#!/usr/bin/env python
# vim: set fileencoding=utf-8 :
# @author: Manuel Guenther <Manuel.Guenther@idiap.ch>
# @date: Thu Oct 25 10:05:55 CEST 2012

from __future__ import print_function

import logging
import os

import clapper.config
import pkg_resources

logger = logging.getLogger("bob.bio.base")


valid_keywords = (
    "database",
    "preprocessor",
    "extractor",
    "algorithm",
    "grid",
    "client",
    "config",
    "annotator",
    "pipeline",
)
"""Keywords for which resources are defined."""


def _collect_config(paths):
    """Collect all python file resources into a module

    This function recursively loads python modules (in a Python 3-compatible way)
    so the last loaded module corresponds to the final state of the loading. In
    this way, we load the first file, resolve its symbols, overwrite with the
    second file and so on. We return a temporarily created module containing all
    resolved variables, respecting the input order.


    Parameters:

      paths : [str]
        A list of resources, modules or files (in order) to collect resources from


    Returns: module

      A valid Python module you can use to configure your tool

    """

    return clapper.config.load(paths, entry_point_group="bob.bio.config")


def read_config_file(filenames, keyword=None):
    """Use this function to read the given configuration file.
    If a keyword is specified, only the configuration according to this keyword is returned.
    Otherwise a dictionary of the configurations read from the configuration file is returned.

    **Parameters:**

    filenames : [str]
      A list (pontentially empty) of configuration files or resources to read
      running options from

    keyword : str or ``None``
      If specified, only the contents of the variable with the given name is returned.
      If ``None``, the whole configuration is returned (a local namespace)

    **Returns:**

    config : object or namespace
      If ``keyword`` is specified, the object inside the configuration with the given name is returned.
      Otherwise, the whole configuration is returned (as a local namespace).
    """

    if not filenames:
        raise RuntimeError(
            "At least one configuration file, resource or "
            "module name must be passed"
        )

    config = _collect_config(filenames)

    if not keyword:
        return config

    if not hasattr(config, keyword):
        raise ImportError(
            "The desired keyword '%s' does not exist in any of "
            "your configuration files: %s" % (keyword, ", ".join(filenames))
        )

    return getattr(config, keyword)


def _get_entry_points(keyword, strip=[], package_prefix="bob.bio."):
    """Returns the list of entry points for registered resources with the given keyword."""
    return [
        entry_point
        for entry_point in pkg_resources.iter_entry_points(
            package_prefix + keyword
        )
        if not entry_point.name.startswith(tuple(strip))
    ]


def load_resource(
    resource,
    keyword,
    imports=["bob.bio.base"],
    package_prefix="bob.bio.",
    preferred_package=None,
):
    """Loads the given resource that is registered with the given keyword.
    The resource can be:

    1. a resource as defined in the setup.py
    2. a configuration file
    3. a string defining the construction of an object. If imports are required for the construction of this object, they can be given as list of strings.

    **Parameters:**

    resource : str
      Any string interpretable as a resource (see above).

    keyword : str
      A valid resource keyword, can be one of :any:`bob.bio.base.utils.resources.valid_keywords`.

    imports : [str]
      A list of strings defining which modules to import, when constructing new objects (option 3).

    package_prefix : str
      Package namespace, in which we search for entry points, e.g., ``bob.bio``.

    preferred_package : str or ``None``
      When several resources with the same name are found in different packages (e.g., in different ``bob.bio`` or other packages), this specifies the preferred package to load the resource from.
      If not specified, the extension that is **not** from ``bob.bio`` is selected.

    **Returns:**

    resource : object
      The resulting resource object is returned, either read from file or resource, or created newly.
    """

    # first, look if the resource is a file name
    if os.path.isfile(resource):
        return read_config_file([resource], keyword)

    if keyword not in valid_keywords:
        logger.warning(
            "The given keyword '%s' is not valid. Please use one of %s!",
            keyword,
            valid_keywords,
        )

    # now, we check if the resource is registered as an entry point in the resource files
    entry_points = [
        entry_point
        for entry_point in _get_entry_points(
            keyword, package_prefix=package_prefix
        )
        if entry_point.name == resource
    ]

    if len(entry_points):
        if len(entry_points) == 1:
            return entry_points[0].load()
        else:
            # TODO: extract current package name and use this one, if possible

            # Now: check if there are only two entry points, and one is from the bob.bio.base, then use the other one
            index = -1
            if preferred_package is not None:
                for i, p in enumerate(entry_points):
                    if p.dist.project_name == preferred_package:
                        index = i
                        break

            if index == -1:
                # by default, use the first one that is not from bob.bio
                for i, p in enumerate(entry_points):
                    if not p.dist.project_name.startswith(package_prefix):
                        index = i
                        break

            if index != -1:
                logger.debug(
                    "RESOURCES: Using the resource '%s' from '%s', and ignoring the one from '%s'",
                    resource,
                    entry_points[index].module_name,
                    entry_points[1 - index].module_name,
                )
                return entry_points[index].load()
            else:
                logger.warn(
                    "Under the desired name '%s', there are multiple entry points defined, we return the first one: %s",
                    resource,
                    [entry_point.module_name for entry_point in entry_points],
                )
                return entry_points[0].load()

    # if the resource is neither a config file nor an entry point,
    # just execute it as a command
    try:
        # first, execute all import commands that are required
        for i in imports:
            exec("import %s" % i)
        # now, evaluate the resource (re-evaluate if the resource is still a string)
        while isinstance(resource, str):
            resource = eval(resource)
        return resource

    except Exception as e:
        raise ImportError(
            "The given command line option '%s' is neither a resource for a '%s', nor an existing configuration file, nor could be interpreted as a command"
            % (resource, keyword)
        ) from e


def extensions(keywords=valid_keywords, package_prefix="bob.bio."):
    """extensions(keywords=valid_keywords, package_prefix='bob.bio.') -> extensions

    Returns a list of packages that define extensions using the given keywords.

    **Parameters:**

    keywords : [str]
      A list of keywords to load entry points for.
      Defaults to all :any:`bob.bio.base.utils.resources.valid_keywords`.

    package_prefix : str
      Package namespace, in which we search for entry points, e.g., ``bob.bio``.
    """
    entry_points = [
        entry_point
        for keyword in keywords
        for entry_point in _get_entry_points(
            keyword, package_prefix=package_prefix
        )
    ]
    return sorted(
        list(set(entry_point.dist.project_name for entry_point in entry_points))
    )


def resource_keys(
    keyword, exclude_packages=[], package_prefix="bob.bio.", strip=["dummy"]
):
    """Reads and returns all resources that are registered with the given keyword.
    Entry points from the given ``exclude_packages`` are ignored."""
    ret_list = [
        entry_point.name
        for entry_point in _get_entry_points(
            keyword, strip=strip, package_prefix=package_prefix
        )
        if entry_point.dist.project_name not in exclude_packages
    ]
    return sorted(ret_list)


def list_resources(
    keyword,
    strip=["dummy"],
    package_prefix="bob.bio.",
    verbose=False,
    packages=None,
):
    """Returns a string containing a detailed list of resources that are registered with the given keyword."""
    if keyword not in valid_keywords:
        raise ValueError(
            "The given keyword '%s' is not valid. Please use one of %s!"
            % (str(keyword), str(valid_keywords))
        )

    entry_points = _get_entry_points(
        keyword, strip, package_prefix=package_prefix
    )
    last_dist = None
    retval = ""
    length = (
        max(len(entry_point.name) for entry_point in entry_points)
        if entry_points
        else 1
    )

    if packages is not None:
        entry_points = [
            entry_point
            for entry_point in entry_points
            if entry_point.dist.project_name in packages
        ]

    for entry_point in sorted(
        entry_points, key=lambda p: (p.dist.project_name, p.name)
    ):
        if last_dist != str(entry_point.dist):
            retval += "\n- %s @ %s: \n" % (
                str(entry_point.dist),
                str(entry_point.dist.location),
            )
            last_dist = str(entry_point.dist)

        if len(entry_point.attrs):
            retval += "  + %s --> %s: %s\n" % (
                entry_point.name + " " * (length - len(entry_point.name)),
                entry_point.module_name,
                entry_point.attrs[0],
            )
        else:
            retval += "  + %s --> %s\n" % (
                entry_point.name + " " * (length - len(entry_point.name)),
                entry_point.module_name,
            )
        if verbose:
            retval += "    ==> " + str(entry_point.load()) + "\n\n"

    return retval


def database_directories(
    strip=["dummy"], replacements=None, package_prefix="bob.bio."
):
    """Returns a dictionary of original directories for all registered databases."""
    entry_points = _get_entry_points(
        "database", strip, package_prefix=package_prefix
    )

    dirs = {}
    for entry_point in sorted(
        entry_points, key=lambda entry_point: entry_point.name
    ):
        try:
            db = load_resource(entry_point.name, "database")
            db.replace_directories(replacements)
            dirs[entry_point.name] = [db.original_directory]
            if db.annotation_directory is not None:
                dirs[entry_point.name].append(db.annotation_directory)
        except (AttributeError, ValueError, ImportError):
            pass

    return dirs


def get_resource_filename(resource_name, group):
    """
    Get the file name of a resource.


    Parameters
    ----------
        resource_name: str
            Name of the resource to be searched

        group: str
            Entry point group

    Return
    ------
        filename: str
            The entrypoint file name

    """

    # Check if it's already a path
    if os.path.exists(resource_name):
        return resource_name

    # If it's a resource get the path of this resource
    resources = [r for r in pkg_resources.iter_entry_points(group)]

    # if resource_name not in [r.name for r in resources]:
    #    raise ValueError(f"Resource not found: `{resource_name}`")

    for r in resources:
        if r.name == resource_name:
            resource = r
            break
    else:
        raise ValueError(f"Resource not found: `{resource_name}`")

    # TODO: This get the root path only
    #        I don't know how to get the filename
    return (
        pkg_resources.resource_filename(
            resource.module_name, resource.module_name.split(".")[-1]
        )
        + ".py"
    )
