"""
Cement mustache extension module.

**Note** This extension has an external dependency on ``pystache``. Cement
explicitly does **not** include external dependencies for optional
extensions.

* In Cement ``>=3.0.8`` you must include ``cement[mustache]`` in your
  applications dependencies.
* In Cement ``<3.0.8`` you must include ``pystache`` in your applications
  dependencies.
"""

from __future__ import annotations
from pystache.renderer import Renderer  # type: ignore
from typing import Any, Dict, Union, TYPE_CHECKING
from ..core.output import OutputHandler
from ..core.template import TemplateHandler
from ..utils.misc import minimal_logger

if TYPE_CHECKING:
    from ..core.foundation import App  # pragma: nocover

LOG = minimal_logger(__name__)


class PartialsLoader(object):

    def __init__(self, handler: TemplateHandler) -> None:
        self.handler = handler

    def get(self, template: str) -> Union[str, bytes, None]:
        content, _type, _path = self.handler.load(template)
        return content


class MustacheOutputHandler(OutputHandler):

    """
    This class implements the :ref:`Output <cement.core.output>` Handler
    interface.  It provides text output from template and uses the
    `Mustache Templating Language <http://mustache.github.com>`_.  Please
    see the developer documentation on
    :cement:`Output Handling <dev/output>`.
    """

    class Meta(OutputHandler.Meta):

        """Handler meta-data."""

        label = 'mustache'

        #: Whether or not to include ``mustache`` as an available to choice
        #: to override the ``output_handler`` via command line options.
        overridable = False

    _meta: Meta  # type: ignore

    def __init__(self, *args: Any, **kw: Any) -> None:
        super(MustacheOutputHandler, self).__init__(*args, **kw)
        self.templater: MustacheTemplateHandler = None  # type: ignore

    def _setup(self, app: App) -> None:
        super(MustacheOutputHandler, self)._setup(app)
        self.templater = self.app.handler.resolve('template', 'mustache',  # type: ignore
                                                  setup=True)

    def render(self, data: Dict[str, Any], template: str = None, **kw: Any) -> str:  # type: ignore
        """
        Take a data dictionary and render it using the given template file.
        Additional keyword arguments passed to ``stache.render()``.

        Args:
            data (dict): The data dictionary to render.

        Keyword Args:
            template (str): The path to the template, after the
                ``template_module`` or ``template_dirs`` prefix as defined in
                the application.

        Returns:
            str: The rendered template text

        """

        LOG.debug(f"rendering content using '{template}' as a template.")
        content, _type, _path = self.templater.load(template)
        return self.templater.render(content, data)


class MustacheTemplateHandler(TemplateHandler):

    """
    This class implements the :ref:`Template <cement.core.template>` Handler
    interface.  It renderd content as template, and supports copying entire
    source template directories using the
    `Mustache Templating Language <http://mustache.github.com>`_.  Please
    see the developer documentation on
    :cement:`Template Handling <dev/template>`.

    **Note** This extension has an external dependency on ``pystache``.  You
    must include ``pystache`` in your applications dependencies as Cement
    explicitly does **not** include external dependencies for optional
    extensions.
    """

    class Meta(TemplateHandler.Meta):

        """Handler meta-data."""

        label = 'mustache'

    _meta: Meta  # type: ignore

    def __init__(self, *args: Any, **kw: Any) -> None:
        super(MustacheTemplateHandler, self).__init__(*args, **kw)
        self._partials_loader = PartialsLoader(self)

    def render(self, content: Union[str, bytes], data: Dict[str, Any]) -> str:
        """
        Render the given ``content`` as template with the ``data`` dictionary.

        Args:
            content (str): The template content to render.
            data (dict): The data dictionary to render.

        Returns:
            str: The rendered template text

        """

        stache = Renderer(partials=self._partials_loader)
        return stache.render(content, data)  # type: ignore


def load(app: App) -> None:
    app.handler.register(MustacheOutputHandler)
    app.handler.register(MustacheTemplateHandler)