package server

import (
	"encoding/json"
	"fmt"
	"git.sa.vin/any-remark/backend/datastore"
	"git.sa.vin/any-remark/backend/types"
	"github.com/dyatlov/go-opengraph/opengraph"
	"net/http"
)

type Server interface {
	OpenGraphHandler(w http.ResponseWriter, r *http.Request)
	ShortLinkHandler(w http.ResponseWriter, r *http.Request)
	ShortenLinkHandler(w http.ResponseWriter, r *http.Request)
	AddComment(w http.ResponseWriter, r *http.Request)
	ListComments(w http.ResponseWriter, r *http.Request)
}

type server struct {
	mapper datastore.Mapper
}

func NewServer(mapper datastore.Mapper) Server {
	// Empty function for NewServer
	return &server{
		mapper: mapper,
	}
}

func (s *server) OpenGraphHandler(w http.ResponseWriter, r *http.Request) {
	// get the url from the query string
	queryParams := r.URL.Query()
	url := queryParams.Get("url")
	og := opengraph.NewOpenGraph()

	if url == "" {
		http.Error(w, "url parameter is required", http.StatusBadRequest)
		return
	}

	// check if our db has the url already
	// get the opengraph data from the db
	ogString, err := s.mapper.GetOpenGraphData(url)
	if err != nil || ogString == "" {
		// if it doesn't, fetch the opengraph data from the url

		// TODO: fetch the url require that it responds with html
		resp, err := http.Get(url) // TODO: use an external proxy to fetch the url
		if err != nil {
			http.Error(w, fmt.Sprintf("error fetching url: %s", err), http.StatusInternalServerError)
			return
		}
		defer resp.Body.Close()
		err = og.ProcessHTML(resp.Body)
		if err != nil {
			// TODO: decide what to do if the given site does not respond with html or doesn't exist etc.
			http.Error(w, fmt.Sprintf("error processing html: %s", err), http.StatusInternalServerError)
			return
		}
		// save the opengraph data to the db
		err = s.mapper.SaveOpenGraphData(url, og.String())
		if err != nil {
			http.Error(w, fmt.Sprintf("error saving opengraph data: %s", err), http.StatusInternalServerError)
			return
		}

		// return the opengraph data
		w.Header().Set("Content-Type", "application/json")
		_, err = w.Write([]byte(og.String()))
		if err != nil {
			http.Error(w, fmt.Sprintf("error writing opengraph data: %s", err), http.StatusInternalServerError)
			return
		}
		return
	}

	// return the opengraph data
	w.Header().Set("Content-Type", "application/json")
	_, err = w.Write([]byte(ogString))
	if err != nil {
		http.Error(w, fmt.Sprintf("error writing opengraph data: %s", err), http.StatusInternalServerError)
		return
	}
}

func (s *server) ShortLinkHandler(w http.ResponseWriter, r *http.Request) {
	// Empty handler for /x/{id}
}

func (s *server) ShortenLinkHandler(w http.ResponseWriter, r *http.Request) {
	// Empty handler for /api/v1/shorten
}

func (s *server) AddComment(w http.ResponseWriter, r *http.Request) {
	var req types.AddCommentRequest
	// unmarshal the request body into the req struct
	err := json.NewDecoder(r.Body).Decode(&req)
	if err != nil {
		http.Error(w, fmt.Sprintf("error decoding request body: %s", err), http.StatusBadRequest)
		return
	}
	err = s.mapper.AddComment(req)
	if err != nil {
		http.Error(w, fmt.Sprintf("error adding comment: %s", err), http.StatusInternalServerError)
		return
	}
	w.WriteHeader(http.StatusCreated)
}

func (s *server) ListComments(w http.ResponseWriter, r *http.Request) {
	comments, err := s.mapper.GetComments(r.URL.Query().Get("url"))
	if err != nil {
		http.Error(w, fmt.Sprintf("error getting comments: %s", err), http.StatusInternalServerError)
		return
	}

	// TODO: add pagination

	// return the comments
	w.Header().Set("Content-Type", "application/json")
	err = json.NewEncoder(w).Encode(comments)
	if err != nil {
		http.Error(w, fmt.Sprintf("error encoding comments: %s", err), http.StatusInternalServerError)
		return
	}
}

// CorsMiddleware is a middleware that allows CORS
func CorsMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// allow all origins
		w.Header().Set("Access-Control-Allow-Origin", "*")
		// allow all headers
		w.Header().Set("Access-Control-Allow-Headers", "*")
		// allow all methods
		w.Header().Set("Access-Control-Allow-Methods", "*")
		// allow credentials
		w.Header().Set("Access-Control-Allow-Credentials", "true")

		// handle pre-flight requests
		if r.Method == http.MethodOptions {
			w.WriteHeader(http.StatusOK)
			return
		}

		// call the next handler
		next.ServeHTTP(w, r)
	})
}