package dyzurbot

import (
	"testing"
	"time"
)

func warsaw(t *testing.T) *time.Location {
	t.Helper()
	loc, err := time.LoadLocation("Europe/Warsaw")
	if err != nil {
		t.Skipf("Europe/Warsaw tzdata unavailable: %v", err)
	}
	return loc
}

func TestNextFire(t *testing.T) {
	loc := warsaw(t)
	at := func(y int, mo time.Month, d, h, mi int) time.Time {
		return time.Date(y, mo, d, h, mi, 0, 0, loc)
	}

	tests := []struct {
		name    string
		now     time.Time
		weekday time.Weekday
		hour    int
		want    time.Time
	}{
		{
			"same weekday before hour -> today",
			at(2026, 6, 15, 8, 0), time.Monday, 9, // Mon 08:00
			at(2026, 6, 15, 9, 0),
		},
		{
			"same weekday exactly at hour -> next week (strictly after)",
			at(2026, 6, 15, 9, 0), time.Monday, 9,
			at(2026, 6, 22, 9, 0),
		},
		{
			"same weekday after hour -> next week",
			at(2026, 6, 15, 10, 0), time.Monday, 9,
			at(2026, 6, 22, 9, 0),
		},
		{
			"later weekday -> upcoming target weekday",
			at(2026, 6, 17, 12, 0), time.Monday, 9, // Wed -> next Mon
			at(2026, 6, 22, 9, 0),
		},
		{
			"day before -> next day",
			at(2026, 6, 21, 23, 0), time.Monday, 9, // Sun 23:00 -> Mon 09:00
			at(2026, 6, 22, 9, 0),
		},
	}
	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			got := nextFire(tc.now, tc.weekday, tc.hour, loc)
			if !got.Equal(tc.want) {
				t.Errorf("nextFire = %s, want %s", got.In(loc), tc.want.In(loc))
			}
			if !got.After(tc.now) {
				t.Errorf("nextFire %s not strictly after now %s", got.In(loc), tc.now.In(loc))
			}
		})
	}
}

// Across the spring-forward (2026-03-29 in Warsaw, clocks jump 02:00->03:00),
// the next Monday 09:00 must still be 09:00 wall-clock in Warsaw, proving the
// fire time is recomputed in the zone rather than by +7d UTC arithmetic.
func TestNextFireAcrossDST(t *testing.T) {
	loc := warsaw(t)
	now := time.Date(2026, 3, 28, 12, 0, 0, 0, loc) // Sat before DST
	got := nextFire(now, time.Monday, 9, loc).In(loc)

	if got.Weekday() != time.Monday || got.Hour() != 9 || got.Minute() != 0 {
		t.Fatalf("got %s, want Monday 09:00 Warsaw", got)
	}
	if y, m, d := got.Date(); y != 2026 || m != time.March || d != 30 {
		t.Errorf("got date %04d-%02d-%02d, want 2026-03-30", y, m, d)
	}
}

func TestReminderText(t *testing.T) {
	// Week of 2026-06-29; target lands inside it.
	target := day(t, "2026-06-30")
	rota := func(p1, p2 string) Rota {
		return Rota{Weeks: []DutyWeek{week(t, "2026-06-29", p1, p2)}}
	}

	tests := []struct {
		name   string
		rota   Rota
		target time.Time
		wantOK bool
		want   string
	}{
		{
			"both people",
			rota("Ala", "Bartek"), target, true,
			"Przypomnienie: w tygodniu od 2026-06-29 dyżur sprzątają Ala i Bartek.",
		},
		{
			"one person",
			rota("Ala", ""), target, true,
			"Przypomnienie: w tygodniu od 2026-06-29 dyżur sprząta Ala.",
		},
		{
			"nobody assigned",
			rota("", ""), target, true,
			"Przypomnienie: w tygodniu od 2026-06-29 dyżur jest nieobsadzony.",
		},
		{
			"no matching week -> skip",
			rota("Ala", "Bartek"), day(t, "2026-09-01"), false,
			"",
		},
	}
	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			got, ok := reminderText(tc.rota, tc.target)
			if ok != tc.wantOK {
				t.Fatalf("ok = %v, want %v", ok, tc.wantOK)
			}
			if ok && got != tc.want {
				t.Errorf("reminderText = %q, want %q", got, tc.want)
			}
		})
	}
}

func TestReminderTextMentions(t *testing.T) {
	target := day(t, "2026-06-30")
	people := []Person{
		{Name: "Ala", Handle: "@ala"},   // stored with leading @
		{Name: "Bartek", Handle: "bart"}, // stored without @ -> normalized
		{Name: "Cela", Handle: ""},       // present but no handle -> plain name
	}
	rota := func(p1, p2 string) Rota {
		return Rota{Weeks: []DutyWeek{week(t, "2026-06-29", p1, p2)}, People: people}
	}

	tests := []struct {
		name string
		rota Rota
		want string
	}{
		{
			"both have handles",
			rota("Ala", "Bartek"),
			"Przypomnienie: w tygodniu od 2026-06-29 dyżur sprzątają @ala i @bart.",
		},
		{
			"one handle, one missing -> mixed",
			rota("Ala", "Cela"),
			"Przypomnienie: w tygodniu od 2026-06-29 dyżur sprzątają @ala i Cela.",
		},
		{
			"name not in people list -> plain name",
			rota("Ala", "Zenon"),
			"Przypomnienie: w tygodniu od 2026-06-29 dyżur sprzątają @ala i Zenon.",
		},
		{
			"single person with handle",
			rota("Bartek", ""),
			"Przypomnienie: w tygodniu od 2026-06-29 dyżur sprząta @bart.",
		},
	}
	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			got, ok := reminderText(tc.rota, target)
			if !ok {
				t.Fatalf("ok = false, want true")
			}
			if got != tc.want {
				t.Errorf("reminderText = %q, want %q", got, tc.want)
			}
		})
	}
}

func TestParseWeekday(t *testing.T) {
	tests := []struct {
		in      string
		want    time.Weekday
		wantErr bool
	}{
		{"Monday", time.Monday, false},
		{"Sunday", time.Sunday, false},
		{"monday", time.Monday, false}, // case-insensitive
		{"Funday", 0, true},
		{"", 0, true},
	}
	for _, tc := range tests {
		t.Run(tc.in, func(t *testing.T) {
			got, err := parseWeekday(tc.in)
			if (err != nil) != tc.wantErr {
				t.Fatalf("err = %v, wantErr %v", err, tc.wantErr)
			}
			if err == nil && got != tc.want {
				t.Errorf("parseWeekday(%q) = %v, want %v", tc.in, got, tc.want)
			}
		})
	}
}