package calendar

import (
	"net/url"
	"strings"
	"testing"
	"time"

	"github.com/google/uuid"
)

var sampleID = uuid.MustParse("11111111-2222-3333-4444-555555555555")

func sampleEvent() Event {
	return Event{
		ID:          sampleID,
		Name:        "Kwaku & Ama's Wedding",
		Venue:       "The Mansfield, 11 W 26th St, New York, NY",
		Description: "Drinks at 6, ceremony at 7. Wear comfortable shoes; the rooftop has uneven cobbles.",
		StartsAt:    time.Date(2026, 6, 12, 18, 0, 0, 0, time.UTC),
	}
}

func TestBuildICS_RequiredFields(t *testing.T) {
	now := time.Date(2026, 5, 17, 9, 30, 0, 0, time.UTC)
	got := BuildICS(sampleEvent(), now)

	wantSubstrings := []string{
		"BEGIN:VCALENDAR",
		"VERSION:2.0",
		"PRODID:-//GuestGuard//RSVP//EN",
		"BEGIN:VEVENT",
		"UID:11111111-2222-3333-4444-555555555555@guestguard.k4scloud",
		"DTSTAMP:20260517T093000Z",
		"DTSTART:20260612T180000Z",
		// Default 2h duration when EndsAt is zero.
		"DTEND:20260612T200000Z",
		// Comma + apostrophe in name; the comma is escaped, the apostrophe is not.
		`SUMMARY:Kwaku & Ama's Wedding`,
		"END:VEVENT",
		"END:VCALENDAR",
	}
	for _, want := range wantSubstrings {
		if !strings.Contains(got, want) {
			t.Errorf("ics missing %q in output:\n%s", want, got)
		}
	}
}

func TestBuildICS_EscapesText(t *testing.T) {
	e := sampleEvent()
	now := time.Date(2026, 5, 17, 9, 30, 0, 0, time.UTC)
	got := BuildICS(e, now)
	// Venue has a comma — must be escaped per RFC 5545.
	if !strings.Contains(got, `LOCATION:The Mansfield\, 11 W 26th St\, New York\, NY`) {
		t.Errorf("expected escaped commas in LOCATION; got:\n%s", got)
	}
	// Description has a semicolon — also must be escaped.
	if !strings.Contains(got, `DESCRIPTION:Drinks at 6\, ceremony at 7. Wear comfortable shoes\; the rooftop has uneven cobbles.`) {
		t.Errorf("expected escaped semicolon in DESCRIPTION; got:\n%s", got)
	}
}

func TestBuildICS_LineEndings(t *testing.T) {
	got := BuildICS(sampleEvent(), time.Now().UTC())
	// RFC 5545 requires CRLF line endings.
	if !strings.Contains(got, "\r\n") {
		t.Error("expected CRLF line endings")
	}
	if strings.Contains(got, "\n\n") {
		t.Error("found bare LFs — must be CRLF")
	}
}

func TestBuildICS_HonoursExplicitEnd(t *testing.T) {
	e := sampleEvent()
	e.EndsAt = time.Date(2026, 6, 12, 23, 30, 0, 0, time.UTC)
	got := BuildICS(e, time.Now().UTC())
	if !strings.Contains(got, "DTEND:20260612T233000Z") {
		t.Errorf("explicit end not honoured: %s", got)
	}
}

func TestBuildICS_OmitsEmptyOptionals(t *testing.T) {
	e := Event{
		ID:       sampleID,
		Name:     "Quiet event",
		StartsAt: time.Date(2026, 6, 12, 18, 0, 0, 0, time.UTC),
	}
	got := BuildICS(e, time.Now().UTC())
	if strings.Contains(got, "LOCATION:") {
		t.Error("LOCATION should be omitted when venue is empty")
	}
	if strings.Contains(got, "DESCRIPTION:") {
		t.Error("DESCRIPTION should be omitted when description is empty")
	}
}

func TestBuildLinks_GoogleEncodesDateRange(t *testing.T) {
	links := BuildLinks(sampleEvent(), "https://example/access/abc/calendar.ics")
	u, err := url.Parse(links.Google)
	if err != nil {
		t.Fatalf("parse google link: %v", err)
	}
	if u.Host != "www.google.com" || u.Path != "/calendar/render" {
		t.Errorf("unexpected google host/path: %s%s", u.Host, u.Path)
	}
	dates := u.Query().Get("dates")
	if dates != "20260612T180000Z/20260612T200000Z" {
		t.Errorf("google dates: got %q want 20260612T180000Z/20260612T200000Z", dates)
	}
	if u.Query().Get("text") != "Kwaku & Ama's Wedding" {
		t.Errorf("google text not preserved: %q", u.Query().Get("text"))
	}
}

func TestBuildLinks_OutlookYahooShape(t *testing.T) {
	links := BuildLinks(sampleEvent(), "https://example/ics")
	if !strings.HasPrefix(links.Outlook, "https://outlook.live.com/calendar/0/deeplink/compose?") {
		t.Errorf("outlook link wrong prefix: %s", links.Outlook)
	}
	if !strings.HasPrefix(links.Yahoo, "https://calendar.yahoo.com/?") {
		t.Errorf("yahoo link wrong prefix: %s", links.Yahoo)
	}
	if links.ICS != "https://example/ics" {
		t.Errorf("ICS url not echoed back: %s", links.ICS)
	}
}

func TestFileName(t *testing.T) {
	cases := map[string]string{
		"Kwaku & Ama's Wedding":     "kwaku-amas-wedding.ics",
		"  Birthday  Party!!  ":    "birthday-party.ics",
		"---":                       "event.ics",
		"":                          "event.ics",
		"Hack/Day 2026":             "hackday-2026.ics",
	}
	for in, want := range cases {
		if got := FileName(in); got != want {
			t.Errorf("FileName(%q) = %q, want %q", in, got, want)
		}
	}
}