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iCalendar.php
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1 <?PHP
2 #
3 # FILE: iCalendar.php
4 #
5 # Part of the Collection Workflow Integration System (CWIS)
6 # Copyright 2013 Edward Almasy and Internet Scout Research Group
7 # http://scout.wisc.edu/cwis/
8 #
9
13 class iCalendar
14 {
15
25 public function __construct($ID, $StartDate, $EndDate, $AllDay, $TimeZoneID=NULL)
26 {
27 # generate the UID and add it to the document
28 $this->AddProperty("VEVENT", "UID", $this->GenerateUID($ID, $StartDate));
29
30 # need to use the time zone parameter if a time zone ID is given
31 $DateParameters = is_null($TimeZoneID) ? array() : array("TZID" => $TimeZoneID);
32
33 if ($AllDay)
34 {
35 # need to offset the end date by one day so that the range spans the
36 # entire 24 hours of the last day
37 $EndDate = date("Y-m-d", strtotime($EndDate)+86400);
38
39 $this->AddDateProperty("VEVENT", "DTSTART", $StartDate, $DateParameters);
40 $this->AddDateProperty("VEVENT", "DTEND", $EndDate, $DateParameters);
41 }
42
43 else
44 {
45 $this->AddDateTimeProperty("VEVENT", "DTSTART", $StartDate, $DateParameters);
46 $this->AddDateTimeProperty("VEVENT", "DTEND", $EndDate, $DateParameters);
47 }
48 }
49
55 public function AddCreated($Value)
56 {
57 $this->AddTextProperty(
58 "VEVENT", "CREATED", $this->GenerateUTCDateTimeString($Value));
59 }
60
66 public function AddSummary($Value)
67 {
68 # add the property
69 $this->AddTextProperty("VEVENT", "SUMMARY", $Value);
70
71 # save the summary for use in generating the file name
72 $this->Summary = $Value;
73 }
74
80 public function AddDescription($Value)
81 {
82 $this->AddTextProperty("VEVENT", "DESCRIPTION", $Value);
83 }
84
90 public function AddCategories(array $Categories)
91 {
92 # don't add the property if there are no categories to add
93 if (!count($Categories))
94 {
95 return;
96 }
97
98 $this->AddProperty(
99 "VEVENT",
100 "CATEGORIES",
101 implode(",", array_map(array($this, "EscapeTextValue"), $Categories)));
102 }
103
109 public function AddURL($Value)
110 {
111 # don't add a blank URL
112 if (!strlen($Value))
113 {
114 return;
115 }
116
117 $this->AddProperty("VEVENT", "URL", $Value);
118 }
119
126 public function AddGeographicPosition($Latitude, $Longitude)
127 {
128 # construct the value for the property
129 $Value = floatval($Latitude) . ";" . floatval($Longitude);
130
131 # add the property to the list
132 $this->AddProperty("VEVENT", "GEO", $Value);
133 }
134
140 public function AddLocation($Value)
141 {
142 $this->AddTextProperty("VEVENT", "LOCATION", $Value);
143 }
144
149 public function GenerateDocument()
150 {
151 # generate a timestamp and add it
152 $Timestamp = $this->GenerateUTCDateTimeString(date("Y-m-d H:i:s"));
153 $this->AddProperty("VEVENT", "DTSTAMP", $Timestamp);
154
155 # start the iCalendar definition
156 $Document = "BEGIN:VCALENDAR\r\n";
157
158 # add basic headers
159 $Document .= "CALSCALE:GREGORIAN\r\n";
160 $Document .= "PRODID:-//Internet Scout//CWIS//EN\r\n";
161 $Document .= "VERSION:2.0\r\n";
162
163 # add each component
164 foreach ($this->Properties as $Component => $Properties)
165 {
166 # don't add empty components
167 if (!count($Properties))
168 {
169 continue;
170 }
171
172 # begin the component definition
173 $Document .= "BEGIN:" . $Component . "\r\n";
174
175 # add each property line
176 foreach ($Properties as $Property => $PropertyLine)
177 {
178 $Document .= $PropertyLine;
179 }
180
181 # end the component definition
182 $Document .= "END:" . $Component . "\r\n";
183 }
184
185 # end the iCalendar definition
186 $Document .= "END:VCALENDAR\r\n";
187
188 # return the generated document
189 return $Document;
190 }
191
199 public function GenerateFileName()
200 {
201 return self::GenerateFileNameFromSummary($this->Summary);
202 }
203
212 public static function GenerateFileNameFromSummary($Summary=NULL)
213 {
214 # just use the date/time if the summary isn't given
215 if (!$Summary)
216 {
217 return date("Ymd-His") . ".ics";
218 }
219
220 # remove any HTML from the summary
221 $Name = strip_tags($Summary);
222
223 # replace problematic characters for most filesystems
224 $Name = str_replace(
225 array("/", "?", "<", ">", "\\", ":", "*", "|", '"', "^"),
226 "-",
227 $Name);
228
229 # remove whitespace at the beginning and end
230 $Name = trim($Name);
231
232 # make sure the name isn't too long because it can cause problems for
233 # some browsers and file systems
234 $Name = substr($Name, 0, 75);
235
236 # return the name plus extension
237 return $Name . ".ics";
238 }
239
245 public static function TransformHTMLToPlainText($HTML)
246 {
247 # remove HTML tags
248 $HTML = strip_tags($HTML);
249
250 # handle a few replacements separately because they aren't handled by
251 # html_entity_decode() or are replaced by a character that isn't ideal.
252 # string to replace => replacement
253 $Replace = array(
254 "&nbsp;" => " ",
255 "&ndash;" => "-",
256 "&mdash;" => "--",
257 "&ldquo;" => '"',
258 "&rdquo;" => '"',
259 "&lsquo;" => "'",
260 "&rsquo;" => "'");
261
262 # do the first pass of replacements
263 $HTML = str_replace(array_keys($Replace), array_values($Replace), $HTML);
264
265 # do the final pass of replacements and return
266 return html_entity_decode($HTML);
267 }
268
281 protected function AddProperty($Component, $Property, $Value, array $Parameters=array())
282 {
283 # construct the property line
284 $Line = $this->GeneratePropertyString($Property, $Parameters) . $Value;
285
286 # fold the line if necessary and add the line ending sequence
287 $Line = $this->FoldString($Line) . "\r\n";
288
289 # add the property line to the list of properties
290 $this->Properties[$Component][$Property] = $Line;
291 }
292
305 protected function AddTextProperty($Component, $Property, $Value, array $Parameters=array())
306 {
307 # don't add empty properties
308 if (!strlen($Value))
309 {
310 return;
311 }
312
313 $this->AddProperty(
314 $Component,
315 $Property,
316 $this->EscapeTextValue($Value),
317 $Parameters);
318 }
319
332 protected function AddDateProperty($Component, $Property, $Value, array $Parameters=array())
333 {
334 $this->AddProperty(
335 $Component,
336 $Property,
337 $this->GenerateDateString($Value),
338 array("VALUE" => "DATE") + $Parameters);
339 }
340
353 protected function AddDateTimeProperty($Component, $Property, $Value, array $Parameters=array())
354 {
355 $this->AddProperty(
356 $Component,
357 $Property,
358 $this->GenerateDateTimeString($Value),
359 $Parameters);
360 }
361
367 protected function EscapeTextValue($Value)
368 {
369 # escape most characters
370 $Value = preg_replace('/([\\;,])/', "\\\\\\1", $Value);
371
372 # escape newlines
373 $Value = preg_replace('/\n/', "\\n", $Value);
374
375 return $Value;
376 }
377
384 protected function GenerateUID($ID, $StartDate)
385 {
386 # concatenate the date string, ID, and host name as in the spec
387 $UID = $this->GenerateUTCDateTimeString($StartDate);
388 $UID .= "-" . $ID;
389 $UID .= "@" . gethostname();
390
391 return $UID;
392 }
393
399 protected function GenerateDateString($Date)
400 {
401 return date("Ymd", strtotime($Date));
402 }
403
409 protected function GenerateDateTimeString($DateTime)
410 {
411 return date("Ymd\THis", strtotime($DateTime));
412 }
413
419 protected function GenerateUTCDateTimeString($DateTime)
420 {
421 return gmdate("Ymd\THis\Z", strtotime($DateTime));
422 }
423
431 protected function GeneratePropertyString($Property, array $Parameters=array())
432 {
433 # start the property string off with the property name
434 $String = $Property;
435
436 # add each property parameter, if any
437 foreach ($Parameters as $Parameter => $Value)
438 {
439 $String .= ";" . $Parameter . "=" . $Value;
440 }
441
442 # add the colon separator and return
443 return $String . ":";
444 }
445
452 protected function FoldString($String, $End="\r\n ")
453 {
454 # split the line into chunks
455 $FoldedString = chunk_split($String, 75, $End);
456
457 # chunk_split() unnecessarily adds the line ending sequence to the end
458 # of the string, so remove it
459 $FoldedString = substr($FoldedString, 0, -strlen($End));
460
461 return $FoldedString;
462 }
463
468 protected $Properties = array(
469 "VEVENT" => array(),
470 "VTODO" => array(),
471 "VJOURNAL" => array(),
472 "VFREEBUSY" => array(),
473 "VTIMEZONE" => array(),
474 "VALARM" => array());
475
480 protected $Summary;
481
482 }
iCalendar\GenerateUID
GenerateUID($ID, $StartDate)
Generate a full UID from an event ID and start date.
Definition: iCalendar.php:384
iCalendar\FoldString
FoldString($String, $End="\r\n ")
Fold a string so that lines are never longer than 75 characters.
Definition: iCalendar.php:452
iCalendar\$Summary
$Summary
The summary property for the iCalendar document.
Definition: iCalendar.php:480
iCalendar\AddCategories
AddCategories(array $Categories)
Add the categories property to the iCalendar document.
Definition: iCalendar.php:90
iCalendar\AddDescription
AddDescription($Value)
Add the description property to the iCalendar document.
Definition: iCalendar.php:80
iCalendar\GenerateFileName
GenerateFileName()
Generate a file name for the iCalendar document.
Definition: iCalendar.php:199
iCalendar\EscapeTextValue
EscapeTextValue($Value)
Escape a text value for inserting into a property line.
Definition: iCalendar.php:367
iCalendar\AddTextProperty
AddTextProperty($Component, $Property, $Value, array $Parameters=array())
Add a text property to the list.
Definition: iCalendar.php:305
iCalendar
Class to generate a simple iCalendar document.
Definition: iCalendar.php:13
iCalendar\GenerateDateTimeString
GenerateDateTimeString($DateTime)
Generate a date/time string from a date parsable by strtotime().
Definition: iCalendar.php:409
iCalendar\AddCreated
AddCreated($Value)
Add the created property to the iCalendar document.
Definition: iCalendar.php:55
iCalendar\GenerateFileNameFromSummary
static GenerateFileNameFromSummary($Summary=NULL)
Create a file name for an iCalendar document using a given summary.
Definition: iCalendar.php:212
iCalendar\$Properties
$Properties
The list of components and properties.
Definition: iCalendar.php:468
PHP
PHP
Definition: RSSClient--Test.php:12
iCalendar\AddSummary
AddSummary($Value)
Add the summary property to the iCalendar document.
Definition: iCalendar.php:66
iCalendar\__construct
__construct($ID, $StartDate, $EndDate, $AllDay, $TimeZoneID=NULL)
Construct a basic iCalendar document.
Definition: iCalendar.php:25
iCalendar\GenerateDocument
GenerateDocument()
Generate the iCalendar document based on the current list of properties.
Definition: iCalendar.php:149
iCalendar\TransformHTMLToPlainText
static TransformHTMLToPlainText($HTML)
Helper method to transform an HTML string to plain text.
Definition: iCalendar.php:245
iCalendar\AddURL
AddURL($Value)
Add the URL property to the iCalendar document.
Definition: iCalendar.php:109
iCalendar\AddDateProperty
AddDateProperty($Component, $Property, $Value, array $Parameters=array())
Add a date property to the list.
Definition: iCalendar.php:332
iCalendar\AddLocation
AddLocation($Value)
Add the location property to the iCalendar document.
Definition: iCalendar.php:140
iCalendar\GeneratePropertyString
GeneratePropertyString($Property, array $Parameters=array())
Generate a property string (property + parameters + ":").
Definition: iCalendar.php:431
iCalendar\AddProperty
AddProperty($Component, $Property, $Value, array $Parameters=array())
Add a generic property, i.e., one whose value is already in the proper form.
Definition: iCalendar.php:281
iCalendar\AddGeographicPosition
AddGeographicPosition($Latitude, $Longitude)
Add the geographic position property to the iCalendar document.
Definition: iCalendar.php:126
iCalendar\GenerateUTCDateTimeString
GenerateUTCDateTimeString($DateTime)
Generate a UTC date/time string from a date parsable by strtotime().
Definition: iCalendar.php:419
iCalendar\AddDateTimeProperty
AddDateTimeProperty($Component, $Property, $Value, array $Parameters=array())
Add a date/time property to the list.
Definition: iCalendar.php:353
iCalendar\GenerateDateString
GenerateDateString($Date)
Generate a date string from a date parsable by strtotime().
Definition: iCalendar.php:399