package api

import (
	"context"
	"encoding/json"
	"testing"
	"time"

	"github.com/ponzischeme89/memby/server/internal/store"
)

// The television has one UserData reader and it must not be able to tell where the block
// came from. This pins the field names against the client's UserItemData, which is the
// contract that keeps viewers from becoming a special case in every screen.
func TestViewerUserDataIsShapedLikeEmbys(t *testing.T) {
	played := time.Date(2026, 8, 19, 21, 14, 0, 0, time.UTC)
	raw := viewerUserData(store.ViewerState{
		ItemID:        "982173",
		PositionTicks: 15_420_000_000,
		RuntimeTicks:  30_840_000_000,
		PlayCount:     2,
		Favourite:     true,
		LastPlayedAt:  &played,
	})

	var parsed struct {
		IsFavorite            bool     `json:"IsFavorite"`
		Played                bool     `json:"Played"`
		PlaybackPositionTicks int64    `json:"PlaybackPositionTicks"`
		PlayCount             int      `json:"PlayCount"`
		PlayedPercentage      *float64 `json:"PlayedPercentage"`
		LastPlayedDate        string   `json:"LastPlayedDate"`
	}
	if err := json.Unmarshal(raw, &parsed); err != nil {
		t.Fatalf("decode viewer user data: %v", err)
	}
	if !parsed.IsFavorite {
		t.Error("favourite was not carried")
	}
	if parsed.Played {
		t.Error("a part-watched title was reported as played")
	}
	if parsed.PlaybackPositionTicks != 15_420_000_000 {
		t.Errorf("position = %d", parsed.PlaybackPositionTicks)
	}
	if parsed.PlayCount != 2 {
		t.Errorf("play count = %d", parsed.PlayCount)
	}
	if parsed.PlayedPercentage == nil || *parsed.PlayedPercentage < 49 || *parsed.PlayedPercentage > 51 {
		t.Errorf("played percentage = %v, want about 50", parsed.PlayedPercentage)
	}
	if parsed.LastPlayedDate != "2026-08-19T21:14:00Z" {
		t.Errorf("last played = %q", parsed.LastPlayedDate)
	}
}

// A title nobody has touched has to render as untouched rather than as a card claiming a
// zero-length progress bar, so the two optional fields are omitted rather than sent empty.
func TestViewerUserDataOmitsWhatItDoesNotKnow(t *testing.T) {
	raw := viewerUserData(store.ViewerState{ItemID: "982173"})
	var fields map[string]any
	if err := json.Unmarshal(raw, &fields); err != nil {
		t.Fatalf("decode viewer user data: %v", err)
	}
	if _, ok := fields["PlayedPercentage"]; ok {
		t.Error("a percentage was claimed for a title with no runtime or position")
	}
	if _, ok := fields["LastPlayedDate"]; ok {
		t.Error("a play date was claimed for a title that has never been played")
	}
	if fields["Played"] != false || fields["IsFavorite"] != false {
		t.Errorf("untouched state rendered as %v", fields)
	}
}

// IsMain is what every mutation branches on, so it is worth stating that it reads the
// stored kind rather than guessing from the id.
func TestViewerIsMainReadsTheStoredKind(t *testing.T) {
	if !(store.Viewer{ID: "abc", Kind: store.ViewerMain}).IsMain() {
		t.Error("a main viewer did not report as main")
	}
	if (store.Viewer{ID: "abc", Kind: store.ViewerShadow}).IsMain() {
		t.Error("a shadow viewer reported as main")
	}
	if (store.Viewer{ID: "abc"}).IsMain() {
		t.Error("a viewer with no kind reported as main")
	}
}

// The ids are the answer, not just the selection: a shadow viewer's Continue Watching is
// ordered by their own history in Postgres, and Emby answers an Ids= query in its own
// order. Handing that back would keep the right titles and discard the reason for them.
func TestOrderItemsByIDRestoresTheOrderAskedFor(t *testing.T) {
	item := func(id string) json.RawMessage {
		return json.RawMessage(`{"Id":"` + id + `","Name":"` + id + `"}`)
	}
	idsOf := func(items []json.RawMessage) []string {
		out := []string{}
		for _, raw := range items {
			out = append(out, itemIDOf(raw))
		}
		return out
	}

	t.Run("emby's order is replaced", func(t *testing.T) {
		got := orderItemsByID(
			[]json.RawMessage{item("c"), item("a"), item("b")},
			[]string{"b", "c", "a"},
		)
		want := []string{"b", "c", "a"}
		if diff := idsOf(got); !equalStrings(diff, want) {
			t.Fatalf("order = %v, want %v", diff, want)
		}
	})

	// A title the catalogue still names but Emby will not answer for leaves a card that
	// cannot be opened, so it is dropped instead.
	t.Run("a missing title is dropped", func(t *testing.T) {
		got := orderItemsByID([]json.RawMessage{item("a")}, []string{"a", "gone", "b"})
		if diff := idsOf(got); !equalStrings(diff, []string{"a"}) {
			t.Fatalf("order = %v, want [a]", diff)
		}
	})

	// Every keyed list on the television throws on a repeated key, and a paging boundary
	// or a duplicated row is exactly where an id comes back twice.
	t.Run("a repeated id draws one card", func(t *testing.T) {
		got := orderItemsByID([]json.RawMessage{item("a"), item("a")}, []string{"a", "a"})
		if diff := idsOf(got); !equalStrings(diff, []string{"a"}) {
			t.Fatalf("order = %v, want one card", diff)
		}
	})

	// Anything Emby volunteers that was not asked for is not part of the answer.
	t.Run("an unasked title is dropped", func(t *testing.T) {
		got := orderItemsByID([]json.RawMessage{item("a"), item("z")}, []string{"a"})
		if diff := idsOf(got); !equalStrings(diff, []string{"a"}) {
			t.Fatalf("order = %v, want [a]", diff)
		}
	})
}

// The account's UserData must be replaced outright rather than merged: a partial overlay
// leaves whichever fields Memby had nothing to say about carrying the account's values.
func TestInjectItemUserDataReplacesRatherThanMerges(t *testing.T) {
	raw := json.RawMessage(
		`{"Id":"1","Name":"Anatomy of a Fall",` +
			`"UserData":{"Played":true,"PlaybackPositionTicks":9999,"IsFavorite":true,"PlayCount":4}}`)
	out := injectItemUserData(raw, viewerUserData(store.ViewerState{ItemID: "1"}))

	var parsed struct {
		Name     string `json:"Name"`
		UserData struct {
			Played                bool  `json:"Played"`
			PlaybackPositionTicks int64 `json:"PlaybackPositionTicks"`
			IsFavorite            bool  `json:"IsFavorite"`
			PlayCount             int   `json:"PlayCount"`
		} `json:"UserData"`
	}
	if err := json.Unmarshal(out, &parsed); err != nil {
		t.Fatalf("decode: %v", err)
	}
	if parsed.Name != "Anatomy of a Fall" {
		t.Errorf("the rest of the item was disturbed: name = %q", parsed.Name)
	}
	if parsed.UserData.Played || parsed.UserData.IsFavorite {
		t.Error("the account's watched or favourite state survived")
	}
	if parsed.UserData.PlaybackPositionTicks != 0 || parsed.UserData.PlayCount != 0 {
		t.Errorf("the account's position or play count survived: %+v", parsed.UserData)
	}
}

// A series and a season are answered from a count of episodes rather than from a row of
// their own, so they have to be told apart from the leaf items around them.
func TestAggregateItemsAreRecognised(t *testing.T) {
	for _, tc := range []struct {
		itemType string
		want     bool
	}{
		{"Series", true},
		{"Season", true},
		{"Episode", false},
		{"Movie", false},
		{"", false},
	} {
		raw := json.RawMessage(`{"Id":"1","Type":"` + tc.itemType + `"}`)
		if got := isAggregateItem(raw); got != tc.want {
			t.Errorf("isAggregateItem(%q) = %v, want %v", tc.itemType, got, tc.want)
		}
	}
}

// Everything downstream keys its cached views on this, so a request that never passed
// through authed must still answer with the value those keys held before viewers existed.
func TestViewerOfFallsBackToTheAccount(t *testing.T) {
	sess := store.Session{EmbyUserID: "emby-user-1", Username: "Matt"}
	viewer := viewerOf(context.Background(), sess)
	if !viewer.IsMain() || viewer.ID != "emby-user-1" {
		t.Fatalf("fallback viewer = %+v, want the account as main", viewer)
	}
	if got := viewerKeyOf(context.Background(), sess); got != "emby-user-1" {
		t.Fatalf("cache key = %q, want the Emby user id", got)
	}

	shadow := store.Viewer{ID: "v0123", Name: "Alessandra", Kind: store.ViewerShadow}
	ctx := withViewer(context.Background(), shadow)
	if got := viewerKeyOf(ctx, sess); got != "v0123" {
		t.Fatalf("cache key = %q, want the shadow viewer", got)
	}
}

func equalStrings(a, b []string) bool {
	if len(a) != len(b) {
		return false
	}
	for i := range a {
		if a[i] != b[i] {
			return false
		}
	}
	return true
}

// The last place a shadow viewer was shown the account's answer. A series card draws its
// tick and its "left to watch" from these fields, and Emby fills them in from children it
// has never heard of for this person.
func TestViewerAggregateUserDataCountsWhatIsLeft(t *testing.T) {
	played := time.Date(2026, 8, 18, 20, 5, 0, 0, time.UTC)
	raw := viewerAggregateUserData(
		store.ViewerState{ItemID: "series-1", Favourite: true},
		store.ViewerAggregate{Total: 10, Played: 4, LastPlayedAt: &played},
	)

	var parsed struct {
		IsFavorite            bool     `json:"IsFavorite"`
		Played                bool     `json:"Played"`
		PlaybackPositionTicks int64    `json:"PlaybackPositionTicks"`
		UnplayedItemCount     *int     `json:"UnplayedItemCount"`
		PlayedPercentage      *float64 `json:"PlayedPercentage"`
		LastPlayedDate        string   `json:"LastPlayedDate"`
	}
	if err := json.Unmarshal(raw, &parsed); err != nil {
		t.Fatalf("decode aggregate user data: %v", err)
	}
	// The favourite is the container's own — somebody marks a show, not the sum of its
	// episodes — so it comes from the row rather than from the count.
	if !parsed.IsFavorite {
		t.Error("the viewer's own favourite on the series was dropped")
	}
	if parsed.Played {
		t.Error("a part-watched series reported as finished")
	}
	if parsed.UnplayedItemCount == nil || *parsed.UnplayedItemCount != 6 {
		t.Errorf("unplayed = %v, want 6", parsed.UnplayedItemCount)
	}
	if parsed.PlayedPercentage == nil || *parsed.PlayedPercentage < 39 || *parsed.PlayedPercentage > 41 {
		t.Errorf("played percentage = %v, want about 40", parsed.PlayedPercentage)
	}
	// A container is never resumable; what resumes is an episode.
	if parsed.PlaybackPositionTicks != 0 {
		t.Errorf("a series carried a resume position: %d", parsed.PlaybackPositionTicks)
	}
	if parsed.LastPlayedDate != "2026-08-18T20:05:00Z" {
		t.Errorf("last played = %q", parsed.LastPlayedDate)
	}

	finished := viewerAggregateUserData(
		store.ViewerState{}, store.ViewerAggregate{Total: 10, Played: 10},
	)
	var done map[string]any
	if err := json.Unmarshal(finished, &done); err != nil {
		t.Fatalf("decode: %v", err)
	}
	if done["Played"] != true {
		t.Errorf("a fully watched series did not report as played: %v", done)
	}
	if count, ok := done["UnplayedItemCount"].(float64); !ok || count != 0 {
		t.Errorf("unplayed on a finished series = %v, want 0", done["UnplayedItemCount"])
	}
}

// "Nothing left to watch" and "I cannot say how much there is" are different answers, and
// only one of them is true for a library the catalogue has not imported yet. Ticking every
// show in the house is the worst thing this could do.
func TestViewerAggregateUserDataSaysNothingItCannotCount(t *testing.T) {
	raw := viewerAggregateUserData(store.ViewerState{}, store.ViewerAggregate{})
	var fields map[string]any
	if err := json.Unmarshal(raw, &fields); err != nil {
		t.Fatalf("decode: %v", err)
	}
	if _, ok := fields["UnplayedItemCount"]; ok {
		t.Error("a count was claimed for a series the catalogue cannot count")
	}
	if _, ok := fields["PlayedPercentage"]; ok {
		t.Error("a percentage was claimed with nothing to divide by")
	}
	if _, ok := fields["LastPlayedDate"]; ok {
		t.Error("a play date was claimed for a series nobody has watched")
	}
	if fields["Played"] != false {
		t.Errorf("an uncountable series reported as watched: %v", fields)
	}
}

// A season is looked up by its own id, and its series is asked for alongside it, because
// the catalogue's indexed column is the series. Getting that wrong costs the season card
// its count on exactly the page — a series detail page — where seasons appear.
func TestContainerIDsCollectSeriesAndSeasons(t *testing.T) {
	items := []json.RawMessage{
		json.RawMessage(`{"Id":"ep-1","Type":"Episode","SeriesId":"show-1"}`),
		json.RawMessage(`{"Id":"show-1","Type":"Series"}`),
		json.RawMessage(`{"Id":"season-2","Type":"Season","SeriesId":"show-2"}`),
		json.RawMessage(`{"Id":"season-2","Type":"Season","SeriesId":"show-2"}`),
		json.RawMessage(`{"Id":"film-1","Type":"Movie"}`),
	}
	seriesIDs, seasonIDs := containerIDsIn([][]json.RawMessage{items})

	if !equalStrings(seasonIDs, []string{"season-2"}) {
		t.Errorf("seasons = %v, want one season and no repeat", seasonIDs)
	}
	// show-2 is there because the season named it; show-1 because it is a card in its own
	// right. Neither the episode nor the film contributes a container.
	if !equalStrings(seriesIDs, []string{"show-1", "show-2"}) {
		t.Errorf("series = %v, want the series card and the season's parent", seriesIDs)
	}
}

// Switched off, an account looks like one nobody has added anybody to — which is how the
// television decides not to offer the picker. It must never look like an account whose
// list failed to load.
func TestMainViewerOnlyLeavesTheAccount(t *testing.T) {
	viewers := []store.Viewer{
		{ID: "emby-user-1", Name: "Matt", Kind: store.ViewerMain},
		{ID: "v01", Name: "Alessandra", Kind: store.ViewerShadow},
		{ID: "v02", Name: "Guest", Kind: store.ViewerShadow},
	}
	got := mainViewerOnly(viewers)
	if len(got) != 1 || !got[0].IsMain() || got[0].ID != "emby-user-1" {
		t.Fatalf("switched-off list = %+v, want the account alone", got)
	}
	if mainViewerOnly(nil) != nil {
		t.Error("a list with no main viewer invented one")
	}
}

// The switch is the operator's and rides the ordinary feature machinery, so what is worth
// pinning is that it is *in* the catalogue and gated on a capability — a household half of
// whose televisions cannot choose between people must not be offered it.
func TestViewersIsAnOperatorFeature(t *testing.T) {
	definition, ok := knownFeature(featureViewers)
	if !ok {
		t.Fatal("viewers is not in the feature catalogue")
	}
	if definition.Capability != "viewers_v1" {
		t.Errorf("capability = %q, want viewers_v1", definition.Capability)
	}
	// Off by default, and deliberately so: this is the switch deciding where a household's
	// watched state is written, and a feature that arrives already on is one every server
	// running this build starts using before anybody decided to.
	if definition.DefaultEnabled {
		t.Error("viewers defaults on; it is opted into rather than out of")
	}
}