feat: implement parseICS with ical.js

src/lib/ical-io.js

@@ -0,0 +1,121 @@
+import ICAL from 'ical.js'
+
+// ------------------------------------------------------------------ //
+// Timezone registration (ical.js does not bundle IANA zones)
+// ------------------------------------------------------------------ //
+function registerTimezones(vcalendar) {
+  for (const vtz of vcalendar.getAllSubcomponents('vtimezone')) {
+    const tzid = vtz.getFirstPropertyValue('tzid')
+    if (tzid) {
+      ICAL.TimezoneService.register(tzid, new ICAL.Timezone({ component: vtz, tzid }))
+    }
+  }
+}
+
+// ------------------------------------------------------------------ //
+// Helpers
+// ------------------------------------------------------------------ //
+function pad2(n) {
+  return String(n).padStart(2, '0')
+}
+
+function timeToISODate(t) {
+  return `${t.year}-${pad2(t.month)}-${pad2(t.day)}`
+}
+
+function timeToHHMM(t) {
+  return `${pad2(t.hour)}:${pad2(t.minute)}`
+}
+
+function getTzid(component, propName) {
+  const prop = component.getFirstProperty(propName)
+  if (!prop) return 'UTC'
+  const tzid = prop.getParameter('tzid')
+  return tzid || 'UTC'
+}
+
+// ------------------------------------------------------------------ //
+// Parse a single VEVENT component -> plain EventModel
+// ------------------------------------------------------------------ //
+function parseEvent(veventComp) {
+  const event = new ICAL.Event(veventComp)
+  const start = event.startDate
+  const end = event.endDate
+
+  // Determine tzid
+  const tzid = getTzid(veventComp, 'dtstart')
+
+  // RRULE
+  const recur = veventComp.getFirstPropertyValue('rrule')
+  let rrule = null
+  if (recur) {
+    const bydayArr = recur.getComponent('byday') // string[]
+    let untilDate = null
+    if (recur.until) {
+      const u = recur.until
+      untilDate = `${u.year}-${pad2(u.month)}-${pad2(u.day)}`
+    }
+    rrule = {
+      freq: recur.freq,
+      interval: recur.interval || 1,
+      byday: bydayArr.length > 0 ? bydayArr[0] : null,
+      untilDate,
+    }
+  }
+
+  // EXDATEs
+  const exdates = []
+  for (const prop of veventComp.getAllProperties('exdate')) {
+    for (const t of prop.getValues()) {
+      exdates.push(timeToISODate(t))
+    }
+  }
+
+  // _raw: capture DTSTAMP and any other unmapped properties
+  // Use toICALString() to preserve the compact RFC5545 form ("20260711T085008Z")
+  // rather than toString()'s ISO 8601 form ("2026-07-11T08:50:08Z").
+  const _raw = {}
+  const dtstamp = veventComp.getFirstPropertyValue('dtstamp')
+  if (dtstamp) _raw.dtstamp = dtstamp.toICALString()
+
+  return {
+    uid: veventComp.getFirstPropertyValue('uid') || '',
+    summary: veventComp.getFirstPropertyValue('summary') || '',
+    location: veventComp.getFirstPropertyValue('location') || '',
+    description: veventComp.getFirstPropertyValue('description') || '',
+    dtstartDate: timeToISODate(start),
+    dtstartTime: timeToHHMM(start),
+    dtendTime: timeToHHMM(end),
+    tzid,
+    rrule,
+    exdates,
+    _raw,
+  }
+}
+
+// ------------------------------------------------------------------ //
+// Parse full ICS text -> { meta, events }
+// ------------------------------------------------------------------ //
+export function parseICS(text) {
+  const jcal = ICAL.parse(text)
+  const vcalendar = new ICAL.Component(jcal)
+
+  // Register timezones from VTIMEZONEs before constructing zoned Times
+  registerTimezones(vcalendar)
+
+  // Meta
+  const meta = {
+    prodid: vcalendar.getFirstPropertyValue('prodid') || '',
+    version: vcalendar.getFirstPropertyValue('version') || '2.0',
+    calscale: vcalendar.getFirstPropertyValue('calscale') || 'GREGORIAN',
+    method: vcalendar.getFirstPropertyValue('method') || null,
+    xWrCalname: vcalendar.getFirstPropertyValue('x-wr-calname') || null,
+    xWrTimezone: vcalendar.getFirstPropertyValue('x-wr-timezone') || null,
+    vtimezones: vcalendar.getAllSubcomponents('vtimezone'),
+  }
+
+  // Events
+  const events = vcalendar.getAllSubcomponents('vevent').map(parseEvent)
+
+  return { meta, events }
+}