SlowAPI/slow/slow.py

import asyncio
import http.client
import json
import re
import urllib.parse
from pathlib import Path
from typing import Any, Awaitable, Callable, Optional

PR = re.compile(r"\<([a-zA-Z_][a-zA-Z0-9_]*)\>")


class Headers:
    def __init__(self):
        self._d: dict[str, str] = {}

    def get(self, key: str, default: Optional[Any] = None) -> str | Any:
        return self._d.get(key.lower(), default)

    def set(self, key: str, value: str) -> None:
        self._d[key.lower()] = value

    def __str__(self):
        return str(self._d)


class Request:
    def __init__(self, method: str, path: str, headers: Headers, body: bytes):
        self.method = method
        self.path = path
        self.headers = headers
        self.body = body

    def __str__(self):
        return str(
            {
                "method": self.method,
                "path": self.path,
                "headers": self.headers,
                "body": self.body,
            }
        )


async def _default_404_route(request: Request):
    return "HTTP/1.1 404 Not Found\r\nContent-Type: text/html\r\n\r\n404 Not Found contact admin".encode(
        encoding="utf-8"
    )


async def _default_405_route(request: Request):
    return "HTTP/1.1 405 Method Not Allowed\r\nContent-Type: text/html\r\n\r\n405 Method Not Allowed".encode(
        encoding="utf-8"
    )


class App:
    def __init__(self):
        self.routes: dict[
            re.Pattern[str], dict[str, Callable[[Request, ...], Awaitable[bytes]]]
        ] = {}
        self.error_routes: dict[int, Callable[[Request, ...], Awaitable[bytes]]] = {
            404: _default_404_route,
            405: _default_405_route,
        }

    def _pattern_to_regex(self, temp) -> re.Pattern[str]:
        re_temp = temp
        iter = PR.finditer(temp)
        for m in iter:
            name = m[1]
            re_temp = re.sub(
                m[0], r"(?P<" + name + r">[a-zA-Z0-9\-._~/:%&=]+)", re_temp
            )
        return re.compile(re_temp)

    def _serve(
        self, path: str, method: str, func: Callable[[Request, ...], Awaitable[bytes]]
    ):
        if method not in ["GET", "POST", "PUT", "DELETE"]:
            raise RuntimeError(f'Invalid method "{method}".')
        pat = self._pattern_to_regex(path)
        if pat not in self.routes:
            self.routes[pat] = {}
        if method in self.routes[pat]:
            raise RuntimeWarning(f'Path "{path}" already exists.')
        self.routes[pat][method] = func

    def GET(self, path: str):
        """Decorator to register a GET HTTP route."""

        def decorator(func: Callable[[Request, ...], Awaitable[bytes]]):
            self._serve(path, "GET", func)
            return func

        return decorator

    def POST(self, path: str):
        """Decorator to register a POST HTTP route."""

        def decorator(func: Callable[[Request, ...], Awaitable[bytes]]):
            self._serve(path, "POST", func)
            return func

        return decorator

    def PUT(self, path: str):
        """Decorator to register a PUT HTTP route."""

        def decorator(func: Callable[[Request, ...], Awaitable[bytes]]):
            self._serve(path, "PUT", func)
            return func

    def DELETE(self, path: str):
        """Decorator to register a DELETE HTTP route."""

        def decorator(func: Callable[[Request, ...], Awaitable[bytes]]):
            self._serve(path, "DELETE", func)
            return func

        return decorator

    def OPTIONS(self, path: str):
        """Decorator to register a OPTIONS HTTP route."""

        def decorator(func: Callable[[Request, ...], Awaitable[bytes]]):
            self._serve(path, "OPTIONS", func)
            return func

        return decorator

    def error(self, code):
        """Decorator to register an error route."""

        def decorator(func):
            self.error_routes[code] = func
            return func

        return decorator

    def resolve(self, path, method) -> tuple[Callable[..., Awaitable[bytes]], dict]:
        for pattern, route in self.routes.items():
            if m := pattern.fullmatch(path):
                if method not in route:
                    return self.error_routes[405], {}
                return route[method], {
                    k: urllib.parse.unquote(v) for k, v in m.groupdict().items()
                }
        return self.error_routes[404], {}

    async def handle_client(
        self, reader: asyncio.StreamReader, writer: asyncio.StreamWriter
    ):
        """Handle an incoming connection (HTTP or WebSocket)."""
        try:
            # Read the initial HTTP request line
            request_line = await reader.readline()
            if not request_line:
                return

            # Parse request line
            parts = request_line.decode(encoding="utf-8").strip().split()
            if len(parts) < 3:
                return

            method, path, protocol = parts[0], parts[1], parts[2]

            assert protocol == "HTTP/1.1"

            headers: Headers = Headers()
            while True:
                line = await reader.readline()
                if line == b"\r\n" or line == b"\n" or not line:  # End of headers
                    break
                line = line.decode("utf-8").strip()
                if ":" in line:
                    key, value = line.split(":", 1)
                    headers.set(key.strip(), value.strip())

            content_length = int(headers.get("Content-Length", 0))
            body = await reader.read(content_length) if content_length else b""

            route, kwargs = self.resolve(path, method)

            response = await route(
                request=Request(
                    method=method,
                    path=path,
                    headers=headers,
                    body=body,
                ),
                **kwargs,
            )
            writer.write(response)

            await writer.drain()
        except Exception as e:
            print(f"Internal Server Error: {e}")
        finally:
            writer.close()
            await writer.wait_closed()

    async def run(self, host="127.0.0.1", port=8000):
        """Start the async server."""

        server = await asyncio.start_server(self.handle_client, host, port)

        print(f"Serving on http://{host}:{port}")
        async with server:
            await server.serve_forever()


AccessControlAllowOrigin = "*"


def HTTPResponse(
    content: str, status=200, content_type="text/plain; charset=utf-8", headers=[]
) -> bytes:
    global AccessControlAllowOrigin
    head: str = f"HTTP/1.1 {status} {http.client.responses.get(status, 'Unkown Status Code')}\r\nContent-Type: {content_type}\r\n"
    head += f"Access-Control-Allow-Origin: {AccessControlAllowOrigin}\r\n"  # CORS
    head += "Access-Control-Allow-Methods: GET, POST, PUT, DELETE, OPTIONS\r\n"  # CORS
    head += "\r\n".join(headers) + ("\r\n" if len(headers) > 0 else "")
    head += "\r\n"
    return (head + content).encode(encoding="utf-8")


_value_pattern = re.compile(r"\{\{\s*([a-zA-Z_][a-zA-Z_0-9]*)\s*\}\}")


def render(file: str | Path, variables: dict[str, Any] = {}) -> bytes:
    if isinstance(file, str):
        file = Path(file)
    content: str = file.read_text(encoding="utf-8")
    for m in _value_pattern.findall(content):
        if m in variables:
            content = re.sub(r"\{\{\s*" + m + r"\s*\}\}", variables[m], content)
    return HTTPResponse(content, content_type="text/html; charset=utf-8")


def JSONResponse(d: dict, status=200) -> bytes:
    return HTTPResponse(
        json.dumps(d), status=status, content_type="text/json; charset=utf-8"
    )


def JSONAPI(func):
    async def wrapper(*args, **kwargs):
        result = await func(*args, **kwargs)
        if not isinstance(result, dict):
            if (
                isinstance(result, tuple)
                and len(result) == 2
                and isinstance(result[1], dict)
                and isinstance(result[0], int)
            ):
                return JSONResponse(result[1], result[0])
            raise RuntimeError("Return value of JSONAPI route is not a dictionary")
        return JSONResponse(result)

    return wrapper