from django.conf import settings
from django.template import Template, Context, TemplateDoesNotExist
from django.utils.html import escape
from django.http import HttpResponseServerError, HttpResponseNotFound
import os, re
from itertools import count, izip
from os.path import dirname, join as pathjoin

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

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 get_template_exception_info(exc_type, exc_value, tb):
    origin, (start, end) = 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)

    template_info = {
        'message': 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,
    }
    exc_info = hasattr(exc_value, 'exc_info') and exc_value.exc_info or (exc_type, exc_value, tb)
    return exc_info + (template_info,)

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():
            if HIDDEN_SETTINGS.search(k):
                settings_dict[k] = '********************'
            else:
                settings_dict[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.
    """
    template_info = None
    template_does_not_exist = False
    loader_debug_info = None
    if issubclass(exc_type, TemplateDoesNotExist):
        from django.template.loader import template_source_loaders
        template_does_not_exist = True
        loader_debug_info = []
        for loader in template_source_loaders:
            try:
                source_list_func = getattr(__import__(loader.__module__, '', '', ['get_template_sources']), '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(exc_value))]
            except (ImportError, AttributeError):
                template_list = []
            loader_debug_info.append({
                'loader': loader.__module__ + '.' + loader.__name__,
                'templates': template_list,
            })
    if settings.TEMPLATE_DEBUG and hasattr(exc_value, 'source'):
        exc_type, exc_value, tb, template_info = get_template_exception_info(exc_type, exc_value, tb)
    frames = []
    while tb is not None:
        filename = tb.tb_frame.f_code.co_filename
        function = tb.tb_frame.f_code.co_name
        lineno = tb.tb_lineno - 1
        pre_context_lineno, pre_context, context_line, post_context = _get_lines_from_file(filename, lineno, 7)
        if pre_context_lineno:
            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

    t = Template(TECHNICAL_500_TEMPLATE)
    c = Context({
        'exception_type': exc_type.__name__,
        'exception_value': exc_value,
        'frames': frames,
        'lastframe': frames[-1],
        'request': request,
        'request_protocol': os.environ.get("HTTPS") == "on" and "https" or "http",
        'settings': get_safe_settings(),
        'template_info': template_info,
        'template_does_not_exist': template_does_not_exist,
        'loader_debug_info': loader_debug_info,
    })
    return HttpResponseServerError(t.render(c), mimetype='text/html')

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):
        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)
    c = Context({
        'root_urlconf': settings.ROOT_URLCONF,
        'urlpatterns': tried,
        'reason': str(exception),
        'request': request,
        'request_protocol': os.environ.get("HTTPS") == "on" and "https" or "http",
        '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)
    c = Context({
        'project_name': settings.SETTINGS_MODULE.split('.')[0]
    })
    return HttpResponseNotFound(t.render(c), mimetype='text/html')

def _get_lines_from_file(filename, lineno, context_lines):
    """
    Returns context_lines before and after lineno from file.
    Returns (pre_context_lineno, pre_context, context_line, post_context).
    """
    try:
        source = open(filename).readlines()
        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
    except (OSError, IOError):
        return None, [], None, []

#
# 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 }}</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; }
    #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; }
  </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>
<body>

<div id="summary">
  <h1>{{ exception_type }} at {{ request.path }}</h1>
  <h2>{{ exception_value|escape }}</h2>
  <table class="meta">
    <tr>
      <th>Request Method:</th>
      <td>{{ request.META.REQUEST_METHOD }}</td>
    </tr>
    <tr>
      <th>Request URL:</th>
      <td>{{ request_protocol }}://{{ request.META.HTTP_HOST }}{{ request.path }}</td>
    </tr>
    <tr>
      <th>Exception Type:</th>
      <td>{{ exception_type }}</td>
    </tr>
    <tr>
      <th>Exception Value:</th>
      <td>{{ exception_value }}</td>
    </tr>
    <tr>
      <th>Exception Location:</th>
      <td>{{ lastframe.filename }} in {{ lastframe.function }}, line {{ lastframe.lineno }}</td>
    </tr>
  </table>
</div>
{% if template_does_not_exist %}
<div id="template-not-exist">
    <h2>Template-loader postmortem</h2>
    {% if loader_debug_info %}
        <p>Django tried loading these templates, in this order:</p>
        <ul>
        {% for loader in loader_debug_info %}
            <li>Using loader <code>{{ loader.loader }}</code>:
                <ul>{% for t in loader.templates %}<li><code>{{ t.name }}</code> (File {% if t.exists %}exists{% else %}does not exist{% endif %})</li>{% endfor %}</ul>
            </li>
        {% endfor %}
        </ul>
    {% else %}
        <p>Django couldn't find any templates because your <code>TEMPLATE_LOADERS</code> setting is empty!</p>
    {% endif %}
</div>
{% endif %}
{% if template_info %}
<div id="template">
   <h2>Template error</h2>
   <p>In template <code>{{ template_info.name }}</code>, error at line <strong>{{ template_info.line }}</strong></p>
   <h3>{{ template_info.message|escape }}</h3>
   <table class="source{% if template_info.top %} cut-top{% endif %}{% ifnotequal template_info.bottom template_info.total %} cut-bottom{% endifnotequal %}">
   {% for source_line in template_info.source_lines %}
   {% ifequal source_line.0 template_info.line %}
       <tr class="error"><th>{{ source_line.0 }}</th>
       <td>{{ template_info.before }}<span class="specific">{{ template_info.during }}</span>{{ template_info.after }}</td></tr>
   {% else %}
      <tr><th>{{ source_line.0 }}</th>
      <td>{{ source_line.1 }}</td></tr>
   {% endifequal %}
   {% endfor %}
   </table>
</div>
{% endif %}
<div id="traceback">
  <h2>Traceback <span>(innermost last)</span></h2>
  <div class="commands"><a href="#" onclick="return switchPastebinFriendly(this);">Switch to copy-and-paste view</a></div>
  <br/>
  <div id="browserTraceback">
    <ul class="traceback">
      {% for frame in frames %}
        <li class="frame">
          <code>{{ frame.filename }}</code> in <code>{{ frame.function }}</code>

          {% if frame.context_line %}
            <div class="context" id="c{{ frame.id }}">
              {% if frame.pre_context %}
                <ol start="{{ frame.pre_context_lineno }}" class="pre-context" id="pre{{ frame.id }}">{% for line in frame.pre_context %}<li onclick="toggle('pre{{ frame.id }}', 'post{{ frame.id }}')">{{ line|escape }}</li>{% endfor %}</ol>
              {% endif %}
              <ol start="{{ frame.lineno }}" class="context-line"><li onclick="toggle('pre{{ frame.id }}', 'post{{ frame.id }}')">{{ frame.context_line|escape }} <span>...</span></li></ol>
              {% if frame.post_context %}
                <ol start='{{ frame.lineno|add:"1" }}' class="post-context" id="post{{ frame.id }}">{% for line in frame.post_context %}<li onclick="toggle('pre{{ frame.id }}', 'post{{ frame.id }}')">{{ line|escape }}</li>{% endfor %}</ol>
              {% endif %}
            </div>
          {% endif %}

          {% if frame.vars %}
            <div class="commands">
                <a href="#" onclick="return varToggle(this, '{{ frame.id }}')"><span>&#x25b6;</span> Local vars</a>
            </div>
            <table class="vars" id="v{{ frame.id }}">
              <thead>
                <tr>
                  <th>Variable</th>
                  <th>Value</th>
                </tr>
              </thead>
              <tbody>
                {% for var in frame.vars|dictsort:"0" %}
                  <tr>
                    <td>{{ var.0 }}</td>
                    <td class="code"><div>{{ var.1|pprint|escape }}</div></td>
                  </tr>
                {% endfor %}
              </tbody>
            </table>
          {% endif %}
        </li>
      {% endfor %}
    </ul>
  </div>
  <div id="pastebinTraceback" class="pastebin">
    <table>
      <tbody>
        <tr>
          <td>
            <code>
Traceback (most recent call last):<br/>
{% for frame in frames %}
  File "{{ frame.filename }}" in {{ frame.function }}<br/>
  {% if frame.context_line %}
    &nbsp;&nbsp;{{ frame.lineno }}. {{ frame.context_line|escape }}<br/>
  {% endif %}
{% endfor %}<br/>
&nbsp;&nbsp;{{ exception_type }} at {{ request.path }}<br/>
&nbsp;&nbsp;{{ exception_value|escape }}</code>
          </td>
        </tr>
      </tbody>
    </table>
  </div>
</div>

<div id="requestinfo">
  <h2>Request information</h2>

  <h3 id="get-info">GET</h3>
  {% if request.GET %}
    <table class="req">
      <thead>
        <tr>
          <th>Variable</th>
          <th>Value</th>
        </tr>
      </thead>
      <tbody>
        {% for var in request.GET.items %}
          <tr>
            <td>{{ var.0 }}</td>
            <td class="code"><div>{{ var.1|pprint|escape }}</div></td>
          </tr>
        {% endfor %}
      </tbody>
    </table>
  {% else %}
    <p>No GET data</p>
  {% endif %}

  <h3 id="post-info">POST</h3>
  {% if request.POST %}
    <table class="req">
      <thead>
        <tr>
          <th>Variable</th>
          <th>Value</th>
        </tr>
      </thead>
      <tbody>
        {% for var in request.POST.items %}
          <tr>
            <td>{{ var.0 }}</td>
            <td class="code"><div>{{ var.1|pprint|escape }}</div></td>
          </tr>
        {% endfor %}
      </tbody>
    </table>
  {% else %}
    <p>No POST data</p>
  {% endif %}

  <h3 id="cookie-info">COOKIES</h3>
  {% if request.COOKIES %}
    <table class="req">
      <thead>
        <tr>
          <th>Variable</th>
          <th>Value</th>
        </tr>
      </thead>
      <tbody>
        {% for var in request.COOKIES.items %}
          <tr>
            <td>{{ var.0 }}</td>
            <td class="code"><div>{{ var.1|pprint|escape }}</div></td>
          </tr>
        {% endfor %}
      </tbody>
    </table>
  {% else %}
    <p>No cookie data</p>
  {% endif %}

  <h3 id="meta-info">META</h3>
  <table class="req">
    <thead>
      <tr>
        <th>Variable</th>
        <th>Value</th>
      </tr>
    </thead>
    <tbody>
      {% for var in request.META.items|dictsort:"0" %}
        <tr>
          <td>{{ var.0 }}</td>
          <td class="code"><div>{{ var.1|pprint|escape }}</div></td>
        </tr>
      {% endfor %}
    </tbody>
  </table>

  <h3 id="settings-info">Settings</h3>
  <h4>Using settings module <code>{{ settings.SETTINGS_MODULE }}</code></h4>
  <table class="req">
    <thead>
      <tr>
        <th>Setting</th>
        <th>Value</th>
      </tr>
    </thead>
    <tbody>
      {% for var in settings.items|dictsort:"0" %}
        <tr>
          <td>{{ var.0 }}</td>
          <td class="code"><div>{{ var.1|pprint|escape }}</div></td>
        </tr>
      {% endfor %}
    </tbody>
  </table>

</div>

<div id="explanation">
  <p>
    You're seeing this error because you have <code>DEBUG = True</code> in your
    Django settings file. Change that to <code>False</code>, and Django will
    display a standard 500 page.
  </p>
</div>

</body>
</html>
"""

TECHNICAL_404_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" />
  <title>Page not found at {{ request.path }}</title>
  <meta name="robots" content="NONE,NOARCHIVE" />
  <style type="text/css">
    html * { padding:0; margin:0; }
    body * { padding:10px 20px; }
    body * * { padding:0; }
    body { font:small sans-serif; background:#eee; }
    body>div { border-bottom:1px solid #ddd; }
    h1 { font-weight:normal; margin-bottom:.4em; }
    h1 span { font-size:60%; color:#666; font-weight:normal; }
    table { border:none; border-collapse: collapse; width:100%; }
    td, th { vertical-align:top; padding:2px 3px; }
    th { width:12em; text-align:right; color:#666; padding-right:.5em; }
    #info { background:#f6f6f6; }
    #info ol { margin: 0.5em 4em; }
    #info ol li { font-family: monospace; }
    #summary { background: #ffc; }
    #explanation { background:#eee; border-bottom: 0px none; }
  </style>
</head>
<body>
  <div id="summary">
    <h1>Page not found <span>(404)</span></h1>
    <table class="meta">
      <tr>
        <th>Request Method:</th>
        <td>{{ request.META.REQUEST_METHOD }}</td>
      </tr>
      <tr>
        <th>Request URL:</th>
      <td>{{ request_protocol }}://{{ request.META.HTTP_HOST }}{{ request.path }}</td>
      </tr>
    </table>
  </div>
  <div id="info">
    {% if urlpatterns %}
      <p>
      Using the URLconf defined in <code>{{ settings.ROOT_URLCONF }}</code>,
      Django tried these URL patterns, in this order:
      </p>
      <ol>
        {% for pattern in urlpatterns %}
          <li>{{ pattern|escape }}</li>
        {% endfor %}
      </ol>
      <p>The current URL, <code>{{ request.path }}</code>, didn't match any of these.</p>
    {% else %}
      <p>{{ reason|escape }}</p>
    {% endif %}
  </div>

  <div id="explanation">
    <p>
      You're seeing this error because you have <code>DEBUG = True</code> in
      your Django settings file. Change that to <code>False</code>, and Django
      will display a standard 404 page.
    </p>
  </div>
</body>
</html>
"""

EMPTY_URLCONF_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>Welcome to Django</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; }
    ul { margin-left: 2em; margin-top: 1em; }
    #summary { background: #e0ebff; }
    #summary h2 { font-weight: normal; color: #666; }
    #explanation { background:#eee; }
    #instructions { background:#f6f6f6; }
    #summary table { border:none; background:transparent; }
  </style>
</head>

<body>
<div id="summary">
  <h1>It worked!</h1>
  <h2>Congratulations on your first Django-powered page.</h2>
</div>

<div id="instructions">
  <p>Of course, you haven't actually done any work yet. Here's what to do next:</p>
  <ul>
    <li>If you plan to use a database, edit the <code>DATABASE_*</code> settings in <code>{{ project_name }}/settings.py</code>.</li>
    <li>Start your first app by running <code>python {{ project_name }}/manage.py startapp [appname]</code>.</li>
  </ul>
</div>

<div id="explanation">
  <p>
    You're seeing this message because you have <code>DEBUG = True</code> in your
    Django settings file and you haven't configured any URLs. Get to work!
  </p>
</div>
</body></html>
"""