package webui

import (
	"testing"
	"time"

	"mailgoserver/internal/db"
)

func TestExpandOccurrencesNonRecurring(t *testing.T) {
	start := time.Date(2026, 3, 10, 14, 0, 0, 0, time.UTC)
	e := db.CalendarEvent{StartAt: start, EndAt: start.Add(time.Hour)}

	rangeStart := time.Date(2026, 3, 1, 0, 0, 0, 0, time.UTC)
	rangeEnd := time.Date(2026, 4, 1, 0, 0, 0, 0, time.UTC)
	got := expandOccurrences(e, rangeStart, rangeEnd)
	if len(got) != 1 || !got[0].Equal(start) {
		t.Fatalf("expected 1 occurrence at %v, got %v", start, got)
	}

	// Outside the queried month entirely.
	outStart := time.Date(2026, 5, 10, 14, 0, 0, 0, time.UTC)
	e2 := db.CalendarEvent{StartAt: outStart, EndAt: outStart.Add(time.Hour)}
	if got := expandOccurrences(e2, rangeStart, rangeEnd); len(got) != 0 {
		t.Fatalf("expected no occurrences outside the range, got %v", got)
	}
}

func TestExpandOccurrencesWeeklyRecurring(t *testing.T) {
	start := time.Date(2026, 3, 3, 9, 0, 0, 0, time.UTC) // a Tuesday
	e := db.CalendarEvent{StartAt: start, EndAt: start.Add(time.Hour), RRule: "FREQ=WEEKLY"}

	rangeStart := time.Date(2026, 3, 1, 0, 0, 0, 0, time.UTC)
	rangeEnd := time.Date(2026, 4, 1, 0, 0, 0, 0, time.UTC)
	got := expandOccurrences(e, rangeStart, rangeEnd)
	// March 2026: Tuesdays on the 3rd, 10th, 17th, 24th, 31st.
	if len(got) != 5 {
		t.Fatalf("expected 5 weekly occurrences in March, got %d: %v", len(got), got)
	}
	for i, want := range []int{3, 10, 17, 24, 31} {
		if got[i].Day() != want {
			t.Errorf("occurrence %d: day = %d, want %d", i, got[i].Day(), want)
		}
	}
}

func TestExpandOccurrencesMonthlyRecurring(t *testing.T) {
	start := time.Date(2026, 1, 15, 9, 0, 0, 0, time.UTC)
	e := db.CalendarEvent{StartAt: start, EndAt: start.Add(time.Hour), RRule: "FREQ=MONTHLY"}

	rangeStart := time.Date(2026, 3, 1, 0, 0, 0, 0, time.UTC)
	rangeEnd := time.Date(2026, 4, 1, 0, 0, 0, 0, time.UTC)
	got := expandOccurrences(e, rangeStart, rangeEnd)
	if len(got) != 1 || got[0].Day() != 15 || got[0].Month() != time.March {
		t.Fatalf("expected exactly the March 15th occurrence, got %v", got)
	}
}