/*
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Calypso - Media Player Remote Control via HTTP for Raspberry Pi
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Copyright (C) 2021-2023 Ulrich Hilger
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU Affero General Public License as
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published by the Free Software Foundation, either version 3 of the
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License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Affero General Public License for more details.
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You should have received a copy of the GNU Affero General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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package de.uhilger.calypso.http;
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import com.sun.net.httpserver.HttpExchange;
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import com.sun.net.httpserver.HttpHandler;
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import java.io.IOException;
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import java.io.OutputStream;
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import java.util.HashMap;
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import java.util.Map;
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import java.util.Set;
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import java.util.logging.Level;
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import java.util.logging.Logger;
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/**
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* Die Klasse HttpApi verwendet die von der Klasse HttpExchange
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* gelieferten Elemente einer HTTP-Anfrage und leitet sie an
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* die abstrakte Methode process, wo Subklassen das jeweilige
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* Kommando aus der HTTP-Anfrage ausfuehren können.
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*
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* @author Ulrich Hilger
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*/
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public abstract class HttpApi implements HttpHandler {
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public static final String AMP = "&";
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public static final String SLASH = "/";
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@Override
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public void handle(HttpExchange exchange) throws IOException {
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String path = exchange.getRequestURI().getPath();
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String[] elems = path.split(SLASH);
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Map params = getQueryMap(exchange);
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String antwort = process(elems, params, exchange);
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antwortSenden(exchange, params, path, antwort);
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}
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/**
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* Eine HTTP-Anfrage ausführen
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*
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* @param elems die Elemente des URI-Pfads
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* @param parameter die Parameter des Query-Teils der URI
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* @return die Antwort, die gesendet werden soll
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*/
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protected abstract String process(String[] elems, Map parameter, HttpExchange exchange);
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/*
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Den Query-Teil einer URL in die Parameter zerlegen
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Die Zerlegung erfolgt mit String.split nach
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& und dann nach =
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*/
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protected Map getQueryMap(HttpExchange t) {
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HashMap map = new HashMap();
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String query = t.getRequestURI().getQuery();
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if(query != null && query.length() > 0) {
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String qParts[] = query.split("&");
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for(String qPart : qParts) {
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Logger logger = Logger.getLogger(de.uhilger.calypso.http.HttpApi.class.getName());
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logger.log(Level.FINER, "qPart: {0}", qPart);
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String pParts[] = qPart.split("=");
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map.put(pParts[0], pParts[1]);
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logger.log(Level.FINER, "pParts[0]: {0} pParts[1]: {1}", new Object[]{pParts[0], pParts[1]});
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}
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}
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return map;
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}
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protected void antwortSenden(HttpExchange exchange, Map params, String cmd, String antwort) throws IOException {
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String httpResponseStr = getResponseString(params, cmd, antwort);
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sendResponse(exchange, httpResponseStr);
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}
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protected String getResponseString(Map map, String cmd, String antwort) {
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Set keys = map.keySet();
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StringBuilder buf = new StringBuilder();
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buf.append(cmd);
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buf.append(System.lineSeparator());
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keys.forEach((Object key) -> {
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buf.append("key: ");
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buf.append(key);
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buf.append(System.lineSeparator());
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buf.append("value: ");
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buf.append(map.get(key));
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buf.append(System.lineSeparator());
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//logger.log(Level.FINE, "key {0} value {1}", new Object[]{key, map.get(key)});
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});
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buf.append(antwort);
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return buf.toString();
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}
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protected void sendResponse(HttpExchange t, String response) throws IOException {
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t.sendResponseHeaders(200, response.length());
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OutputStream os = t.getResponseBody();
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os.write(response.getBytes());
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os.close();
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}
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}
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