package caldav

import (
	"context"
	"fmt"
	"io"
	"log/slog"
	"net/http"
	"net/http/httptest"
	"path/filepath"
	"strings"
	"testing"

	ical "github.com/emersion/go-ical"
	"git.arnef.de/arnef/nidus/internal/auth"
	"git.arnef.de/arnef/nidus/internal/config"
	"git.arnef.de/arnef/nidus/internal/db"
	"git.arnef.de/arnef/nidus/internal/store"
)

func newTestBackend(t *testing.T) (*Backend, *db.DB) {
	t.Helper()
	dir := t.TempDir()

	st, err := store.NewStore(filepath.Join(dir, "data"))
	if err != nil {
		t.Fatalf("NewStore: %v", err)
	}
	dbase, err := db.Open(filepath.Join(dir, "test.db"))
	if err != nil {
		t.Fatalf("db.Open: %v", err)
	}
	t.Cleanup(func() { dbase.Close() })

	cfg := &config.Config{}
	if err := dbase.CreateUser("alice", "pw", "", ""); err != nil {
		t.Fatalf("CreateUser alice: %v", err)
	}
	if err := dbase.CreateUser("bob", "pw", "", ""); err != nil {
		t.Fatalf("CreateUser bob: %v", err)
	}
	if err := dbase.CreateCalendar("alice", "work"); err != nil {
		t.Fatalf("CreateCalendar alice/work: %v", err)
	}
	if err := dbase.CreateCalendar("bob", "personal"); err != nil {
		t.Fatalf("CreateCalendar bob/personal: %v", err)
	}
	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
	return NewBackend(cfg, st, dbase, logger), dbase
}

func ctxFor(username string) context.Context {
	return auth.NewContext(context.Background(), &auth.Principal{Username: username})
}

// minimalEvent returns a minimal, valid VCALENDAR/VEVENT for use in tests.
func minimalEvent() *ical.Calendar {
	const raw = "BEGIN:VCALENDAR\r\n" +
		"VERSION:2.0\r\n" +
		"PRODID:-//nidus//test//EN\r\n" +
		"BEGIN:VEVENT\r\n" +
		"UID:event1@nidus.test\r\n" +
		"DTSTAMP:20240101T000000Z\r\n" +
		"DTSTART:20240101T100000Z\r\n" +
		"SUMMARY:Test Event\r\n" +
		"END:VEVENT\r\n" +
		"END:VCALENDAR\r\n"
	cal, err := ical.NewDecoder(strings.NewReader(raw)).Decode()
	if err != nil {
		panic(fmt.Sprintf("minimalEvent: %v", err))
	}
	return cal
}

func TestListCalendarsIncludesSharedCalendar(t *testing.T) {
	b, dbase := newTestBackend(t)

	if err := dbase.ShareCalendar("alice", "work", "bob", db.PermRead); err != nil {
		t.Fatalf("ShareCalendar: %v", err)
	}
	// The shared calendar must exist on disk for it to be listed; normally
	// this happens when alice's own ListCalendars runs and ensures it.
	if _, err := b.ListCalendars(ctxFor("alice")); err != nil {
		t.Fatalf("ListCalendars(alice): %v", err)
	}

	cals, err := b.ListCalendars(ctxFor("bob"))
	if err != nil {
		t.Fatalf("ListCalendars: %v", err)
	}

	var found bool
	wantPath := calHomePath() + sharedCalendarName("alice", "work") + "/"
	for _, c := range cals {
		if c.Path == wantPath && c.Name == "work" {
			found = true
		}
	}
	if !found {
		t.Errorf("shared calendar with path %q and display name %q not found in ListCalendars result: %+v", wantPath, "work", cals)
	}
}

func TestSharedCalendarReadOnlyRejectsWrite(t *testing.T) {
	b, dbase := newTestBackend(t)

	if err := dbase.ShareCalendar("alice", "work", "bob", db.PermRead); err != nil {
		t.Fatalf("ShareCalendar: %v", err)
	}

	localName := sharedCalendarName("alice", "work")
	objPath := calObjectPath(localName, "event1.ics")

	_, err := b.PutCalendarObject(ctxFor("bob"), objPath, minimalEvent(), nil)
	if err == nil {
		t.Fatal("expected error writing to read-only shared calendar, got nil")
	}
}

func TestSharedCalendarWriteAllowed(t *testing.T) {
	b, dbase := newTestBackend(t)

	if err := dbase.ShareCalendar("alice", "work", "bob", db.PermWrite); err != nil {
		t.Fatalf("ShareCalendar: %v", err)
	}

	localName := sharedCalendarName("alice", "work")
	objPath := calObjectPath(localName, "event1.ics")

	if _, err := b.PutCalendarObject(ctxFor("bob"), objPath, minimalEvent(), nil); err != nil {
		t.Fatalf("PutCalendarObject with write share: %v", err)
	}

	// The object should now be visible under alice's own calendar too,
	// since it's stored in her namespace.
	obj, err := b.GetCalendarObject(ctxFor("alice"), calObjectPath("work", "event1.ics"), nil)
	if err != nil {
		t.Fatalf("GetCalendarObject as owner: %v", err)
	}
	if obj == nil {
		t.Fatal("expected non-nil object")
	}
}

func TestUnauthorizedUserCannotAccessUnsharedCalendar(t *testing.T) {
	b, _ := newTestBackend(t)

	localName := sharedCalendarName("alice", "work")
	_, err := b.GetCalendar(ctxFor("bob"), calHomePath()+localName+"/")
	if err == nil {
		t.Fatal("expected error accessing unshared calendar, got nil")
	}
}

// TestPropFindEmitsCalendarColor verifies that a PROPFIND on a calendar
// with a color set returns the Apple/DAVx5 calendar-color property, and
// that a calendar without a color doesn't (since a client should fall
// back to its own default in that case).
func TestPropFindEmitsCalendarColor(t *testing.T) {
	dir := t.TempDir()
	st, err := store.NewStore(filepath.Join(dir, "data"))
	if err != nil {
		t.Fatalf("NewStore: %v", err)
	}
	dbase, err := db.Open(filepath.Join(dir, "test.db"))
	if err != nil {
		t.Fatalf("db.Open: %v", err)
	}
	t.Cleanup(func() { dbase.Close() })

	if err := dbase.CreateUser("alice", "pw", "", ""); err != nil {
		t.Fatalf("CreateUser alice: %v", err)
	}
	if err := dbase.CreateCalendarWithColor("alice", "work", "#3b82f6"); err != nil {
		t.Fatalf("CreateCalendarWithColor: %v", err)
	}
	if err := dbase.CreateCalendar("alice", "personal"); err != nil {
		t.Fatalf("CreateCalendar: %v", err)
	}

	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
	handler := NewHandler(&config.Config{}, st, dbase, logger)

	req := httptest.NewRequest("PROPFIND", "/cal/home/", strings.NewReader(
		`<?xml version="1.0"?><a:propfind xmlns:a="DAV:"><a:allprop/></a:propfind>`))
	req.SetBasicAuth("alice", "pw")
	req.Header.Set("Content-Type", "text/xml")
	req.Header.Set("Depth", "1")
	req = req.WithContext(ctxFor("alice"))

	rr := httptest.NewRecorder()
	req = req.WithContext(auth.NewContext(context.Background(), &auth.Principal{Username: "alice"}))
	handler.ServeHTTP(rr, req)

	if rr.Code != http.StatusMultiStatus {
		t.Fatalf("expected 207, got %d: %s", rr.Code, rr.Body.String())
	}
	body := rr.Body.String()
	if !strings.Contains(body, `<calendar-color xmlns="http://apple.com/ns/ical/">#3b82f6FF</calendar-color>`) {
		t.Fatalf("expected calendar-color for work calendar, got: %s", body)
	}

	// The "personal" calendar has no color, so its <response> block
	// shouldn't contain the property at all.
	personalIdx := strings.Index(body, "/cal/home/personal/")
	if personalIdx < 0 {
		t.Fatalf("expected personal calendar in response, got: %s", body)
	}
	// Find personal's response block boundaries loosely by looking for the
	// nearest calendar-color occurrence and ensuring it isn't right next to
	// the personal href (colors are per-block, checked via count instead).
	// Two calendar-color elements are expected: one for "work" (explicit
	// color) and one for the always-present synthetic "birthdays" calendar
	// (default color, since it wasn't explicitly set here).
	if strings.Count(body, "<calendar-color ") != 2 {
		t.Fatalf("expected exactly two calendar-color elements (work + birthdays default), got: %s", body)
	}
	if !strings.Contains(body, `<calendar-color xmlns="http://apple.com/ns/ical/">`+defaultBirthdayColor+`FF</calendar-color>`) {
		t.Fatalf("expected default birthdays calendar-color, got: %s", body)
	}
}

// TestPropFindExplicitCalendarColorRequest verifies that when a client
// (like DAVx5) explicitly asks for the Apple calendar-color property by
// name, it gets back a single 200 OK propstat with the color — not a
// duplicate/conflicting 404 propstat alongside it, which is what
// go-webdav's stock property map produces on its own for an unknown
// property and which real clients (dav4jvm) were observed to prefer over
// the injected 200, hiding the color entirely.
func TestPropFindExplicitCalendarColorRequest(t *testing.T) {
	dir := t.TempDir()
	st, err := store.NewStore(filepath.Join(dir, "data"))
	if err != nil {
		t.Fatalf("NewStore: %v", err)
	}
	dbase, err := db.Open(filepath.Join(dir, "test.db"))
	if err != nil {
		t.Fatalf("db.Open: %v", err)
	}
	t.Cleanup(func() { dbase.Close() })

	if err := dbase.CreateUser("alice", "pw", "", ""); err != nil {
		t.Fatalf("CreateUser alice: %v", err)
	}
	if err := dbase.CreateCalendarWithColor("alice", "work", "#3b82f6"); err != nil {
		t.Fatalf("CreateCalendarWithColor: %v", err)
	}
	if err := st.EnsureCollection("alice", "cal-work"); err != nil {
		t.Fatalf("EnsureCollection: %v", err)
	}

	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
	handler := NewHandler(&config.Config{}, st, dbase, logger)

	req := httptest.NewRequest("PROPFIND", "/cal/home/work/", strings.NewReader(
		`<?xml version="1.0"?><D:propfind xmlns:D="DAV:" xmlns:A="http://apple.com/ns/ical/">`+
			`<D:prop><D:displayname/><A:calendar-color/></D:prop></D:propfind>`))
	req.SetBasicAuth("alice", "pw")
	req.Header.Set("Content-Type", "text/xml")
	req.Header.Set("Depth", "0")
	req = req.WithContext(auth.NewContext(context.Background(), &auth.Principal{Username: "alice"}))

	rr := httptest.NewRecorder()
	handler.ServeHTTP(rr, req)

	if rr.Code != http.StatusMultiStatus {
		t.Fatalf("expected 207, got %d: %s", rr.Code, rr.Body.String())
	}
	body := rr.Body.String()
	if strings.Count(body, "<propstat") != 1 {
		t.Fatalf("expected exactly one propstat (no leftover 404 for calendar-color), got: %s", body)
	}
	if !strings.Contains(body, `<calendar-color xmlns="http://apple.com/ns/ical/">#3b82f6FF</calendar-color>`) {
		t.Fatalf("expected calendar-color in the single 200 OK propstat, got: %s", body)
	}
	if !strings.Contains(body, "200 OK") || strings.Contains(body, "404") {
		t.Fatalf("expected a single 200 OK propstat with no 404, got: %s", body)
	}
}

// TestSharedCalendarNameCollidingWithOwnGetsDisambiguated covers the case
// where a calendar shared with a user has the same name as one of that
// user's own calendars: DAVx5 (and any other client) would otherwise show
// two calendars with an identical, indistinguishable title, so the shared
// one's display name gets the owner's username appended in parentheses.
func TestSharedCalendarNameCollidingWithOwnGetsDisambiguated(t *testing.T) {
	b, dbase := newTestBackend(t)

	// alice creates her own "personal" calendar, colliding with bob's
	// pre-existing "personal" calendar (see newTestBackend), then shares
	// it with bob.
	if err := dbase.CreateCalendar("alice", "personal"); err != nil {
		t.Fatalf("CreateCalendar alice/personal: %v", err)
	}
	if err := dbase.ShareCalendar("alice", "personal", "bob", db.PermRead); err != nil {
		t.Fatalf("ShareCalendar: %v", err)
	}
	if _, err := b.ListCalendars(ctxFor("alice")); err != nil {
		t.Fatalf("ListCalendars(alice): %v", err)
	}

	cals, err := b.ListCalendars(ctxFor("bob"))
	if err != nil {
		t.Fatalf("ListCalendars(bob): %v", err)
	}

	wantPath := calHomePath() + sharedCalendarName("alice", "personal") + "/"
	var sharedName, ownName string
	for _, c := range cals {
		if c.Path == wantPath {
			sharedName = c.Name
		}
		if c.Path == calHomePath()+"personal/" {
			ownName = c.Name
		}
	}
	if ownName != "personal" {
		t.Fatalf("expected bob's own calendar to keep its plain name, got %q", ownName)
	}
	if want := "personal (alice)"; sharedName != want {
		t.Fatalf("expected shared calendar display name %q, got %q", want, sharedName)
	}

	// GetCalendar (single-collection lookup, as used by PROPFIND on the
	// calendar's own URL) must disambiguate the same way.
	cal, err := b.GetCalendar(ctxFor("bob"), wantPath)
	if err != nil {
		t.Fatalf("GetCalendar: %v", err)
	}
	if want := "personal (alice)"; cal.Name != want {
		t.Fatalf("GetCalendar: expected display name %q, got %q", want, cal.Name)
	}
}