/*
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Mediazentrale - Personal Media Center
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Copyright (C) 2021 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.mediaz.api;
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import com.google.gson.Gson;
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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 de.uhilger.mediaz.App;
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import de.uhilger.mediaz.Server;
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import static de.uhilger.mediaz.Server.RB_SLASH;
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import de.uhilger.mediaz.store.FileStorage;
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import de.uhilger.mediaz.entity.Entity;
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import java.io.BufferedReader;
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import java.io.File;
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.InputStreamReader;
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import java.io.OutputStream;
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import java.util.List;
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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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* HttpHandler fuer die Verwaltung von Entitaeten der Mediazentrale
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*
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* @author Ulrich Hilger
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* @version 1, 5.4.2021
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*/
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public class StorageHandler implements HttpHandler {
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private static final Logger logger = Logger.getLogger(StorageHandler.class.getName());
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/*
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Das REST-Muster sieht je Entitaet fuenf Faelle vor (Beispiel Ablageort):
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1. HTTP GET Ablageort/[Name]: Liefere den Ablageort als JSON
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2. HTTP GET Ablageort/: Liefere einer Liste von Ablageorten als JSON
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3. HTTP PUT: schreibe einen neuen Ablageort auf die Platte
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4. HTTP POST: schreibe Aenderungen auf die Platte
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5. HTTP DELETE: loesche den Ablageort
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Beispiele:
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HTTP GET an /mz/api/store/Ablageort/
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liefert eine Liste der Namen vorhandener Ablageorte
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HTTP GET an /mz/api/store/Ablageort/Katalog
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liest den Ablageort namens "Katalog"
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HTTP POST an /mz/api/store/Ablageort
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schreibt den neuen Ablageort im Body der Anfrage (Neu)
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HTTP PUT an /mz/api/store/Ablageort
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sucht den Ablageort mit dem Namen laut Body der Anfrage
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und schreibt den Inhalt aus der Anfrage in die Datei (Aenderung)
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HTTP DELETE an /mz/api/store/Ablageort/Katalog
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löscht den Ablageort namens "Katalog"
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*/
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/** Name der HTTP Methode GET */
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public static final String HTTP_GET = "GET";
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/** Name der HTTP Methode PUT */
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public static final String HTTP_PUT = "PUT";
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/** Name der HTTP Methode POST */
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public static final String HTTP_POST = "POST";
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/** Name der HTTP Methode DELETE */
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public static final String HTTP_DELETE = "DELETE";
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@Override
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public void handle(HttpExchange e) throws IOException {
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String method = e.getRequestMethod();
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String response = "";
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int code = 200;
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switch(method) {
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case HTTP_GET:
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String json = lesen(e);
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if(json != null) {
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response = json;
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} else {
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response = "nicht gefunden";
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code = 404;
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}
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break;
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case HTTP_PUT:
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response = aendern(e);
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break;
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case HTTP_POST:
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response = neu(e);
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break;
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case HTTP_DELETE:
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boolean geloescht = loeschen(e);
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if(geloescht) {
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response = "geloescht";
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} else {
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response = "nicht geloescht";
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}
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break;
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}
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logger.info(response);
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e.sendResponseHeaders(code, response.length());
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OutputStream os = e.getResponseBody();
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os.write(response.getBytes());
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os.close();
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}
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private String neu(HttpExchange e) throws IOException {
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return schreiben(e, false);
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}
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private String aendern(HttpExchange e) throws IOException {
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return schreiben(e, true);
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}
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private String schreiben(HttpExchange e, boolean overwrite) throws IOException {
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String path = e.getRequestURI().toString();
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String[] elems = path.split(App.getRs(Server.RB_SLASH));
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String type = elems[elems.length - 1];
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String body = bodyLesen(e);
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String filename = "";
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FileStorage fs = new FileStorage(App.getInitParameter(App.getRs(App.RB_AP_CONF)));
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Gson gson = new Gson();
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logger.log(Level.INFO, "type: {0}", type);
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Object o = gson.fromJson(body, fs.typeFromName(type).getType());
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if(o instanceof Entity) {
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Object antwortObjekt = fs.write((Entity) o, overwrite);
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if(antwortObjekt instanceof File) {
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File file = (File) antwortObjekt;
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logger.log(Level.INFO, "Datei {0} geschrieben.", file.getAbsolutePath());
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filename = file.getName();
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return type + FileHandler.STR_BLANK + filename;
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}
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}
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return type + FileHandler.STR_BLANK + " Operation 'neu' fuer bereits existierende Entitaet.";
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}
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/*
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private String aendern(HttpExchange e) throws IOException {
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return neu(e); // einstweilen wird einfach ueberschrieben
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}
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*/
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private boolean loeschen(HttpExchange e) {
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String path = e.getRequestURI().toString();
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String[] elems = path.split(App.getRs(Server.RB_SLASH));
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String type = elems[elems.length - 2];
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String elemName = elems[elems.length - 1];
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FileStorage fs = new FileStorage(App.getInitParameter(App.getRs(App.RB_AP_CONF)));
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return fs.delete(type, elemName);
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}
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private String lesen(HttpExchange e) {
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String path = e.getRequestURI().toString();
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String[] elems = path.split(App.getRs(Server.RB_SLASH));
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FileStorage fs = new FileStorage(App.getInitParameter(App.getRs(App.RB_AP_CONF)));
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if(path.endsWith(App.getRs(RB_SLASH))) {
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String type = elems[elems.length - 1];
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logger.info(type);
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List list = fs.list(type);
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return jsonWithEnclosingType(list);
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} else {
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String type = elems[elems.length - 2];
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String elemName = elems[elems.length - 1];
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return fs.readJson(type, elemName);
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}
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}
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private String jsonWithEnclosingType(Object o) {
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StringBuilder sb = new StringBuilder();
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sb.append("{\"");
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sb.append(o.getClass().getSimpleName());
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sb.append("\": ");
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Gson gson = new Gson();
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sb.append(gson.toJson(o));
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sb.append("}");
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return sb.toString();
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}
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private String bodyLesen(HttpExchange e) throws IOException {
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InputStream is = e.getRequestBody();
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BufferedReader r = new BufferedReader(new InputStreamReader(is));
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StringBuilder sb = new StringBuilder();
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String line = r.readLine();
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while(line != null) {
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sb.append(line);
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line = r.readLine();
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}
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r.close();
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String json = sb.toString();
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logger.log(Level.INFO, "json: {0}", json);
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return json;
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}
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}
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