import { describe, expect, it } from "vitest";
import { generateAppointmentIcs } from "../ics";

const BASE_INPUT = {
  appointmentId: "appt_123",
  businessName: "Blake Heritage Barbershop",
  businessAddress: "79 Joel Street, HA6 1LW",
  staffName: "Marcus Reed",
  serviceNames: ["Haircut & Style"],
  startAt: new Date("2026-08-10T09:00:00.000Z"),
  endAt: new Date("2026-08-10T09:30:00.000Z"),
};

describe("generateAppointmentIcs", () => {
  it("produces a well-formed VCALENDAR/VEVENT block", () => {
    const ics = generateAppointmentIcs(BASE_INPUT);
    expect(ics).toMatch(/^BEGIN:VCALENDAR\r\n/);
    expect(ics).toContain("BEGIN:VEVENT\r\n");
    expect(ics).toContain("END:VEVENT\r\n");
    expect(ics.trimEnd()).toMatch(/END:VCALENDAR$/);
  });

  it("formats DTSTART/DTEND as UTC instants regardless of local time zone", () => {
    const ics = generateAppointmentIcs(BASE_INPUT);
    expect(ics).toContain("DTSTART:20260810T090000Z");
    expect(ics).toContain("DTEND:20260810T093000Z");
  });

  it("includes a UID derived from the appointment id, stable across re-generation", () => {
    const first = generateAppointmentIcs(BASE_INPUT);
    const second = generateAppointmentIcs(BASE_INPUT);
    const uidPattern = /UID:appt_123@nextchair/;
    expect(first).toMatch(uidPattern);
    expect(second).toMatch(uidPattern);
  });

  it("combines multiple service names in the summary and description", () => {
    const ics = generateAppointmentIcs({ ...BASE_INPUT, serviceNames: ["Haircut & Style", "Beard Trim"] });
    expect(ics).toContain("SUMMARY:Haircut & Style + Beard Trim at Blake Heritage Barbershop");
    expect(ics).toContain("Services: Haircut & Style\\, Beard Trim");
  });

  it("escapes commas, semicolons, and backslashes per RFC 5545", () => {
    const ics = generateAppointmentIcs({
      ...BASE_INPUT,
      businessName: "Sam's Cuts; Trims, & More\\Co",
    });
    // Escaped backslash first, then semicolon, then comma — order matters so
    // the escaping backslashes themselves don't get re-escaped.
    expect(ics).toContain("Sam's Cuts\\; Trims\\, & More\\\\Co");
  });

  it("escapes newlines in notes as literal \\n rather than breaking the content line", () => {
    const ics = generateAppointmentIcs({ ...BASE_INPUT, notes: "Line one\nLine two" });
    expect(ics).toContain("Line one\\nLine two");
    // No raw, unescaped newline should appear inside the DESCRIPTION value itself.
    const descriptionLine = ics.split("\r\n").find((l) => l.startsWith("DESCRIPTION"));
    expect(descriptionLine).toBeDefined();
  });

  it("omits the Notes line entirely when there are no notes", () => {
    const ics = generateAppointmentIcs(BASE_INPUT);
    expect(ics).not.toContain("Notes:");
  });

  it("falls back to just the business name when no address is given", () => {
    const ics = generateAppointmentIcs({ ...BASE_INPUT, businessAddress: undefined });
    expect(ics).toContain("LOCATION:Blake Heritage Barbershop");
  });

  it("folds content lines longer than 75 octets per RFC 5545", () => {
    const longNotes = "N".repeat(200);
    const ics = generateAppointmentIcs({ ...BASE_INPUT, notes: longNotes });
    const rawLines = ics.split("\r\n");
    // No single physical line (before folding continuation) should exceed 75 octets.
    for (const line of rawLines) {
      expect(line.length).toBeLessThanOrEqual(75);
    }
    // Continuation lines start with a single space, per the spec.
    const descriptionStart = rawLines.findIndex((l) => l.startsWith("DESCRIPTION"));
    expect(rawLines[descriptionStart + 1]?.startsWith(" ")).toBe(true);
  });

  it("uses CRLF line endings throughout", () => {
    const ics = generateAppointmentIcs(BASE_INPUT);
    expect(ics.includes("\r\n")).toBe(true);
    // Every bare \n should be immediately preceded by \r.
    for (let i = 0; i < ics.length; i++) {
      if (ics[i] === "\n") {
        expect(ics[i - 1]).toBe("\r");
      }
    }
  });
});