package dyzurbot

import (
	"testing"
	"time"
)

// week is a small helper to build a DutyWeek from a YYYY-MM-DD start.
func week(t *testing.T, start, p1, p2 string) DutyWeek {
	t.Helper()
	ws, err := time.Parse("2006-01-02", start)
	if err != nil {
		t.Fatalf("bad date %q: %v", start, err)
	}
	return DutyWeek{WeekStart: ws, Person1: p1, Person2: p2}
}

func day(t *testing.T, d string) time.Time {
	t.Helper()
	tm, err := time.Parse("2006-01-02", d)
	if err != nil {
		t.Fatalf("bad date %q: %v", d, err)
	}
	return tm
}

func TestCurrentDuty(t *testing.T) {
	rota := Rota{Weeks: []DutyWeek{
		week(t, "2026-06-15", "Ala", "Bartek"),
		week(t, "2026-06-22", "Celina", "Darek"),
	}}

	tests := []struct {
		name      string
		today     time.Time
		wantOK    bool
		wantStart string // WeekStart of the matched week, when wantOK
	}{
		{"inside first week", day(t, "2026-06-17"), true, "2026-06-15"},
		{"first day of first week", day(t, "2026-06-15"), true, "2026-06-15"},
		{"last day of first week", day(t, "2026-06-21"), true, "2026-06-15"},
		{"first day of second week", day(t, "2026-06-22"), true, "2026-06-22"},
		{"before all weeks", day(t, "2026-06-14"), false, ""},
		{"after all weeks", day(t, "2026-06-29"), false, ""},
	}
	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			got, ok := currentDuty(rota, tc.today)
			if ok != tc.wantOK {
				t.Fatalf("ok = %v, want %v", ok, tc.wantOK)
			}
			if ok && got.WeekStart.Format("2006-01-02") != tc.wantStart {
				t.Errorf("matched week %s, want %s",
					got.WeekStart.Format("2006-01-02"), tc.wantStart)
			}
		})
	}
}

func TestCurrentDutyEmptyRota(t *testing.T) {
	if _, ok := currentDuty(Rota{}, day(t, "2026-06-17")); ok {
		t.Error("empty rota should not match any week")
	}
}

// A local time just after midnight in a +02:00 zone is still the previous day
// in UTC. currentDuty must match on the local calendar date, so 2026-06-15
// (Poland) lands in the week starting 2026-06-15, not the prior week.
func TestCurrentDutyLocalMidnight(t *testing.T) {
	rota := Rota{Weeks: []DutyWeek{week(t, "2026-06-15", "Ala", "Bartek")}}
	today := time.Date(2026, 6, 15, 0, 30, 0, 0, time.FixedZone("CEST", 2*3600))

	got, ok := currentDuty(rota, today)
	if !ok {
		t.Fatal("expected a match for local 2026-06-15")
	}
	if got.Person1 != "Ala" {
		t.Errorf("matched wrong week: %+v", got)
	}
}

func TestFormatDuty(t *testing.T) {
	tests := []struct {
		name string
		week DutyWeek
		ok   bool
		want string
	}{
		{
			"both people",
			week(t, "2026-06-15", "Ala", "Bartek"), true,
			"Dyżur w tym tygodniu (od 2026-06-15): Ala i Bartek",
		},
		{
			"only person1",
			week(t, "2026-06-15", "Ala", ""), true,
			"Dyżur w tym tygodniu (od 2026-06-15): Ala",
		},
		{
			"only person2",
			week(t, "2026-06-15", "", "Bartek"), true,
			"Dyżur w tym tygodniu (od 2026-06-15): Bartek",
		},
		{
			"nobody assigned",
			week(t, "2026-06-15", "", ""), true,
			"Dyżur w tym tygodniu (od 2026-06-15): brak przypisania",
		},
		{
			"not found",
			DutyWeek{}, false,
			"Nie znalazłem dyżuru na ten tydzień.",
		},
	}
	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			if got := formatDuty(tc.week, tc.ok); got != tc.want {
				t.Errorf("formatDuty = %q, want %q", got, tc.want)
			}
		})
	}
}