package main

import (
	"context"
	"fmt"
	// "log"
	"net/http"
	"os"
	// "strconv"
	"strings"

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

// Define a custom context key for storing user information
var userCtxKey = &contextKey{"user"}

type contextKey struct {
	name string
}

// TODO: Provide user with JWT for login/guest

// AuthMiddleware is our JWT verification middleware
func auth_middleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// 1. Extract the JWT from the request (e.g., Authorization header)
		authHeader := r.Header.Get("Authorization")
		if authHeader == "" {
			http.Error(w, "Unauthorized", http.StatusUnauthorized)
			return
		}

		tokenString := ""
		parts := strings.Split(authHeader, " ")
		if len(parts) == 2 && strings.ToLower(parts[0]) == "bearer" {
			tokenString = parts[1]
		} else {
			http.Error(w, "Invalid Authorization header format", http.StatusUnauthorized)
			return
		}

		// 2. Verify the JWT
		token, err := jwt.Parse(tokenString, func(token *jwt.Token) (interface{}, error) {
			// Validate the signing method
			if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
				return nil, fmt.Errorf("invalid signing method: %v", token.Header["alg"])
			}
			// Replace "your-secret-key" with your actual secret key
			return []byte(os.Getenv("API_SECRET_KEY")), nil
		})

		if err != nil {
			http.Error(w, "Invalid token", http.StatusUnauthorized)
			return
		}

		if claims, ok := token.Claims.(jwt.MapClaims); ok && token.Valid {
			// 3. Optionally, extract user information from the claims and add it to the request context
			user_id_raw, ok := claims["user_id"].(float64)
			if !ok {
				http.Error(w, "Invalid user ID in token", http.StatusInternalServerError)
				return
			}

			user_id := int(user_id_raw)

			// Create a new context with the user information
			ctx := context.WithValue(r.Context(), userCtxKey, user_id)
			// Call the next handler in the chain, passing the new context
			next.ServeHTTP(w, r.WithContext(ctx))
		} else {
			http.Error(w, "Invalid token claims", http.StatusUnauthorized)
			return
		}
	})
}

// Helper function to extract user information from the context in your handlers
func user_id_from_context(ctx context.Context) (int, bool) {
	userID, ok := ctx.Value(userCtxKey).(int)
	return userID, ok
}