Untitled

	package hr.fer.zemris.java.tecaj10.tcp;
	import java.awt.Color;
	import java.awt.Graphics;
	import java.awt.image.BufferedImage;
	import java.io.BufferedInputStream;
	import java.io.BufferedOutputStream;
	import java.io.ByteArrayOutputStream;
	import java.io.IOException;
	import java.io.InputStream;
	import java.io.OutputStream;
	import java.net.InetAddress;
	import java.net.InetSocketAddress;
	import java.net.ServerSocket;
	import java.net.Socket;
	import java.nio.charset.StandardCharsets;
	import java.time.LocalDateTime;
	import java.util.ArrayList;
	import java.util.List;

	import javax.imageio.ImageIO;


	public class HTTPServer {

		public static void main(String[] args) throws IOException {
			if(args.length!=1) {
				System.out.println("Očekivao sam port");
				return;
			}

			int port = Integer.parseInt(args[0]);

			ServerSocket serverSocket = new ServerSocket();
			serverSocket.bind(
				new InetSocketAddress((InetAddress)null, port)
			);
			while(true) {
				Socket toClient = serverSocket.accept();
				serve(toClient);
			}
		}

		private static void serve(Socket toClient) throws IOException {
			try {
				InputStream cis = new BufferedInputStream(
					toClient.getInputStream()
				);
				OutputStream cos = new BufferedOutputStream(
					toClient.getOutputStream()
				);

				byte[] request = readRequest(cis);
				if(request==null) {
					sendError(cos, 400, "Bad request");
					return;
				}
				String requestStr = new String(
					request,
					StandardCharsets.US_ASCII
				);

				List<String> headers = extractHeaders(requestStr);
				String[] firstLine = headers.isEmpty() ?
					null : headers.get(0).split(" ");
				if(firstLine==null || firstLine.length != 3) {
					sendError(cos, 400, "Bad request");
					return;
				}

				String method = firstLine[0].toUpperCase();
				if(!method.equals("GET")) {
					sendError(cos, 405, "Method Not Allowed");
					return;
				}

				String version = firstLine[2].toUpperCase();
				if(!version.equals("HTTP/1.1")) {
					sendError(cos, 505, "HTTP Version Not Supported");
					return;
				}

				String path = firstLine[1];

				if (path.equals("/tocno-vrijeme")) {
					sendDate(cos);
					return;
				}

				composeResponse(
					cos, path, version,
					headers.subList(1, headers.size())
				);
			} catch (Exception ex) {
				System.out.println("Pogreška: " + ex.getMessage());
			} finally {
				toClient.close();
			}
		}

		private static void composeResponse(OutputStream cos,
			String path, String version, List<String> headers)
			throws IOException {

			StringBuilder sb = new StringBuilder(
				"<html>\r\n" +
				"  <head>\r\n" +
				"    <title>Ispis zaglavlja</title>\r\n"+
				"  </head>\r\n" +
				"  <body>\r\n" +
				"    <h1>Informacije o poslanom upitu</h1>\r\n" +
				"    <p>Zatražen resurs: " + path + "</p>\r\n" +
				"    <p>Definirane varijable:</p>\r\n" +
				"    <table border='1'>\r\n");
			for(String redak : headers) {
				int pos = redak.indexOf(':');
				sb.append("      <tr><td>")
					.append(redak.substring(0, pos).trim())
					.append("</td><td>")
					.append(redak.substring(pos+1).trim())
					.append("</td></tr>\r\n");
			}
			sb.append(
				"    </table>\r\n" +
				"  </body>\r\n" +
				"</html>\r\n");

			byte[] tijeloOdgovora = sb.toString().getBytes(
				StandardCharsets.UTF_8
			);
			byte[] zaglavljeOdgovora = (version+" 200 OK\r\n" +
				"Server: simple java server\r\n"+
				"Content-Type: text/html;charset=UTF-8\r\n"+
				"Content-Length: "+tijeloOdgovora.length+"\r\n"+
				"Connection: close\r\n"+
				"\r\n").getBytes(StandardCharsets.US_ASCII);

			cos.write(zaglavljeOdgovora);
			cos.write(tijeloOdgovora);
			cos.flush();
		}

		private static void sendError(OutputStream cos,
			int statusCode, String statusText) throws IOException {

			cos.write(
				("HTTP/1.1 "+statusCode+" "+statusText+"\r\n"+
				"Server: simple java server\r\n"+
				"Content-Type: text/plain;charset=UTF-8\r\n"+
				"Content-Length: 0\r\n"+
				"Connection: close\r\n"+
				"\r\n").getBytes(StandardCharsets.US_ASCII)
			);
			cos.flush();

		}


		private static void sendDate(OutputStream cos) throws IOException {

			BufferedImage bim = new BufferedImage(400, 200, BufferedImage.TYPE_3BYTE_BGR);
			Graphics g = bim.createGraphics();

			g.setColor(new Color(255, 192, 203));
			g.fillRect(0, 0, bim.getWidth(), bim.getHeight());

			LocalDateTime ldt = LocalDateTime.now();
			String datum = ldt.toString();

			g.setColor(Color.blue);
			g.drawString(datum, 10, bim.getHeight() - 10);

			g.dispose();

			ByteArrayOutputStream bos = new ByteArrayOutputStream();
			ImageIO.write(bim, "png", bos);

			byte[] okteti = bos.toByteArray();

			cos.write(
				("HTTP/1.1 200 To mi radiiiii\r\n"+
				"Server: simple java server\r\n"+
				"Content-Type: image/png\r\n"+
				"Content-Length: " + okteti.length + "\r\n"+
				"Connection: close\r\n"+
				"\r\n").getBytes(StandardCharsets.US_ASCII)
			);
			cos.write(okteti);
			cos.flush();

		}

		private static List<String> extractHeaders(
			String requestHeader) {

			List<String> headers = new ArrayList<String>();
			String currentLine = null;
			for(String s : requestHeader.split("\n")) {
				if(s.isEmpty()) break;
				char c = s.charAt(0);
				if(c==9 || c==32) {
					currentLine += s;
				} else {
					if(currentLine != null) {
						headers.add(currentLine);
					}
					currentLine = s;
				}
			}
			if(!currentLine.isEmpty()) {
				headers.add(currentLine);
			}
			return headers;
		}

		private static byte[] readRequest(InputStream is)
			throws IOException {

			ByteArrayOutputStream bos = new ByteArrayOutputStream();
			int state = 0;
	l:		while(true) {
				int b = is.read();
				if(b==-1) return null;
				if(b!=13) {
					bos.write(b);
				}
				switch(state) {
				case 0:
					if(b==13) { state=1; } else if(b==10) state=4;
					break;
				case 1:
					if(b==10) { state=2; } else state=0;
					break;
				case 2:
					if(b==13) { state=3; } else state=0;
					break;
				case 3:
					if(b==10) { break l; } else state=0;
					break;
				case 4:
					if(b==10) { break l; } else state=0;
					break;
				}
			}
			return bos.toByteArray();
		}
	}