.abspath(os.path.dirname(__file__))

DEFAULT_SEARCH_PATHS = [("", dirname)]

del dirname


def default_search_paths():
    return DEFAULT_SEARCH_PATHS


def add_default_search_paths(search_paths):
    DEFAULT_SEARCH_PATHS.extend(search_paths)


def search_paths_from_description(desc):
    """Return the search paths for the Category/WidgetDescription.
    """
    paths = []
    if desc.package:
        dirname = package_dirname(desc.package)
        paths.append(("", dirname))
    elif desc.qualified_name:
        dirname = package_dirname(package(desc.qualified_name))
        paths.append(("", dirname))

    if hasattr(desc, "search_paths"):
        paths.extend(desc.search_paths)
    return paths


class resource_loader(object):
    def __init__(self, search_paths=[]):
        self._search_paths = []
        self.add_search_paths(search_paths)

    @classmethod
    def from_description(cls, desc):
        """Construct an resource from a Widget or Category description.
        """
        paths = search_paths_from_description(desc)
        return icon_loader(search_paths=paths)

    def add_search_paths(self, paths):
        """Add `paths` to the list of search paths.
        """
        self._search_paths.extend(paths)

    def search_paths(self):
        """Return a list of all search paths.
        """
        return self._search_paths + default_search_paths()

    def split_prefix(self, path):
        # type: (str) -> Tuple[str, str]
        """Split prefixed path.
        """
        if self.is_valid_prefixed(path) and ":" in path:
            prefix, path = path.split(":", 1)
        else:
            prefix = ""
        return prefix, path

    def is_valid_prefixed(self, path):
        # type: (str) -> bool
        i = path.find(":")
        return i != 1

    def find(self, name):
        # type: (str) -> Optional[str]
        """Find a resource matching `name`.
        """
        prefix, path = self.split_prefix(name)
        if prefix == "" and self.match(path):
            return path
        elif self.is_valid_prefixed(path):
            for pp, search_path in self.search_paths():
                if pp == prefix and \
                        self.match(os.path.join(search_path, path)):
                    return os.path.join(search_path, path)

        return None

    def match(self, path):
        # type: (str) -> bool
        return os.path.exists(path)

    def get(self, name):
        # type: (str) -> bytes
        return self.load(name)

    def load(self, name):
        # type: (str) -> bytes
        return self.open(name).read()

    def open(self, name):
        # type: (str) -> IO[bytes]
        path = self.find(name)
        if path is not None:
            return open(path, "rb")
        else:
            raise FileNotFoundError("Cannot find %r" % name)


class icon_loader(resource_loader):
    _icon_cache = {}  # type: Dict[Tuple[str, ...], QIcon]
    DEFAULT_ICON = "icons/default-widget.svg"

    def match(self, path):
        # type: (str) -> bool
        if super().match(path):
            return True
        return self.is_icon_glob(path)

    def icon_glob(self, path):
        # type: (str) -> List[str]
        name, ext = os.path.splitext(path)
        pattern = name + "_*" + ext
        return glob.glob(pattern)

    def is_icon_glob(self, path):
        # type: (str) -> bool
        name, ext = os.path.splitext(path)
        pattern = name + "_*" + ext
        return bool(glob.glob(pattern))

    def get(self, name, default=None):
        # type: (str, Optional[str]) -> QIcon
        if name:
            path = self.find(name)
        else:
            path = None

        if path is None:
            path = self.find(self.DEFAULT_ICON if default is None else default)
        if path is None:
            return QIcon()

        if self.is_icon_glob(path):
            icons = self.icon_glob(path)
        else:
            icons = [path]

        cache_key = tuple(icons)
        icon = QIcon()
        if icons:
            if cache_key not in self._icon_cache:
                for path in icons:
                    icon.addFile(path)
                self._icon_cache[cache_key] = icon
            else:
                icon = self._icon_cache[cache_key]
        return QIcon(icon)

    def open(self, name):
        raise NotImplementedError

    def load(self, name):
        # type: (str) -> QIcon
        return self.get(name)


def load_styled_svg_icon(
        name: str, styleobject: Optional[QObject] = None
) -> QIcon:
    """
    Load a styled svg icon from the `icons` resource directory.

    .. seealso:: StyledSvgIconEngine
    """
    try:
        c = pkgutil.get_data(__name__, f"icons/{name}")
    except Exception:
        return QIcon()
    return QIcon(StyledSvgIconEngine(c, styleObject=styleobject))
