import json

from django.http import HttpResponse, HttpResponseRedirect
from django.shortcuts import get_object_or_404, render
from django.template import RequestContext, loader
from django.urls import reverse
from django.views.decorators.csrf import csrf_exempt
from pygments import highlight
from pygments.formatters import HtmlFormatter
from pygments.lexers import get_lexer_by_name

from webtools import settings

from paste.forms import PasteForm
from paste.models import Language, Paste


@csrf_exempt
def index(request):
    """Displays form."""
    if request.method == "GET":
        return render(request, "paste/index.html")
    paste = Paste()
    paste.choose_slug()
    if request.FILES:
        (language_name, the_file), *_ = request.FILES.items()
        language = Language.by_name(language_name)
        form = PasteForm(
            {
                "language": language.id,
                "content": the_file.read().decode(),
            },
            instance=paste,
        )
    if not form.is_valid():
        return HttpResponse(json.dumps(form.errors, indent=4))
    form.save()
    location = request.build_absolute_uri(
        reverse("short_paste", kwargs={"slug": paste.slug})
    )
    return HttpResponseRedirect(
        location, content=location + "\n", content_type="text/plain"
    )


def show(request, slug):
    """Display paste."""

    paste = get_object_or_404(Paste, slug=slug)
    paste.incr_viewcount()

    if "html" in request.headers["accept"]:
        render_method = render_pygments
    else:
        render_method = render_raw
    return render_method(request, paste, {"slug": slug})


def render_pygments(request, paste, data):
    """Renders Pygments template."""
    lexer = get_lexer_by_name(paste.language.slug)
    formatter = HtmlFormatter(style="emacs")
    highlighted_content = highlight(paste.content, lexer, formatter)
    data["paste"] = paste
    data["highlighted"] = highlighted_content
    rendered = loader.render_to_string("paste/show-pygments.html", data, request)
    return HttpResponse(rendered)


def render_raw(request, paste, data):
    """Renders RAW content."""
    return HttpResponse(paste.content, content_type="text/plain")