import { describe, expect, it } from "vitest";
import {
  busyIntervals,
  canonicalRepair,
  findConflicts,
  findFreeSlots,
  localTimeCandidates,
  mergeCalendars,
  parseCalendar,
  previewOccurrences,
  timezoneDiagnostics,
} from "../../src/calendar/model";
import {
  exportJCal,
  exportJSCalendar,
  importJCal,
  importJSCalendar,
} from "../../src/calendar/interchange";

const recurring = `BEGIN:VCALENDAR\r\nVERSION:2.0\r\nPRODID:-//test//EN\r\nBEGIN:VEVENT\r\nUID:a\r\nDTSTAMP:20260101T000000Z\r\nDTSTART:20260901T100000Z\r\nDTEND:20260901T110000Z\r\nRRULE:FREQ=DAILY;COUNT=3\r\nSUMMARY:A\r\nEND:VEVENT\r\nBEGIN:VEVENT\r\nUID:b\r\nDTSTART:20260901T103000Z\r\nDTEND:20260901T120000Z\r\nSUMMARY:B\r\nEND:VEVENT\r\nEND:VCALENDAR\r\n`;

describe("calendar model", () => {
  it("parses and expands recurrence under a bound", () => {
    const document = parseCalendar(recurring);
    expect(document.events).toHaveLength(2);
    const preview = previewOccurrences(document, 10, 30);
    expect(preview.occurrences.filter((item) => item.uid === "a")).toHaveLength(
      3,
    );
    expect(findConflicts(preview.occurrences)).toEqual(
      expect.arrayContaining([expect.objectContaining({ kind: "overlap" })]),
    );
  });

  it("applies moved, cancelled, duration, and THISANDFUTURE exceptions", () => {
    const source = `BEGIN:VCALENDAR\r\nVERSION:2.0\r\nPRODID:-//test//EN\r\nBEGIN:VEVENT\r\nUID:series\r\nDTSTART:20260901T100000Z\r\nDTEND:20260901T110000Z\r\nRRULE:FREQ=DAILY;COUNT=5\r\nSUMMARY:Original\r\nEND:VEVENT\r\nBEGIN:VEVENT\r\nUID:series\r\nRECURRENCE-ID:20260902T100000Z\r\nDTSTART:20260902T120000Z\r\nDTEND:20260902T133000Z\r\nSUMMARY:Moved\r\nEND:VEVENT\r\nBEGIN:VEVENT\r\nUID:series\r\nRECURRENCE-ID:20260903T100000Z\r\nDTSTART:20260903T100000Z\r\nDTEND:20260903T110000Z\r\nSTATUS:CANCELLED\r\nEND:VEVENT\r\nBEGIN:VEVENT\r\nUID:series\r\nRECURRENCE-ID;RANGE=THISANDFUTURE:20260904T100000Z\r\nDTSTART:20260904T110000Z\r\nDTEND:20260904T130000Z\r\nSUMMARY:Shifted future\r\nEND:VEVENT\r\nEND:VCALENDAR\r\n`;
    const preview = previewOccurrences(parseCalendar(source), 10, 30);
    expect(preview.occurrences).toHaveLength(4);
    expect(preview.occurrences.map((item) => item.startText)).toEqual([
      "2026-09-01T10:00:00",
      "2026-09-02T12:00:00",
      "2026-09-04T11:00:00",
      "2026-09-05T11:00:00",
    ]);
    expect(preview.occurrences[1]).toMatchObject({
      summary: "Moved",
      endText: "2026-09-02T13:30:00",
    });
    expect(preview.occurrences[3]).toMatchObject({
      summary: "Shifted future",
      endText: "2026-09-05T13:00:00",
    });
  });

  it("canonicalizes line endings and supplies required metadata", () => {
    const input = `BEGIN:VCALENDAR\nBEGIN:VEVENT\nUID:x\nDTSTART:20260901T100000Z\nDTEND:20260901T110000Z\nEND:VEVENT\nEND:VCALENDAR\n`;
    const repaired = canonicalRepair(input);
    expect(repaired.source).toContain("VERSION:2.0\r\n");
    expect(repaired.source).toContain("PRODID:");
    expect(repaired.source).not.toMatch(/(?<!\r)\n/u);
  });

  it("merges event identity using sequence then stamp", () => {
    const newer = recurring.replace(
      "SUMMARY:A",
      "SEQUENCE:2\r\nSUMMARY:Updated A",
    );
    const merged = mergeCalendars([
      parseCalendar(recurring),
      parseCalendar(newer),
    ]);
    expect(merged.deduplicated).toBe(2);
    expect(merged.source).toContain("SUMMARY:Updated A");
    expect(parseCalendar(merged.source).events).toHaveLength(2);
  });

  it("never deduplicates separate UID-less events", () => {
    const uidless = `BEGIN:VCALENDAR\r\nVERSION:2.0\r\nPRODID:-//test//EN\r\nBEGIN:VEVENT\r\nDTSTART:20260901T100000Z\r\nDTEND:20260901T110000Z\r\nSUMMARY:No identity\r\nEND:VEVENT\r\nEND:VCALENDAR\r\n`;
    const merged = mergeCalendars([
      parseCalendar(uidless),
      parseCalendar(uidless),
    ]);
    expect(merged.deduplicated).toBe(0);
    expect(parseCalendar(merged.source).events).toHaveLength(2);
    expect(merged.diagnostics.map((item) => item.message).join(" ")).toMatch(
      /UID-less/u,
    );
  });

  it("uses embedded VTIMEZONE observances for custom TZIDs", () => {
    const custom = `BEGIN:VCALENDAR\r\nVERSION:2.0\r\nPRODID:-//test//EN\r\nBEGIN:VTIMEZONE\r\nTZID:Custom/Test\r\nBEGIN:STANDARD\r\nDTSTART:19700101T000000\r\nTZOFFSETFROM:+0230\r\nTZOFFSETTO:+0230\r\nTZNAME:CST\r\nEND:STANDARD\r\nEND:VTIMEZONE\r\nBEGIN:VEVENT\r\nUID:custom\r\nDTSTART;TZID=Custom/Test:20260901T100000\r\nDTEND;TZID=Custom/Test:20260901T110000\r\nSUMMARY:Custom zone\r\nEND:VEVENT\r\nEND:VCALENDAR\r\n`;
    const document = parseCalendar(custom);
    expect(document.timezones[0]?.tzid).toBe("Custom/Test");
    expect(document.events[0]?.startMs).toBe(
      Date.parse("2026-09-01T07:30:00.000Z"),
    );
  });

  it("classifies DST overlaps and reports yearly transitions", () => {
    const candidates = localTimeCandidates("2026-10-25T02:30", "Europe/Berlin");
    expect(candidates).toHaveLength(2);
    expect(timezoneDiagnostics("Europe/Berlin", 2026).transitions).toHaveLength(
      2,
    );
  });

  it("inspects tasks, journals, free-busy periods, and alarms", () => {
    const source = `BEGIN:VCALENDAR\r\nVERSION:2.0\r\nPRODID:-//test//EN\r\nBEGIN:VTODO\r\nUID:task-1\r\nDTSTART:20260901T080000Z\r\nDUE:20260901T090000Z\r\nSUMMARY:Write tests\r\nPERCENT-COMPLETE:25\r\nPRIORITY:3\r\nBEGIN:VALARM\r\nACTION:DISPLAY\r\nTRIGGER:-PT15M\r\nDESCRIPTION:Reminder\r\nEND:VALARM\r\nEND:VTODO\r\nBEGIN:VJOURNAL\r\nUID:journal-1\r\nDTSTART;VALUE=DATE:20260901\r\nSUMMARY:Daily note\r\nDESCRIPTION:Done locally\r\nEND:VJOURNAL\r\nBEGIN:VFREEBUSY\r\nUID:busy-1\r\nDTSTART:20260901T080000Z\r\nDTEND:20260901T120000Z\r\nFREEBUSY:20260901T100000Z/20260901T110000Z\r\nEND:VFREEBUSY\r\nEND:VCALENDAR\r\n`;
    const document = parseCalendar(source);
    expect(document.tasks[0]).toMatchObject({
      uid: "task-1",
      percentComplete: 25,
      priority: 3,
    });
    expect(document.alarms[0]).toMatchObject({
      ownerUid: "task-1",
      trigger: "-PT15M",
    });
    expect(document.journals[0]).toMatchObject({
      uid: "journal-1",
      dateText: "2026-09-01",
    });
    expect(document.freeBusy[0]?.intervals[0]).toMatchObject({
      startMs: Date.parse("2026-09-01T10:00:00Z"),
      endMs: Date.parse("2026-09-01T11:00:00Z"),
    });
    const windowStart = Date.parse("2026-09-01T09:00:00Z");
    const windowEnd = Date.parse("2026-09-01T12:00:00Z");
    expect(busyIntervals(document, windowStart, windowEnd)).toHaveLength(1);
    expect(findFreeSlots(document, windowStart, windowEnd, 30)).toEqual([
      {
        startMs: windowStart,
        endMs: Date.parse("2026-09-01T10:00:00Z"),
        minutes: 60,
      },
      {
        startMs: Date.parse("2026-09-01T11:00:00Z"),
        endMs: windowEnd,
        minutes: 60,
      },
    ]);
  });

  it("round-trips jCal and focused JSCalendar Event/Task groups", () => {
    const document = parseCalendar(recurring);
    expect(parseCalendar(importJCal(exportJCal(document))).events).toHaveLength(
      2,
    );
    const exported = exportJSCalendar(document);
    expect(exported.data).toMatchObject({ "@type": "Group" });
    const imported = parseCalendar(importJSCalendar(exported.data));
    expect(imported.events).toHaveLength(2);

    const task = parseCalendar(
      importJSCalendar({
        "@type": "Task",
        uid: "task-json",
        title: "Imported task",
        due: "2026-09-02T12:00:00Z",
        progress: 0.5,
      }),
    );
    expect(task.tasks[0]).toMatchObject({
      uid: "task-json",
      summary: "Imported task",
      percentComplete: 50,
    });
  });

  it("rejects unbounded and malformed inputs", () => {
    expect(() => previewOccurrences(parseCalendar(recurring), 501, 30)).toThrow(
      /1–500/u,
    );
    expect(() => parseCalendar("not a calendar")).toThrow(
      /parse failed|root component/u,
    );
  });
});