package com.ankurm.ssews;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Profile;
import org.springframework.web.socket.server.standard.ServletServerContainerFactoryBean;

/**
 * The other half of the message size limit — the half that is not in Spring.
 *
 * <p>{@code WebSocketTransportRegistration.setMessageSizeLimit(64 * 1024)} is not the limit that
 * bites first. Spring's {@code SubProtocolWebSocketHandler} does not support partial messages,
 * so the servlet container has to buffer each WebSocket text message whole before handing it
 * over &mdash; and Tomcat's buffer defaults to <strong>8&nbsp;192 bytes</strong>. Cross that and
 * Tomcat closes the connection with WebSocket status <strong>1009</strong> before Spring ever
 * sees the frame, so raising Spring's limit alone changes nothing.
 *
 * <p>Active under the {@code bigframes} profile so the companion test can show both behaviours
 * from one build.
 *
 * @see <a href="../../../../../docs/05-limits.md">docs/05-limits.md</a>
 */
@Configuration
@Profile("bigframes")
public class WebSocketBufferConfig {

    @Bean
    public ServletServerContainerFactoryBean createWebSocketContainer(
            @org.springframework.beans.factory.annotation.Value("${ws.buffer-bytes:262144}") int bytes) {
        ServletServerContainerFactoryBean container = new ServletServerContainerFactoryBean();
        container.setMaxTextMessageBufferSize(bytes);
        container.setMaxBinaryMessageBufferSize(bytes);
        return container;
    }
}