feat: export to .ics file

frontend/src/components/plan-item.tsx

@@ -4,6 +4,7 @@ import { format } from "date-fns";
 import { useAtom } from "jotai";
 import {
   CopyIcon,
+  Download,
   EllipsisVerticalIcon,
   Loader2Icon,
   Pencil,
@@ -34,6 +35,7 @@ import {
 } from "@/components/ui/dropdown-menu";
 import { usePlan } from "@/lib/use-plan";
 import { pluralize } from "@/lib/utils";
+import { generateICSFile } from "@/lib/utils/generate-ics-file";
 
 import { Button } from "./ui/button";
 import {
@@ -176,13 +178,21 @@ export function PlanItem({
               <EllipsisVerticalIcon className="size-4" />
             </Button>
           </DropdownMenuTrigger>
-          <DropdownMenuContent align="start" side="top" className="w-44">
+          <DropdownMenuContent align="start" side="top" className="w-50">
             <DropdownMenuLabel>Wybierz akcję</DropdownMenuLabel>
             <DropdownMenuSeparator />
             <DropdownMenuItem onClick={copyPlan}>
               <CopyIcon />
               <span>Kopiuj</span>
             </DropdownMenuItem>
+            <DropdownMenuItem
+              onClick={() => {
+                generateICSFile(plan.allGroups);
+              }}
+            >
+              <Download />
+              <span>Eksportuj do pliku .ics</span>
+            </DropdownMenuItem>
             <DropdownMenuItem
               onClick={() => {
                 setDropdownOpened(false);

frontend/src/lib/utils/generate-ics-file.ts

@@ -0,0 +1,217 @@
+import type { ExtendedGroup } from "@/atoms/plan-family";
+
+const polishToEnglishDays: Record<string, string> = {
+  poniedziałek: "MO",
+  wtorek: "TU",
+  środa: "WE",
+  czwartek: "TH",
+  piątek: "FR",
+  sobota: "SA",
+  niedziela: "SU",
+};
+
+const englishDays = ["SU", "MO", "TU", "WE", "TH", "FR", "SA"];
+
+const changeDateToUTC = (date: Date) => {
+  return date
+    .toISOString()
+    .replaceAll(/[-:]/g, "")
+    .replace(/\.\d{3}/, "");
+};
+
+interface Override {
+  date: string;
+  day: string;
+  week: "odd" | "even";
+}
+
+const overrides: Override[] = [
+  {
+    date: "2024-10-07",
+    day: "poniedziałek",
+    week: "even",
+  },
+  {
+    date: "2024-10-08",
+    day: "wtorek",
+    week: "even",
+  },
+  {
+    date: "2024-11-08",
+    day: "piątek",
+    week: "even",
+  },
+  {
+    date: "2024-12-10",
+    day: "wtorek",
+    week: "odd",
+  },
+  {
+    date: "2024-12-11",
+    day: "piątek",
+    week: "odd",
+  },
+  {
+    date: "2025-01-28",
+    day: "wtorek",
+    week: "even",
+  },
+  {
+    date: "2025-01-29",
+    day: "środa",
+    week: "even",
+  },
+  {
+    date: "2025-01-30",
+    day: "czwartek",
+    week: "even",
+  },
+  {
+    date: "2025-01-31",
+    day: "poniedziałek",
+    week: "even",
+  },
+  {
+    date: "2025-02-03",
+    day: "piątek",
+    week: "even",
+  },
+  {
+    date: "2025-02-04",
+    day: "poniedziałek",
+    week: "even",
+  },
+];
+
+const freeDays: { date: string; description: string }[] = [
+  {
+    date: "2024-10-01",
+    description: "Inauguracja Roku Akademickiego - dzień wolny od zajęć",
+  },
+  { date: "2024-10-31", description: "Dzień wolny od zajęć" },
+  { date: "2024-11-01", description: "Święto Wszystkich Świętych" },
+  { date: "2024-11-11", description: "Święto Niepodległości" },
+  {
+    date: "2024-11-15",
+    description: "Święto Politechniki Wrocławskiej - dzień wolny od zajęć",
+  },
+];
+
+const holidayStart = new Date("2024-12-23");
+const holidayEnd = new Date("2025-01-06");
+
+for (
+  let currentDate = new Date(holidayStart);
+  // eslint-disable-next-line no-unmodified-loop-condition
+  currentDate <= holidayEnd;
+  currentDate.setDate(currentDate.getDate() + 1)
+) {
+  freeDays.push({
+    date: currentDate.toISOString().split("T")[0],
+    description: "Ferie świąteczne - dzień wolny od zajęć",
+  });
+}
+
+const isEvenOrOddWeek = (
+  targetDate: Date,
+  referenceDate = new Date("2024-09-30"),
+  referenceIsEven = true,
+): "even" | "odd" => {
+  const msPerWeek = 7 * 24 * 60 * 60 * 1000;
+
+  const diffInMs = targetDate.getTime() - referenceDate.getTime();
+  const diffInWeeks = Math.floor(diffInMs / msPerWeek);
+
+  return (diffInWeeks % 2 === 0) === referenceIsEven ? "even" : "odd";
+};
+
+const extractStartTimeUTCEndTimeUTC = (
+  currentDate: Date,
+  group: ExtendedGroup,
+) => {
+  const startDateTime = new Date(currentDate);
+  const endDateTime = new Date(currentDate);
+  const [startHour, startMinute] = group.startTime.split(":").map(Number);
+  const [endHour, endMinute] = group.endTime.split(":").map(Number);
+  startDateTime.setUTCHours(startHour, startMinute, 0, 0);
+  endDateTime.setUTCHours(endHour, endMinute, 0, 0);
+  const startTimeUTC = changeDateToUTC(startDateTime);
+  const endTimeUTC = changeDateToUTC(endDateTime);
+  return { startTimeUTC, endTimeUTC };
+};
+
+export const generateICSFile = (
+  groups: ExtendedGroup[],
+  startDate = new Date("2024-10-01"),
+  endDate = new Date("2025-02-05"),
+) => {
+  const checkedGroups = groups.filter((group) => group.isChecked);
+  let icsContent = `BEGIN:VCALENDAR\nVERSION:2.0\nPRODID:-//Planer Solvro//NONSGML v1.0//EN\n`;
+
+  icsContent += `BEGIN:VTIMEZONE\nTZID:Europe/Warsaw\nX-LIC-LOCATION:Europe/Warsaw\nBEGIN:DAYLIGHT\nTZOFFSETFROM:+0100\nTZOFFSETTO:+0200\nTZNAME:CEST\nDTSTART:20240331T020000\nRRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=-1SU\nEND:DAYLIGHT\nBEGIN:STANDARD\nTZOFFSETFROM:+0200\nTZOFFSETTO:+0100\nTZNAME:CET\nDTSTART:20241027T030000\nRRULE:FREQ=YEARLY;BYMONTH=10;BYDAY=-1SU\nEND:STANDARD\nEND:VTIMEZONE\n`;
+
+  for (
+    let currentDate = new Date(startDate);
+    // eslint-disable-next-line no-unmodified-loop-condition
+    currentDate <= endDate;
+    currentDate.setDate(currentDate.getDate() + 1)
+  ) {
+    const freeDay = freeDays.find(
+      (day) => day.date === currentDate.toISOString().split("T")[0],
+    );
+    if (freeDay != null) {
+      continue;
+    }
+    for (const group of checkedGroups) {
+      let currentDay = currentDate.getUTCDay();
+      let currentWeek = isEvenOrOddWeek(currentDate);
+
+      const groupDayOfWeek = polishToEnglishDays[group.day.toLowerCase()];
+      if (!groupDayOfWeek) {
+        continue;
+      }
+      const indexOfGroupDay = englishDays.indexOf(groupDayOfWeek);
+
+      const override = overrides.find(
+        (o) => o.date === currentDate.toISOString().split("T")[0],
+      );
+
+      if (override != null) {
+        currentWeek = override.week;
+        const overrideDayOfWeek =
+          polishToEnglishDays[override.day.toLowerCase()];
+        const ovverideIndexOfDay = englishDays.indexOf(overrideDayOfWeek);
+        currentDay = ovverideIndexOfDay;
+      }
+
+      if (indexOfGroupDay !== currentDay) {
+        continue;
+      }
+      if (
+        (group.week === "TP" && currentWeek === "odd") ||
+        (group.week === "TN" && currentWeek === "even")
+      ) {
+        continue;
+      }
+
+      const { startTimeUTC, endTimeUTC } = extractStartTimeUTCEndTimeUTC(
+        currentDate,
+        group,
+      );
+      icsContent += `BEGIN:VEVENT\n`;
+      icsContent += `SUMMARY:${group.courseName}\n`;
+      icsContent += `DESCRIPTION:${group.lecturer}\n`;
+      icsContent += `DTSTART;TZID=Europe/Warsaw:${startTimeUTC}\n`;
+      icsContent += `DTEND;TZID=Europe/Warsaw:${endTimeUTC}\n`;
+      icsContent += `STATUS:CONFIRMED\n`;
+      icsContent += `END:VEVENT\n`;
+    }
+  }
+
+  icsContent += "END:VCALENDAR\n";
+  const blob = new Blob([icsContent], { type: "text/calendar" });
+  const link = document.createElement("a");
+  link.href = URL.createObjectURL(blob);
+  link.download = "events.ics";
+  link.click();
+};