package web

import (
	"context"
	"fmt"
	"net/http"

	"github.com/golang-jwt/jwt/v5"
)

type contextKey string

const userIDKey contextKey = "userID"

func (s *Server) hasAuth(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		cookie, err := r.Cookie("nfeeder_token")
		if err != nil {
			http.Redirect(w, r, "/login", http.StatusSeeOther)
			return
		}

		// parse and validate
		claims := &jwt.RegisteredClaims{}
		token, err := jwt.ParseWithClaims(cookie.Value, claims, func(t *jwt.Token) (interface{}, error) {
			// check alg
			if _, ok := t.Method.(*jwt.SigningMethodHMAC); !ok {
				return nil, fmt.Errorf("unexpected signing method: %v", t.Header["alg"])
			}

			return jwtKey, nil
		})

		/// golang-jwt  the library internally runs a Valid():
		/// Time Check: It compares time.Now() against the ExpiresAt value.
		/// Not Before Check: It checks if the nbf (Not Before) time has passed.
		/// Issued At Check: It ensures the iat isn't in the future.
		if err != nil || !token.Valid {
			http.Redirect(w, r, "/login", http.StatusSeeOther)
			return
		}

		// Verify issuer
		if claims.Issuer != ISSUER {
			http.Redirect(w, r, "/login", http.StatusSeeOther)
			return
		}

		// Success! Store userID in context for handlers to use
		ctx := context.WithValue(r.Context(), userIDKey, claims.Subject)
		next.ServeHTTP(w, r.WithContext(ctx))
	})
}