package admin

import (
	"crypto/subtle"
	"net/http"
)

// TokenAuthMiddleware protects admin routes with a static bearer token.
// All /admin/* routes require the Authorization: Bearer <token> header
// matching the configured admin.secret_token.
func TokenAuthMiddleware(secretToken string) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			token := r.Header.Get("Authorization")

			// Expect "Bearer <token>" format
			const bearerPrefix = "Bearer "
			if len(token) < len(bearerPrefix) {
				http.Error(w, `{"error":"unauthorized"}`, http.StatusUnauthorized)
				return
			}

			token = token[len(bearerPrefix):]

			// Constant-time comparison to prevent timing attacks
			if subtle.ConstantTimeCompare([]byte(token), []byte(secretToken)) != 1 {
				http.Error(w, `{"error":"unauthorized"}`, http.StatusUnauthorized)
				return
			}

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