"""
Authorisation related functions.

The actions a User is authorised to perform are dependent on their reputation
and superuser status.
"""
import datetime
from django.utils.translation import ugettext as _
from django.db import transaction
from forum.models import Repute
from forum.models import Question
from forum.models import Answer
from forum.models import signals
import logging

from forum.conf import settings as forum_settings

def can_moderate_users(user):
    return user.is_superuser

def can_vote_up(user):
    """Determines if a User can vote Questions and Answers up."""
    return user.is_authenticated() and (
        user.reputation >= forum_settings.MIN_REP_TO_VOTE_UP or
        user.is_superuser)

def can_flag_offensive(user):
    """Determines if a User can flag Questions and Answers as offensive."""
    return user.is_authenticated() and (
        user.reputation >= forum_settings.MIN_REP_TO_FLAG_OFFENSIVE or
        user.is_superuser)

def can_add_comments(user, subject):
    """Determines if a User can add comments to Questions and Answers."""
    if user.is_authenticated():
        if user.id == subject.author.id:
            return True
        if user.reputation >= forum_settings.MIN_REP_TO_LEAVE_COMMENTS:
            return True
        if user.is_superuser:
            return True
        if isinstance(subject, Answer):
            if subject.question.author.id == user.id:
                return True
    return False

def can_vote_down(user):
    """Determines if a User can vote Questions and Answers down."""
    if user.is_authenticated():
        if user.reputation >= forum_settings.MIN_REP_TO_VOTE_DOWN:
            return True
        if user.is_superuser:
            return True
    return False

def can_retag_questions(user):
    """Determines if a User can retag Questions."""
    if user.is_authenticated():
        if user.reputation >= forum_settings.MIN_REP_TO_RETAG_OTHERS_QUESTIONS:
            if user.reputation < forum_settings.MIN_REP_TO_EDIT_OTHERS_POSTS:
                return True
        if user.is_superuser:
            return True
    return False

def can_edit_post(user, post):
    """Determines if a User can edit the given Question or Answer."""
    if user.is_authenticated():
        if user.id == post.author_id:
            return True
        if post.wiki:
            if user.reputation >= forum_settings.MIN_REP_TO_EDIT_WIKI:
                return True
        if user.reputation >= forum_settings.MIN_REP_TO_EDIT_OTHERS_POSTS:
            return True
        if user.is_superuser:
            return True
    return False

def can_delete_comment(user, comment):
    """Determines if a User can delete the given Comment."""
    return user.is_authenticated() and (
        user.id == comment.user_id or
        user.reputation >= forum_settings.MIN_REP_TO_DELETE_OTHERS_COMMENTS or
        user.is_superuser)

def can_view_offensive_flags(user):
    """Determines if a User can view offensive flag counts."""
    return user.is_authenticated() and (
        user.reputation >= forum_settings.MIN_REP_TO_VIEW_OFFENSIVE_FLAGS or
        user.is_superuser)

def can_close_question(user, question):
    """Determines if a User can close the given Question."""
    return user.is_authenticated() and (
        (user.id == question.author_id and
         user.reputation >= forum_settings.MIN_REP_TO_CLOSE_OWN_QUESTIONS) or
        user.reputation >= forum_settings.MIN_REP_TO_CLOSE_OTHERS_QUESTIONS or
        user.is_superuser)

def can_lock_posts(user):
    """Determines if a User can lock Questions or Answers."""
    return user.is_authenticated() and (
        user.reputation >= forum_settings.MIN_REP_TO_LOCK_POSTS or
        user.is_superuser)

def can_follow_url(user):
    """Determines if the URL link can be followed by Google search engine."""
    return user.reputation >= forum_settings.MIN_REP_TO_DISABLE_URL_NOFOLLOW

def can_accept_answer(user, question, answer):
    if user.is_superuser:
        return True
    if user.is_authenticated():
        if question.author != answer.author and question.author == user:
            return True
    return False

# now only support to reopen own question except superuser
def can_reopen_question(user, question):
    if user.is_superuser:
        return True
    if user.is_authenticated() and user.id == question.author_id:
        if user.reputation >= forum_settings.MIN_REP_TO_REOPEN_OWN_QUESTIONS:
            return True
    return False

def can_delete_post(user, post):
    if user.is_superuser:
        return True
    elif user.is_authenticated() and user == post.author:
        if isinstance(post, Answer):
            return True
        elif isinstance(post, Question):
            answers = post.answers.all()
            for answer in answers:
                if user != answer.author and answer.deleted == False:
                    return False
            return True
        else:
            return False
    else:
        return False

def can_view_deleted_post(user, post):
    return user.is_superuser

# user preferences view permissions
def is_user_self(request_user, target_user):
    return (request_user.is_authenticated() and request_user == target_user)
    
def can_view_user_votes(request_user, target_user):
    return (request_user.is_authenticated() and request_user == target_user)

def can_view_user_preferences(request_user, target_user):
    return (request_user.is_authenticated() and request_user == target_user)

def can_view_user_edit(request_user, target_user):
    return (request_user.is_authenticated() and request_user == target_user)

def can_upload_files(request_user):
    if request_user.is_superuser:
        return True
    if request_user.is_authenticated():
        if request_user.reputation >= forum_settings.MIN_REP_TO_UPLOAD_FILES:
            return True
    return False

###########################################
## actions and reputation changes event
###########################################
def calculate_reputation(origin, offset):
    result = int(origin) + int(offset)
    if (result > 0):
        return result
    else:
        return 1

@transaction.commit_on_success
def onFlaggedItem(item, post, user, timestamp=None):
    if timestamp is None:
        timestamp = datetime.datetime.now()

    item.save()
    post.offensive_flag_count = post.offensive_flag_count + 1
    post.save()

    post.author.reputation = calculate_reputation(
                                post.author.reputation,
                                forum_settings.REP_LOSS_FOR_RECEIVING_DOWNVOTE
                            )
    post.author.save()

    question = post
    if isinstance(post, Answer):
        question = post.question

    reputation = Repute(
                    user=post.author,
                    negative=forum_settings.REP_LOSS_FOR_RECEIVING_DOWNVOTE,
                    question=question, reputed_at=timestamp,
                    reputation_type=-4,
                    reputation=post.author.reputation
                )
    reputation.save()

    #todo: These should be updated to work on same revisions.
    if post.offensive_flag_count ==  forum_settings.MIN_FLAGS_TO_HIDE_POST:
        post.author.reputation = \
            calculate_reputation(
                post.author.reputation,
                forum_settings.REP_LOSS_FOR_RECEIVING_THREE_FLAGS_PER_REVISION
            )

        post.author.save()

        reputation = Repute(
            user=post.author,
            negative=\
                forum_settings.REP_LOSS_FOR_RECEIVING_THREE_FLAGS_PER_REVISION,
            question=question,
            reputed_at=timestamp,
            reputation_type=-6,
            reputation=post.author.reputation
        )
        reputation.save()

    elif post.offensive_flag_count == forum_settings.MIN_FLAGS_TO_DELETE_POST:
        post.author.reputation = \
            calculate_reputation(
                post.author.reputation,
                forum_settings.REP_LOSS_FOR_RECEIVING_FIVE_FLAGS_PER_REVISION
            )

        post.author.save()

        reputation = Repute(
            user=post.author,
            negative=\
                forum_settings.REP_LOSS_FOR_RECEIVING_FIVE_FLAGS_PER_REVISION,
            question=question,
            reputed_at=timestamp,
            reputation_type=-7,
            reputation=post.author.reputation
        )
        reputation.save()

        post.deleted = True
        #post.deleted_at = timestamp
        #post.deleted_by = Admin
        post.save()
        signals.mark_offensive.send(
            sender=post.__class__, 
            instance=post, 
            mark_by=user
        )

@transaction.commit_on_success
def onAnswerAccept(answer, user, timestamp=None):
    if timestamp is None:
        timestamp = datetime.datetime.now()

    answer.accepted = True
    answer.accepted_at = timestamp
    answer.question.answer_accepted = True
    answer.save()
    answer.question.save()

    answer.author.reputation = calculate_reputation(
                        answer.author.reputation,
                        forum_settings.REP_GAIN_FOR_RECEIVING_ANSWER_ACCEPTANCE
                    )
    answer.author.save()
    reputation = Repute(user=answer.author,
               positive=forum_settings.REP_GAIN_FOR_RECEIVING_ANSWER_ACCEPTANCE,
               question=answer.question,
               reputed_at=timestamp,
               reputation_type=2,
               reputation=answer.author.reputation)
    reputation.save()

    user.reputation = calculate_reputation(user.reputation,
                            forum_settings.REP_GAIN_FOR_ACCEPTING_ANSWER)
    user.save()
    reputation = Repute(user=user,
               positive=forum_settings.REP_GAIN_FOR_ACCEPTING_ANSWER,
               question=answer.question,
               reputed_at=timestamp,
               reputation_type=3,
               reputation=user.reputation)
    reputation.save()

@transaction.commit_on_success
def onAnswerAcceptCanceled(answer, user, timestamp=None):
    if timestamp is None:
        timestamp = datetime.datetime.now()
    answer.accepted = False
    answer.accepted_at = None
    answer.question.answer_accepted = False
    answer.save()
    answer.question.save()

    answer.author.reputation = calculate_reputation(
        answer.author.reputation,
        forum_settings.REP_LOSS_FOR_RECEIVING_CANCELATION_OF_ANSWER_ACCEPTANCE
    )
    answer.author.save()
    reputation = Repute(
        user=answer.author,
        negative=\
         forum_settings.REP_LOSS_FOR_RECEIVING_CANCELATION_OF_ANSWER_ACCEPTANCE,
        question=answer.question,
        reputed_at=timestamp,
        reputation_type=-2,
        reputation=answer.author.reputation
    )
    reputation.save()

    user.reputation = calculate_reputation(user.reputation,
                    forum_settings.REP_LOSS_FOR_CANCELING_ANSWER_ACCEPTANCE)
    user.save()
    reputation = Repute(user=user,
               negative=forum_settings.REP_LOSS_FOR_CANCELING_ANSWER_ACCEPTANCE,
               question=answer.question,
               reputed_at=timestamp,
               reputation_type=-1,
               reputation=user.reputation)
    reputation.save()

@transaction.commit_on_success
def onUpVoted(vote, post, user, timestamp=None):
    if timestamp is None:
        timestamp = datetime.datetime.now()
    vote.save()

    post.vote_up_count = int(post.vote_up_count) + 1
    post.score = int(post.score) + 1
    post.save()

    if not post.wiki:
        author = post.author
        todays_rep_gain = Repute.objects.get_reputation_by_upvoted_today(author)
        if todays_rep_gain <  forum_settings.MAX_REP_GAIN_PER_USER_PER_DAY:
            author.reputation = calculate_reputation(author.reputation,
                              forum_settings.REP_GAIN_FOR_RECEIVING_UPVOTE)
            author.save()

            question = post
            if isinstance(post, Answer):
                question = post.question

            reputation = Repute(user=author,
                       positive=forum_settings.REP_GAIN_FOR_RECEIVING_UPVOTE,
                       question=question,
                       reputed_at=timestamp,
                       reputation_type=1,
                       reputation=author.reputation)
            reputation.save()

@transaction.commit_on_success
def onUpVotedCanceled(vote, post, user, timestamp=None):
    if timestamp is None:
        timestamp = datetime.datetime.now()
    vote.delete()

    post.vote_up_count = int(post.vote_up_count) - 1
    if post.vote_up_count < 0:
        post.vote_up_count  = 0
    post.score = int(post.score) - 1
    post.save()

    if not post.wiki:
        author = post.author
        author.reputation = \
                calculate_reputation(
                    author.reputation,
                    forum_settings.REP_LOSS_FOR_RECEIVING_UPVOTE_CANCELATION
                )
        author.save()

        question = post
        if isinstance(post, Answer):
            question = post.question

        reputation = Repute(
            user=author,
            negative=forum_settings.REP_LOSS_FOR_RECEIVING_UPVOTE_CANCELATION,
            question=question,
            reputed_at=timestamp,
            reputation_type=-8,
            reputation=author.reputation
        )
        reputation.save()

@transaction.commit_on_success
def onDownVoted(vote, post, user, timestamp=None):
    if timestamp is None:
        timestamp = datetime.datetime.now()
    vote.save()

    post.vote_down_count = int(post.vote_down_count) + 1
    post.score = int(post.score) - 1
    post.save()

    if not post.wiki:
        author = post.author
        author.reputation = calculate_reputation(
                                        author.reputation,
                                        forum_settings.REP_LOSS_FOR_DOWNVOTING
                                    )
        author.save()

        question = post
        if isinstance(post, Answer):
            question = post.question

        reputation = Repute(user=author,
                   negative=forum_settings.REP_LOSS_FOR_DOWNVOTING,
                   question=question,
                   reputed_at=timestamp,
                   reputation_type=-3,
                   reputation=author.reputation)
        reputation.save()

        user.reputation = calculate_reputation(
                                user.reputation,
                                forum_settings.REP_LOSS_FOR_RECEIVING_DOWNVOTE
                            )
        user.save()

        reputation = Repute(user=user,
                   negative=forum_settings.REP_LOSS_FOR_RECEIVING_DOWNVOTE,
                   question=question,
                   reputed_at=timestamp,
                   reputation_type=-5,
                   reputation=user.reputation)
        reputation.save()

@transaction.commit_on_success
def onDownVotedCanceled(vote, post, user, timestamp=None):
    if timestamp is None:
        timestamp = datetime.datetime.now()
    vote.delete()

    post.vote_down_count = int(post.vote_down_count) - 1
    if post.vote_down_count < 0:
        post.vote_down_count  = 0
    post.score = post.score + 1
    post.save()

    if not post.wiki:
        author = post.author
        author.reputation = calculate_reputation(
                author.reputation,
                forum_settings.REP_GAIN_FOR_RECEIVING_DOWNVOTE_CANCELATION
            )
        author.save()

        question = post
        if isinstance(post, Answer):
            question = post.question

        reputation = Repute(user=author,
                positive=\
                    forum_settings.REP_GAIN_FOR_RECEIVING_DOWNVOTE_CANCELATION,
                question=question,
                reputed_at=timestamp,
                reputation_type=4,
                reputation=author.reputation
            )
        reputation.save()

        user.reputation = calculate_reputation(user.reputation,
                        forum_settings.REP_GAIN_FOR_CANCELING_DOWNVOTE)
        user.save()

        reputation = Repute(user=user,
                   positive=forum_settings.REP_GAIN_FOR_CANCELING_DOWNVOTE,
                   question=question,
                   reputed_at=timestamp,
                   reputation_type=5,
                   reputation=user.reputation)
        reputation.save()

#here timestamp is not used, I guess added for consistency
def onDeleteCanceled(post, user, timestamp=None):
    post.deleted = False
    post.deleted_by = None 
    post.deleted_at = None 
    post.save()
    logging.debug('now restoring something')
    if isinstance(post, Answer):
        logging.debug(
                    'updated answer count on undelete, have %d' \
                    % post.question.answer_count
                )
        Question.objects.update_answer_count(post.question)
    elif isinstance(post, Question):
        for tag in list(post.tags.all()):
            if tag.used_count == 1 and tag.deleted:
                tag.deleted = False
                tag.deleted_by = None
                tag.deleted_at = None 
                tag.save()

def onDeleted(post, user, timestamp=None):
    if timestamp is None:
        timestamp = datetime.datetime.now()
    post.deleted = True
    post.deleted_by = user
    post.deleted_at = timestamp
    post.save()

    if isinstance(post, Question):
        for tag in list(post.tags.all()):
            if tag.used_count == 1:
                tag.deleted = True
                tag.deleted_by = user
                tag.deleted_at = timestamp
            else:
                tag.used_count = tag.used_count - 1 
            tag.save()

        answers = post.answers.all()
        if user == post.author:
            if len(answers) > 0:
                msg = _(
                    'Your question and all of it\'s answers have been deleted'
                    )
            else:
                msg = _('Your question has been deleted')
        else:
            if len(answers) > 0:
                msg = _(
                    'The question and all of it\'s answers have been deleted'
                    )
            else:
                msg = _('The question has been deleted')
        user.message_set.create(message=msg)
        logging.debug('posted a message %s' % msg)
        for answer in answers:
            onDeleted(answer, user)
    elif isinstance(post, Answer):
        Question.objects.update_answer_count(post.question)
        logging.debug('updated answer count to %d' % post.question.answer_count)
    signals.delete_post_or_answer.send(
        sender=post.__class__,
        instance=post,
        delete_by=user
    )