# -*- coding: utf-8 -*-

# Copyright(C) 2014 Romain Bignon
#
# This file is part of weboob.
#
# weboob is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# weboob is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with weboob. If not, see <http://www.gnu.org/licenses/>.

from __future__ import absolute_import

import requests
import re
import sys
from copy import deepcopy
from cStringIO import StringIO

from weboob.tools.ordereddict import OrderedDict
from weboob.tools.regex_helper import normalize
from weboob.tools.parsers.lxmlparser import LxmlHtmlParser
from weboob.tools.log import getLogger

from .browser import DomainBrowser
from .filters import _Filter, CleanText


class URL(object):
    """
    A description of an URL on the PagesBrowser website.

    It takes one or several regexps to match urls, and an optional BasePage
    class which is instancied by PagesBrowser.open if the page matches a regex.
    """
    _creation_counter = 0

    def __init__(self, *args):
        self.urls = []
        self.klass = None
        self.browser = None
        for arg in args:
            if isinstance(arg, basestring):
                self.urls.append(arg)
            if isinstance(arg, type):
                self.klass = arg

        self._creation_counter = URL._creation_counter
        URL._creation_counter += 1

    def is_here(self):
        """
        Returns True if the current page of browser matches this URL.
        """
        return self.browser.page and isinstance(self.browser.page, self.klass)

    def stay_or_go(self, **kwargs):
        """
        Request to go on this url only if we aren't already here.

        Arguments are optional parameters for url.

        >>> url = URL('http://exawple.org/(?P<pagename>).html')
        >>> url.stay_or_go(pagename='index')
        """
        if self.browser.page and isinstance(self.browser.page, self.klass):
            return self.browser.page

        return self.go(**kwargs)

    def go(self, **kwargs):
        """
        Request to go on this url.

        Arguments are optional parameters for url.

        >>> url = URL('http://exawple.org/(?P<pagename>).html')
        >>> url.stay_or_go(pagename='index')
        """
        patterns = []
        for url in self.urls:
            patterns += normalize(url)

        for pattern, args in patterns:
            url = pattern % kwargs
            return self.browser.location(url)

    def handle(self, response):
        """
        Handle a HTTP response to get an instance of the klass if it matches.
        """
        for regex in self.urls:
            if regex.startswith('/'):
                regex = self.browser.BASEURL + regex
            m = re.match(regex, response.url)
            if m:
                return self.klass(self.browser, response, m.groupdict())


class _PagesBrowserMeta(type):
    """
    Private meta-class used to keep order of URLs instances of PagesBrowser.
    """
    def __new__(cls, name, bases, attrs):
        urls = [(url_name, attrs.pop(url_name)) for url_name, obj in attrs.items() if isinstance(obj, URL)]
        urls.sort(key=lambda x: x[1]._creation_counter)

        new_class = super(_PagesBrowserMeta, cls).__new__(cls, name, bases, attrs)
        if new_class._urls is None:
            new_class._urls = OrderedDict()
        else:
            new_class._urls = deepcopy(new_class._urls)
        new_class._urls.update(urls)
        return new_class

class PagesBrowser(DomainBrowser):
    """
    A browser which works pages and keep state of navigation.

    To use it, you have to derive it and to create URL objects as class
    attributes. When open() or location() are called, if the url matches
    one of URL objects, it returns a BasePage object. In case of location(), it
    stores it in self.page.

    Example:

        class MyBrowser(PagesBrowser):
            BASEURL = 'http://example.org'

            home = URL('/(index\.html)?', HomePage)
            list = URL('/list\.html', ListPage)

    You can then use URL instances to go on pages.
    """


    _urls = None
    __metaclass__ = _PagesBrowserMeta

    def __getattr__(self, name):
        if self._urls is not None and name in self._urls:
            return self._urls[name]
        else:
            raise AttributeError("'%s' object has no attribute '%s'" % (
                self.__class__.__name__, name))

    def __init__(self, *args, **kwargs):
        super(PagesBrowser, self).__init__(*args, **kwargs)

        self.page = None
        self._urls = deepcopy(self._urls)
        for url in self._urls.itervalues():
            url.browser = self

    def open(self, *args, **kwargs):
        response = super(PagesBrowser, self).open(*args, **kwargs)

        # Try to handle the response page with an URL instance.
        for url in self._urls.itervalues():
            page = url.handle(response)
            if page is not None:
                self.logger.debug('Handle %s with %s' % (response.url, page.__class__.__name__))
                return page

        self.logger.debug('Unable to handle %s' % response.url)
        return response

    def location(self, *args, **kwargs):
        if self.page is not None:
            # Call leave hook.
            self.page.on_leave()

        page = self.open(*args, **kwargs)

        # If open() returns a BasePage instance, store it as the current page.
        if isinstance(page, BasePage):
            response = page.response
            self.page = page
        else:
            response = page
            self.page = None

        self.response = response
        self.url = response.url

        if self.page is not None:
            # Call load hook.
            self.page.on_load()

        return page

    def pagination(self, func, *args, **kwargs):
        """
        This helper function can be used to handle pagination pages easily.

        When the called function raises an exception `NextPage`, it goes on the
        wanted page and recall the function.

        NextPage constructor can take an url or a Request object.

        >>> class Page(HTMLPage):
        ...     def iter_values(self):
        ...         for el in self.doc.xpath('//li'):
        ...             yield el.text
        ...         for next in self.doc.xpath('//a'):
        ...             raise NextPage(next.attrib['href'])
        ...
        >>> class Browser(PagesBrowser):
        ...     BASEURL = 'http://people.symlink.me'
        ...     list = URL('/~rom1/projects/weboob/list-(?P<pagenum>\d+).html', Page)
        ...
        >>> b = Browser()
        >>> b.list.go(pagenum=1)
        >>> list(b.pagination(lambda: b.page.iter_values()))
        ['One', 'Two', 'Three', 'Four']
        """
        while True:
            try:
                for r in func(*args, **kwargs):
                    yield r
            except NextPage as e:
                self.location(e.request)
            else:
                return

class NextPage(Exception):
    """
    Exception used for example in a BasePage to tell PagesBrowser.pagination to
    go on the next page.

    See PagesBrowser.pagination.
    """
    def __init__(self, request):
        self.request = request


def need_login(func):
    """
    Decorator used to require to be logged to access to this function.
    """
    def inner(browser, *args, **kwargs):
        if browser.page is None or not browser.page.logged:
            browser.do_login()
        return func(browser, *args, **kwargs)

    return inner


class LoginBrowser(PagesBrowser):
    """
    A browser which supports login.
    """
    def __init__(self, username, password, *args, **kwargs):
        super(LoginBrowser, self).__init__(*args, **kwargs)
        self.username = username
        self.password = password

    def do_login(self):
        """"
        Abstract method to implement to login on website.

        It is call when a login is needed.
        """
        raise NotImplementedError()


class BasePage(object):
    """
    Base page.
    """
    logged = False

    def __init__(self, browser, response, params):
        self.browser = browser
        self.logger = getLogger(self.__class__.__name__.lower(), browser.logger)
        self.response = response
        self.url = self.response.url
        self.params = params

    def on_load(self):
        pass

    def on_leave(self):
        pass

class FormNotFound(Exception):
    pass

class Form(OrderedDict):
    """
    Represents a form of an HTML page.

    It is used as a dict with pre-filled values from HTML. You can set new
    values as strings by setting an item value.
    """

    def __init__(self, page, el):
        super(Form, self).__init__()
        self.page = page
        self.el = el
        self.method = el.attrib.get('method', 'GET')
        self.url = el.attrib.get('action', page.url)

        for el in el.xpath('.//input'):
            try:
                name = el.attrib['name']
            except KeyError:
                continue
            value = el.attrib.get('value', u'')
            self[name] = value

    @property
    def request(self):
        """
        Get the Request object from the form.
        """
        return requests.Request(self.method, self.url, data=self)

    def submit(self):
        """
        Submit the form and tell browser to be located to the new page.
        """
        return self.page.browser.location(self.request)


class HTMLPage(BasePage):
    """
    HTML page.
    """
    FORM_CLASS = Form

    def __init__(self, browser, response, *args, **kwargs):
        super(HTMLPage, self).__init__(browser, response, *args, **kwargs)
        parser = LxmlHtmlParser()
        self.doc = parser.parse(StringIO(response.content), response.encoding)

    def get_form(self, xpath=None, name=None, nr=None):
        """
        Get a Form object from a xpath selector.
        """
        if xpath is None:
            xpath = '//form'

        i = 0
        for el in self.doc.xpath(xpath):
            if name is not None and el.attrib.get('name', '') != name:
                continue
            i += i
            if nr is not None and i != nr:
                continue

            return self.FORM_CLASS(self, el)

        raise FormNotFound()


def method(klass):
    """
    Class-decorator to call it as a method.
    """
    def inner(self, *args, **kwargs):
        return klass(self)(*args, **kwargs)
    return inner


class AbstractElement(object):
    def __init__(self, page, parent=None, el=None):
        self.page = page
        self.parent = parent
        if el is not None:
            self.el = el
        elif parent is not None:
            self.el = parent.el
        else:
            self.el = page.doc

        if parent is not None:
            self.env = deepcopy(parent.env)
        else:
            self.env = deepcopy(page.params)

    def use_selector(self, func):
        if isinstance(func, _Filter):
            value = func(self)
        elif callable(func):
            value = func()
        else:
            value = deepcopy(func)

        return value

    def parse(self, obj):
        pass

    def xpath(self, *args, **kwargs):
        return self.el.xpath(*args, **kwargs)


class ListElement(AbstractElement):
    item_xpath = None
    flush_at_end = False

    def __init__(self, *args, **kwargs):
        super(ListElement, self).__init__(*args, **kwargs)

        self.objects = {}

    def __call__(self):
        return self.__iter__()

    def __iter__(self):
        self.parse(self.el)

        if self.item_xpath is not None:
            for el in self.el.xpath(self.item_xpath):
                for obj in self.handle_element(el):
                    if not self.flush_at_end:
                        yield obj
        else:
            for obj in self.handle_element(self.el):
                if not self.flush_at_end:
                    yield obj

        if self.flush_at_end:
            for obj in self.objects.itervalues():
                yield obj

        self.check_next_page()

    def check_next_page(self):
        if not hasattr(self, 'next_page'):
            return

        next_page = getattr(self, 'next_page')
        try:
            value = self.use_selector(next_page)
        except IndexError:
            return

        if value is None:
            return

        raise NextPage(value)


    def store(self, obj):
        if obj.id:
            if obj.id in self.objects:
                raise ValueError('There are two objects with the same ID! %s' % obj.id)
            self.objects[obj.id] = obj
        return obj

    def handle_element(self, el):
        for attrname in dir(self):
            attr = getattr(self, attrname)
            if isinstance(attr, type) and issubclass(attr, AbstractElement) and attr != type(self):
                for obj in attr(self.page, self, el):
                    yield self.store(obj)


class SkipItem(Exception):
    pass


class _ItemElementMeta(type):
    """
    Private meta-class used to keep order of obj_* attributes in ItemElement.
    """
    def __new__(cls, name, bases, attrs):
        _attrs = []
        for base in bases:
            if hasattr(base, '_attrs'):
                _attrs += base._attrs

        filters = [(re.sub('^obj_', '', attr_name), attrs[attr_name]) for attr_name, obj in attrs.items() if attr_name.startswith('obj_')]
        # constants first, then filters, then methods
        filters.sort(key=lambda x: x[1]._creation_counter if hasattr(x[1], '_creation_counter') else (sys.maxint if callable(x[1]) else 0))

        new_class = super(_ItemElementMeta, cls).__new__(cls, name, bases, attrs)
        new_class._attrs = _attrs + [f[0] for f in filters]
        return new_class


class ItemElement(AbstractElement):
    __metaclass__ = _ItemElementMeta

    _attrs = None
    klass = None
    condition = None

    class Index(object):
        pass

    def __init__(self, *args, **kwargs):
        super(ItemElement, self).__init__(*args, **kwargs)
        self.obj = None

    def build_object(self):
        return self.klass()

    def __call__(self, obj=None):
        if obj is not None:
            self.obj = obj

        for obj in self:
            return obj

    def __iter__(self):
        if self.condition is not None and not self.condition():
            return

        try:
            if self.obj is None:
                self.obj = self.build_object()
            self.parse(self.el)
            for attr in self._attrs:
                self.handle_attr(attr, getattr(self, 'obj_%s' % attr))
        except SkipItem:
            return

        yield self.obj

    def handle_attr(self, key, func):
        value = self.use_selector(func)
        setattr(self.obj, key, value)


class TableElement(ListElement):
    head_xpath = None
    cleaner = CleanText

    def __init__(self, *args, **kwargs):
        super(TableElement, self).__init__(*args, **kwargs)

        self._cols = {}

        columns = {}
        for attrname in dir(self):
            m = re.match('col_(.*)', attrname)
            if m:
                columns[m.group(1)] = getattr(self, attrname)

        for colnum, el in enumerate(self.el.xpath(self.head_xpath)):
            title = self.cleaner.clean(el)
            for name, titles in columns.iteritems():
                if title in titles or title == titles:
                    self._cols[name] = colnum

    def get_colnum(self, name):
        return self._cols.get(name, None)