package library

import (
	"context"
	"encoding/json"
	"errors"
	"io"
	"log/slog"
	"net/url"
	"testing"
	"time"

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

// fakeStore is the queue and the catalogue as maps. Everything the worker does is visible
// in it, which is the point of the store being an interface here.
type fakeStore struct {
	jobs     map[string]*store.IngestJob
	order    []string
	items    map[string]store.LibraryItem
	deleted  []string
	series   []store.SeriesRef
	episodes []store.CreditsEpisodeRow
	named    []store.NamedItem
	failNext error
}

func newFakeStore() *fakeStore {
	return &fakeStore{jobs: map[string]*store.IngestJob{}, items: map[string]store.LibraryItem{}}
}

func (f *fakeStore) EnqueueIngest(_ context.Context, job store.IngestJob) (bool, error) {
	existing, found := f.jobs[job.Key]
	if found {
		// The real table's ON CONFLICT: one row, and a re-delivery never pulls the settle
		// delay forward.
		if job.DueAt.After(existing.DueAt) {
			existing.DueAt = job.DueAt
		}
		existing.State = store.IngestPending
		return false, nil
	}
	stored := job
	stored.State = store.IngestPending
	f.jobs[job.Key] = &stored
	f.order = append(f.order, job.Key)
	return true, nil
}

func (f *fakeStore) ClaimIngest(_ context.Context, now time.Time, limit int) ([]store.IngestJob, error) {
	out := []store.IngestJob{}
	for _, key := range f.order {
		job := f.jobs[key]
		if job.State != store.IngestPending || job.DueAt.After(now) {
			continue
		}
		out = append(out, *job)
		if len(out) == limit {
			break
		}
	}
	return out, nil
}

func (f *fakeStore) FinishIngest(
	_ context.Context, key, state, outcome, itemID, errorText string, retryAt time.Time,
) error {
	job, found := f.jobs[key]
	if !found {
		return errors.New("no such job")
	}
	job.State, job.Outcome, job.ItemID = state, outcome, itemID
	job.LastError, job.DueAt = errorText, retryAt
	job.Attempts++
	return nil
}

func (f *fakeStore) UpsertLibraryItems(
	_ context.Context, items []store.LibraryItem, _ time.Time,
) (int64, error) {
	if f.failNext != nil {
		err := f.failNext
		f.failNext = nil
		return 0, err
	}
	for _, item := range items {
		f.items[item.ID] = item
	}
	return int64(len(items)), nil
}

func (f *fakeStore) DeleteLibraryItem(_ context.Context, itemID string) (int64, error) {
	f.deleted = append(f.deleted, itemID)
	delete(f.items, itemID)
	return 1, nil
}

func (f *fakeStore) SeriesRefs(context.Context) ([]store.SeriesRef, error) { return f.series, nil }

func (f *fakeStore) CreditsSeriesEpisodes(
	context.Context, []string,
) ([]store.CreditsEpisodeRow, error) {
	return f.episodes, nil
}

func (f *fakeStore) LibraryItemsByName(
	_ context.Context, _, _ string,
) ([]store.NamedItem, error) {
	return f.named, nil
}

// fakeEmby answers the two lookups and counts the nudges.
type fakeEmby struct {
	items       []json.RawMessage
	episodes    []json.RawMessage
	refreshed   []string
	itemQueries []url.Values
	seasons     []string
	err         error
}

func (f *fakeEmby) Items(
	_ context.Context, _ emby.Credentials, params url.Values,
) (*emby.ItemsResult, error) {
	f.itemQueries = append(f.itemQueries, params)
	if f.err != nil {
		return nil, f.err
	}
	return &emby.ItemsResult{Items: f.items}, nil
}

func (f *fakeEmby) Episodes(
	_ context.Context, _ emby.Credentials, _ string, params url.Values,
) (*emby.ItemsResult, error) {
	f.seasons = append(f.seasons, params.Get("Season"))
	if f.err != nil {
		return nil, f.err
	}
	return &emby.ItemsResult{Items: f.episodes}, nil
}

func (f *fakeEmby) RefreshItem(_ context.Context, _ emby.Credentials, itemID string) error {
	f.refreshed = append(f.refreshed, itemID)
	return nil
}

func testIngester(st *fakeStore, source *fakeEmby) *Ingester {
	return &Ingester{
		Store: st,
		Emby:  source,
		Credentials: func(context.Context) (emby.Credentials, error) {
			return emby.Credentials{UserID: "u", Token: "t"}, nil
		},
		Log:    slog.New(slog.NewTextHandler(io.Discard, nil)),
		Settle: time.Minute,
	}
}

func episodePayload(id string, season, episode int) json.RawMessage {
	raw, _ := json.Marshal(map[string]any{
		"Id": id, "Name": "The Job", "Type": "Episode", "SeriesId": "emby-series",
		"ParentIndexNumber": season, "IndexNumber": episode,
	})
	return raw
}

func enqueueOne(t *testing.T, ingester *Ingester, request IngestRequest) {
	t.Helper()
	if _, err := ingester.Enqueue(context.Background(), "sonarr", []IngestRequest{request}); err != nil {
		t.Fatalf("enqueue: %v", err)
	}
}

func episodeRequest() IngestRequest {
	return IngestRequest{
		Key: "sonarr:episodefile:8123:551", Action: ActionRefresh, Kind: KindEpisode,
		Reason: ReasonImport, Series: "Blue Bloods", SeriesYear: 2010, Season: 6, Episode: 7,
	}
}

// The ordinary path: the series is already in the catalogue, so Emby is asked for one
// season and the episode is written.
func TestImportWritesTheEpisodeFromOneSeasonLookup(t *testing.T) {
	st := newFakeStore()
	st.series = []store.SeriesRef{{ID: "emby-series", Name: "Blue Bloods", Year: 2010}}
	source := &fakeEmby{episodes: []json.RawMessage{
		episodePayload("emby-ep-6", 6, 6),
		episodePayload("emby-ep-7", 6, 7),
	}}
	ingester := testIngester(st, source)
	enqueueOne(t, ingester, episodeRequest())

	ingester.work(context.Background(), *st.jobs["sonarr:episodefile:8123:551"])

	if _, written := st.items["emby-ep-7"]; !written {
		t.Fatalf("the episode was not written: %v", st.items)
	}
	if _, extra := st.items["emby-ep-6"]; extra {
		t.Fatal("an episode nobody asked about was written")
	}
	if len(source.seasons) != 1 || source.seasons[0] != "6" {
		t.Fatalf("expected one season-scoped lookup, got %v", source.seasons)
	}
	// A series already in the catalogue costs no search at all.
	if len(source.itemQueries) != 0 {
		t.Fatalf("the catalogue was not used for the series: %v", source.itemQueries)
	}
	job := st.jobs["sonarr:episodefile:8123:551"]
	if job.State != store.IngestDone || job.Outcome != "imported" {
		t.Fatalf("unexpected outcome: %+v", job)
	}
}

// The field set must be the scheduled import's own, or an event-imported title arrives
// without the cast, streams and provider ids everything downstream reads.
func TestLookupsAskForTheFullSyncFields(t *testing.T) {
	st := newFakeStore()
	source := &fakeEmby{}
	ingester := testIngester(st, source)
	enqueueOne(t, ingester, IngestRequest{
		Key: "radarr:moviefile:441:import", Action: ActionRefresh, Kind: KindMovie,
		Reason: ReasonImport, Title: "Arrival", Year: 2016,
	})
	ingester.work(context.Background(), *st.jobs["radarr:moviefile:441:import"])

	if len(source.itemQueries) != 1 {
		t.Fatalf("expected one lookup, got %d", len(source.itemQueries))
	}
	query := source.itemQueries[0]
	if query.Get("Fields") != syncFields {
		t.Fatalf("a thinner field set was requested: %q", query.Get("Fields"))
	}
	if query.Get("EnableUserData") != "false" {
		t.Fatal("the shared catalogue must never carry one viewer's user data")
	}
}

// Emby not having scanned the file yet is the expected first answer, not a fault: the row
// waits, one nudge is sent, and the backoff widens.
func TestNotFoundDefersWithABackoffRatherThanFailing(t *testing.T) {
	st := newFakeStore()
	st.series = []store.SeriesRef{{ID: "emby-series", Name: "Blue Bloods", Year: 2010}}
	source := &fakeEmby{}
	ingester := testIngester(st, source)
	enqueueOne(t, ingester, episodeRequest())
	key := "sonarr:episodefile:8123:551"

	before := time.Now().UTC()
	ingester.work(context.Background(), *st.jobs[key])

	job := st.jobs[key]
	if job.State != store.IngestPending || job.Outcome != "not_found" {
		t.Fatalf("expected a deferral, got %+v", job)
	}
	if !job.DueAt.After(before) {
		t.Fatal("the next attempt was not scheduled into the future")
	}
	if len(source.refreshed) != 1 || source.refreshed[0] != "emby-series" {
		t.Fatalf("expected one rescan nudge at the series, got %v", source.refreshed)
	}
	if len(st.items) != 0 {
		t.Fatal("nothing should have been written")
	}
}

// Attempts are given up on eventually, because past the last step of the backoff the cause
// is not timing and a row retrying for ever is one nobody looks at.
func TestRepeatedFailureIsEventuallyGivenUpOn(t *testing.T) {
	st := newFakeStore()
	source := &fakeEmby{err: errors.New("emby is not answering")}
	ingester := testIngester(st, source)
	enqueueOne(t, ingester, episodeRequest())
	key := "sonarr:episodefile:8123:551"

	for attempt := 0; attempt < maxAttempts; attempt++ {
		ingester.work(context.Background(), *st.jobs[key])
	}
	if st.jobs[key].State != store.IngestFailed {
		t.Fatalf("expected the row to be given up on, got %+v", st.jobs[key])
	}
	if st.jobs[key].LastError == "" {
		t.Fatal("a failed row must record why")
	}
}

func TestRetryDelayWidensAndSettles(t *testing.T) {
	previous := time.Duration(0)
	for attempt := 1; attempt <= 6; attempt++ {
		delay := IngestRetryDelay(attempt)
		if delay < previous {
			t.Fatalf("the backoff narrowed at attempt %d: %s after %s", attempt, delay, previous)
		}
		previous = delay
	}
	if IngestRetryDelay(1) != time.Minute {
		t.Fatalf("the first retry should be quick, got %s", IngestRetryDelay(1))
	}
}

// A delete resolves against the catalogue, not against Emby: the file is gone, and Emby is
// the least likely thing to still be able to name it.
func TestDeleteRemovesTheEpisodeFromTheCatalogue(t *testing.T) {
	st := newFakeStore()
	st.series = []store.SeriesRef{{ID: "emby-series", Name: "Blue Bloods", Year: 2010}}
	st.episodes = []store.CreditsEpisodeRow{
		{ItemID: "emby-ep-6", SeriesID: "emby-series", Season: 6, Episode: 6},
		{ItemID: "emby-ep-7", SeriesID: "emby-series", Season: 6, Episode: 7},
	}
	source := &fakeEmby{}
	ingester := testIngester(st, source)
	request := episodeRequest()
	request.Action, request.Reason, request.Key = ActionRemove, ReasonDelete, "sonarr:episodefile:8123:delete"
	enqueueOne(t, ingester, request)

	ingester.work(context.Background(), *st.jobs[request.Key])

	if len(st.deleted) != 1 || st.deleted[0] != "emby-ep-7" {
		t.Fatalf("unexpected deletions: %v", st.deleted)
	}
	if len(source.itemQueries) != 0 || len(source.seasons) != 0 {
		t.Fatal("a delete must not need to ask Emby anything")
	}
}

// A delete of something the catalogue never held is settled rather than retried: there is
// nothing to remove and no later attempt could change that.
func TestDeleteOfSomethingAbsentSettlesQuietly(t *testing.T) {
	st := newFakeStore()
	ingester := testIngester(st, &fakeEmby{})
	request := IngestRequest{
		Key: "radarr:moviefile:9:delete", Action: ActionRemove, Kind: KindMovie,
		Reason: ReasonDelete, Title: "Never Imported", Year: 1999,
	}
	enqueueOne(t, ingester, request)
	ingester.work(context.Background(), *st.jobs[request.Key])

	job := st.jobs[request.Key]
	if job.State != store.IngestDone || job.Outcome != "absent" {
		t.Fatalf("expected a quiet settle, got %+v", job)
	}
	if len(st.deleted) != 0 {
		t.Fatalf("something was deleted: %v", st.deleted)
	}
}

// A brand-new show is the case the local index cannot answer, and it is exactly the case
// this feature exists for. Emby is asked, and the series row is written beside its episode
// so the episode is not a child of a show the catalogue has never heard of.
func TestANewSeriesIsResolvedThroughEmbyAndWrittenToo(t *testing.T) {
	st := newFakeStore()
	seriesRaw, _ := json.Marshal(map[string]any{
		"Id": "emby-series", "Name": "Blue Bloods", "Type": "Series", "ProductionYear": 2010,
	})
	source := &fakeEmby{
		items:    []json.RawMessage{seriesRaw},
		episodes: []json.RawMessage{episodePayload("emby-ep-7", 6, 7)},
	}
	ingester := testIngester(st, source)
	enqueueOne(t, ingester, episodeRequest())
	ingester.work(context.Background(), *st.jobs["sonarr:episodefile:8123:551"])

	if _, written := st.items["emby-series"]; !written {
		t.Fatalf("the new series row was not written: %v", st.items)
	}
	if _, written := st.items["emby-ep-7"]; !written {
		t.Fatal("the episode was not written")
	}
}

// The year separates a remake from its original where both systems know it, and the title
// alone is the fallback because they disagree about years more often than about names.
func TestMovieMatchingPrefersTheYearAndFallsBackToTheTitle(t *testing.T) {
	original, _ := json.Marshal(map[string]any{
		"Id": "old", "Name": "The Thing", "Type": "Movie", "ProductionYear": 1982,
	})
	remake, _ := json.Marshal(map[string]any{
		"Id": "new", "Name": "The Thing", "Type": "Movie", "ProductionYear": 2011,
	})
	items := []json.RawMessage{original, remake}

	if _, id := pickByTitle(items, "The Thing", 2011); id != "new" {
		t.Fatalf("the year did not decide: %q", id)
	}
	if _, id := pickByTitle(items, "The Thing", 0); id != "old" {
		t.Fatalf("expected the first title match as the fallback, got %q", id)
	}
	if _, id := pickByTitle(items, "Something Else", 0); id != "" {
		t.Fatalf("an unrelated title matched: %q", id)
	}
}

// A repeated webhook is one row, and it never pulls the settle delay forward — the whole
// point of the delay is that the file has finished being written.
func TestRepeatedEnqueueIsOneRowAndKeepsTheSettleDelay(t *testing.T) {
	st := newFakeStore()
	ingester := testIngester(st, &fakeEmby{})
	request := episodeRequest()

	fresh, err := ingester.Enqueue(context.Background(), "sonarr", []IngestRequest{request})
	if err != nil || fresh != 1 {
		t.Fatalf("first delivery: fresh=%d err=%v", fresh, err)
	}
	first := st.jobs[request.Key].DueAt

	fresh, err = ingester.Enqueue(context.Background(), "sonarr", []IngestRequest{request})
	if err != nil || fresh != 0 {
		t.Fatalf("a repeat was treated as news: fresh=%d err=%v", fresh, err)
	}
	if len(st.jobs) != 1 {
		t.Fatalf("a repeat produced %d rows", len(st.jobs))
	}
	if st.jobs[request.Key].DueAt.Before(first) {
		t.Fatal("a repeat pulled the settle delay forward")
	}
}

// Quiet time stands the worker down without touching the queue, which is the arrangement
// that lets the hook accept an event at any hour.
func TestQuietTimeStopsTheWorkerAndNotTheQueue(t *testing.T) {
	st := newFakeStore()
	st.series = []store.SeriesRef{{ID: "emby-series", Name: "Blue Bloods", Year: 2010}}
	source := &fakeEmby{episodes: []json.RawMessage{episodePayload("emby-ep-7", 6, 7)}}
	ingester := testIngester(st, source)
	ingester.Paused = func() bool { return true }
	enqueueOne(t, ingester, episodeRequest())

	ctx, cancel := context.WithCancel(context.Background())
	done := make(chan struct{})
	go func() { ingester.Run(ctx); close(done) }()
	time.Sleep(50 * time.Millisecond)
	cancel()
	<-done

	if len(st.items) != 0 {
		t.Fatal("work was done during quiet time")
	}
	if st.jobs["sonarr:episodefile:8123:551"].State != store.IngestPending {
		t.Fatal("the queued work was lost rather than deferred")
	}
}

// A finished scan is the moment there is something truthful to announce, which is why the
// hook fires from here rather than from the webhook. It must carry Emby's own names: the
// *arr and Emby disagree about punctuation often enough that a banner built from the
// webhook would name the same thing differently from the card underneath it.
func TestAFinishedImportIsAnnouncedWithEmbysOwnNames(t *testing.T) {
	st := newFakeStore()
	st.series = []store.SeriesRef{{ID: "emby-series", Name: "Blue Bloods", Year: 2010}}
	source := &fakeEmby{episodes: []json.RawMessage{episodeWithArtwork("emby-ep-7", 6, 7)}}
	ingester := testIngester(st, source)

	var announced []IngestResult
	ingester.Announce = func(_ context.Context, result IngestResult) {
		announced = append(announced, result)
	}
	enqueueOne(t, ingester, episodeRequest())
	ingester.work(context.Background(), *st.jobs["sonarr:episodefile:8123:551"])

	if len(announced) != 1 {
		t.Fatalf("expected one announcement, got %d", len(announced))
	}
	result := announced[0]
	if result.ItemID != "emby-ep-7" || result.Name != "The Job" {
		t.Errorf("announced %q/%q, want Emby's id and episode title", result.ItemID, result.Name)
	}
	if result.SeriesName != "Blue Bloods" {
		t.Errorf("series = %q, want Emby's series name", result.SeriesName)
	}
	if result.Season != 6 || result.Episode != 7 {
		t.Errorf("position = S%02dE%02d, want S06E07", result.Season, result.Episode)
	}
	if result.ImageTag != "poster-tag" {
		t.Errorf("image tag = %q, want the poster from the stored payload", result.ImageTag)
	}
	if result.Reason != ReasonImport || result.Kind != KindEpisode {
		t.Errorf("result = %+v, want the import reason and kind carried through", result)
	}
}

// Nothing is announced for work that did not land. The banner claims the title is in the
// catalogue, so a lookup that found nothing must stay silent and simply be retried.
func TestNothingIsAnnouncedWhenEmbyHasNotScannedYet(t *testing.T) {
	st := newFakeStore()
	st.series = []store.SeriesRef{{ID: "emby-series", Name: "Blue Bloods", Year: 2010}}
	ingester := testIngester(st, &fakeEmby{})

	announcements := 0
	ingester.Announce = func(context.Context, IngestResult) { announcements++ }
	enqueueOne(t, ingester, episodeRequest())
	ingester.work(context.Background(), *st.jobs["sonarr:episodefile:8123:551"])

	if announcements != 0 {
		t.Fatalf("announced %d times for an episode Emby has not scanned", announcements)
	}
}

func episodeWithArtwork(id string, season, episode int) json.RawMessage {
	raw, _ := json.Marshal(map[string]any{
		"Id": id, "Name": "The Job", "Type": "Episode", "SeriesId": "emby-series",
		"SeriesName":        "Blue Bloods",
		"ParentIndexNumber": season, "IndexNumber": episode,
		"ImageTags": map[string]string{"Primary": "poster-tag"},
	})
	return raw
}