package middleware

import (
	"net/http"
	"strings"
)

// CORSConfig holds the configuration for CORS middleware.
type CORSConfig struct {
	AllowedOrigins []string
}

// CORS adds Cross-Origin Resource Sharing headers to the response.
// If allowedOrigins contains "*", it allows all origins.
// Otherwise, it checks if the request origin is in the allowed list.
func CORSWithConfig(cfg CORSConfig) func(http.Handler) http.Handler {
	allowAll := false
	originsMap := make(map[string]bool)
	for _, origin := range cfg.AllowedOrigins {
		if origin == "*" {
			allowAll = true
			break
		}
		originsMap[strings.ToLower(origin)] = true
	}

	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			origin := r.Header.Get("Origin")

			if allowAll {
				w.Header().Set("Access-Control-Allow-Origin", "*")
			} else if origin != "" && originsMap[strings.ToLower(origin)] {
				w.Header().Set("Access-Control-Allow-Origin", origin)
				w.Header().Set("Vary", "Origin")
			}

			w.Header().Set("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS, PATCH")
			w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Authorization")
			w.Header().Set("Access-Control-Max-Age", "86400")

			// Handle preflight requests
			if r.Method == http.MethodOptions {
				w.WriteHeader(http.StatusOK)
				return
			}

			next.ServeHTTP(w, r)
		})
	}
}

// CORS is a compatibility wrapper that allows all origins.
// Deprecated: Use CORSWithConfig for more control.
func CORS(next http.Handler) http.Handler {
	return CORSWithConfig(CORSConfig{AllowedOrigins: []string{"*"}})(next)
}