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abersheeran/asgi-debug-middleware.py

Created February 2, 2023 18:16
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asgi-debug-middleware.py
from __future__ import annotations
import html
import inspect
import os
import traceback
from baize.typing import ASGIApp, Message, Receive, Scope, Send
from baize.asgi import Request, Response, HTMLResponse, PlainTextResponse
STYLES = """
:root {
font-family: 'Segoe UI', Helvetica, Arial, sans-serif;
}
* {
box-sizing: border-box;
}
body {
margin: 0 auto;
padding: 0 3em;
min-height: calc(100vh - 3em + 1px);
}
code, pre, .code {
font-family: "Biaodian Pro Sans CNS", Menlo, Consolas, Courier, "Zhuyin Heiti", "Han Heiti", monospace;
}
.traceback-container {
border: 3px solid #038BB8;
}
.traceback-title {
background-color: #038BB8;
color: lemonchiffon;
padding: 15px;
font-size: 20px;
margin: 0px;
}
.frame {
position: relative;
}
.frame .more {
display: block;
height: 100%;
width: 100%;
opacity: 0;
position: absolute;
z-index: 1;
top: 0;
}
.frame .more + .detail {
display: none;
position: relative;
z-index: 2;
}
.frame .more:checked + .detail {
display: block;
}
.frame-line {
padding-left: 10px;
}
.center-line {
background-color: #038BB8;
color: #f9f6e1;
padding: 5px 0px 5px 5px;
}
.lineno {
margin-right: 5px;
}
.frame-title {
font-weight: unset;
padding: 15px 10px;
margin: 0px;
color: #191f21;
font-size: 17px;
border-top: 2px solid #038BB8;
background-color: lightgoldenrodyellow;
}
.source {
font-size: small;
background-color: lavender;
padding: 1em 0;
}
table {
width: 100%;
border-spacing: 0px;
padding: 0 10px;
}
table pre.value {
white-space: pre-wrap;
word-break: break-all;
}
table tr {
max-width: 100%;
}
table td {
padding: 10px;
border-top: 1px solid #c7dce8;
}
table tr td:nth-child(1) {
padding-left: 0px;
}
"""
TEMPLATE = """
<html>
<head>
<style type='text/css'>
{styles}
</style>
<title>Index.py Debugger</title>
</head>
<body>
<h1>500 Server Error</h1>
<div class="traceback-container">
<p class="traceback-title">{error}</p>
<div>{exc_html}</div>
</div>
<div class="environs">
{environs}
</div>
</body>
</html>
"""
FRAME_TEMPLATE = """
<div class="frame">
<p class="frame-title"><code class="frame-filename">{frame_filename}</code>
in <b><code>{frame_name}</code></b> at line {frame_lineno}</p>
<input type="radio" name="more" {checked} class="more"/>
<div class="detail">
<div id="{frame_filename}-{frame_lineno}" class="source">
{code_context}
</div>
{locals}
</div>
</div>
"""
LOCAL_VARS = """
<table class="local-vars">
<tbody>
{vars}
</tbody>
</table>
"""
ENVIRON_VARS = """
<table class="environ-vars">
<thead>
<tr>
<td>
<strong>OS Environ</strong>
</td>
</tr>
<tr>
<td>
<strong>Name</strong>
</td>
<td>
<strong>Value</strong>
</td>
</tr>
</thead>
<tbody>
{vars}
</tbody>
</table>
"""
VAR = """
<tr>
<td>
<pre class="name">{name}</pre>
</td>
<td>
<pre class="value">{value}</pre>
</td>
</tr>
"""
LINE = """
<p><span class="frame-line code">
<span class="lineno">{lineno}.</span> {line}</span></p>
"""
CENTER_LINE = """
<p class="center-line"><span class="frame-line center-line code">
<span class="lineno">{lineno}.</span> {line}</span></p>
"""
class DebugMiddleware:
def __init__(self, app: ASGIApp) -> None:
self.app = app
async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
if scope["type"] != "http":
await self.app(scope, receive, send)
return
response_started = False
async def _send(message: Message) -> None:
nonlocal response_started
if message["type"] == "http.response.start":
response_started = True
await send(message)
try:
await self.app(scope, receive, _send)
except Exception as exc:
if not response_started:
request = scope["app"].factory_class.http(scope)
response = self.debug_response(request, exc)
await response(scope, receive, send)
raise exc
def format_line(
self, index: int, line: str, frame_lineno: int, frame_index: int
) -> str:
values = {
# HTML escape - line could contain < or >
"line": html.escape(line).replace(" ", "&nbsp"),
"lineno": (frame_lineno - frame_index) + index,
}
if index != frame_index:
return LINE.format(**values)
return CENTER_LINE.format(**values)
def generate_frame_html(self, frame: inspect.FrameInfo, is_collapsed: bool) -> str:
code_context = "".join(
self.format_line(index, line, frame.lineno, frame.index) # type: ignore
for index, line in enumerate(frame.code_context or [])
)
_locals_vars = frame.frame.f_locals.copy()
locals_var = LOCAL_VARS.format(
vars=(
"".join(
VAR.format(name=name, value=html.escape(format(value)))
for name, value in _locals_vars.items()
)
)
)
values = {
# HTML escape - filename could contain < or >, especially if it's a virtual file e.g. <stdin> in the REPL
"frame_filename": html.escape(frame.filename),
"frame_lineno": frame.lineno,
# HTML escape - if you try very hard it's possible to name a function with < or >
"frame_name": html.escape(frame.function),
"code_context": code_context,
"checked": "checked" if not is_collapsed else "",
"locals": locals_var,
}
return FRAME_TEMPLATE.format(**values)
def generate_html(self, exc: Exception, limit: int = 7) -> str:
traceback_obj = traceback.TracebackException.from_exception(
exc, capture_locals=True
)
exc_html = ""
is_collapsed = False
exc_traceback = exc.__traceback__
if exc_traceback is not None:
frames = inspect.getinnerframes(exc_traceback, limit)
for frame in reversed(frames):
exc_html += self.generate_frame_html(frame, is_collapsed)
is_collapsed = True
error = f"{html.escape(traceback_obj.exc_type.__name__)}: {html.escape(str(traceback_obj))}"
environs = ENVIRON_VARS.format(
vars="".join(
VAR.format(name=name, value=html.escape(value))
for name, value in os.environ.items()
)
)
return TEMPLATE.format(
styles=STYLES, error=error, exc_html=exc_html, environs=environs
)
def generate_plain_text(self, exc: Exception) -> str:
return "".join(traceback.format_tb(exc.__traceback__))
def debug_response(self, request: Request, exc: Exception) -> Response:
if request.accepts("text/html"):
content = self.generate_html(exc)
return HTMLResponse(content, status_code=500)
else:
content = self.generate_plain_text(exc)
return PlainTextResponse(content, status_code=500)
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