package library

import (
	"context"
	"errors"
	"fmt"
	"io"
	"log/slog"
	"path/filepath"
	"sync"
	"testing"

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

// TestLoudnessBackfill_Integration pins which tracks a pass measures, what it
// stores for each kind of result, that a pass ends, and that the gauge counts
// what the passes wrote.
func TestLoudnessBackfill_Integration(t *testing.T) {
	pool := newPool(t)
	ctx := context.Background()
	q := dbq.New(pool)
	dir := t.TempDir()

	_, album, artist := seedTrack(t, pool, filepath.Join(dir, "unmeasured.mp3"))
	addTrack := func(name string) dbq.Track {
		t.Helper()
		tr, err := q.UpsertTrack(ctx, dbq.UpsertTrackParams{
			Title: name, AlbumID: album.ID, ArtistID: artist.ID,
			DurationMs: 180000, FilePath: filepath.Join(dir, name+".mp3"), FileSize: 100, FileFormat: "mp3",
		})
		if err != nil {
			t.Fatalf("track %s: %v", name, err)
		}
		return tr
	}
	lufs := func(v float32) *float32 { return &v }
	current := addTrack("current")
	stale := addTrack("stale")
	missing := addTrack("missing")
	for _, seed := range []struct {
		track   dbq.Track
		version int16
	}{
		{current, loudnessVersion},
		{stale, loudnessVersion - 1},
	} {
		if err := q.UpsertTrackLoudness(ctx, dbq.UpsertTrackLoudnessParams{
			TrackID: seed.track.ID, IntegratedLufs: lufs(-9), AnalysisVersion: seed.version,
		}); err != nil {
			t.Fatalf("seed loudness: %v", err)
		}
	}
	if _, err := pool.Exec(ctx, "UPDATE tracks SET missing_since = now() WHERE id = $1", missing.ID); err != nil {
		t.Fatalf("mark missing: %v", err)
	}

	settings, err := NewLoudnessSettingsService(ctx, pool)
	if err != nil {
		t.Fatalf("loudness settings: %v", err)
	}
	w := NewLoudnessBackfillWorker(pool, slog.New(slog.NewTextHandler(io.Discard, nil)), settings)
	// A batch of one forces the keyset cursor across several queries in a pass.
	w.batch = 1
	var mu sync.Mutex
	calls := map[string]int{}
	durations := map[string]int32{}
	start := int16(500)
	w.analyze = func(_ context.Context, path string, durationMs int32) loudnessResult {
		name := filepath.Base(path)
		mu.Lock()
		calls[name]++
		durations[name] = durationMs
		mu.Unlock()
		switch name {
		case "stall.mp3":
			return loudnessResult{err: fmt.Errorf("ffmpeg: %w", errLoudnessTimeout)}
		case "corrupt.mp3":
			return loudnessResult{err: errors.New("ffmpeg exited 1: invalid data")}
		case "silent.mp3":
			return loudnessResult{}
		default:
			return loudnessResult{
				integratedLUFS: lufs(-12.5), truePeakDBTP: lufs(-0.4), rangeLU: lufs(6),
				hist: blockHistogram{start: start, counts: []int32{3, 0, 7}},
			}
		}
	}
	callCount := func(name string) int {
		mu.Lock()
		defer mu.Unlock()
		return calls[name]
	}

	// 1. Only the unmeasured track and the stale one are measured, never the
	// current one or the missing one, and the track's length reaches the
	// analyzer (it sets the deadline).
	res, err := w.pass(ctx)
	if err != nil {
		t.Fatalf("first pass: %v", err)
	}
	if res.Processed != 2 || res.Measured != 2 {
		t.Fatalf("first pass = %+v, want 2 processed, 2 measured", res)
	}
	for name, want := range map[string]int{
		"unmeasured.mp3": 1, "stale.mp3": 1, "current.mp3": 0, "missing.mp3": 0,
	} {
		if got := callCount(name); got != want {
			t.Errorf("%s measured %d times, want %d", name, got, want)
		}
	}
	if durations["stale.mp3"] != 180000 {
		t.Errorf("analyzer got duration %d for stale.mp3, want 180000", durations["stale.mp3"])
	}
	var (
		gotLUFS, gotPeak *float32
		gotStart         *int16
		gotHist          []int32
		gotVersion       int16
	)
	if err := pool.QueryRow(ctx, `SELECT integrated_lufs, true_peak_dbtp, block_hist_start, block_hist, analysis_version
	                                FROM track_loudness WHERE track_id = $1`, stale.ID).
		Scan(&gotLUFS, &gotPeak, &gotStart, &gotHist, &gotVersion); err != nil {
		t.Fatalf("read stale row back: %v", err)
	}
	if gotLUFS == nil || *gotLUFS != -12.5 || gotPeak == nil || *gotPeak != -0.4 ||
		gotStart == nil || *gotStart != start || len(gotHist) != 3 || gotHist[2] != 7 ||
		gotVersion != loudnessVersion {
		t.Errorf("stale row after re-measuring = lufs %v peak %v hist %v@%v version %d",
			gotLUFS, gotPeak, gotHist, gotStart, gotVersion)
	}

	// Each stored measurement told the sync feed, so caching clients re-read
	// the track and pick up its gain (#4997).
	var logged int
	if err := pool.QueryRow(ctx, `SELECT count(*) FROM library_changes
	                               WHERE entity_type = 'track' AND op = 'upsert' AND entity_id = $1`,
		syncpkg.FormatUUID(stale.ID)).Scan(&logged); err != nil {
		t.Fatalf("count sync changes: %v", err)
	}
	if logged != 1 {
		t.Errorf("re-measuring stale.mp3 logged %d track changes, want 1", logged)
	}

	// 2. A pass after a complete one is a no-op.
	res, err = w.pass(ctx)
	if err != nil {
		t.Fatalf("second pass: %v", err)
	}
	if res.Processed != 0 {
		t.Fatalf("second pass processed %d tracks, want 0", res.Processed)
	}

	// 3. A stall is tried once and the pass ends; silence and a corrupt file are
	// verdicts, stored and not tried again.
	addTrack("stall")
	addTrack("corrupt")
	silent := addTrack("silent")
	res, err = w.pass(ctx)
	if err != nil {
		t.Fatalf("third pass: %v", err)
	}
	if res.Processed != 3 || res.Inconclusive != 1 || res.Unreadable != 1 || res.Silent != 1 {
		t.Fatalf("third pass = %+v, want 3 processed: 1 inconclusive, 1 unreadable, 1 silent", res)
	}
	if got := callCount("stall.mp3"); got != 1 {
		t.Fatalf("stalling file tried %d times in one pass, want exactly 1", got)
	}
	var silentHist []int32
	var silentUnreadable bool
	if err := pool.QueryRow(ctx, "SELECT block_hist, unreadable FROM track_loudness WHERE track_id = $1",
		silent.ID).Scan(&silentHist, &silentUnreadable); err != nil {
		t.Fatalf("read silent row: %v", err)
	}
	if silentHist != nil || silentUnreadable {
		t.Errorf("silent row = hist %v unreadable %v, want no histogram and readable", silentHist, silentUnreadable)
	}
	res, err = w.pass(ctx)
	if err != nil {
		t.Fatalf("fourth pass: %v", err)
	}
	if res.Processed != 1 || callCount("stall.mp3") != 2 || callCount("corrupt.mp3") != 1 {
		t.Fatalf("fourth pass = %+v; want only the stalled file retried", res)
	}

	// 4. The gauge counts what the passes wrote, and its buckets add up. Six
	// present tracks: unmeasured, current, stale, stall, corrupt, silent.
	cov, err := LoudnessCoverage(ctx, pool)
	if err != nil {
		t.Fatalf("coverage: %v", err)
	}
	if cov.Total != 6 || cov.Measured != 3 || cov.Silent != 1 || cov.Unreadable != 1 || cov.Pending != 1 {
		t.Errorf("coverage = %+v, want total 6, measured 3, silent 1, unreadable 1, pending 1", cov)
	}
	if cov.Measured+cov.Silent+cov.Unreadable+cov.Pending != cov.Total {
		t.Errorf("coverage buckets %+v do not sum to the total", cov)
	}

	// 5. A changed file loses its measurement, so it is measured again.
	if err := q.DeleteTrackLoudness(ctx, current.ID); err != nil {
		t.Fatalf("delete loudness: %v", err)
	}
	// 6. Switched off, the backfill does nothing, even with work waiting.
	off := DefaultLoudnessSettings
	off.Enabled = false
	if _, err := settings.Set(ctx, off); err != nil {
		t.Fatalf("switch analysis off: %v", err)
	}
	res, err = w.pass(ctx)
	if err != nil {
		t.Fatalf("pass with analysis off: %v", err)
	}
	if res.Processed != 0 || callCount("current.mp3") != 0 {
		t.Fatalf("pass with analysis off = %+v, want nothing done", res)
	}
	if _, err := settings.Set(ctx, DefaultLoudnessSettings); err != nil {
		t.Fatalf("switch analysis on: %v", err)
	}
	res, err = w.pass(ctx)
	if err != nil {
		t.Fatalf("pass after switching back on: %v", err)
	}
	if callCount("current.mp3") != 1 {
		t.Fatalf("changed file measured %d times after switching back on (pass %+v), want 1",
			callCount("current.mp3"), res)
	}
}

// The Go defaults must match the migration's, or a database that cannot be
// read would analyze differently from a fresh install.
func TestLoudnessSettings_DefaultsMatchMigration(t *testing.T) {
	pool := newPool(t)
	s, err := NewLoudnessSettingsService(context.Background(), pool)
	if err != nil {
		t.Fatalf("load: %v", err)
	}
	got := s.Get()
	got.UpdatedAt = DefaultLoudnessSettings.UpdatedAt
	if got != DefaultLoudnessSettings {
		t.Errorf("migration defaults = %+v, Go defaults = %+v", got, DefaultLoudnessSettings)
	}
}