package middleware

import (
	"net/http"
	"os"
	"strings"
)

// CORSMiddleware handles Cross-Origin Resource Sharing
// IMPORTANT: Configure CORS_ORIGINS env var in production
func CORSMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		origins := os.Getenv("CORS_ORIGINS")
		if origins == "" {
			origins = "http://localhost:3000"
		}

		origin := r.Header.Get("Origin")
		allowOrigin := ""

		// Check if origin is in allowed list
		for _, o := range strings.Split(origins, ",") {
			if strings.TrimSpace(o) == origin {
				allowOrigin = origin
				break
			}
		}

		if allowOrigin != "" {
			w.Header().Set("Access-Control-Allow-Origin", allowOrigin)
		}

		w.Header().Set("Access-Control-Allow-Credentials", "true")
		w.Header().Set("Access-Control-Allow-Methods", "GET, POST, PUT, PATCH, DELETE, OPTIONS")
		w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Authorization, X-CSRF-Token")

		if r.Method == "OPTIONS" {
			w.WriteHeader(http.StatusOK)
			return
		}

		next.ServeHTTP(w, r)
	})
}