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package org.meshbay.client.phonesync
import java.text.SimpleDateFormat
import java.util.Date
import java.util.Locale
import java.util.TimeZone
/** One event as the calendar provider stores it, as much of it as a backup needs. */
data class CalEvent(
val id: Long,
val calendar: String,
/** RFC 5545 UID from the provider, when the event came with one. */
val uid: String?,
val title: String?,
val description: String?,
val location: String?,
/** Milliseconds; for an all-day event, midnight UTC of its first day. */
val start: Long,
val end: Long?,
/** Android's form, `P3600S` or `P1D`, set instead of `end` on a recurring event. */
val duration: String?,
val allDay: Boolean,
/** Olson id (`Europe/Paris`), or null. */
val timeZone: String?,
val rrule: String?,
val rdate: String?,
val exdate: String?,
/** On an exception to a recurring event: the event it changes, and the instance. */
val originalId: Long?,
val originalTime: Long?,
val originalAllDay: Boolean,
/** 0 tentative, 1 confirmed, 2 cancelled, or null. */
val status: Int?,
val reminderMinutes: List<Int>,
val organizer: String?,
val attendees: List<Attendee>,
)
data class Attendee(val email: String, val name: String?)
/**
* Events written as one iCalendar file (RFC 5545), the format every calendar
* imports. Pure, so the JVM tests hold it; `line` receives each folded line
* without its CRLF, so the caller can write it and leave the DTSTAMP lines out
* of the hash that says whether anything changed.
*/
object Ics {
fun write(events: List<CalEvent>, stamp: Long, line: (String) -> Unit) {
val uids = events.associate { it.id to uidOf(it) }
line("BEGIN:VCALENDAR")
line("VERSION:2.0")
line("PRODID:-//MeshBay//Android backup//EN")
line("CALSCALE:GREGORIAN")
for (e in events) {
val out = ArrayList<String>()
out += "BEGIN:VEVENT"
// An exception carries the UID of the event it changes.
out += "UID:" + text(e.originalId?.let { uids[it] } ?: uids.getValue(e.id))
out += "DTSTAMP:" + utc(stamp)
if (e.originalId != null && e.originalTime != null) {
out += "RECURRENCE-ID" + time(e.originalTime, e.originalAllDay, e.timeZone)
}
out += "DTSTART" + time(e.start, e.allDay, e.timeZone)
when {
e.end != null && e.end >= e.start -> out += "DTEND" + time(e.end, e.allDay, e.timeZone)
e.duration != null -> duration(e.duration)?.let { out += "DURATION:$it" }
}
e.title?.takeIf { it.isNotEmpty() }?.let { out += "SUMMARY:" + text(it) }
e.description?.takeIf { it.isNotEmpty() }?.let { out += "DESCRIPTION:" + text(it) }
e.location?.takeIf { it.isNotEmpty() }?.let { out += "LOCATION:" + text(it) }
e.rrule?.takeIf { it.isNotBlank() }?.let { out += "RRULE:" + it.trim() }
e.rdate?.let { dates("RDATE", it) }?.let { out += it }
e.exdate?.let { dates("EXDATE", it) }?.let { out += it }
when (e.status) {
0 -> out += "STATUS:TENTATIVE"
1 -> out += "STATUS:CONFIRMED"
2 -> out += "STATUS:CANCELLED"
}
out += "X-MESHBAY-CALENDAR:" + text(e.calendar)
e.organizer?.takeIf { it.isNotBlank() }?.let { out += "ORGANIZER:mailto:" + it.trim() }
for (a in e.attendees) {
val cn = a.name?.takeIf { it.isNotBlank() }?.let { ";CN=" + param(it) } ?: ""
out += "ATTENDEE$cn:mailto:" + a.email.trim()
}
for (m in e.reminderMinutes.distinct()) {
out += "BEGIN:VALARM"
out += "ACTION:DISPLAY"
out += "DESCRIPTION:" + text(e.title ?: "Reminder")
out += "TRIGGER:-PT${maxOf(0, m)}M"
out += "END:VALARM"
}
out += "END:VEVENT"
for (l in out) fold(l, line)
}
line("END:VCALENDAR")
}
private fun uidOf(e: CalEvent): String =
e.uid?.takeIf { it.isNotBlank() }?.trim() ?: "android-${e.id}@meshbay"
/** `;VALUE=DATE:20261010`, `;TZID=Europe/Paris:20261010T090000` or `:20261010T070000Z`. */
fun time(ms: Long, allDay: Boolean, zone: String?): String {
if (allDay) return ";VALUE=DATE:" + fmt("yyyyMMdd", "UTC", ms)
val tz = zone?.takeIf { it.isNotBlank() && it != "UTC" && it != "GMT" && it in zones }
return if (tz == null) ":" + utc(ms) else ";TZID=$tz:" + fmt("yyyyMMdd'T'HHmmss", tz, ms)
}
private val zones by lazy { TimeZone.getAvailableIDs().toHashSet() }
fun utc(ms: Long) = fmt("yyyyMMdd'T'HHmmss'Z'", "UTC", ms)
private fun fmt(pattern: String, zone: String, ms: Long) =
SimpleDateFormat(pattern, Locale.ROOT).apply { timeZone = TimeZone.getTimeZone(zone) }.format(Date(ms))
/** Android's `P3600S` is not RFC 5545, which wants `PT3600S`; days and weeks are the same. */
fun duration(android: String): String? {
val m = Regex("^([+-]?)P(?:(\\d+)W)?(?:(\\d+)D)?(?:T?(?:(\\d+)H)?(?:(\\d+)M)?(?:(\\d+)S)?)?$")
.matchEntire(android.trim()) ?: return null
val (sign, w, d, h, min, s) = m.destructured
if (listOf(w, d, h, min, s).all { it.isEmpty() }) return null
val time = (if (h.isEmpty()) "" else "${h}H") + (if (min.isEmpty()) "" else "${min}M") +
(if (s.isEmpty()) "" else "${s}S")
return sign + "P" + (if (w.isEmpty()) "" else "${w}W") + (if (d.isEmpty()) "" else "${d}D") +
(if (time.isEmpty()) "" else "T$time")
}
/**
* Android keeps RDATE and EXDATE as `20261010T090000Z,20261017T090000Z`,
* or with a zone first: `Europe/Paris;20261010T090000,…`.
*/
fun dates(name: String, value: String): String? {
val v = value.trim().ifEmpty { return null }
val semi = v.indexOf(';')
if (semi > 0) return "$name;TZID=${v.substring(0, semi)}:${v.substring(semi + 1)}"
return if (v.split(',').all { it.length == 8 }) "$name;VALUE=DATE:$v" else "$name:$v"
}
/** A TEXT value: backslash, semicolon, comma and line breaks escaped. */
fun text(s: String): String = buildString {
for (c in s) when (c) {
'\\' -> append("\\\\")
';' -> append("\\;")
',' -> append("\\,")
'\n' -> append("\\n")
'\r' -> {}
else -> if (c < ' ' && c != '\t') {} else append(c)
}
}
/** A parameter value, quoted when it holds what would end it. */
private fun param(s: String): String {
val clean = s.replace("\"", "'").filter { it >= ' ' }
return if (clean.any { it == ';' || it == ':' || it == ',' }) "\"$clean\"" else clean
}
/** Lines of at most 75 octets, continued with a space; never inside a character. */
fun fold(l: String, line: (String) -> Unit) {
var rest = l
var limit = 75
while (rest.toByteArray(Charsets.UTF_8).size > limit) {
var cut = 0
var bytes = 0
while (cut < rest.length) {
val cp = rest.codePointAt(cut)
val n = String(Character.toChars(cp)).toByteArray(Charsets.UTF_8).size
if (bytes + n > limit) break
bytes += n
cut += Character.charCount(cp)
}
line((if (limit == 74) " " else "") + rest.substring(0, cut))
rest = rest.substring(cut)
limit = 74
}
line((if (limit == 74) " " else "") + rest)
}
}
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