from typing import Callable
from django.http import HttpRequest, HttpResponse
from signposting import Signpost

from bs4 import BeautifulSoup
import json
from django.utils.deprecation import MiddlewareMixin
from django.conf import settings
from .utils import jsonld_to_signposts


class SignpostingMiddleware:
    def __init__(self, get_response: Callable[[HttpRequest], HttpResponse]):
        self.get_response = get_response

    def __call__(self, request: HttpRequest) -> HttpResponse:
        response = self.get_response(request)

        # no signposts on errors
        if response.status_code >= 400:
            return response

        if not hasattr(response, "_signposts"):
            return response
        self._add_signposts(response, response._signposts)

        return response

    def _add_signposts(self, response: HttpResponse, signposts: list[Signpost]):
        """Adds signposting headers to the respones.
        params:
          response - the response object
          signposts - a list of Signposts
        """

        link_snippets = []
        for signpost in signposts:
            link_snippets.append(f'<{signpost.target}> ; rel="{signpost.rel}"')
            if signpost.type:
                link_snippets[-1] += f' ; type="{signpost.type}"'

        response["Link"] = " , ".join(link_snippets)

class HtmlSignpostingMiddleware(SignpostingMiddleware):
    def __init__(self, get_response: Callable[[HttpRequest], HttpResponse]):
        self.get_response = get_response

    def __call__(self, request: HttpRequest) -> HttpResponse:
        response = self.get_response(request)

        if not hasattr(response, "_signposts"):
            return response
        
        # Adding Signposts via HTML is only supported for HTML responses
        if not response.headers["Content-Type"].startswith("text/html"):
            return response
        
        content = response.content.decode("utf-8")
        soup = BeautifulSoup(content, "html.parser")

        # Html should have a root element        
        if not soup.html:
            raise Exception("Could not find HTML root element")

        # Add head element if not present
        if not soup.head:
            head_tag = soup.new_tag("head")
            soup.html.insert(0, head_tag)

        
        # BUild links for each signpost and add them to the html
        for signpost in response._signposts:
            link_tag = soup.new_tag("link")
            link_tag["rel"] = signpost.rel
            link_tag["href"] = signpost.target
            if signpost.type:
                link_tag["type"] = signpost.type
            soup.head.append(link_tag)

        # Override the original content with the new HTML
        response.content = soup.prettify().encode("utf-8")
        response['Content-Length'] = len(response.content)
        
        return response


class JsonLdSignpostingParserMiddleware(MiddlewareMixin):

    def process_response(
        self, request: HttpRequest, response: HttpResponse
    ) -> HttpResponse:
        if not getattr(settings, "SIGNPOSTING_PARSE_JSONLD", True):
            return response

        if response.get("Content-Type", "").startswith("text/html"):
            soup = BeautifulSoup(response.content, "html.parser")
            for script in soup.find_all("script", type="application/ld+json"):
                try:
                    jsonld = json.loads(script.string)
                    signposts = jsonld_to_signposts(jsonld)

                    response._signposts = signposts
                except json.JSONDecodeError as e:
                    print(e)
                    continue

        return response