# Copyright The IETF Trust 2007-2021, All Rights Reserved
# -*- coding: utf-8 -*-


from django.http import HttpResponsePermanentRedirect, Http404, BadHeaderError
from django.shortcuts import get_object_or_404
import re

import debug                            # pyflakes:ignore

from ietf.redirects.models import Redirect, Command

def redirect(request, path="", script=""):
    if path:
        script = path + "/" + script
    redir = get_object_or_404(Redirect, cgi=script)
    url = "/" + redir.url + "/"
    (rest, remove) = (redir.rest, redir.remove)
    remove_args = []
    cmd = None
    #
    # First look for flag items, stored in the database
    # as a command with a leading "^".
    if request.method == 'POST':
        rparam = request.POST
    else:
        rparam = request.GET    
    for flag in redir.commands.all().filter(command__startswith='^'):
        fc = flag.command[1:].split("^")
        if len(fc) > 1:
            if rparam.get('command') != fc[1]:
                continue
        if fc[0] in rparam:
            remove_args.append(fc[0])
            num = re.match(r'(\d+)', rparam[fc[0]])
            if (num and int(num.group(1))) or (num is None):
                cmd = flag
            break
    #
    # If that search didn't result in a match, then look
    # for an exact match for the command= parameter.
    if cmd is None:
        try:
            cmd = redir.commands.all().get(command=rparam['command'])
        except Command.DoesNotExist:
            pass	# it's ok, there's no more-specific request.
        except KeyError:
            pass	# it's ok, request didn't have 'command'.
        except:
            pass	# strange exception like the one described in
                        # https://trac.ietf.org/trac/ietfdb/ticket/179?
                        # just ignore the command string.
    if cmd is not None:
        remove_args.append('command')
        if cmd.url:
            rest = cmd.url + "/"
        else:
            rest = ""
        if cmd.suffix:
            rest = rest + cmd.suffix.rest
            remove = cmd.suffix.remove
        else:
            remove = ""
    try:
        # This throws exception (which gets caught below) if request 
        # contains non-ASCII characters. The old scripts didn't support 
        # non-ASCII characters anyway, so there's no need to handle 
        # them fully correctly in these redirects.
        (rest % rparam).encode('ascii')
        url += (rest % rparam) + "/"
    except:
        # rest had something in it that request didn't have, so just
        # redirect to the root of the tool.
        pass
    # Be generous in what you accept: collapse multiple slashes
    url = re.sub(r'/+', '/', url)
    if remove:
        url = re.sub(re.escape(remove) + "/?$", "", url)
    # If there is a dot in the last url segment, remove the
    # trailing slash.  This is basically the inverse of the
    # APPEND_SLASH middleware.
    if '/' in url and '.' in url.split('/')[-2]:
        url = url.rstrip('/')
    # Copy the GET arguments, remove all the ones we were
    # expecting and if there are any left, add them to the URL.
    get = request.GET.copy()
    remove_args += re.findall(r'%\(([^)]+)\)', rest)
    for arg in remove_args:
        if arg in get:
            get.pop(arg)
    if get:
        url += '?' + get.urlencode()
    try:
        return HttpResponsePermanentRedirect(url)
    except BadHeaderError:
        raise Http404