"""
API versioning middleware.

NOTE: This module is currently not used. To enable API versioning:
1. Import VersionMiddleware in main.py
2. Add it to the app middleware stack

Example usage:
    from app.middleware.versioning import APIVersionMiddleware
    app.add_middleware(APIVersionMiddleware)

This middleware adds X-API-Version header to responses based on the
version extracted from the URL path (e.g., /v1/... or /v2/...).
"""
from __future__ import annotations

from datetime import datetime

from fastapi import Request
from starlette.middleware.base import BaseHTTPMiddleware


class APIVersionMiddleware(BaseHTTPMiddleware):
    """API versioning middleware."""

    # API version definitions
    VERSIONS = {
        "v1": {
            "status": "stable",
            "deprecated": False,
            "sunset_date": None,
            "release_date": "2026-06-17",
        },
        "v2": {
            "status": "development",
            "deprecated": False,
            "sunset_date": None,
            "release_date": None,
        },
    }

    async def dispatch(self, request: Request, call_next):
        # Extract version from URL path
        version = self._extract_version(request.url.path)

        # Process request
        response = await call_next(request)

        # Add version header
        if version:
            response.headers["X-API-Version"] = version

            # Add deprecation headers if version is deprecated
            version_info = self.VERSIONS.get(version, {})
            if version_info.get("deprecated"):
                response.headers["X-API-Deprecated"] = "true"

                sunset_date = version_info.get("sunset_date")
                if sunset_date:
                    response.headers["X-API-Sunset-Date"] = sunset_date

                response.headers["X-API-Deprecation-Info"] = f"https://docs.xiaoxia-saas.com/api/deprecation/{version}"

        return response

    def _extract_version(self, path: str) -> str | None:
        """Extract version from URL path."""
        parts = path.split("/")
        for part in parts:
            if part.startswith("v") and part[1:].isdigit():
                return part
        return None


class VersionNotFoundMiddleware(BaseHTTPMiddleware):
    """Middleware to reject requests for unsupported API versions."""

    UNSUPPORTED_VERSIONS = []  # Add deprecated versions here

    async def dispatch(self, request: Request, call_next):
        version = self._extract_version(request.url.path)

        if version in self.UNSUPPORTED_VERSIONS:
            from fastapi.responses import JSONResponse

            return JSONResponse(
                status_code=410,
                content={
                    "error": {
                        "code": "API_VERSION_SUNSET",
                        "message": f"API {version} has been sunset and is no longer available",
                        "sunset_date": "2028-07-01",
                        "migration_guide": f"https://docs.xiaoxia-saas.com/api/migration/{version}",
                    }
                },
            )

        return await call_next(request)

    def _extract_version(self, path: str) -> str | None:
        """Extract version from URL path."""
        parts = path.split("/")
        for part in parts:
            if part.startswith("v") and part[1:].isdigit():
                return part
        return None