implemented ical exports

Signed-off-by: Stephan Richter <s.richter@srsoftware.de>

de.srsoftware.cal.api/src/main/java/de/srsoftware/cal/api/Appointment.java

@@ -38,9 +38,10 @@ public interface Appointment {
 
 	/**
 	 * represent this event as ical entry
+	 * @param calendarIdentifier used to generate a unique id. pass something that is unique, but stable over time, e.g. a hostname
 	 * @return the ical string
 	 */
-	String ical();
+	String ical(String calendarIdentifier);
 
 	/**
 	 * ID of the appointment – unique within this system

de.srsoftware.cal.api/src/main/java/de/srsoftware/cal/api/Coords.java

@@ -10,6 +10,18 @@ import org.json.JSONObject;
  * @param latitude the latitude
  */
 public record Coords(double longitude, double latitude) {
+	/**
+	 * get a string representing this coords in the ICAL format, see <a href="https://datatracker.ietf.org/doc/html/rfc5545#section-3.8.1.6">iCalendar spec</a>
+	 * @return the formatted coords
+	 */
+	public String icalFormat(){
+		return "%s;%s".formatted(latitude,longitude);
+	}
+
+	/**
+	 * create a JSON object containing lat and lon of this coordinate
+	 * @return the json object
+	 */
 	public JSONObject json() {
 		return new JSONObject(Map.of("lon", longitude, "lat", latitude));
 	}

de.srsoftware.cal.base/src/main/java/de/srsoftware/cal/BaseAppointment.java

@@ -1,6 +1,7 @@
 /* © SRSoftware 2024 */
 package de.srsoftware.cal;
 
+import static de.srsoftware.cal.Util.*;
 import static de.srsoftware.tools.Optionals.nullable;
 
 import de.srsoftware.cal.api.Appointment;
@@ -124,10 +125,24 @@ public class BaseAppointment implements Appointment {
 	}
 
 	@Override
-	public String ical() { // TODO: implement
+	public String ical(String calendarIdentifier) { // TODO: implement
-		return "converting event (%s) to ical not implemented".formatted(title);
+		var sb = new StringBuilder();
+		sb.append(contentLine(BEGIN,VEVENT));
+		if (calendarIdentifier != null) sb.append(contentLine(UID,"%s@%s".formatted(id(),calendarIdentifier)));
+		sb.append(contentLine(DTSTART,start().format(ICAL_DATE_FORMAT).replace(" ","T")));
+		end().map(end -> contentLine(DTEND,end.format(ICAL_DATE_FORMAT).replace(" ","T"))).ifPresent(sb::append);
+		sb.append(contentLine(SUMMARY,title()));
+		sb.append(contentLine(DESCRIPTION,description()));
+		coords().map(Coords::icalFormat).map(geo -> contentLine(GEO,geo)).ifPresent(sb::append);
+		if (!location().isBlank()) sb.append(contentLine(LOCATION,location()));
+		for (var attachment : attachments()) sb.append(contentLine("ATTACH;FMTYPE=%s".formatted(attachment.mime()),attachment.url().toString()));
+		for (var link : links) sb.append(contentLine("ATTACH;TITLE="+paramText(link.desciption()),link.url().toString()));
+		sb.append(contentLine("CLASS","PUBLIC"));
+		sb.append(contentLine(END,VEVENT));
+		return sb.toString();
 	}
 
+
 	@Override
 	public long id() {
 		return id;

de.srsoftware.cal.base/src/main/java/de/srsoftware/cal/Util.java

@@ -6,8 +6,51 @@ import static de.srsoftware.tools.Error.error;
 import de.srsoftware.cal.api.Coords;
 import de.srsoftware.tools.Payload;
 import de.srsoftware.tools.Result;
+import java.time.format.DateTimeFormatter;
+import java.util.ArrayList;
 
 public class Util {
+	public static final String BEGIN = "BEGIN";
+	public static final String END = "END";
+	public static final String DESCRIPTION = "DESCRIPTION";
+	public static final String DTEND = "DTEND";
+	public static final String DTSTAMP = "DTSTAMP";
+	public static final String DTSTART = "DTSTART";
+	public static final String GEO = "GEO";
+	public static final DateTimeFormatter ICAL_DATE_FORMAT = DateTimeFormatter.ofPattern("yyyyMMdd HHmmss");
+	public static final String LOCATION = "LOCATION";
+	public static final String PRODID = "PRODID";
+	public static final String SUMMARY = "SUMMARY";
+	public static final String UID = "UID";
+	public static final String VERSION = "VERSION";
+	public static final String VEVENT = "VEVENT";
+	public static final String VCALENDAR = "VCALENDAR";
+
+	private Util(){}
+
+	/**
+	 * formats a content line as defined in <a href="https://datatracker.ietf.org/doc/html/rfc5545#section-3.1">iCalendar spec</a>
+	 * @param key the content line key
+	 * @param value the content line value
+	 * @return content line formatted as described in the spec
+	 */
+	public static String contentLine(String key, String value){
+		var contentLine = "%s:%s".formatted(key,value).trim();
+		// escape line breaks
+		contentLine = contentLine.replace("\\n","\\\\n").replace("\r\n","\\n").replace("\r","\\n").replace("\n","\\n");
+		var lines = new ArrayList<String>();
+		while (contentLine.length()>70){
+			var pos = contentLine.lastIndexOf(" ",70);
+			if (pos < 10) pos = 70;
+			var dummy = contentLine.substring(0,pos);
+			lines.add(dummy);
+			contentLine = '\t'+contentLine.substring(pos);
+		}
+		lines.add(contentLine);
+		lines.add("");
+		return String.join("\r\n",lines);
+	}
+
 	public static Result<Coords> extractCoords(String coords) {
 		if (coords == null) return error("Argument is null");
 		if (coords.isBlank()) return error("Argument is blank");
@@ -21,4 +64,35 @@ public class Util {
 			return error(nfe, "Failed to parse coords from %s", coords);
 		}
 	}
+
+
+
+	public static String paramText(String param) {
+		return param
+				.replace("\n","\\n")
+				.replace("\"","''")
+				.replace(";","/")
+				.replace(",","/")
+				.replace(":","/");
+	}
+
+
+	/**
+	 * wraps a text (list of vevents in a vcalendar, as described in th <a href="https://datatracker.ietf.org/doc/html/rfc5545#section-3.4">iCalendar spec</a>
+	 * @param ical the vevents list
+	 * @param prodId the producer id of this icalendar
+	 * @return the completed ical string
+	 */
+	public static Result<String> wrapIcal(Result<String> ical, String prodId) {
+		if (ical instanceof Payload<String> payload){
+			var calendar = new StringBuilder();
+			calendar.append(contentLine(BEGIN,VCALENDAR));
+			calendar.append(contentLine(VERSION,"2.0"));
+			calendar.append(contentLine(PRODID,prodId));
+			calendar.append(payload.get());
+			calendar.append(contentLine(END,VCALENDAR));
+			return Payload.of(calendar.toString());
+		}
+		return ical;
+	}
 }

de.srsoftware.cal.base/src/test/java/de/srsoftware/cal/UtilTest.java

@@ -0,0 +1,25 @@
+/* © SRSoftware 2024 */
+package de.srsoftware.cal;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class UtilTest {
+
+	@Test
+	public void testContentLine(){
+		var longText = """
+This text block, spanning several long lines, should be distributed over several lines, when passing it to the contentLine function.
+Let`s see what happens… New line breaks should be introduced at roughly every 70 characters,
+while the existing line breaks should be converted to '\n' escapes.""";
+		var expected = """
+Test:This text block, spanning several long lines, should be\r
+\t distributed over several lines, when passing it to the contentLine\r
+\t function.\\nLet`s see what happens… New line breaks should be\r
+\t introduced at roughly every 70 characters,\\nwhile the existing line\r
+\t breaks should be converted to '\\n' escapes.\r\n""";
+		var result = Util.contentLine("Test",longText);
+		assertEquals(expected,result);
+	}
+}

de.srsoftware.cal.db/src/main/java/de/srsoftware/cal/db/MariaDB.java

@@ -33,7 +33,7 @@ public class MariaDB implements Database {
 	private static final String	   URLS	           = "urls";
 	private static final String	   APPOINTMENT_ATTACHMENTS = "appointment_attachments";
 	private static final String	   TAGS	           = "tags";
-	private static Connection	   connection;
+	private Connection	   connection;
 
 	private MariaDB(Connection conn) throws SQLException {
 		connection = conn;
@@ -180,7 +180,7 @@ public class MariaDB implements Database {
 	public Result<Appointment> loadEvent(long id) {
 		try {
 			var	    rs     = select(ALL).from(APPOINTMENTS).where(AID, equal(id)).exec(connection);
-			Result<Appointment> result = rs.next() ? createAppointmentOf(rs).map(MariaDB::loadExtra) : NotFound.of("Failed to find appointment with id %s", id);
+			Result<Appointment> result = rs.next() ? createAppointmentOf(rs).map(this::loadExtra) : NotFound.of("Failed to find appointment with id %s", id);
 			rs.close();
 			return result;
 		} catch (SQLException e) {
@@ -192,7 +192,7 @@ public class MariaDB implements Database {
 	public Result<Appointment> loadEvent(String location, LocalDateTime start) {
 		try {
 			var	    rs     = select(ALL).from(APPOINTMENTS).where(LOCATION, equal(location)).where(START, equal(Timestamp.valueOf(start))).exec(connection);
-			Result<Appointment> result = rs.next() ? createAppointmentOf(rs).map(MariaDB::loadExtra) : error("Failed to find appointment starting %s @ %s", start, location);
+			Result<Appointment> result = rs.next() ? createAppointmentOf(rs).map(this::loadExtra) : error("Failed to find appointment starting %s @ %s", start, location);
 			rs.close();
 			return result;
 		} catch (SQLException e) {
@@ -200,11 +200,11 @@ public class MariaDB implements Database {
 		}
 	}
 
-	private static Result<Appointment> loadExtra(Result<BaseAppointment> res) {
+	private Result<Appointment> loadExtra(Result<BaseAppointment> res) {
-		return loadTags(res).map(MariaDB::loadLinks).map(MariaDB::loadAttachments);
+		return loadTags(res).map(this::loadLinks).map(this::loadAttachments);
 	}
 
-	private static Result<BaseAppointment> loadTags(Result<BaseAppointment> res) {
+	private Result<BaseAppointment> loadTags(Result<BaseAppointment> res) {
 		if (res.optional().isEmpty()) return transform(res);
 		BaseAppointment event = res.optional().get();
 		var	id    = event.id();
@@ -218,7 +218,7 @@ public class MariaDB implements Database {
 		}
 	}
 
-	private static Result<BaseAppointment> loadLinks(Result<BaseAppointment> res) {
+	private Result<BaseAppointment> loadLinks(Result<BaseAppointment> res) {
 		if (res.optional().isEmpty()) return transform(res);
 		BaseAppointment event = res.optional().get();
 		var	id    = event.id();
@@ -241,7 +241,7 @@ public class MariaDB implements Database {
 		}
 	}
 
-	private static Result<Appointment> loadAttachments(Result<BaseAppointment> res) {
+	private Result<Appointment> loadAttachments(Result<BaseAppointment> res) {
 		if (res.optional().isEmpty()) return transform(res);
 		BaseAppointment event = res.optional().get();
 		var	id    = event.id();

de.srsoftware.cal.web/src/main/java/de/srsoftware/cal/ApiEndpoint.java

@@ -91,15 +91,20 @@ public class ApiEndpoint extends PathHandler {
 
 	@Override
 	public boolean doGet(String path, HttpExchange ex) throws IOException {
+		String hostname = "TODO"; // TODO
+		String prodId = "TODO";
 		return switch (path) {
 			case "/event" -> sendContent(ex,getEvent(ex).map(ApiEndpoint::toJson).map(ApiEndpoint::httpError));
-			case "/events/ical"-> sendContent(ex,eventList(ex).map(ApiEndpoint::toIcal).map(ApiEndpoint::httpError));
+			case "/event/ical"-> sendContent(ex,getEvent(ex).map(event -> toIcal(event,hostname)).map(ical -> Util.wrapIcal(ical,prodId)).map(ApiEndpoint::httpError));
+			case "/events/ical"-> sendContent(ex,eventList(ex).map(list -> toIcalList(list,hostname)).map(ical -> Util.wrapIcal(ical,prodId)).map(ApiEndpoint::httpError));
 			case "/events/json" -> sendContent(ex,eventList(ex).map(ApiEndpoint::toJsonList).map(ApiEndpoint::httpError));
             case "/tags" -> listTags(ex);
             default -> unknownPath(ex, path);
         };
     }
 
+
+
 	@Override
     public boolean doPatch(String path, HttpExchange ex) throws IOException {
         if ("/event".equals(path)) return sendContent(ex, updateEvent(ex));
@@ -260,10 +265,15 @@ public class ApiEndpoint extends PathHandler {
 		return Payload.of(event);
 	}
 
-	private static Result<String> toIcal(Result<List<Appointment>> res) {
+	private static Result<String> toIcal(Result<Appointment> res, String hostname) {
+		var opt = res.optional();
+		return opt.isEmpty() ? transform(res) : Payload.of(opt.get().ical(hostname));
+	}
+
+	private static Result<String> toIcalList(Result<List<Appointment>> res, String hostname) {
 		var opt = res.optional();
 		if (opt.isEmpty()) return transform(res);
-		var list = opt.get().stream().map(Appointment::ical).collect(Collectors.joining("\n"));
+		var list = opt.get().stream().map(event -> event.ical(hostname)).collect(Collectors.joining("\n"));
 		return Payload.of(list);
 	}
 

de.srsoftware.cal.web/src/main/resources/event.html

@@ -10,12 +10,13 @@
     </head>
     <body class="event">
         <nav />
-        <h1 id="title">Loading…</h1>
         <span id="buttons">
             <button title="create a copy of this event" onclick="window.top.location.href = location.href.replace('/static/event','/static/edit').replace('id=','copy=')">⧉ copy</button>
             <button title="edit the details of this event" onclick="window.top.location.href = location.href.replace('/static/event','/static/edit')">✍ edit</button>
             <button title="delete this event" onclick="confirmDelete()">🗑 delete</button>
+            <button title="download this event" onclick="ical()"><u>⬇</u> download</button>
         </span>
+        <h1 id="title">Loading…</h1>
         <div id="time">Loading time…</div>
         <div id="description">Loading description…</div>
         <div id="links">Loading links…</div>

de.srsoftware.cal.web/src/main/resources/occ.css

@@ -160,3 +160,7 @@ table#eventlist{
 .highlight{
     background: wheat;
 }
+
+.event h1{
+    margin-top: 40px;
+}

de.srsoftware.cal.web/src/main/resources/script/event.js

@@ -20,10 +20,10 @@ async function handleEventData(response){
     if (response.ok){
         var event = await response.json();
         document.getElementsByTagName('h1')[0].innerHTML = event.title ? event.title : '';
-        document.getElementById('time').innerHTML = event.start + (event.end ? '…'+event.end : '');
+        element('time').innerHTML = '<b>'+event.start +'</b>'+ (event.end ? '…'+event.end : '') + ' @ '+event.location;
         addDescription(event);
-        document.getElementById('tags').innerHTML = "Tags: "+event.tags.join(" ");
+        element('tags').innerHTML = "Tags: "+event.tags.join(" ");
-        var links = document.getElementById('links');
+        var links = element('links');
         links.innerHTML = "";
         links.appendChild(linkList(event.links));
         attachmentList(event.attachments);
@@ -79,3 +79,14 @@ function confirmDelete(){
         }).then(handleDeleted);
     }
 }
+
+function ical(){
+    const urlParams = new URLSearchParams(window.location.search);
+    var id = urlParams.get('id');
+    if (id) {
+        var elem = create('a');
+        elem.setAttribute('href',location.href.replace('/static/event','/api/event/ical'));
+        elem.setAttribute('download',`event-${id}.ics`);
+        elem.click();
+    }
+}

de.srsoftware.cal.web/src/main/resources/script/index.js

@@ -115,19 +115,21 @@ function loadCurrentEvents(){
 function openIcal(){
     var url = location.href;
     var query = location.search;
+    var params = new URLSearchParams(query);
+    var tags = params.get('tags');
     var pos = url.indexOf('?');
     if (pos>1) url = url.substring(0,pos);
     if (!url.endsWith('/')) url += '/';
     url += 'api/events/ical'+query;
     var elem = create('a');
     elem.setAttribute('href',url);
-    elem.setAttribute('download','calendar.ical');
+    elem.setAttribute('download',(tags?tags.replace(',','+'):'calendar')+'.ics');
     elem.click();
 }
 
 // shows the given url in an overlayed iframe
 function showOverlay(url){
-    var div = document.getElementById('overlay');
+    var div = element('overlay');
     div.innerHTML = '';
     var iframe = document.createElement('iframe');
     iframe.src = url;

doc/openapi3_0.yaml

@@ -119,6 +119,42 @@ paths:
           description: server fault
       summary:
         store a new event in the database
+  /api/event/ical: 
+    get:
+      parameters:
+        - description: the appointment id
+          in: query
+          name: id
+          required: true
+          schema:
+            example: 42
+            format: int64
+            type: number
+      responses:
+        '200':
+          description: successful operation
+          content:
+            text/calendar:
+              schema:
+                description: event in ical format
+                example: |-
+                  BEGIN:VCALENDAR
+                  VERSION:2.0
+                  PRODID:OpenCloudCal
+                  BEGIN:VEVENT
+                  UID:42@cal.srsoftware.de
+                  DTSTART:20241230T100757Z
+                  DTEND:20241231T100757Z
+                  SUMMARY:Demolition of the earth
+                  END:VEVENT
+                  END:VCALENDAR
+                type: string
+        '400':
+          description: invalid input
+        '500':
+          description: server fault
+      summary: get an event as ical file
+ 
   /api/events/ical:
     get:
       description: |-