import re
import mimetypes
from pathlib import Path
from typing import Dict, Any, Optional, Pattern
from starlette.requests import Request
from starlette.responses import Response, FileResponse, PlainTextResponse
from .logging_utils import get_logger

logger = get_logger(__name__)


class RouteMatch:
    def __init__(self, config: Dict[str, Any], params: Optional[Dict[str, str]] = None):
        self.config = config
        self.params = params or {}


class Router:
    def __init__(self, static_dir: str = "./static"):
        self.static_dir = Path(static_dir)
        self.routes: Dict[Pattern, Dict[str, Any]] = {}
        self.exact_routes: Dict[str, Dict[str, Any]] = {}
        self.default_route: Optional[Dict[str, Any]] = None

    def add_route(self, pattern: str, config: Dict[str, Any]) -> None:
        if pattern.startswith("="):
            exact_path = pattern[1:]
            self.exact_routes[exact_path] = config
            logger.debug(f"Added exact route: {exact_path}")
            return

        if pattern == "__default__":
            self.default_route = config
            logger.debug("Added default route")
            return

        if pattern.startswith("~"):
            case_insensitive = pattern.startswith("~*")
            regex_pattern = pattern[2:] if case_insensitive else pattern[1:]

            flags = re.IGNORECASE if case_insensitive else 0
            try:
                compiled_pattern = re.compile(regex_pattern, flags)
                self.routes[compiled_pattern] = config
                logger.debug(f"Added regex route: {pattern}")
            except re.error as e:
                logger.error(f"Regex compilation error {pattern}: {e}")

    def match(self, path: str) -> Optional[RouteMatch]:
        if path in self.exact_routes:
            return RouteMatch(self.exact_routes[path])

        for pattern, config in self.routes.items():
            match = pattern.search(path)
            if match:
                params = match.groupdict()
                return RouteMatch(config, params)

        if self.default_route:
            return RouteMatch(self.default_route)

        return None


class RequestHandler:
    def __init__(self, router: Router, static_dir: str = "./static"):
        self.router = router
        self.static_dir = Path(static_dir)

    async def handle(self, request: Request) -> Response:
        path = request.url.path

        logger.info(f"{request.method} {path}")

        route_match = self.router.match(path)
        if not route_match:
            return PlainTextResponse("404 Not Found", status_code=404)

        try:
            return await self._process_route(request, route_match)
        except Exception as e:
            logger.error(f"Request processing error {path}: {e}")
            return PlainTextResponse("500 Internal Server Error", status_code=500)

    async def _process_route(self, request: Request, route_match: RouteMatch) -> Response:
        config = route_match.config
        # HINT: Not using it right now
        # path = request.url.path

        if "return" in config:
            status_text = config["return"]
            if " " in status_text:
                status_code, text = status_text.split(" ", 1)
                status_code = int(status_code)
            else:
                status_code = int(status_text)
                text = ""

            content_type = config.get("content_type", "text/plain")
            return PlainTextResponse(text, status_code=status_code,
                                     media_type=content_type)

        if "proxy_pass" in config:
            return await self._handle_proxy(request, config, route_match.params)

        if "root" in config:
            return await self._handle_static(request, config)

        if config.get("spa_fallback"):
            return await self._handle_spa_fallback(request, config)

        return PlainTextResponse("404 Not Found", status_code=404)

    async def _handle_static(self, request: Request, config: Dict[str, Any]) -> Response:
        root = Path(config["root"])
        path = request.url.path.lstrip("/")

        if not path or path == "/":
            index_file = config.get("index_file", "index.html")
            file_path = root / index_file
        else:
            file_path = root / path

        try:
            file_path = file_path.resolve()
            root = root.resolve()
            if not str(file_path).startswith(str(root)):
                return PlainTextResponse("403 Forbidden", status_code=403)
        except OSError:
            return PlainTextResponse("404 Not Found", status_code=404)

        if not file_path.exists() or not file_path.is_file():
            return PlainTextResponse("404 Not Found", status_code=404)

        content_type, _ = mimetypes.guess_type(str(file_path))

        response = FileResponse(str(file_path), media_type=content_type)

        if "headers" in config:
            for header in config["headers"]:
                if ":" in header:
                    name, value = header.split(":", 1)
                    response.headers[name.strip()] = value.strip()

        if "cache_control" in config:
            response.headers["Cache-Control"] = config["cache_control"]

        return response

    async def _handle_spa_fallback(self, request: Request, config: Dict[str, Any]) -> Response:
        path = request.url.path

        exclude_patterns = config.get("exclude_patterns", [])
        for pattern in exclude_patterns:
            if path.startswith(pattern):
                return PlainTextResponse("404 Not Found", status_code=404)

        root = Path(config.get("root", self.static_dir))
        index_file = config.get("index_file", "index.html")
        file_path = root / index_file

        if file_path.exists() and file_path.is_file():
            return FileResponse(str(file_path), media_type="text/html")

        return PlainTextResponse("404 Not Found", status_code=404)

    async def _handle_proxy(self, request: Request, config: Dict[str, Any],
                            params: Dict[str, str]) -> Response:
        # TODO: implement real proxying
        proxy_url = config["proxy_pass"]

        for key, value in params.items():
            proxy_url = proxy_url.replace(f"{{{key}}}", value)

        logger.info(f"Proxying request to: {proxy_url}")

        return PlainTextResponse(f"Proxy to: {proxy_url}", status_code=200)


def create_router_from_config(regex_locations: Dict[str, Dict[str, Any]]) -> Router:
    router = Router()

    for pattern, config in regex_locations.items():
        router.add_route(pattern, config)

    return router