import importlib
import os
import inspect
import logging


class bcolors:
    HEADER = '\033[95m'
    OKBLUE = '\033[94m'
    OKGREEN = '\033[92m'
    WARNING = '\033[93m'
    FAIL = '\033[91m'
    ENDC = '\033[0m'
    BOLD = '\033[1m'
    UNDERLINE = '\033[4m'


def module_from_file(plugin_path):
    # Expand environment variables in path string
    plugin_path = os.path.expandvars(plugin_path)
    # Expand user directory in path string
    plugin_path = os.path.expanduser(plugin_path)

    # Check if the path is to a file
    if not os.path.isfile(plugin_path):
        logging.warning(bcolors.FAIL + "No valid plugin found at {}.".format(plugin_path) + bcolors.ENDC)
        return None, None, None

    else:
        # Get name of plugin from the file
        plugin_name = os.path.splitext(os.path.basename(plugin_path))[0]

        plugin_spec = importlib.util.spec_from_file_location(plugin_name, plugin_path)
        plugin_module = importlib.util.module_from_spec(plugin_spec)

        return plugin_spec, plugin_module, plugin_name


def load_plugin_module(plugin_path):
    # First, try importing from standard modules
    try:
        plugin_module = importlib.import_module(plugin_path)
    except ImportError:
        plugin_spec, plugin_module, plugin_name = module_from_file(plugin_path)

        # If a valid plugin was found
        if plugin_spec and plugin_module:
            # Execute the module, so we have access to it
            plugin_spec.loader.exec_module(plugin_module)
    else:
        plugin_name = plugin_path.split('.')[-1]

    return plugin_module, plugin_name


def load_plugin_class(plugin_path, plugin_class_name):
    plugin_module, plugin_name = load_plugin_module(plugin_path)
    if plugin_module:
        # Now try to extract the class
        try:
            plugin_class = getattr(plugin_module, plugin_class_name)
        except AttributeError:
            logging.warning(bcolors.FAIL + "Class {} does not exist in plugin {}. Skipping.".format(plugin_class_name, plugin_path) + bcolors.ENDC)
            return None, None
        else:
            return plugin_class, plugin_name
    else:
        return None, None


def class_from_map(plugin_map):
    plugin_arr = plugin_map.split(':')

    if not len(plugin_arr) == 2:
        logging.warning(bcolors.WARNING + "Malformed plugin map {}. Skipping.".format(plugin_map) + bcolors.ENDC)
        return None, None
    else:
        return load_plugin_class(*plugin_arr)


class PluginMount(object):
    """
    A mount-point for all loaded plugins. Attaches to a Microscope object.

    Args:
        parent (:py:class:`openflexure_microscope.microscope.Microscope`): The parent Microscope object to attach to.
    """
    def __init__(self, parent):
        self.parent = parent
        self.plugins = []
        print("Creating plugin mount")

    @property
    def members(self):
        plugin_array = []
        for obj_name in dir(self):
            if not obj_name == "plugins" and not obj_name[:2] == '__':
                obj = getattr(self, obj_name)
                if isinstance(obj, MicroscopePlugin):
                    plugin_members = [member for member in inspect.getmembers(obj) if not member[0][:2] == '__']
                    plugin_info = (obj_name, plugin_members)
                    plugin_array.append(plugin_info)
        return plugin_array

    def attach(self, plugin_map):
        """
        Attach a MicroscopePlugin instance to the plugin mount.

        Args:
            plugin_map (str): A plugin map describing the file or module to load a MicroscopePlugin child from. Maps should be in the format 'module.to.load:ClassName' or '/path/to/file:ClassName'.
        """
        plugin_class, plugin_name = class_from_map(plugin_map)

        if plugin_class and plugin_name:
            plugin_object = plugin_class()

            if hasattr(self, plugin_name):  # If a plugin with the same name is already attached.
                logging.warning(bcolors.WARNING + "A plugin named {} has already been loaded. Skipping {}.".format(plugin_name, plugin_map) + bcolors.ENDC)

            elif isinstance(plugin_object, MicroscopePlugin):  # If plugin_object is an instance of MicroscopePlugin
                # Attach plugin_object to the plugin mount
                setattr(self, plugin_name, plugin_object)
                self.plugins.append((plugin_name, plugin_object))

                # Grant plugin access to the hardware
                plugin_object.microscope = self.parent

                logging.info(bcolors.OKGREEN + "Plugin {} loaded as {}.".format(plugin_map, plugin_name) + bcolors.ENDC)


class MicroscopePlugin():
    """
    Parent class for all microscope plugins.

    Initially only defines an empty object for microscope. All plugins
    must be an instance of this class to successfully attach to PluginMount.
    """

    api_views = {}  # Initially empty dictionary of API views associated with the plugin

    def __init__(self):
        self.microscope = None  #: :py:class:`openflexure_microscope.microscope.Microscope`: Microscope object