package classes_test

import (
	"strings"
	"testing"
	"time"

	"git.golem15.com/golem15/summercms/modules/lagoon"
	"git.golem15.com/jakub/sm-bm-plugin/classes"
	"git.golem15.com/jakub/sm-bm-plugin/models"
)

func sp(s string) *string { return &s }
func up(n uint) *uint     { return &n }

func calendarFixture() classes.CalendarData {
	updated := time.Date(2026, 10, 2, 12, 30, 0, 0, time.UTC)
	glob := &models.Course{ID: 1, Name: "Globalizacja i regionalizacja", Form: models.FormWyklad, Lecturer: sp("prof. dr hab. Piotr Mikiewicz")}
	hist := &models.Course{ID: 8, Name: "Historia wojen i konfliktów do 1945 roku", Form: models.FormInne, ElectiveGroup: sp("historia-koncepcje")}
	konc := &models.Course{ID: 9, Name: "Koncepcje wojny i pokoju – historia i współczesność", Form: models.FormInne, ElectiveGroup: sp("historia-koncepcje")}
	m3 := &models.Meeting{ID: 3, Number: 3, StartsOn: day("2026-10-24"), EndsOn: day("2026-10-25"), Notes: sp("stacjonarny (Koszarowa 3, bud. 21)"), UpdatedAt: updated}
	m2 := &models.Meeting{ID: 2, Number: 2, StartsOn: day("2026-10-17"), EndsOn: day("2026-10-18"), Notes: sp("online"), UpdatedAt: updated}
	return classes.CalendarData{
		Sessions: []models.ClassSession{
			{ID: 11, CourseID: up(1), Course: glob, MeetingID: up(3), Meeting: m3, StartsAt: ts("2026-10-24T08:00:00+02:00"), EndsAt: ts("2026-10-24T09:30:00+02:00"), Room: sp("237"), Notes: sp("prof. P. Mikiewicz"), UpdatedAt: updated},
			{ID: 12, CourseID: up(8), Course: hist, MeetingID: up(3), Meeting: m3, StartsAt: ts("2026-10-25T08:00:00+01:00"), EndsAt: ts("2026-10-25T09:30:00+01:00"), Room: sp("110"), UpdatedAt: updated},
			{ID: 13, CourseID: up(9), Course: konc, MeetingID: up(2), Meeting: m2, StartsAt: ts("2026-10-17T10:00:00+02:00"), EndsAt: ts("2026-10-17T11:30:00+02:00"), IsOnline: true, Room: sp("237"), UpdatedAt: updated},
		},
		Meetings: []models.Meeting{*m2, *m3},
		Deadlines: []models.Deadline{
			{ID: 21, Title: "Esej; wersja 1, szkic", DueAt: ts("2026-11-30T23:59:00+01:00"), CourseID: up(1), Course: glob, Description: sp("Wysłać\nmailem"), UpdatedAt: updated},
			{ID: 22, Title: "Esej z koncepcji", DueAt: ts("2026-12-01T12:00:00+01:00"), CourseID: up(9), Course: konc, UpdatedAt: updated},
			{ID: 23, Title: "Ślubowanie", DueAt: ts("2026-10-05T23:59:00+02:00"), UpdatedAt: updated},
		},
	}
}

// unfold returns the content lines of an ICS stream.
func unfold(t *testing.T, ics []byte) []string {
	t.Helper()
	s := string(ics)
	if !strings.HasSuffix(s, "\r\n") {
		t.Fatalf("stream does not end with CRLF")
	}
	for _, line := range strings.Split(strings.TrimSuffix(s, "\r\n"), "\r\n") {
		if len(line) > 75 {
			t.Errorf("line of %d octets: %q", len(line), line)
		}
	}
	return strings.Split(strings.TrimSuffix(strings.ReplaceAll(s, "\r\n ", ""), "\r\n"), "\r\n")
}

// events splits the content lines into VEVENTs keyed by UID.
func events(lines []string) map[string][]string {
	out := map[string][]string{}
	var cur []string
	for _, l := range lines {
		switch {
		case l == "BEGIN:VEVENT":
			cur = []string{}
		case l == "END:VEVENT":
			for _, c := range cur {
				if uid, ok := strings.CutPrefix(c, "UID:"); ok {
					out[uid] = cur
				}
			}
			cur = nil
		case cur != nil:
			cur = append(cur, l)
		}
	}
	return out
}

func has(lines []string, want string) bool {
	for _, l := range lines {
		if l == want {
			return true
		}
	}
	return false
}

func TestBuildCalendarHeaderAndBalance(t *testing.T) {
	lines := unfold(t, classes.BuildCalendar(calendarFixture(), classes.CalendarOptions{IncludeMeetings: true, IncludeDeadlines: true, SiteURL: "https://bm.jakubzych.com"}))
	if lines[0] != "BEGIN:VCALENDAR" || lines[len(lines)-1] != "END:VCALENDAR" {
		t.Errorf("first/last lines %q %q", lines[0], lines[len(lines)-1])
	}
	for _, want := range []string{
		"PRODID:-//jakubzych//BM UWr//PL", "VERSION:2.0", "CALSCALE:GREGORIAN", "METHOD:PUBLISH",
		"X-WR-CALNAME:BM UWr – plan zajęć", "X-WR-TIMEZONE:Europe/Warsaw",
		"REFRESH-INTERVAL;VALUE=DURATION:PT6H", "X-PUBLISHED-TTL:PT6H",
	} {
		if !has(lines, want) {
			t.Errorf("missing %q", want)
		}
	}
	depth := map[string]int{}
	for _, l := range lines {
		if c, ok := strings.CutPrefix(l, "BEGIN:"); ok {
			depth[c]++
		}
		if c, ok := strings.CutPrefix(l, "END:"); ok {
			depth[c]--
		}
	}
	for c, d := range depth {
		if d != 0 {
			t.Errorf("BEGIN/END of %s off by %d", c, d)
		}
	}
	if n := len(events(lines)); n != 3+2+3 {
		t.Errorf("%d events, want 8", n)
	}
}

func TestBuildCalendarSessions(t *testing.T) {
	ev := events(unfold(t, classes.BuildCalendar(calendarFixture(), classes.CalendarOptions{SiteURL: "https://bm.jakubzych.com"})))
	glob := ev["session-11@bm.jakubzych.com"]
	for _, want := range []string{
		"DTSTART:20261024T060000Z", "DTEND:20261024T073000Z",
		"DTSTAMP:20261002T123000Z", "LAST-MODIFIED:20261002T123000Z", "SEQUENCE:0",
		"SUMMARY:Globalizacja i regionalizacja – wykład",
		`LOCATION:Koszarowa 3\, s. 237 (bud. 21 ISMiB)`,
		`DESCRIPTION:Prowadzący: prof. dr hab. Piotr Mikiewicz\nZjazd 3\nprof. P. Mikiewicz\nhttps://bm.jakubzych.com/przedmioty/1`,
	} {
		if !has(glob, want) {
			t.Errorf("session 11 lacks %q:\n%s", want, strings.Join(glob, "\n"))
		}
	}
	// After the DST change Warsaw is UTC+1.
	hist := ev["session-12@bm.jakubzych.com"]
	if !has(hist, "DTSTART:20261025T070000Z") || !has(hist, "SUMMARY:Historia wojen i konfliktów do 1945 roku") {
		t.Errorf("session 12:\n%s", strings.Join(hist, "\n"))
	}
	if !has(hist, `DESCRIPTION:Zjazd 3\nPrzedmiot do wyboru\nhttps://bm.jakubzych.com/przedmioty/8`) {
		t.Errorf("session 12 description:\n%s", strings.Join(hist, "\n"))
	}
	online := ev["session-13@bm.jakubzych.com"]
	if !has(online, "SUMMARY:Koncepcje wojny i pokoju – historia i współczesność (online)") || !has(online, "LOCATION:online") {
		t.Errorf("online session:\n%s", strings.Join(online, "\n"))
	}
	if len(ev) != 3 {
		t.Errorf("meetings or deadlines without being asked: %v", ev)
	}
}

func TestBuildCalendarExclusions(t *testing.T) {
	ev := events(unfold(t, classes.BuildCalendar(calendarFixture(), classes.CalendarOptions{ExcludedCourseIDs: []uint{9}, IncludeDeadlines: true})))
	if _, ok := ev["session-13@bm.jakubzych.com"]; ok {
		t.Error("a session of an excluded course is listed")
	}
	if _, ok := ev["deadline-22@bm.jakubzych.com"]; ok {
		t.Error("a deadline of an excluded course is listed")
	}
	for _, uid := range []string{"session-11@bm.jakubzych.com", "session-12@bm.jakubzych.com", "deadline-21@bm.jakubzych.com", "deadline-23@bm.jakubzych.com"} {
		if _, ok := ev[uid]; !ok {
			t.Errorf("%s is missing", uid)
		}
	}
	// Without a site URL there is no link.
	if has(ev["session-11@bm.jakubzych.com"], "URL:https://bm.jakubzych.com/przedmioty/1") {
		t.Error("link without a site URL")
	}
}

func TestBuildCalendarMeetingsAreAllDay(t *testing.T) {
	ev := events(unfold(t, classes.BuildCalendar(calendarFixture(), classes.CalendarOptions{IncludeMeetings: true})))
	m3 := ev["meeting-3@bm.jakubzych.com"]
	for _, want := range []string{
		"DTSTART;VALUE=DATE:20261024", "DTEND;VALUE=DATE:20261026",
		"SUMMARY:3. zjazd (stacjonarny)", "TRANSP:TRANSPARENT",
		`DESCRIPTION:stacjonarny (Koszarowa 3\, bud. 21)`,
	} {
		if !has(m3, want) {
			t.Errorf("meeting 3 lacks %q:\n%s", want, strings.Join(m3, "\n"))
		}
	}
	if !has(ev["meeting-2@bm.jakubzych.com"], "SUMMARY:2. zjazd (online)") {
		t.Errorf("meeting 2: %v", ev["meeting-2@bm.jakubzych.com"])
	}
}

func TestBuildCalendarDeadlines(t *testing.T) {
	lines := unfold(t, classes.BuildCalendar(calendarFixture(), classes.CalendarOptions{IncludeDeadlines: true}))
	d := events(lines)["deadline-21@bm.jakubzych.com"]
	for _, want := range []string{
		"DTSTART:20261130T222900Z", "DTEND:20261130T225900Z",
		`SUMMARY:Termin: Esej\; wersja 1\, szkic`,
		`DESCRIPTION:Przedmiot: Globalizacja i regionalizacja\nWysłać\nmailem`,
		"BEGIN:VALARM", "ACTION:DISPLAY", "TRIGGER:-P1D", "END:VALARM",
	} {
		if !has(d, want) {
			t.Errorf("deadline lacks %q:\n%s", want, strings.Join(d, "\n"))
		}
	}
	if strings.Contains(strings.Join(lines, "\n"), "VALARM") && has(events(lines)["session-11@bm.jakubzych.com"], "BEGIN:VALARM") {
		t.Error("a session has an alarm")
	}
}

func TestSummaries(t *testing.T) {
	for form, want := range map[string]string{
		models.FormWyklad: "X – wykład", models.FormCwiczenia: "X – ćwiczenia", models.FormKonwersatorium: "X – konwersatorium",
		models.FormSeminarium: "X – seminarium", models.FormInne: "X",
	} {
		if got := classes.SessionSummary(models.ClassSession{Course: &models.Course{Name: "X", Form: form}}); got != want {
			t.Errorf("%s: %q, want %q", form, got, want)
		}
	}
	if got := classes.MeetingSummary(models.Meeting{Number: 7}); got != "7. zjazd" {
		t.Errorf("meeting without notes = %q", got)
	}
}

func day(s string) lagoon.Date {
	d, err := lagoon.ParseDate(s)
	if err != nil {
		panic(err)
	}
	return d
}

func ts(s string) time.Time {
	t, err := time.Parse(time.RFC3339, s)
	if err != nil {
		panic(err)
	}
	return t
}