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/***************************************************************************************************
* Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
**************************************************************************************************/
package at.bitfire.ical4android
import net.fortuna.ical4j.model.Calendar
import net.fortuna.ical4j.model.Property
import net.fortuna.ical4j.transform.rfc5545.CreatedPropertyRule
import net.fortuna.ical4j.transform.rfc5545.DateListPropertyRule
import net.fortuna.ical4j.transform.rfc5545.DatePropertyRule
import net.fortuna.ical4j.transform.rfc5545.Rfc5545PropertyRule
import org.apache.commons.io.IOUtils
import java.io.IOException
import java.io.Reader
import java.io.StringReader
import java.util.*
import java.util.logging.Level
/**
* Applies some rules to increase compatibility or parsed iCalendars:
*
* - [CreatedPropertyRule] to make sure CREATED is UTC
* - [DatePropertyRule], [DateListPropertyRule]: to rename Outlook-specific TZID parameters
* (like "W. Europe Standard Time" to an Android-friendly name like "Europe/Vienna")
*
*/
object ICalPreprocessor {
private val TZOFFSET_REGEXP = Regex("^(TZOFFSET(FROM|TO):[+\\-]?)((18|19|[2-6]\\d)\\d\\d)$", RegexOption.MULTILINE)
private val propertyRules = arrayOf(
CreatedPropertyRule(), // make sure CREATED is UTC
DatePropertyRule(), // These two rules also replace VTIMEZONEs of the iCalendar ...
DateListPropertyRule() // ... by the ical4j VTIMEZONE with the same TZID!
)
/**
* Some servers modify UTC offsets in TZOFFSET(FROM,TO) like "+005730" to an invalid "+5730".
*
* Rewrites values of all TZOFFSETFROM and TZOFFSETTO properties which match [TZOFFSET_REGEXP]
* so that an hour value of 00 is inserted.
*
* @param reader Reader that reads the potentially broken iCalendar (which for instance contains `TZOFFSETFROM:+5730`)
* @return Reader that reads the fixed iCalendar (for instance `TZOFFSETFROM:+005730`)
*/
fun fixInvalidUtcOffset(reader: Reader): Reader {
fun fixStringFromReader() =
IOUtils.toString(reader).replace(TZOFFSET_REGEXP) {
Ical4Android.log.log(Level.FINE, "Applying Synology WebDAV fix to invalid utc-offset", it.value)
"${it.groupValues[1]}00${it.groupValues[3]}"
}
var result: String? = null
val resetSupported = try {
reader.reset()
true
} catch(e: IOException) {
false
}
if (resetSupported) {
// reset is supported, no need to copy the whole stream to another String (unless we have to fix the TZOFFSET)
if (Scanner(reader).findWithinHorizon(TZOFFSET_REGEXP.toPattern(), 0) != null) {
reader.reset()
result = fixStringFromReader()
}
} else
result = fixStringFromReader()
if (result != null)
return StringReader(result)
// not modified, return original iCalendar
reader.reset()
return reader
}
/**
* Applies the set of rules (see class definition) to a given calendar object.
*
* @param calendar the calendar object that is going to be modified
*/
fun preProcess(calendar: Calendar) {
for (component in calendar.components) {
for (property in component.properties)
applyRules(property)
}
}
@Suppress("UNCHECKED_CAST")
private fun applyRules(property: Property) {
propertyRules
.filter { rule -> rule.supportedType.isAssignableFrom(property::class.java) }
.forEach {
val beforeStr = property.toString()
(it as Rfc5545PropertyRule<Property>).applyTo(property)
val afterStr = property.toString()
if (beforeStr != afterStr)
Ical4Android.log.log(Level.FINER, "$beforeStr -> $afterStr")
}
}
}
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