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

from .responses import HTTPResponse, JSONResponse, Response

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


class CORS:
    Origins: set[str]
    Methods: set[str]
    Disabled: bool

    def __init__(self):
        self.Disabled = False
        self.Origins: set[str] = {}
        self.Methods: set[str] = {"GET", "POST", "PUT", "DELETE", "PATCH", "HEAD"}


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)

    def __contains__(self, key):
        return self._d.__contains__(key)


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,
            }
        )

    def json(self) -> dict | None:
        try:
            return json.loads(self.body)
        except JSONDecodeError:
            return None


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[Response]]]
        ] = {}
        self.error_routes: dict[int, Callable[[Request, ...], Awaitable[Response]]] = {
            404: _default_404_route,
            405: _default_405_route,
        }
        self.CORS = CORS()

    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[Response]],
    ):
        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[Response]]):
            self._serve(path, "GET", func)

            async def wrapper(*args, **kwargs):
                res: Response = await func(*args, **kwargs)
                res.no_header = True
                return res

            self._serve(path, "HEAD", wrapper)
            return func

        return decorator

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

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

        return decorator

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

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

        return decorator

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

        def decorator(func: Callable[[Request, ...], Awaitable[Response]]):
            self._serve(path, "HEAD", 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[Response]], 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], {}

    def methods(self, path) -> set[str]:
        for pattern, route in self.routes.items():
            if pattern.fullmatch(path):
                return set(route.keys())
        return set()

    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""

            if (
                method == "OPTIONS"
            ):  # FIXME Should handle responding with available methods as well
                if "origin" in headers and headers.get("origin") in self.CORS.Origins:
                    origin = headers.get("origin")
                    head = [
                        "Content-Type: text/plain",
                        "Content-Length: 0",
                        f"Access-Control-Allow-Origin: {origin}",
                        f"Access-Control-Allow-Methods: {','.join(self.CORS.Methods)}",
                        "Access-Control-Allow-Headers: Content-Type,Authorization",  # CORS
                        "Vary: Origin",
                    ]

                    writer.write(Response(200, head, b"").render(self))

                    await writer.drain()

                else:
                    writer.write(Response(403, ["Vary: Origin"], b"").render(self))

                    await writer.drain()

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

                response: Response = await route(
                    request=Request(
                        method=method, path=path, headers=headers, body=body
                    ),
                    **kwargs,
                )
                response.headers.append("Vary: Origin")
                if (
                    "origin" in headers
                    and self.CORS.Disabled
                    and headers.get("origin") in self.CORS.Origins
                ):  # CORS
                    response.headers.append(
                        f"Access-Control-Allow-Origin: {headers.get('origin')}"
                    )
                    response.headers.append(
                        f"Access-Control-Allow-Methods: {','.join(self.CORS.Methods & self.methods(path))}"
                    )
                    response.headers.append(
                        "Access-Control-Allow-Headers: Content-Type,Authorization\r\n"
                    )

                writer.write(response.render(self))

                await writer.drain()
        except Exception as e:
            raise 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()


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


def render(
    file: str | Path, variables: dict[str, Any] = {}
) -> Response:  # TODO Move to another module
    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 redirect(location: str):  # TODO Move to another module
    return Response(307, ["Location: {location}"], b"")


def JSONAPI(func):  # TODO Move to another module
    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