# -*- coding: utf-8 -*-
# BSD 2-Clause License
#
# Apprise - Push Notification Library.
# Copyright (c) 2024, Chris Caron <lead2gold@gmail.com>
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# 1. Redistributions of source code must retain the above copyright notice,
#    this list of conditions and the following disclaimer.
#
# 2. Redistributions in binary form must reproduce the above copyright notice,
#    this list of conditions and the following disclaimer in the documentation
#    and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.

import os
import re
import sys
import time
import hashlib
import inspect
import threading
from .utils import import_module
from .utils import Singleton
from .utils import parse_list
from os.path import dirname
from os.path import abspath
from os.path import join

from .logger import logger


class PluginManager(metaclass=Singleton):
    """
    Designed to be a singleton object to maintain all initialized loading
    of modules in memory.
    """

    # Description (used for logging)
    name = 'Singleton Plugin'

    # Memory Space
    _id = 'undefined'

    # Our Module Python path name
    module_name_prefix = f'apprise.{_id}'

    # The module path to scan
    module_path = join(abspath(dirname(__file__)), _id)

    # For filtering our result when scanning a module
    module_filter_re = re.compile(r'^(?P<name>((?!_)[A-Za-z0-9]+))$')

    # thread safe loading
    _lock = threading.Lock()

    def __init__(self, *args, **kwargs):
        """
        Over-ride our class instantiation to provide a singleton
        """

        self._module_map = None
        self._schema_map = None

        # This contains a mapping of all plugins dynamicaly loaded at runtime
        # from external modules such as the @notify decorator
        #
        # The elements here will be additionally added to the _schema_map if
        # there is no conflict otherwise.
        # The structure looks like the following:
        # Module path, e.g. /usr/share/apprise/plugins/my_notify_hook.py
        # {
        #   'path': path,
        #
        #   'notify': {
        #     'schema': {
        #       'name': 'Custom schema name',
        #       'fn_name': 'name_of_function_decorator_was_found_on',
        #       'url': 'schema://any/additional/info/found/on/url'
        #       'plugin': <CustomNotifyWrapperPlugin>
        #    },
        #     'schema2': {
        #       'name': 'Custom schema name',
        #       'fn_name': 'name_of_function_decorator_was_found_on',
        #       'url': 'schema://any/additional/info/found/on/url'
        #       'plugin': <CustomNotifyWrapperPlugin>
        #    }
        #  }
        # Note: that the <CustomNotifyWrapperPlugin> inherits from
        #       NotifyBase
        self._custom_module_map = {}

        # Track manually disabled modules (by their schema)
        self._disabled = set()

        # Hash of all paths previously scanned so we don't waste
        # effort/overhead doing it again
        self._paths_previously_scanned = set()

        # Track loaded module paths to prevent from loading them again
        self._loaded = set()

    def unload_modules(self, disable_native=False):
        """
        Reset our object and unload all modules
        """

        with self._lock:
            if self._custom_module_map:
                # Handle Custom Module Assignments
                for meta in self._custom_module_map.values():
                    if meta['name'] not in self._module_map:
                        # Nothing to remove
                        continue

                    # For the purpose of tidying up un-used modules in memory
                    loaded = [m for m in sys.modules.keys()
                              if m.startswith(
                                  self._module_map[meta['name']]['path'])]

                    for module_path in loaded:
                        del sys.modules[module_path]

            # Reset disabled plugins (if any)
            for schema in self._disabled:
                self._schema_map[schema].enabled = True
            self._disabled.clear()

            # Reset our variables
            self._schema_map = {}
            self._custom_module_map = {}
            if disable_native:
                self._module_map = {}

            else:
                self._module_map = None
                self._loaded = set()

            # Reset our path cache
            self._paths_previously_scanned = set()

    def load_modules(self, path=None, name=None, force=False):
        """
        Load our modules into memory
        """

        # Default value
        module_name_prefix = self.module_name_prefix if name is None else name
        module_path = self.module_path if path is None else path

        with self._lock:
            if not force and module_path in self._loaded:
                # We're done
                return

            # Our base reference
            module_count = len(self._module_map) if self._module_map else 0
            schema_count = len(self._schema_map) if self._schema_map else 0

            if not self:
                # Initialize our maps
                self._module_map = {}
                self._schema_map = {}
                self._custom_module_map = {}

            # Used for the detection of additional Notify Services objects
            # The .py extension is optional as we support loading directories
            # too
            module_re = re.compile(
                r'^(?P<name>(?!base|_)[a-z0-9_]+)(\.py)?$',
                re.I)

            t_start = time.time()
            for f in os.listdir(module_path):
                tl_start = time.time()
                match = module_re.match(f)
                if not match:
                    # keep going
                    continue

                # Store our notification/plugin name:
                module_name = match.group('name')
                module_pyname = '{}.{}'.format(module_name_prefix, module_name)

                if module_name in self._module_map:
                    logger.warning(
                        "%s(s) (%s) already loaded; ignoring %s",
                        self.name, module_name, os.path.join(module_path, f))
                    continue

                try:
                    module = __import__(
                        module_pyname,
                        globals(), locals(),
                        fromlist=[module_name])

                except ImportError:
                    # No problem, we can try again another way...
                    module = import_module(
                        os.path.join(module_path, f), module_pyname)
                    if not module:
                        # logging found in import_module and not needed here
                        continue

                module_class = None
                for m_class in [obj for obj in dir(module)
                                if self.module_filter_re.match(obj)]:
                    # Get our plugin
                    plugin = getattr(module, m_class)
                    if not hasattr(plugin, 'app_id'):
                        # Filter out non-notification modules
                        logger.trace(
                            "(%s) import failed; no app_id defined in %s",
                            self.name, m_class, os.path.join(module_path, f))
                        continue

                    # Add our plugin name to our module map
                    self._module_map[module_name] = {
                        'plugin': set([plugin]),
                        'module': module,
                        'path': '{}.{}'.format(
                            module_name_prefix, module_name),
                        'native': True,
                    }

                    fn = getattr(plugin, 'schemas', None)
                    schemas = set([]) if not callable(fn) else fn(plugin)

                    # map our schema to our plugin
                    for schema in schemas:
                        if schema in self._schema_map:
                            logger.error(
                                "{} schema ({}) mismatch detected - {} to {}"
                                .format(self.name, schema, self._schema_map,
                                        plugin))
                            continue

                        # Assign plugin
                        self._schema_map[schema] = plugin

                    # Store our class
                    module_class = m_class
                    break

                if not module_class:
                    # Not a library we can load as it doesn't follow the simple
                    # rule that the class must bear the same name as the
                    # notification file itself.
                    logger.trace(
                        "%s (%s) import failed; no filename/Class "
                        "match found in %s",
                        self.name, module_name, os.path.join(module_path, f))
                    continue

                logger.trace(
                    '{} {} loaded in {:.6f}s'.format(
                        self.name, module_name, (time.time() - tl_start)))

            # Track the directory loaded so we never load it again
            self._loaded.add(module_path)

            logger.debug(
                '{} {}(s) and {} Schema(s) loaded in {:.4f}s'
                .format(
                    self.name,
                    len(self._module_map) - module_count,
                    len(self._schema_map) - schema_count,
                    (time.time() - t_start)))

    def module_detection(self, paths, cache=True):
        """
        Leverage the @notify decorator and load all objects found matching
        this.
        """
        # A simple restriction that we don't allow periods in the filename at
        # all so it can't be hidden (Linux OS's) and it won't conflict with
        # Python path naming.  This also prevents us from loading any python
        # file that starts with an underscore or dash
        # We allow for __init__.py as well
        module_re = re.compile(
            r'^(?P<name>[_a-z0-9][a-z0-9._-]+)?(\.py)?$', re.I)

        # Validate if we're a loadable Python file or not
        valid_python_file_re = re.compile(r'.+\.py(o|c)?$', re.IGNORECASE)

        if isinstance(paths, str):
            paths = [paths, ]

        if not paths or not isinstance(paths, (tuple, list)):
            # We're done
            return

        def _import_module(path):
            # Since our plugin name can conflict (as a module) with another
            # we want to generate random strings to avoid steping on
            # another's namespace
            if not (path and valid_python_file_re.match(path)):
                # Ignore file/module type
                logger.trace('Plugin Scan: Skipping %s', path)
                return

            t_start = time.time()
            module_name = hashlib.sha1(path.encode('utf-8')).hexdigest()
            module_pyname = "{prefix}.{name}".format(
                prefix='apprise.custom.module', name=module_name)

            if module_pyname in self._custom_module_map:
                # First clear out existing entries
                for schema in \
                        self._custom_module_map[module_pyname]['notify']\
                        .keys():

                    # Remove any mapped modules to this file
                    del self._schema_map[schema]

                # Reset
                del self._custom_module_map[module_pyname]

            # Load our module
            module = import_module(path, module_pyname)
            if not module:
                # No problem, we can't use this object
                logger.warning('Failed to load custom module: %s', _path)
                return

            # Print our loaded modules if any
            if module_pyname in self._custom_module_map:
                logger.debug(
                    'Custom module %s - %d schema(s) (name=%s) '
                    'loaded in %.6fs', _path,
                    len(self._custom_module_map[module_pyname]['notify']),
                    module_name, (time.time() - t_start))

                # Add our plugin name to our module map
                self._module_map[module_name] = {
                    'plugin': set(),
                    'module': module,
                    'path': module_pyname,
                    'native': False,
                }

                for schema, meta in\
                        self._custom_module_map[module_pyname]['notify']\
                        .items():

                    # For mapping purposes; map our element in our main list
                    self._module_map[module_name]['plugin'].add(
                        self._schema_map[schema])

                    # Log our success
                    logger.info('Loaded custom notification: %s://', schema)
            else:
                # The code reaches here if we successfully loaded the Python
                # module but no hooks/triggers were found. So we can safely
                # just remove/ignore this entry
                del sys.modules[module_pyname]
                return

            # end of _import_module()
            return

        for _path in paths:
            path = os.path.abspath(os.path.expanduser(_path))
            if (cache and path in self._paths_previously_scanned) \
                    or not os.path.exists(path):
                # We're done as we've already scanned this
                continue

            # Store our path as a way of hashing it has been handled
            self._paths_previously_scanned.add(path)

            if os.path.isdir(path) and not \
                    os.path.isfile(os.path.join(path, '__init__.py')):

                logger.debug('Scanning for custom plugins in: %s', path)
                for entry in os.listdir(path):
                    re_match = module_re.match(entry)
                    if not re_match:
                        # keep going
                        logger.trace('Plugin Scan: Ignoring %s', entry)
                        continue

                    new_path = os.path.join(path, entry)
                    if os.path.isdir(new_path):
                        # Update our path
                        new_path = os.path.join(path, entry, '__init__.py')
                        if not os.path.isfile(new_path):
                            logger.trace(
                                'Plugin Scan: Ignoring %s',
                                os.path.join(path, entry))
                            continue

                    if not cache or \
                            (cache and new_path not in
                             self._paths_previously_scanned):
                        # Load our module
                        _import_module(new_path)

                        # Add our subdir path
                        self._paths_previously_scanned.add(new_path)
            else:
                if os.path.isdir(path):
                    # This logic is safe to apply because we already
                    # validated the directories state above; update our
                    # path
                    path = os.path.join(path, '__init__.py')
                    if cache and path in self._paths_previously_scanned:
                        continue

                    self._paths_previously_scanned.add(path)

                # directly load as is
                re_match = module_re.match(os.path.basename(path))
                # must be a match and must have a .py extension
                if not re_match or not re_match.group(1):
                    # keep going
                    logger.trace('Plugin Scan: Ignoring %s', path)
                    continue

                # Load our module
                _import_module(path)

        return None

    def add(self, plugin, schemas=None, url=None, send_func=None):
        """
        Ability to manually add Notification services to our stack
        """

        if not self:
            # Lazy load
            self.load_modules()

        # Acquire a list of schemas
        p_schemas = parse_list(plugin.secure_protocol, plugin.protocol)
        if isinstance(schemas, str):
            schemas = [schemas, ]

        elif schemas is None:
            # Default
            schemas = p_schemas

        if not schemas or not isinstance(schemas, (set, tuple, list)):
            # We're done
            logger.error(
                'The schemas provided (type %s) is unsupported; '
                'loaded from %s.',
                type(schemas),
                send_func.__name__ if send_func else plugin.__class__.__name__)
            return False

        # Convert our schemas into a set
        schemas = set([s.lower() for s in schemas]) | set(p_schemas)

        # Valdation
        conflict = [s for s in schemas if s in self]
        if conflict:
            # we're already handling this schema
            logger.warning(
                'The schema(s) (%s) are already defined and could not be '
                'loaded from %s%s.',
                ', '.join(conflict),
                'custom notify function ' if send_func else '',
                send_func.__name__ if send_func else plugin.__class__.__name__)
            return False

        if send_func:
            # Acquire the function name
            fn_name = send_func.__name__

            # Acquire the python filename path
            path = inspect.getfile(send_func)

            # Acquire our path to our module
            module_name = str(send_func.__module__)

            if module_name not in self._custom_module_map:
                # Support non-dynamic includes as well...
                self._custom_module_map[module_name] = {
                    # Name can be useful for indexing back into the
                    # _module_map object; this is the key to do it with:
                    'name': module_name.split('.')[-1],

                    # The path to the module loaded
                    'path': path,

                    # Initialize our template
                    'notify': {},
                }

            for schema in schemas:
                self._custom_module_map[module_name]['notify'][schema] = {
                    # The name of the send function the @notify decorator
                    # wrapped
                    'fn_name': fn_name,
                    # The URL that was provided in the @notify decorator call
                    # associated with the 'on='
                    'url': url,
                }

        else:
            module_name = hashlib.sha1(
                ''.join(schemas).encode('utf-8')).hexdigest()
            module_pyname = "{prefix}.{name}".format(
                prefix='apprise.adhoc.module', name=module_name)

            # Add our plugin name to our module map
            self._module_map[module_name] = {
                'plugin': set([plugin]),
                'module': None,
                'path': module_pyname,
                'native': False,
            }

        for schema in schemas:
            # Assign our mapping
            self._schema_map[schema] = plugin

        return True

    def remove(self, *schemas):
        """
        Removes a loaded element (if defined)
        """
        if not self:
            # Lazy load
            self.load_modules()

        for schema in schemas:
            try:
                del self[schema]

            except KeyError:
                pass

    def plugins(self, include_disabled=True):
        """
        Return all of our loaded plugins
        """
        if not self:
            # Lazy load
            self.load_modules()

        for module in self._module_map.values():
            for plugin in module['plugin']:
                if not include_disabled and not plugin.enabled:
                    continue
                yield plugin

    def schemas(self, include_disabled=True):
        """
        Return all of our loaded schemas

        if include_disabled == True, then even disabled notifications are
        returned
        """
        if not self:
            # Lazy load
            self.load_modules()

        # Return our list
        return list(self._schema_map.keys()) if include_disabled else \
            [s for s in self._schema_map.keys() if self._schema_map[s].enabled]

    def disable(self, *schemas):
        """
        Disables the modules associated with the specified schemas
        """
        if not self:
            # Lazy load
            self.load_modules()

        for schema in schemas:
            if schema not in self._schema_map:
                continue

            if not self._schema_map[schema].enabled:
                continue

            # Disable
            self._schema_map[schema].enabled = False
            self._disabled.add(schema)

    def enable_only(self, *schemas):
        """
        Disables the modules associated with the specified schemas
        """
        if not self:
            # Lazy load
            self.load_modules()

        # convert to set for faster indexing
        schemas = set(schemas)

        for plugin in self.plugins():
            # Get our plugin's schema list
            p_schemas = set(
                parse_list(plugin.secure_protocol, plugin.protocol))

            if not schemas & p_schemas:
                if plugin.enabled:
                    # Disable it (only if previously enabled); this prevents us
                    # from adjusting schemas that were disabled due to missing
                    # libraries or other environment reasons
                    plugin.enabled = False
                    self._disabled |= p_schemas
                continue

            # If we reach here, our schema was flagged to be enabled
            if p_schemas & self._disabled:
                # Previously disabled; no worries, let's clear this up
                self._disabled -= p_schemas
                plugin.enabled = True

    def __contains__(self, schema):
        """
        Checks if a schema exists
        """
        if not self:
            # Lazy load
            self.load_modules()

        return schema in self._schema_map

    def __delitem__(self, schema):
        if not self:
            # Lazy load
            self.load_modules()

        # Get our plugin (otherwise we throw a KeyError) which is
        # intended on del action that doesn't align
        plugin = self._schema_map[schema]

        # Our list of all schema entries
        p_schemas = set([schema])

        for key in list(self._module_map.keys()):
            if plugin in self._module_map[key]['plugin']:
                # Remove our plugin
                self._module_map[key]['plugin'].remove(plugin)

                # Custom Plugin Entry; Clean up cross reference
                module_pyname = self._module_map[key]['path']
                if not self._module_map[key]['native'] and \
                        module_pyname in self._custom_module_map:

                    del self.\
                        _custom_module_map[module_pyname]['notify'][schema]

                    if not self._custom_module_map[module_pyname]['notify']:
                        #
                        # Last custom loaded element
                        #

                        # Free up custom object entry
                        del self._custom_module_map[module_pyname]

                if not self._module_map[key]['plugin']:
                    #
                    # Last element
                    #
                    if self._module_map[key]['native']:
                        # Get our plugin's schema list
                        p_schemas = \
                            set([s for s in parse_list(
                                 plugin.secure_protocol, plugin.protocol)
                                 if s in self._schema_map])

                    # free system memory
                    if self._module_map[key]['module']:
                        del sys.modules[self._module_map[key]['path']]

                    # free last remaining pointer in module map
                    del self._module_map[key]

        for schema in p_schemas:
            # Final Tidy
            del self._schema_map[schema]

    def __setitem__(self, schema, plugin):
        """
        Support fast assigning of Plugin/Notification Objects
        """
        if not self:
            # Lazy load
            self.load_modules()

        # Set default values if not otherwise set
        if not plugin.service_name:
            # Assign service name if one doesn't exist
            plugin.service_name = f'{schema}://'

        p_schemas = set(
            parse_list(plugin.secure_protocol, plugin.protocol))
        if not p_schemas:
            # Assign our protocol
            plugin.secure_protocol = schema
            p_schemas.add(schema)

        elif schema not in p_schemas:
            # Add our others (if defined)
            plugin.secure_protocol = \
                set([schema] + parse_list(plugin.secure_protocol))
            p_schemas.add(schema)

        if not self.add(plugin, schemas=p_schemas):
            raise KeyError('Conflicting Assignment')

    def __getitem__(self, schema):
        """
        Returns the indexed plugin identified by the schema specified
        """
        if not self:
            # Lazy load
            self.load_modules()

        return self._schema_map[schema]

    def __iter__(self):
        """
        Returns an iterator so we can iterate over our loaded modules
        """
        if not self:
            # Lazy load
            self.load_modules()

        return iter(self._module_map.values())

    def __len__(self):
        """
        Returns the number of modules/plugins loaded
        """
        if not self:
            # Lazy load
            self.load_modules()

        return len(self._module_map)

    def __bool__(self):
        """
        Determines if object has loaded or not
        """
        return True if self._loaded and self._module_map is not None else False
