package library

import (
	"context"
	"crypto/sha256"
	"io"
	"log/slog"
	"os"
	"path/filepath"
	"testing"
	"time"

	"github.com/jackc/pgx/v5/pgtype"
	"github.com/jackc/pgx/v5/pgxpool"

	"git.fabledsword.com/bvandeusen/minstrel/internal/db/dbq"
	"git.fabledsword.com/bvandeusen/minstrel/internal/dbtest"
	syncpkg "git.fabledsword.com/bvandeusen/minstrel/internal/sync"
)

func TestPairStillHolds(t *testing.T) {
	missing := pgtype.UUID{Bytes: [16]byte{1}, Valid: true}
	present := pgtype.UUID{Bytes: [16]byte{2}, Valid: true}
	marked := pgtype.Timestamptz{Time: time.Now(), Valid: true}
	row := func(id pgtype.UUID, missingSince pgtype.Timestamptz) dbq.LockTracksForPairingRow {
		return dbq.LockTracksForPairingRow{ID: id, MissingSince: missingSince}
	}
	cases := []struct {
		name string
		rows []dbq.LockTracksForPairingRow
		want bool
	}{
		{"still a pair", []dbq.LockTracksForPairingRow{row(missing, marked), row(present, pgtype.Timestamptz{})}, true},
		{"missing row restored", []dbq.LockTracksForPairingRow{row(missing, pgtype.Timestamptz{}), row(present, pgtype.Timestamptz{})}, false},
		{"present row marked", []dbq.LockTracksForPairingRow{row(missing, marked), row(present, marked)}, false},
		{"missing row gone", []dbq.LockTracksForPairingRow{row(present, pgtype.Timestamptz{})}, false},
		{"present row gone", []dbq.LockTracksForPairingRow{row(missing, marked)}, false},
	}
	for _, c := range cases {
		if got := pairStillHolds(c.rows, missing, present); got != c.want {
			t.Errorf("%s: pairStillHolds = %v, want %v", c.name, got, c.want)
		}
	}
}

// pairFixture seeds tracks straight into the tables: the pass reads rows, not
// files, so no file needs to exist.
type pairFixture struct {
	t      *testing.T
	pool   *pgxpool.Pool
	q      *dbq.Queries
	artist dbq.Artist
}

func (f pairFixture) exec(sql string, args ...any) {
	f.t.Helper()
	if _, err := f.pool.Exec(context.Background(), sql, args...); err != nil {
		f.t.Fatalf("exec %q: %v", sql, err)
	}
}

func (f pairFixture) album(title, releaseGroup string) dbq.Album {
	f.t.Helper()
	a, err := f.q.UpsertAlbum(context.Background(), dbq.UpsertAlbumParams{
		Title: title, SortTitle: title, ArtistID: f.artist.ID,
	})
	if err != nil {
		f.t.Fatalf("album %s: %v", title, err)
	}
	if releaseGroup != "" {
		f.exec(`UPDATE albums SET release_group_mbid = $2 WHERE id = $1`, a.ID, releaseGroup)
	}
	return a
}

// track adds a row; mbid "" leaves it without one, and missing marks it missing.
func (f pairFixture) track(album dbq.Album, title, path, mbid string, missing bool) dbq.Track {
	f.t.Helper()
	tr, err := f.q.UpsertTrack(context.Background(), dbq.UpsertTrackParams{
		Title: title, AlbumID: album.ID, ArtistID: f.artist.ID,
		DurationMs: 200000, FilePath: path, FileSize: 100, FileFormat: filepath.Ext(path)[1:],
	})
	if err != nil {
		f.t.Fatalf("track %s: %v", path, err)
	}
	if mbid != "" {
		f.exec(`UPDATE tracks SET mbid = $2, mbid_source = 'tag' WHERE id = $1`, tr.ID, mbid)
	}
	if missing {
		f.exec(`UPDATE tracks SET missing_since = now() - interval '1 day' WHERE id = $1`, tr.ID)
	}
	return tr
}

func (f pairFixture) exists(tr dbq.Track) bool {
	f.t.Helper()
	var n int
	if err := f.pool.QueryRow(context.Background(), `SELECT count(*) FROM tracks WHERE id = $1`, tr.ID).Scan(&n); err != nil {
		f.t.Fatalf("count: %v", err)
	}
	return n == 1
}

func (f pairFixture) count(sql string, args ...any) int {
	f.t.Helper()
	var n int
	if err := f.pool.QueryRow(context.Background(), sql, args...).Scan(&n); err != nil {
		f.t.Fatalf("count %q: %v", sql, err)
	}
	return n
}

// The M485 proof on rows: each rule folds the pair it should, history moves onto
// the replacement, and every shape the pass must leave alone is left alone.
func TestPairMissingTracks_Integration(t *testing.T) {
	pool := newPool(t)
	ctx := context.Background()
	q := dbq.New(pool)
	artist, err := q.UpsertArtist(ctx, dbq.UpsertArtistParams{Name: "Pair Artist", SortName: "Pair Artist"})
	if err != nil {
		t.Fatalf("artist: %v", err)
	}
	f := pairFixture{t: t, pool: pool, q: q, artist: artist}

	albumA := f.album("Pair Album", "rg-pair")
	edition := f.album("Pair Album (Deluxe)", "rg-pair") // same release group as albumA
	other := f.album("Other Album", "rg-other")

	// Rule title: the mp3 went, the flac came, no MBID on either, and the title's
	// case differs as it does between old and new tags.
	oldMp3 := f.track(albumA, "Song One", "/m/a/01 - Song One.mp3", "", true)
	newFlac := f.track(albumA, "song one", "/m/a/01 - song one.flac", "", false)

	// Rule mbid: the same recording, retitled and filed under another edition of
	// the same release group.
	oldByMbid := f.track(albumA, "Old Name", "/m/a/02 - Old Name.mp3", "rec-2", true)
	newByMbid := f.track(edition, "New Name", "/m/d/02 - New Name.flac", "rec-2", false)

	// Ambiguous, missing side: two present copies could be its replacement.
	twice := f.track(albumA, "Twice", "/m/a/03 - Twice.mp3", "", true)
	f.track(albumA, "Twice", "/m/a/03 - Twice.flac", "", false)
	f.track(albumA, "Twice", "/m/a/03 - Twice (live).flac", "", false)

	// Ambiguous, present side: one present copy, two missing rows claiming it.
	echo1 := f.track(albumA, "Echo", "/m/a/04 - Echo.mp3", "", true)
	echo2 := f.track(albumA, "Echo", "/m/a/04 - Echo (1).mp3", "", true)
	f.track(albumA, "Echo", "/m/a/04 - Echo.flac", "", false)

	// Conflicting MBIDs: the tags say these are different recordings.
	clash := f.track(albumA, "Clash", "/m/a/05 - Clash.mp3", "rec-x", true)
	f.track(albumA, "Clash", "/m/a/05 - Clash.flac", "rec-y", false)

	// Negative controls across albums: a title match must stay inside one album
	// row, and an MBID match inside one release group.
	lonely := f.track(other, "Lonely", "/m/o/01 - Lonely.mp3", "", true)
	f.track(albumA, "Lonely", "/m/a/06 - Lonely.flac", "", false)
	cross := f.track(other, "Cross", "/m/o/02 - Cross.mp3", "rec-3", true)
	f.track(albumA, "Cross Over", "/m/a/07 - Cross Over.flac", "rec-3", false)

	// History on the row being folded.
	user, err := q.CreateUser(ctx, dbq.CreateUserParams{
		Username: dbtest.TestUserPrefix + "pair-alice", PasswordHash: "x", ApiTokenHash: "pair-alice-token",
	})
	if err != nil {
		t.Fatalf("user: %v", err)
	}
	f.exec(`INSERT INTO general_likes (user_id, track_id) VALUES ($1, $2)`, user.ID, oldMp3.ID)
	now := pgtype.Timestamptz{Time: time.Now(), Valid: true}
	session, err := q.InsertPlaySession(ctx, dbq.InsertPlaySessionParams{UserID: user.ID, StartedAt: now})
	if err != nil {
		t.Fatalf("session: %v", err)
	}
	for i := 0; i < 2; i++ {
		if _, err := q.InsertPlayEvent(ctx, dbq.InsertPlayEventParams{
			UserID: user.ID, TrackID: oldMp3.ID, SessionID: session.ID, StartedAt: now,
		}); err != nil {
			t.Fatalf("play event: %v", err)
		}
	}
	pl, err := q.CreatePlaylist(ctx, dbq.CreatePlaylistParams{UserID: user.ID, Name: "pair-mix"})
	if err != nil {
		t.Fatalf("playlist: %v", err)
	}
	if _, err := q.AppendPlaylistTrack(ctx, dbq.AppendPlaylistTrackParams{PlaylistID: pl.ID, TrackID: oldMp3.ID}); err != nil {
		t.Fatalf("playlist entry: %v", err)
	}

	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
	res, err := PairMissingTracks(ctx, pool, logger)
	if err != nil {
		t.Fatalf("PairMissingTracks: %v", err)
	}
	want := PairResult{ByMbid: 1, ByTitle: 1, Ambiguous: 3}
	if res != want {
		t.Errorf("result = %+v, want %+v", res, want)
	}

	if f.exists(oldMp3) || f.exists(oldByMbid) {
		t.Error("a folded missing row is still in the table")
	}
	if !f.exists(newFlac) || !f.exists(newByMbid) {
		t.Fatal("a replacement row was deleted")
	}
	for _, tr := range []dbq.Track{twice, echo1, echo2, clash, lonely, cross} {
		if !f.exists(tr) {
			t.Errorf("%s was folded; it should have been left alone", tr.FilePath)
		}
	}

	if n := f.count(`SELECT count(*) FROM general_likes WHERE track_id = $1`, newFlac.ID); n != 1 {
		t.Errorf("likes on the replacement = %d, want 1", n)
	}
	if n := f.count(`SELECT count(*) FROM play_events WHERE track_id = $1`, newFlac.ID); n != 2 {
		t.Errorf("plays on the replacement = %d, want 2", n)
	}
	if n := f.count(`SELECT count(*) FROM playlist_tracks WHERE playlist_id = $1 AND track_id = $2`, pl.ID, newFlac.ID); n != 1 {
		t.Errorf("playlist entries on the replacement = %d, want 1", n)
	}
	if n := f.count(`SELECT count(*) FROM library_changes WHERE entity_type = 'track' AND entity_id = $1 AND op = 'delete'`,
		syncpkg.FormatUUID(oldMp3.ID)); n != 1 {
		t.Errorf("track delete sync changes for the folded row = %d, want 1", n)
	}

	// Idempotent: a second pass has nothing left to fold.
	again, err := PairMissingTracks(ctx, pool, logger)
	if err != nil {
		t.Fatalf("second pass: %v", err)
	}
	if again.Folded() != 0 || again.Failed != 0 {
		t.Errorf("second pass = %+v, want nothing folded", again)
	}
}

// The case that made M485: a Lidarr quality upgrade. The mp3 is removed and a
// re-encode of it arrives at a new path with no recording MBID, so move adoption
// has nothing to match. The scan must still end with one row, carrying the old
// row's history.
func TestScanner_FoldsUpgradedFile_Integration(t *testing.T) {
	pool := newPool(t)
	ctx := context.Background()
	logger := slog.New(slog.NewTextHandler(io.Discard, nil))

	root := t.TempDir()
	oldPath := filepath.Join(root, "artistU/albumU/01 - Upgraded.mp3")
	tags := map[string]string{"TIT2": "Upgraded", "TPE1": "Artist U", "TALB": "Album U", "TRCK": "1"}
	writeTestMP3(t, oldPath, tags)
	// Filler so one removal stays under the mark cap.
	for i := 1; i <= 7; i++ {
		writeTestMP3(t, filepath.Join(root, "artistU/albumU/filler", string(rune('a'+i))+".mp3"),
			map[string]string{"TIT2": "Filler " + string(rune('0'+i)), "TPE1": "Artist U", "TALB": "Album U"})
	}

	scanner := New(pool, logger, []string{root}, nil)
	// A re-encode never shares the audio hash, so each file gets its own: the
	// synthetic files would otherwise hash alike and adopt by hash instead.
	scanner.fingerprint = func(_ context.Context, path string, _ fingerprintOptions) fingerprintResult {
		sum := sha256.Sum256([]byte(path))
		return fingerprintResult{streamSHA256: sum[:]}
	}
	if _, err := scanner.Scan(ctx, nil); err != nil {
		t.Fatalf("first scan: %v", err)
	}

	q := dbq.New(pool)
	before, err := q.GetTrackByPath(ctx, oldPath)
	if err != nil {
		t.Fatalf("track not indexed on first scan: %v", err)
	}
	user, err := q.CreateUser(ctx, dbq.CreateUserParams{
		Username: dbtest.TestUserPrefix + "upgrade-bob", PasswordHash: "x", ApiTokenHash: "upgrade-bob-token",
	})
	if err != nil {
		t.Fatalf("user: %v", err)
	}
	if _, err := pool.Exec(ctx, `INSERT INTO general_likes (user_id, track_id) VALUES ($1, $2)`, user.ID, before.ID); err != nil {
		t.Fatalf("like: %v", err)
	}

	// The upgrade: the old file goes, the new one lands beside it.
	if err := os.Remove(oldPath); err != nil {
		t.Fatalf("remove: %v", err)
	}
	newPath := filepath.Join(root, "artistU/albumU/01 - Upgraded (lossless).mp3")
	writeTestMP3(t, newPath, tags)

	if _, err := scanner.Scan(ctx, nil); err != nil {
		t.Fatalf("second scan: %v", err)
	}

	after, err := q.GetTrackByPath(ctx, newPath)
	if err != nil {
		t.Fatalf("replacement not indexed: %v", err)
	}
	if after.ID == before.ID {
		t.Fatal("the replacement adopted the old row; this test needs the fold path, so adoption must not match")
	}
	if _, err := q.GetTrackByPath(ctx, oldPath); err == nil {
		t.Error("the old row is still there after the scan; it should have been folded")
	}
	var likes int
	if err := pool.QueryRow(ctx, `SELECT count(*) FROM general_likes WHERE track_id = $1`, after.ID).Scan(&likes); err != nil {
		t.Fatalf("likes: %v", err)
	}
	if likes != 1 {
		t.Errorf("likes on the replacement = %d, want 1", likes)
	}
	var total int
	if err := pool.QueryRow(ctx, `SELECT count(*) FROM tracks`).Scan(&total); err != nil {
		t.Fatalf("count: %v", err)
	}
	if total != 8 {
		t.Errorf("tracks = %d, want 8 — an upgrade must not leave a second row", total)
	}
}