package com.example;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.junit.Before;
import org.junit.Test;
import org.springframework.mock.web.MockHttpServletRequest;
import org.springframework.mock.web.MockHttpServletResponse;
import org.springframework.security.web.header.HeaderWriter;
import org.springframework.security.web.header.HeaderWriterFilter;

@SuppressWarnings("serial")
public class HeaderWriterFilterNotWrittingHeadersTest {
	private HeaderWriterFilter subject;
	private MockHttpServletRequest req;
	private MockHttpServletResponse res;
	private FilterChain filterChain;
	private final static Map<String, String> HEADERS = Collections.unmodifiableMap(new HashMap<String, String>() {{
		put("header", "value");
	}});
	private static final List<HeaderWriter> WRITERS = Collections.unmodifiableList(Arrays.asList(new HeaderWriter() {
		@Override
		public void writeHeaders(HttpServletRequest request,
				HttpServletResponse response) {
			assertFalse("attempted to write headers on an already committed response - API offense", response.isCommitted());
			HEADERS.forEach((h, v) -> response.setHeader(h, v));
		}
	}));
	
	
	@Before
	public void setup() throws UnsupportedEncodingException {
		subject = new HeaderWriterFilter(WRITERS);
		req = new MockHttpServletRequest();
		res = new MockHttpServletResponse();
		filterChain = new FilterChain() {
			@Override
			public void doFilter(ServletRequest request, ServletResponse response)
					throws IOException, ServletException {
				//do nothing
			}
		};
	}
	
	@Test
	public void testWritingHeaders() throws ServletException, IOException {
		//arrange (some filter in the chain commits the response before the HeaderWriterFilter could wrap the original response with the extended header-writer capabilities
		res.getWriter().write("lets flush the stream");
		res.flushBuffer();
		
		//act
		subject.doFilter(req, res, filterChain);
		
		//assert
		HEADERS.forEach((h, v) -> assertEquals(v, res.getHeader(h)));
	}
}