import datetime

import os

import re

import sys

from django.conf import settings

from django.http import HttpResponse, HttpResponseServerError, HttpResponseNotFound

from django.template import (Template, Context, TemplateDoesNotExist,

    TemplateSyntaxError)

from django.utils.html import escape

from django.utils.importlib import import_module

from django.utils.encoding import smart_unicode, smart_str

HIDDEN_SETTINGS = re.compile('SECRET|PASSWORD|PROFANITIES_LIST')

def linebreak_iter(template_source):

    yield 0

    p = template_source.find('\n')

    while p >= 0:

        yield p+1

        p = template_source.find('\n', p+1)

    yield len(template_source) + 1

def cleanse_setting(key, value):

    """Cleanse an individual setting key/value of sensitive content.

    If the value is a dictionary, recursively cleanse the keys in

    that dictionary.

    """

    try:

        if HIDDEN_SETTINGS.search(key):

            cleansed = '********************'

        else:

            if isinstance(value, dict):

                cleansed = dict((k, cleanse_setting(k, v)) for k,v in value.items())

            else:

                cleansed = value

    except TypeError:

        # If the key isn't regex-able, just return as-is.

        cleansed = value

    return cleansed

def get_safe_settings():

    "Returns a dictionary of the settings module, with sensitive settings blurred out."

    settings_dict = {}

    for k in dir(settings):

        if k.isupper():

            settings_dict[k] = cleanse_setting(k, getattr(settings, k))

    return settings_dict

def technical_500_response(request, exc_type, exc_value, tb):

    """

    Create a technical server error response. The last three arguments are

    the values returned from sys.exc_info() and friends.

    """

    reporter = ExceptionReporter(request, exc_type, exc_value, tb)

    html = reporter.get_traceback_html()

    return HttpResponseServerError(html, mimetype='text/html')

class ExceptionReporter:

    """

    A class to organize and coordinate reporting on exceptions.

    """

    def __init__(self, request, exc_type, exc_value, tb):

        self.request = request

        self.exc_type = exc_type

        self.exc_value = exc_value

        self.tb = tb

        self.template_info = None

        self.template_does_not_exist = False

        self.loader_debug_info = None

        # Handle deprecated string exceptions

        if isinstance(self.exc_type, basestring):

            self.exc_value = Exception('Deprecated String Exception: %r' % self.exc_type)

            self.exc_type = type(self.exc_value)

    def get_traceback_html(self):

        "Return HTML code for traceback."

        if issubclass(self.exc_type, TemplateDoesNotExist):

            from django.template.loader import template_source_loaders

            self.template_does_not_exist = True

            self.loader_debug_info = []

            for loader in template_source_loaders:

                try:

                    module = import_module(loader.__module__)

                    source_list_func = module.get_template_sources

                    # NOTE: This assumes exc_value is the name of the template that

                    # the loader attempted to load.

                    template_list = [{'name': t, 'exists': os.path.exists(t)} \

                        for t in source_list_func(str(self.exc_value))]

                except (ImportError, AttributeError):

                    template_list = []

                if hasattr(loader, '__class__'):

                    loader_name = loader.__module__ + '.' + loader.__class__.__name__

                else:

                    loader_name = loader.__module__ + '.' + loader.__name__

                self.loader_debug_info.append({

                    'loader': loader_name,

                    'templates': template_list,

                })

        if (settings.TEMPLATE_DEBUG and hasattr(self.exc_value, 'source') and

            isinstance(self.exc_value, TemplateSyntaxError)):

            self.get_template_exception_info()

        frames = self.get_traceback_frames()

        unicode_hint = ''

        if issubclass(self.exc_type, UnicodeError):

            start = getattr(self.exc_value, 'start', None)

            end = getattr(self.exc_value, 'end', None)

            if start is not None and end is not None:

                unicode_str = self.exc_value.args[1]

                unicode_hint = smart_unicode(unicode_str[max(start-5, 0):min(end+5, len(unicode_str))], 'ascii', errors='replace')

        from django import get_version

        t = Template(TECHNICAL_500_TEMPLATE, name='Technical 500 template')

        c = Context({

            'exception_type': self.exc_type.__name__,

            'exception_value': smart_unicode(self.exc_value, errors='replace'),

            'unicode_hint': unicode_hint,

            'frames': frames,

            'lastframe': frames[-1],

            'request': self.request,

            'settings': get_safe_settings(),

            'sys_executable': sys.executable,

            'sys_version_info': '%d.%d.%d' % sys.version_info[0:3],

            'server_time': datetime.datetime.now(),

            'django_version_info': get_version(),

            'sys_path' : sys.path,

            'template_info': self.template_info,

            'template_does_not_exist': self.template_does_not_exist,

            'loader_debug_info': self.loader_debug_info,

        })

        return t.render(c)

    def get_template_exception_info(self):

        origin, (start, end) = self.exc_value.source

        template_source = origin.reload()

        context_lines = 10

        line = 0

        upto = 0

        source_lines = []

        before = during = after = ""

        for num, next in enumerate(linebreak_iter(template_source)):

            if start >= upto and end <= next:

                line = num

                before = escape(template_source[upto:start])

                during = escape(template_source[start:end])

                after = escape(template_source[end:next])

            source_lines.append( (num, escape(template_source[upto:next])) )

            upto = next

        total = len(source_lines)

        top = max(1, line - context_lines)

        bottom = min(total, line + 1 + context_lines)

        self.template_info = {

            'message': self.exc_value.args[0],

            'source_lines': source_lines[top:bottom],

            'before': before,

            'during': during,

            'after': after,

            'top': top,

            'bottom': bottom,

            'total': total,

            'line': line,

            'name': origin.name,

        }

    def _get_lines_from_file(self, filename, lineno, context_lines, loader=None, module_name=None):

        """

        Returns context_lines before and after lineno from file.

        Returns (pre_context_lineno, pre_context, context_line, post_context).

        """

        source = None

        if loader is not None and hasattr(loader, "get_source"):

            source = loader.get_source(module_name)

            if source is not None:

                source = source.splitlines()

        if source is None:

            try:

                f = open(filename)

                try:

                    source = f.readlines()

                finally:

                    f.close()

            except (OSError, IOError):

                pass

        if source is None:

            return None, [], None, []

        encoding = 'ascii'

        for line in source[:2]:

            # File coding may be specified. Match pattern from PEP-263

            # (http://www.python.org/dev/peps/pep-0263/)

            match = re.search(r'coding[:=]\s*([-\w.]+)', line)

            if match:

                encoding = match.group(1)

                break

        source = [unicode(sline, encoding, 'replace') for sline in source]

        lower_bound = max(0, lineno - context_lines)

        upper_bound = lineno + context_lines

        pre_context = [line.strip('\n') for line in source[lower_bound:lineno]]

        context_line = source[lineno].strip('\n')

        post_context = [line.strip('\n') for line in source[lineno+1:upper_bound]]

        return lower_bound, pre_context, context_line, post_context

    def get_traceback_frames(self):

        frames = []

        tb = self.tb

        while tb is not None:

            # support for __traceback_hide__ which is used by a few libraries

            # to hide internal frames.

            if tb.tb_frame.f_locals.get('__traceback_hide__'):

                tb = tb.tb_next

                continue

            filename = tb.tb_frame.f_code.co_filename

            function = tb.tb_frame.f_code.co_name

            lineno = tb.tb_lineno - 1

            loader = tb.tb_frame.f_globals.get('__loader__')

            module_name = tb.tb_frame.f_globals.get('__name__')

            pre_context_lineno, pre_context, context_line, post_context = self._get_lines_from_file(filename, lineno, 7, loader, module_name)

            if pre_context_lineno is not None:

                frames.append({

                    'tb': tb,

                    'filename': filename,

                    'function': function,

                    'lineno': lineno + 1,

                    'vars': tb.tb_frame.f_locals.items(),

                    'id': id(tb),

                    'pre_context': pre_context,

                    'context_line': context_line,

                    'post_context': post_context,

                    'pre_context_lineno': pre_context_lineno + 1,

                })

            tb = tb.tb_next

        if not frames:

            frames = [{

                'filename': '<unknown>',

                'function': '?',

                'lineno': '?',

                'context_line': '???',

            }]

        return frames

    def format_exception(self):

        """

        Return the same data as from traceback.format_exception.

        """

        import traceback

        frames = self.get_traceback_frames()

        tb = [ (f['filename'], f['lineno'], f['function'], f['context_line']) for f in frames ]

        list = ['Traceback (most recent call last):\n']

        list += traceback.format_list(tb)

        list += traceback.format_exception_only(self.exc_type, self.exc_value)

        return list

def technical_404_response(request, exception):

    "Create a technical 404 error response. The exception should be the Http404."

    try:

        tried = exception.args[0]['tried']

    except (IndexError, TypeError, KeyError):

        tried = []

    else:

        if not tried:

            # tried exists but is an empty list. The URLconf must've been empty.

            return empty_urlconf(request)

    t = Template(TECHNICAL_404_TEMPLATE, name='Technical 404 template')

    c = Context({

        'root_urlconf': settings.ROOT_URLCONF,

        'request_path': request.path_info[1:], # Trim leading slash

        'urlpatterns': tried,

        'reason': smart_str(exception, errors='replace'),

        'request': request,

        'settings': get_safe_settings(),

    })

    return HttpResponseNotFound(t.render(c), mimetype='text/html')

def empty_urlconf(request):

    "Create an empty URLconf 404 error response."

    t = Template(EMPTY_URLCONF_TEMPLATE, name='Empty URLConf template')

    c = Context({

        'project_name': settings.SETTINGS_MODULE.split('.')[0]

    })

    return HttpResponse(t.render(c), mimetype='text/html')

#

# Templates are embedded in the file so that we know the error handler will

# always work even if the template loader is broken.

#

TECHNICAL_500_TEMPLATE = """

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html lang="en">

<head>

  <meta http-equiv="content-type" content="text/html; charset=utf-8">

  <meta name="robots" content="NONE,NOARCHIVE">

  <title>{{ exception_type }} at {{ request.path_info|escape }}</title>

  <style type="text/css">

    html * { padding:0; margin:0; }

    body * { padding:10px 20px; }

    body * * { padding:0; }

    body { font:small sans-serif; }

    body>div { border-bottom:1px solid #ddd; }

    h1 { font-weight:normal; }

    h2 { margin-bottom:.8em; }

    h2 span { font-size:80%; color:#666; font-weight:normal; }

    h3 { margin:1em 0 .5em 0; }

    h4 { margin:0 0 .5em 0; font-weight: normal; }

    table { border:1px solid #ccc; border-collapse: collapse; width:100%; background:white; }

    tbody td, tbody th { vertical-align:top; padding:2px 3px; }

    thead th { padding:1px 6px 1px 3px; background:#fefefe; text-align:left; font-weight:normal; font-size:11px; border:1px solid #ddd; }

    tbody th { width:12em; text-align:right; color:#666; padding-right:.5em; }

    table.vars { margin:5px 0 2px 40px; }

    table.vars td, table.req td { font-family:monospace; }

    table td.code { width:100%; }

    table td.code div { overflow:hidden; }

    table.source th { color:#666; }

    table.source td { font-family:monospace; white-space:pre; border-bottom:1px solid #eee; }

    ul.traceback { list-style-type:none; }

    ul.traceback li.frame { margin-bottom:1em; }

    div.context { margin: 10px 0; }

    div.context ol { padding-left:30px; margin:0 10px; list-style-position: inside; }

    div.context ol li { font-family:monospace; white-space:pre; color:#666; cursor:pointer; }

    div.context ol.context-line li { color:black; background-color:#ccc; }

    div.context ol.context-line li span { float: right; }

    div.commands { margin-left: 40px; }

    div.commands a { color:black; text-decoration:none; }

    #summary { background: #ffc; }

    #summary h2 { font-weight: normal; color: #666; }

    #explanation { background:#eee; }

    #template, #template-not-exist { background:#f6f6f6; }

    #template-not-exist ul { margin: 0 0 0 20px; }

    #unicode-hint { background:#eee; }

    #traceback { background:#eee; }

    #requestinfo { background:#f6f6f6; padding-left:120px; }

    #summary table { border:none; background:transparent; }

    #requestinfo h2, #requestinfo h3 { position:relative; margin-left:-100px; }

    #requestinfo h3 { margin-bottom:-1em; }

    .error { background: #ffc; }

    .specific { color:#cc3300; font-weight:bold; }

    h2 span.commands { font-size:.7em;}

    span.commands a:link {color:#5E5694;}

    pre.exception_value { font-family: sans-serif; color: #666; font-size: 1.5em; margin: 10px 0 10px 0; }

  </style>

  <script type="text/javascript">

  //<!--

    function getElementsByClassName(oElm, strTagName, strClassName){

        // Written by Jonathan Snook, http://www.snook.ca/jon; Add-ons by Robert Nyman, http://www.robertnyman.com

        var arrElements = (strTagName == "*" && document.all)? document.all :

        oElm.getElementsByTagName(strTagName);

        var arrReturnElements = new Array();

        strClassName = strClassName.replace(/\-/g, "\\-");

        var oRegExp = new RegExp("(^|\\s)" + strClassName + "(\\s|$)");

        var oElement;

        for(var i=0; i<arrElements.length; i++){

            oElement = arrElements[i];

            if(oRegExp.test(oElement.className)){

                arrReturnElements.push(oElement);

            }

        }

        return (arrReturnElements)

    }

    function hideAll(elems) {

      for (var e = 0; e < elems.length; e++) {

        elems[e].style.display = 'none';

      }

    }

    window.onload = function() {

      hideAll(getElementsByClassName(document, 'table', 'vars'));

      hideAll(getElementsByClassName(document, 'ol', 'pre-context'));

      hideAll(getElementsByClassName(document, 'ol', 'post-context'));

      hideAll(getElementsByClassName(document, 'div', 'pastebin'));

    }

    function toggle() {

      for (var i = 0; i < arguments.length; i++) {

        var e = document.getElementById(arguments[i]);

        if (e) {

          e.style.display = e.style.display == 'none' ? 'block' : 'none';

        }

      }

      return false;

    }

    function varToggle(link, id) {

      toggle('v' + id);

      var s = link.getElementsByTagName('span')[0];

      var uarr = String.fromCharCode(0x25b6);

      var darr = String.fromCharCode(0x25bc);

      s.innerHTML = s.innerHTML == uarr ? darr : uarr;

      return false;

    }

    function switchPastebinFriendly(link) {

      s1 = "Switch to copy-and-paste view";

      s2 = "Switch back to interactive view";

      link.innerHTML = link.innerHTML == s1 ? s2 : s1;

      toggle('browserTraceback', 'pastebinTraceback');

      return false;

    }

    //-->

  </script>

</head>