from django import http
from django.conf import settings
from utils import next_redirect, confirmation_view
from django.core.exceptions import ObjectDoesNotExist
from django.db import models
from django.shortcuts import render_to_response
from django.template import RequestContext
from django.template.loader import render_to_string
from django.utils.html import escape
from django.contrib import comments
from django.contrib.comments import signals

class CommentPostBadRequest(http.HttpResponseBadRequest):
    """
    Response returned when a comment post is invalid. If ``DEBUG`` is on a
    nice-ish error message will be displayed (for debugging purposes), but in
    production mode a simple opaque 400 page will be displayed.
    """
    def __init__(self, why):
        super(CommentPostBadRequest, self).__init__()
        if settings.DEBUG:
            self.content = render_to_string("comments/400-debug.html", {"why": why})

def post_comment(request, next=None):
    """
    Post a comment.

    HTTP POST is required. If ``POST['submit'] == "preview"`` or if there are
    errors a preview template, ``comments/preview.html``, will be rendered.
    """

    # Require POST
    if request.method != 'POST':
        return http.HttpResponseNotAllowed(["POST"])

    # Fill out some initial data fields from an authenticated user, if present
    data = request.POST.copy()
    if request.user.is_authenticated():
        if "name" not in data:
            data["name"] = request.user.get_full_name()
        if "email" not in data:
            data["email"] = request.user.email

    # Look up the object we're trying to comment about
    ctype = data.get("content_type")
    object_pk = data.get("object_pk")
    if ctype is None or object_pk is None:
        return CommentPostBadRequest("Missing content_type or object_pk field.")
    try:
        model = models.get_model(*ctype.split(".", 1))
        target = model._default_manager.get(pk=object_pk)
    except TypeError:
        return CommentPostBadRequest(
            "Invalid content_type value: %r" % escape(ctype))
    except AttributeError:
        return CommentPostBadRequest(
            "The given content-type %r does not resolve to a valid model." % \
                escape(ctype))
    except ObjectDoesNotExist:
        return CommentPostBadRequest(
            "No object matching content-type %r and object PK %r exists." % \
                (escape(ctype), escape(object_pk)))

    # Do we want to preview the comment?
    preview = data.get("submit", "").lower() == "preview" or \
              data.get("preview", None) is not None

    # Construct the comment form
    form = comments.get_form()(target, data=data)

    # Check security information
    if form.security_errors():
        return CommentPostBadRequest(
            "The comment form failed security verification: %s" % \
                escape(str(form.security_errors())))

    # If there are errors or if we requested a preview show the comment
    if form.errors or preview:
        template_list = [
            "comments/%s_%s_preview.html" % tuple(str(model._meta).split(".")),
            "comments/%s_preview.html" % model._meta.app_label,
            "comments/preview.html",
        ]
        return render_to_response(
            template_list, {
                "comment" : form.data.get("comment", ""),
                "form" : form,
            }, 
            RequestContext(request, {})
        )

    # Otherwise create the comment
    comment = form.get_comment_object()
    comment.ip_address = request.META.get("REMOTE_ADDR", None)
    if request.user.is_authenticated():
        comment.user = request.user

    # Signal that the comment is about to be saved
    responses = signals.comment_will_be_posted.send(
        sender  = comment.__class__,
        comment = comment,
        request = request
    )

    for (receiver, response) in responses:
        if response == False:
            return CommentPostBadRequest(
                "comment_will_be_posted receiver %r killed the comment" % receiver.__name__)

    # Save the comment and signal that it was saved
    comment.save()
    signals.comment_was_posted.send(
        sender  = comment.__class__,
        comment = comment,
        request = request
    )

    return next_redirect(data, next, comment_done, c=comment._get_pk_val())

comment_done = confirmation_view(
    template = "comments/posted.html",
    doc = """Display a "comment was posted" success page."""
)