#! /usr/bin/env python
# -*- coding: utf-8  -*-
#
# Copyright (C) 2009-2015 Ben Kurtovic <ben.kurtovic@gmail.com>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

import imp
from os import listdir, path
from re import sub
from threading import RLock, Thread
from time import gmtime, strftime

from earwigbot.commands import Command
from earwigbot.tasks import Task

__all__ = ["CommandManager", "TaskManager"]

class _ResourceManager(object):
    """
    **EarwigBot: Resource Manager**

    Resources are essentially objects dynamically loaded by the bot, both
    packaged with it (built-in resources) and created by users (plugins, aka
    custom resources). Currently, the only two types of resources are IRC
    commands and bot tasks. These are both loaded from two locations: the
    :py:mod:`earwigbot.commands` and :py:mod:`earwigbot.tasks packages`, and
    the :file:`commands/` and :file:`tasks/` directories within the bot's
    working directory.

    This class handles the low-level tasks of (re)loading resources via
    :py:meth:`load`, retrieving specific resources via :py:meth:`get`, and
    iterating over all resources via :py:meth:`__iter__`.
    """
    def __init__(self, bot, name, base):
        self.bot = bot
        self.logger = bot.logger.getChild(name)

        self._resources = {}
        self._resource_name = name  # e.g. "commands" or "tasks"
        self._resource_base = base  # e.g. Command or Task
        self._resource_access_lock = RLock()

    def __repr__(self):
        """Return the canonical string representation of the manager."""
        res = "{0}(bot={1!r}, name={2!r}, base={3!r})"
        return res.format(self.__class__.__name__, self.bot,
                          self._resource_name, self._resource_base)

    def __str__(self):
        """Return a nice string representation of the manager."""
        return "<{0} of {1}>".format(self.__class__.__name__, self.bot)

    def __iter__(self):
        with self.lock:
            for resource in self._resources.itervalues():
                yield resource

    def _load_resource(self, name, path, klass):
        """Instantiate a resource class and add it to the dictionary."""
        res_type = self._resource_name[:-1]  # e.g. "command" or "task"
        if hasattr(klass, "name"):
            res_config = getattr(self.bot.config, self._resource_name)
            if getattr(klass, "name") in res_config.get("disable", []):
                log = "Skipping disabled {0} {1}"
                self.logger.debug(log.format(res_type, getattr(klass, "name")))
                return
        try:
            resource = klass(self.bot)  # Create instance of resource
        except Exception:
            e = "Error instantiating {0} class in '{1}' (from {2})"
            self.logger.exception(e.format(res_type, name, path))
        else:
            self._resources[resource.name] = resource
            self.logger.debug("Loaded {0} {1}".format(res_type, resource.name))

    def _load_module(self, name, path):
        """Load a specific resource from a module, identified by name and path.

        We'll first try to import it using imp magic, and if that works, make
        instances of any classes inside that are subclasses of the base
        (:py:attr:`self._resource_base <_resource_base>`), add them to the
        resources dictionary with :py:meth:`self._load_resource()
        <_load_resource>`, and finally log the addition. Any problems along
        the way will either be ignored or logged.
        """
        f, path, desc = imp.find_module(name, [path])
        try:
            module = imp.load_module(name, f, path, desc)
        except Exception:
            e = "Couldn't load module '{0}' (from {1})"
            self.logger.exception(e.format(name, path))
            return
        finally:
            f.close()

        for obj in vars(module).values():
            if type(obj) is type:
                isresource = issubclass(obj, self._resource_base)
                if isresource and not obj is self._resource_base:
                    self._load_resource(name, path, obj)

    def _load_directory(self, dir):
        """Load all valid resources in a given directory."""
        self.logger.debug("Loading directory {0}".format(dir))
        res_config = getattr(self.bot.config, self._resource_name)
        disabled = res_config.get("disable", [])
        processed = []
        for name in listdir(dir):
            if not name.endswith(".py") and not name.endswith(".pyc"):
                continue
            if name.startswith("_") or name.startswith("."):
                continue
            modname = sub("\.pyc?$", "", name)  # Remove extension
            if modname in disabled:
                log = "Skipping disabled module {0}".format(modname)
                self.logger.debug(log)
                continue
            if modname not in processed:
                self._load_module(modname, dir)
                processed.append(modname)

    @property
    def lock(self):
        """The resource access/modify lock."""
        return self._resource_access_lock

    def load(self):
        """Load (or reload) all valid resources into :py:attr:`_resources`."""
        name = self._resource_name  # e.g. "commands" or "tasks"
        with self.lock:
            self._resources.clear()
            builtin_dir = path.join(path.dirname(__file__), name)
            plugins_dir = path.join(self.bot.config.root_dir, name)
            if getattr(self.bot.config, name).get("disable") is True:
                log = "Skipping disabled builtins directory: {0}"
                self.logger.debug(log.format(builtin_dir))
            else:
                self._load_directory(builtin_dir)  # Built-in resources
            if path.exists(plugins_dir) and path.isdir(plugins_dir):
                self._load_directory(plugins_dir)  # Custom resources, plugins
            else:
                log = "Skipping nonexistent plugins directory: {0}"
                self.logger.debug(log.format(plugins_dir))

        if self._resources:
            msg = "Loaded {0} {1}: {2}"
            resources = ", ".join(self._resources.keys())
            self.logger.info(msg.format(len(self._resources), name, resources))
        else:
            self.logger.info("Loaded 0 {0}".format(name))

    def get(self, key):
        """Return the class instance associated with a certain resource.

        Will raise :py:exc:`KeyError` if the resource (a command or task) is
        not found.
        """
        with self.lock:
            return self._resources[key]


class CommandManager(_ResourceManager):
    """
    Manages (i.e., loads, reloads, and calls) IRC commands.
    """
    def __init__(self, bot):
        super(CommandManager, self).__init__(bot, "commands", Command)

    def _wrap_check(self, command, data):
        """Check whether a command should be called, catching errors."""
        try:
            return command.check(data)
        except Exception:
            e = "Error checking command '{0}' with data: {1}:"
            self.logger.exception(e.format(command.name, data))

    def _wrap_process(self, command, data):
        """process() the message, catching and reporting any errors."""
        try:
            command.process(data)
        except Exception:
            e = "Error executing command '{0}':"
            self.logger.exception(e.format(command.name))

    def call(self, hook, data):
        """Respond to a hook type and a :py:class:`Data` object."""
        for command in self:
            if hook in command.hooks and self._wrap_check(command, data):
                thread = Thread(target=self._wrap_process,
                                args=(command, data))
                start_time = strftime("%b %d %H:%M:%S")
                thread.name = "irc:{0} ({1})".format(command.name, start_time)
                thread.daemon = True
                thread.start()
                return


class TaskManager(_ResourceManager):
    """
    Manages (i.e., loads, reloads, schedules, and runs) wiki bot tasks.
    """
    def __init__(self, bot):
        super(TaskManager, self).__init__(bot, "tasks", Task)

    def _wrapper(self, task, **kwargs):
        """Wrapper for task classes: run the task and catch any errors."""
        try:
            task.run(**kwargs)
        except Exception:
            msg = "Task '{0}' raised an exception and had to stop:"
            self.logger.exception(msg.format(task.name))
        else:
            msg = "Task '{0}' finished successfully"
            self.logger.info(msg.format(task.name))

    def start(self, task_name, **kwargs):
        """Start a given task in a new daemon thread, and return the thread.

        kwargs are passed to :py:meth:`task.run() <earwigbot.tasks.Task.run>`.
        If the task is not found, ``None`` will be returned and an error will
        be logged.
        """
        msg = "Starting task '{0}' in a new thread"
        self.logger.info(msg.format(task_name))

        try:
            task = self.get(task_name)
        except KeyError:
            e = "Couldn't find task '{0}'"
            self.logger.error(e.format(task_name))
            return

        task_thread = Thread(target=self._wrapper, args=(task,), kwargs=kwargs)
        start_time = strftime("%b %d %H:%M:%S")
        task_thread.name = "{0} ({1})".format(task_name, start_time)
        task_thread.daemon = True
        task_thread.start()
        return task_thread

    def schedule(self, now=None):
        """Start all tasks that are supposed to be run at a given time."""
        if not now:
            now = gmtime()
        # Get list of tasks to run this turn:
        tasks = self.bot.config.schedule(now.tm_min, now.tm_hour, now.tm_mday,
                                         now.tm_mon, now.tm_wday)

        for task in tasks:
            if isinstance(task, list):          # They've specified kwargs,
                self.start(task[0], **task[1])  # so pass those to start
            else:  # Otherwise, just pass task_name
                self.start(task)