mpckit/internal/project/project_test.go

package project

import (
	"bytes"
	"compress/gzip"
	"encoding/binary"
	"fmt"
	"io"
	"math"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"testing"

	"git.monoexp.com/bajdev/mpckit/internal/xpj"
)

const testdata = "../../testdata"

func decompress(t *testing.T, path string) []byte {
	t.Helper()
	fh, err := os.Open(path)
	if err != nil {
		t.Fatal(err)
	}
	defer fh.Close()
	zr, err := gzip.NewReader(fh)
	if err != nil {
		t.Fatal(err)
	}
	b, err := io.ReadAll(zr)
	if err != nil {
		t.Fatal(err)
	}
	return b
}

func encode(t *testing.T, p *Project) []byte {
	t.Helper()
	b, err := p.File().Encode()
	if err != nil {
		t.Fatal(err)
	}
	return b
}

func must(t *testing.T, err error) {
	t.Helper()
	if err != nil {
		t.Fatal(err)
	}
}

func newProject(t *testing.T) *Project {
	t.Helper()
	p, err := New("Test")
	must(t, err)
	return p
}

// leaves flattens a tree into path -> literal text, for comparing files.
func leaves(n *xpj.Node, path string, out map[string]string) map[string]string {
	if out == nil {
		out = map[string]string{}
	}
	switch n.Kind {
	case xpj.Object:
		for _, m := range n.Members {
			leaves(m.Value, path+"."+m.Key, out)
		}
	case xpj.Array:
		for i, it := range n.Items {
			leaves(it, fmt.Sprintf("%s[%d]", path, i), out)
		}
		if len(n.Items) == 0 {
			out[path] = "[]"
		}
	default:
		b, _ := n.MarshalJSON()
		out[path] = string(b)
	}
	return out
}

func diffPaths(a, b *xpj.Node) []string {
	la, lb := leaves(a, "", nil), leaves(b, "", nil)
	var diff []string
	for k, v := range la {
		if lb[k] != v {
			diff = append(diff, k)
		}
	}
	for k := range lb {
		if _, ok := la[k]; !ok {
			diff = append(diff, k)
		}
	}
	return diff
}

// The prototype's edits for MpckitT1 and T3 (build plan appendix), made
// through the model. The output must equal the files the device accepted.
func buildAccepted(t *testing.T, name string, shared bool) *Project {
	t.Helper()
	p, err := New(name)
	must(t, err)
	dir := filepath.Join(testdata, "accepted", name+DataSuffix)
	must(t, p.AssignSample(0, filepath.Join(dir, "Linn 9000 kick.wav")))
	second := "Linn 9000 kick001.wav"
	if shared {
		second = "Linn 9000 kick.wav"
	}
	must(t, p.AssignSample(16, filepath.Join(dir, second)))
	must(t, p.SetTune(16, 5, 0))
	must(t, p.SetSequence(0, "Verse", 96, 8))
	must(t, p.AddSequence(1))
	must(t, p.SetSequence(1, "Chorus", 96, 4))
	return p
}

func TestGoldenMpckitT1(t *testing.T) {
	p := buildAccepted(t, "MpckitT1", false)
	want := decompress(t, filepath.Join(testdata, "accepted", "MpckitT1.xpj"))
	if got := encode(t, p); !bytes.Equal(got, want) {
		f, _ := xpj.Decode(want)
		t.Fatalf("differs from MpckitT1.xpj at %v", diffPaths(p.File().Root, f.Root))
	}
	if p.SampleCount() != 2 {
		t.Errorf("%d samples, want 2", p.SampleCount())
	}
}

func TestGoldenMpckitT3(t *testing.T) {
	p := buildAccepted(t, "MpckitT3", true)
	want := decompress(t, filepath.Join(testdata, "accepted", "MpckitT3.xpj"))
	if got := encode(t, p); !bytes.Equal(got, want) {
		f, _ := xpj.Decode(want)
		t.Fatalf("differs from MpckitT3.xpj at %v", diffPaths(p.File().Root, f.Root))
	}
	if p.SampleCount() != 1 {
		t.Errorf("%d samples, want 1 shared", p.SampleCount())
	}
}

// Rebuild Demo02 from the blank template and compare with the device's file.
func TestRebuildDemo02(t *testing.T) {
	dir := filepath.Join(testdata, "device", "Demo02"+DataSuffix)
	p := newProject(t)
	must(t, p.AssignSample(0, filepath.Join(dir, "Linn 9000 kick.wav")))
	must(t, p.AssignSample(4, filepath.Join(dir, "Linn 9000 kick001.wav")))
	must(t, p.SetTune(4, 12, 40))
	// Start/end trim is a 2.0 feature; its fields are verified, so set them
	// directly to complete the rebuild.
	l, err := layer(p.pad(4))
	must(t, err)
	must(t, l.Set("sliceInfo.Start", xpj.NewInt(328)))
	must(t, l.Set("sliceInfo.LoopStart", xpj.NewInt(328)))
	must(t, l.Set("sliceInfo.End", xpj.NewInt(3777)))
	must(t, p.SetSequence(0, "Sequence 01", 105, 2))
	must(t, p.AddSequence(1))
	must(t, p.SetSequence(1, "Sequence 02", 105, 4))

	want, err := xpj.ReadFile(filepath.Join(testdata, "device", "Demo02.xpj"))
	must(t, err)
	got, wantLeaves := leaves(p.File().Root, "", nil), leaves(want.Root, "", nil)
	var unexpected []string
	for _, path := range diffPaths(p.File().Root, want.Root) {
		switch {
		case sameFloat(got[path], wantLeaves[path]):
			// The device prints some floats with 17 digits where we print
			// the shortest form: pitch 12.399999618530274 vs ...273 is the
			// same float64.
		case path == ".data.tracks[0].colour",
			path == ".data.assignableEnvelopeFollowerAssignments.currentControlIndex",
			strings.Contains(path, ".eventList.events"):
			// Known noise and recorded notes (build plan M2).
		case path == ".data.tracks[0].program.drum.instruments[4].layersv[0].sliceInfo.LoopCrossfadeLength":
			// The device wrote a different value on the pad it trimmed; we
			// write -1 as for every assigned sample (format doc section 3).
		default:
			unexpected = append(unexpected, path)
		}
	}
	if len(unexpected) > 0 {
		t.Errorf("unexpected differences from Demo02: %v", unexpected)
	}
}

func sameFloat(a, b string) bool {
	fa, errA := strconv.ParseFloat(a, 64)
	fb, errB := strconv.ParseFloat(b, 64)
	return errA == nil && errB == nil && fa == fb
}

// writeWAV writes a short 16-bit mono WAV of frames frames.
func writeWAV(t *testing.T, path string, frames int) string {
	t.Helper()
	data := make([]byte, frames*2)
	var b bytes.Buffer
	le := binary.LittleEndian
	b.WriteString("RIFF")
	binary.Write(&b, le, uint32(4+8+16+8+len(data)))
	b.WriteString("WAVEfmt ")
	for _, v := range []any{uint32(16), uint16(1), uint16(1), uint32(44100), uint32(88200), uint16(2), uint16(16)} {
		binary.Write(&b, le, v)
	}
	b.WriteString("data")
	binary.Write(&b, le, uint32(len(data)))
	b.Write(data)
	must(t, os.MkdirAll(filepath.Dir(path), 0o755))
	must(t, os.WriteFile(path, b.Bytes(), 0o644))
	return path
}

func padOf(t *testing.T, p *Project, slot int) Pad {
	t.Helper()
	v, err := p.Pad(slot)
	must(t, err)
	return v
}

func TestAssignAndPoolReuse(t *testing.T) {
	dir := t.TempDir()
	kick := writeWAV(t, filepath.Join(dir, "kick.wav"), 100)
	p := newProject(t)
	must(t, p.AssignSample(0, kick))
	must(t, p.AssignSample(1, kick))
	if p.SampleCount() != 1 {
		t.Fatalf("same source on two pads: %d pool entries, want 1", p.SampleCount())
	}
	a := padOf(t, p, 1)
	if a.File != "kick.wav" || a.SampleName != "kick" || a.End != 99 {
		t.Errorf("pad A2 = %+v", a)
	}
	if !p.dirty {
		t.Error("not dirty after assign")
	}
	// Reassigning the same source to its only pad keeps the entry.
	must(t, p.ClearPad(1))
	must(t, p.AssignSample(0, kick))
	if p.SampleCount() != 1 || padOf(t, p, 0).File != "kick.wav" {
		t.Errorf("reassign same source: %d entries, pad %+v", p.SampleCount(), padOf(t, p, 0))
	}
	// The source is the file itself, with any links resolved (macOS's
	// temporary folder is behind one).
	want, err := filepath.EvalSymlinks(kick)
	must(t, err)
	if got := p.sources["kick.wav"]; got != want {
		t.Errorf("source = %q, want %q", got, want)
	}
	// Replacing drops the old entry when no pad uses it.
	snare := writeWAV(t, filepath.Join(dir, "snare.wav"), 50)
	must(t, p.AssignSample(0, snare))
	if p.SampleCount() != 1 || p.inPool("kick.wav") || p.sources["kick.wav"] != "" {
		t.Errorf("replace did not drop kick: %d entries", p.SampleCount())
	}
}

func TestNameCollision(t *testing.T) {
	dir := t.TempDir()
	p := newProject(t)
	must(t, p.AssignSample(0, writeWAV(t, filepath.Join(dir, "a", "kick.wav"), 10)))
	must(t, p.AssignSample(1, writeWAV(t, filepath.Join(dir, "b", "kick.wav"), 20)))
	must(t, p.AssignSample(2, writeWAV(t, filepath.Join(dir, "c", "Kick.WAV"), 30)))
	want := []string{"kick.wav", "kick001.wav", "Kick002.WAV"}
	for i, w := range want {
		if got := padOf(t, p, i); got.File != w || got.SampleName != strings.TrimSuffix(w, filepath.Ext(w)) {
			t.Errorf("pad %d = %q/%q, want %q", i, got.SampleName, got.File, w)
		}
	}
	// Both pools hold the same entries; the track pool in reverse order.
	var pool, track []string
	for _, e := range p.pool().Items {
		pool = append(pool, e.Lookup("path").Text)
	}
	for _, e := range p.trackPool().Items {
		track = append(track, e.Lookup("path").Text)
	}
	if strings.Join(pool, ",") != "kick.wav,kick001.wav,Kick002.WAV" || strings.Join(track, ",") != "Kick002.WAV,kick001.wav,kick.wav" {
		t.Errorf("pool %v, track pool %v", pool, track)
	}
}

func TestSampleLimit(t *testing.T) {
	dir := t.TempDir()
	p := newProject(t)
	// With one sample per pad the pool can only fill up when it also holds
	// entries no pad uses, as a loaded project may. Simulate one.
	p.addPoolEntry("unused.wav")
	for i := 0; i < MaxSamples-1; i++ {
		must(t, p.AssignSample(i, writeWAV(t, filepath.Join(dir, fmt.Sprintf("s%03d.wav", i)), 4)))
	}
	if p.SampleCount() != MaxSamples {
		t.Fatalf("%d samples, want %d", p.SampleCount(), MaxSamples)
	}
	err := p.AssignSample(127, writeWAV(t, filepath.Join(dir, "x.wav"), 4))
	if err == nil || !strings.Contains(err.Error(), "128") {
		t.Fatalf("129th sample: %v", err)
	}
	if !padOf(t, p, 127).Empty() || p.SampleCount() != MaxSamples {
		t.Error("refused assign changed the project")
	}
	// Reusing a file already in the pool needs no new entry.
	must(t, p.AssignSample(127, filepath.Join(dir, "s000.wav")))
	// Replacing a pad's only sample frees its entry first.
	must(t, p.AssignSample(1, filepath.Join(dir, "x.wav")))
	if p.SampleCount() != MaxSamples || padOf(t, p, 1).File != "x.wav" {
		t.Errorf("replace at the limit: %d samples, pad %+v", p.SampleCount(), padOf(t, p, 1))
	}
}

func TestAssignRejectsBadFiles(t *testing.T) {
	dir := t.TempDir()
	p := newProject(t)
	bad := filepath.Join(dir, "bad.wav")
	must(t, os.WriteFile(bad, []byte("not a wav"), 0o644))
	if err := p.AssignSample(0, bad); err == nil {
		t.Error("non-WAV accepted")
	}
	if err := p.AssignSample(0, filepath.Join(dir, "missing.wav")); err == nil {
		t.Error("missing file accepted")
	}
	if err := p.AssignSample(128, writeWAV(t, filepath.Join(dir, "ok.wav"), 4)); err == nil {
		t.Error("slot 128 accepted")
	}
	if p.dirty || p.SampleCount() != 0 {
		t.Error("failed assigns changed the project")
	}
}

func TestClearCopyMoveSwap(t *testing.T) {
	dir := t.TempDir()
	p := newProject(t)
	kick := writeWAV(t, filepath.Join(dir, "kick.wav"), 10)
	snare := writeWAV(t, filepath.Join(dir, "snare.wav"), 20)
	must(t, p.AssignSample(0, kick))
	must(t, p.AssignSample(1, snare))
	must(t, p.SetTune(0, 3, -20))
	must(t, p.SetMuteGroup(0, 2))

	// Copy across banks keeps tuning and mute group and shares the entry.
	must(t, p.CopyPad(0, 40))
	c := padOf(t, p, 40)
	if c.File != "kick.wav" || c.Coarse != 3 || c.Fine != -20 || c.MuteGroup != 2 || p.SampleCount() != 2 {
		t.Errorf("copy: %+v, %d samples", c, p.SampleCount())
	}
	// The copy is independent of its source.
	must(t, p.SetTune(40, 0, 0))
	if padOf(t, p, 0).Coarse != 3 {
		t.Error("copy shares data with its source")
	}

	// Move onto a filled pad replaces it; the snare's entry goes.
	must(t, p.MovePad(0, 1))
	if !padOf(t, p, 0).Empty() || padOf(t, p, 1).File != "kick.wav" || p.inPool("snare.wav") {
		t.Errorf("move: A1 %+v, A2 %+v", padOf(t, p, 0), padOf(t, p, 1))
	}
	blank, _ := template.pad.MarshalJSON()
	if got, _ := p.pad(0).MarshalJSON(); !bytes.Equal(got, blank) {
		t.Error("moved-from pad is not the blank pad")
	}

	// Swap.
	must(t, p.AssignSample(5, snare))
	must(t, p.SwapPads(1, 5))
	if padOf(t, p, 1).File != "snare.wav" || padOf(t, p, 5).File != "kick.wav" {
		t.Error("swap")
	}

	// Clearing the last user drops the entry; clearing a shared one keeps it.
	must(t, p.ClearPad(5))
	if !p.inPool("kick.wav") {
		t.Error("cleared a shared entry (kick is still on pad 40)")
	}
	must(t, p.ClearPad(40))
	if p.inPool("kick.wav") || p.SampleCount() != 1 {
		t.Errorf("kick entry kept after its last pad was cleared (%d samples)", p.SampleCount())
	}

	// No-ops and range checks.
	p.dirty = false
	must(t, p.ClearPad(100))
	must(t, p.CopyPad(1, 1))
	must(t, p.MovePad(1, 1))
	must(t, p.SwapPads(1, 1))
	if p.dirty {
		t.Error("no-op marked the project dirty")
	}
	for _, err := range []error{p.CopyPad(-1, 0), p.MovePad(0, 128), p.SwapPads(200, 0), p.ClearPad(128), p.SetTune(128, 0, 0), p.SetMuteGroup(-1, 0)} {
		if err == nil {
			t.Error("out-of-range slot accepted")
		}
	}
}

func TestTuneAndMuteGroup(t *testing.T) {
	p := newProject(t)
	must(t, p.SetTune(0, 12, 40))
	l, _ := layer(p.pad(0))
	if got := l.Lookup("pitch").Text; got != "12.399999618530273" {
		t.Errorf("pitch = %s", got)
	}
	must(t, p.SetTune(0, 99, -500))
	if v := padOf(t, p, 0); v.Coarse != 24 || v.Fine != -90 {
		t.Errorf("clamped tune = %d %d", v.Coarse, v.Fine)
	}
	if got := l.Lookup("pitch").Text; got != "23.100000381469727" {
		t.Errorf("pitch = %s", got)
	}
	must(t, p.SetMuteGroup(3, 1))
	if padOf(t, p, 3).MuteGroup != 1 {
		t.Error("mute group")
	}
	must(t, p.SetMuteGroup(3, 16))
	if err := p.SetMuteGroup(3, MaxMuteGroup+1); err == nil {
		t.Error("mute group out of range accepted")
	}
}

func TestSequences(t *testing.T) {
	p := newProject(t)
	must(t, p.AddSequence(4))
	s := p.Sequences()
	if len(s) != 2 || s[1] != (Sequence{Slot: 4, Name: "Sequence 05", BPM: DefaultBPM, Bars: 2}) {
		t.Fatalf("after add: %+v", s)
	}
	if err := p.AddSequence(4); err == nil {
		t.Error("duplicate slot accepted")
	}
	if err := p.AddSequence(MaxSequences); err == nil {
		t.Error("slot 128 accepted")
	}

	must(t, p.SetSequence(4, "Drop", 140.5, 16))
	must(t, p.AddSequence(127))
	s = p.Sequences()
	if s[1].Name != "Drop" || s[1].BPM != 140.5 || s[1].Bars != 16 || s[2].Name != "Sequence 128" || s[2].BPM != 140.5 {
		t.Errorf("after edit: %+v", s)
	}
	// Newest first in the file, as the device writes.
	if num(p.sequences().Items[0].Lookup("key")) != 127 {
		t.Error("new sequence not inserted first")
	}

	// All 26 length fields.
	v := p.sequences().Items[p.findSequence(4)].Lookup("value")
	n := 0
	for path, val := range leaves(v, "", nil) {
		if strings.HasSuffix(path, "lengthBars") || strings.HasSuffix(path, "loopEndBar") {
			n++
			if val != "16" {
				t.Errorf("%s = %s", path, val)
			}
		}
		if strings.HasSuffix(path, ".lengthPulses") || strings.HasSuffix(path, "loopEndPulses") || strings.HasSuffix(path, ".endPulses") {
			n++
			if val != "61440" {
				t.Errorf("%s = %s", path, val)
			}
		}
	}
	if n != 26 {
		t.Errorf("%d length fields, want 26", n)
	}

	for _, bad := range []struct {
		name string
		bpm  float64
		bars int
	}{{"", 120, 2}, {"a/b", 120, 2}, {"ok", 0, 2}, {"ok", -1, 2}, {"ok", 19.9, 2}, {"ok", 999.5, 2}, {"ok", math.NaN(), 2}, {"ok", math.Inf(1), 2}, {"ok", 120, 0}, {"ok", 120, MaxBars + 1}} {
		if err := p.SetSequence(4, bad.name, bad.bpm, bad.bars); err == nil {
			t.Errorf("SetSequence(%q, %v, %d) accepted", bad.name, bad.bpm, bad.bars)
		}
	}
	must(t, p.SetSequence(4, "Min", MinBPM, 1))
	must(t, p.SetSequence(4, "Max", MaxBPM, MaxBars))
	if err := p.SetSequence(9, "x", 120, 2); err == nil {
		t.Error("missing sequence accepted")
	}

	// Remove: current sequence moves to the lowest remaining slot.
	must(t, p.data.SetKey("currentSequence", xpj.NewInt(4)))
	must(t, p.RemoveSequence(4))
	if cur := num(p.data.Lookup("currentSequence")); cur != 0 {
		t.Errorf("currentSequence = %d, want 0", cur)
	}
	must(t, p.RemoveSequence(0))
	if cur := num(p.data.Lookup("currentSequence")); cur != 127 {
		t.Errorf("currentSequence = %d, want 127", cur)
	}
	if err := p.RemoveSequence(127); err == nil {
		t.Error("removed the last sequence")
	}
	if err := p.RemoveSequence(3); err == nil {
		t.Error("removed a missing sequence")
	}
}

func TestLoadDemoFile(t *testing.T) {
	p, warnings, err := Load(filepath.Join(testdata, "device", "DemoFile.xpj"))
	must(t, err)
	if len(warnings) != 0 {
		t.Errorf("warnings: %v", warnings)
	}
	if p.Name != "DemoFile" || p.dirty || p.SampleCount() != 6 {
		t.Errorf("name %q dirty %v samples %d", p.Name, p.dirty, p.SampleCount())
	}
	for file, src := range p.sources {
		if _, err := os.Stat(src); err != nil {
			t.Errorf("source for %s: %v", file, err)
		}
	}
	// The sequences have notes on A1-A4 (36-39); the other pads have none.
	for slot := 0; slot < Pads; slot++ {
		if got, want := p.PadHasNotes(slot), slot < 4; got != want {
			t.Errorf("PadHasNotes(%s) = %v", SlotName(slot), got)
		}
	}
	s := p.Sequences()
	if len(s) != 2 || s[0].Name != "Intro" || !s[0].HasNotes || s[1].Name != "Sequence 02" || !s[1].HasNotes {
		t.Errorf("sequences %+v", s)
	}
	if v := padOf(t, p, 2); v.MuteGroup != 1 || v.File != "80s-Hat-Dreamer1 SA.wav" {
		t.Errorf("A3 = %+v", v)
	}
	// Loaded and unchanged: writes back byte-identical.
	want := decompress(t, filepath.Join(testdata, "device", "DemoFile.xpj"))
	if !bytes.Equal(encode(t, p), want) {
		t.Error("loaded project does not write back unchanged")
	}

	// Assigning a file already in the project folder reuses its entry.
	must(t, p.AssignSample(50, filepath.Join(testdata, "device", "DemoFile"+DataSuffix, "Bass-Pure C.wav")))
	if p.SampleCount() != 6 {
		t.Errorf("%d samples after reusing a loaded file", p.SampleCount())
	}
}

func TestBlankPadsAndTemplate(t *testing.T) {
	p := newProject(t)
	if !bytes.Equal(encode(t, p), decompress(t, filepath.Join(testdata, "device", "DemoBlank.xpj"))) {
		t.Error("New() is not DemoBlank (is internal/project/template out of date?)")
	}
	for slot := 0; slot < Pads; slot++ {
		if !padOf(t, p, slot).Empty() || p.PadHasNotes(slot) {
			t.Fatalf("pad %d not empty", slot)
		}
	}
}

func TestNames(t *testing.T) {
	p := newProject(t)
	must(t, p.SetName("My Kit 2"))
	if p.Name != "My Kit 2" || !p.dirty {
		t.Error("SetName")
	}
	for _, bad := range []string{"", "  ", "a:b", "a?", "end.", "end ", "CON", "com1.txt", "tab\there"} {
		if err := ValidName(bad); err == nil {
			t.Errorf("ValidName(%q) accepted", bad)
		}
	}
	if _, err := New("bad|name"); err == nil {
		t.Error("New with a bad name accepted")
	}
	for slot, want := range map[int]string{0: "A1", 4: "A5", 16: "B1", 17: "B2", 127: "H16"} {
		if got := SlotName(slot); got != want {
			t.Errorf("SlotName(%d) = %s, want %s", slot, got, want)
		}
	}
}

func TestPoolFileName(t *testing.T) {
	for in, want := range map[string]string{
		"kick.wav":        "kick.wav",
		`kick\one.wav`:    "kick_one.wav",
		"a:b*c?.wav":      "a_b_c_.wav",
		`"q"<>|.wav`:      "_q____.wav",
		"tab\there.wav":   "tab_here.wav",
		"Ünïcode 80s.wav": "Ünïcode 80s.wav",
		"":                "sample.wav",
		".":               "sample.wav",
		"..":              "sample.wav",
		"CON.wav":         "CON_.wav",
		"aux.wav":         "aux_.wav",
		"com1.loop.wav":   "com1_.loop.wav",
		"Lpt9":            "Lpt9_",
		"console.wav":     "console.wav",
		"com10.wav":       "com10.wav",
	} {
		got := poolFileName(in)
		if got != want {
			t.Errorf("poolFileName(%q) = %q, want %q", in, got, want)
		}
		if err := PlainFileName(got); err != nil || reservedOnWindows(got) {
			t.Errorf("poolFileName(%q) = %q: not a safe name", in, got)
		}
	}
}

func TestAssignFollowsLink(t *testing.T) {
	dir := t.TempDir()
	kick := writeWAV(t, filepath.Join(dir, "library", "kick.wav"), 100)
	link := filepath.Join(dir, "favourite.wav")
	if err := os.Symlink(kick, link); err != nil {
		t.Skipf("cannot create a symlink: %v", err)
	}
	p := newProject(t)
	must(t, p.AssignSample(0, link))
	want, err := filepath.EvalSymlinks(kick)
	must(t, err)
	// The pool file is named after the link; it is copied from the target.
	if got := p.PoolFiles(); len(got) != 1 || got[0] != "favourite.wav" || p.sources["favourite.wav"] != want {
		t.Errorf("pool %q, source %q; want favourite.wav from %q", got, p.sources["favourite.wav"], want)
	}
	// The target itself is the same source: no second pool entry.
	must(t, p.AssignSample(1, kick))
	if p.SampleCount() != 1 {
		t.Errorf("%d pool entries, want 1", p.SampleCount())
	}
}

// loadDemo loads a copy of the device's DemoFile, with its data folder,
// after applying change to its data.
func loadDemo(t *testing.T, change func(d *xpj.Node)) *Project {
	t.Helper()
	dir := t.TempDir()
	f, err := xpj.ReadFile(filepath.Join(testdata, "device", "DemoFile.xpj"))
	must(t, err)
	d, err := f.Data()
	must(t, err)
	change(d)
	path := filepath.Join(dir, "DemoFile.xpj")
	must(t, f.WriteFile(path))
	p, _, err := Load(path)
	must(t, err)
	return p
}

// unchanged fails the test if p differs from the encoding and sources
// taken before, or has become dirty.
func unchanged(t *testing.T, p *Project, before []byte, sources map[string]string) {
	t.Helper()
	if !bytes.Equal(encode(t, p), before) {
		t.Error("the project file changed")
	}
	if fmt.Sprint(p.sources) != fmt.Sprint(sources) {
		t.Errorf("sources changed: %v, want %v", p.sources, sources)
	}
	if p.Dirty() {
		t.Error("dirty after a failed edit")
	}
}

func TestFailedEditsChangeNothing(t *testing.T) {
	dir := t.TempDir()
	good := writeWAV(t, filepath.Join(dir, "good.wav"), 100)
	notWAV := filepath.Join(dir, "notes.wav")
	must(t, os.WriteFile(notWAV, []byte("not a WAV file"), 0o644))

	p := loadDemo(t, func(d *xpj.Node) {
		// A2's first layer is not an object, B5 is not an object at all,
		// and a clip of the first sequence has no value.
		must(t, d.Set("tracks[0].program.drum.instruments[1].layersv[0]", xpj.NewInt(7)))
		must(t, d.Set("tracks[0].program.drum.instruments[20]", xpj.NewInt(7)))
		clip, err := d.Get("sequences[0].value.trackClipMaps[0][3]")
		must(t, err)
		clip.DeleteKey("value")
	})
	before := encode(t, p)
	sources := map[string]string{}
	for k, v := range p.sources {
		sources[k] = v
	}
	seq := p.Sequences()[1] // sequences[0] in the file is slot 1

	for _, c := range []struct {
		name string
		edit func() error
	}{
		{"assign a missing file", func() error { return p.AssignSample(0, filepath.Join(dir, "gone.wav")) }},
		{"assign a file that is not a WAV", func() error { return p.AssignSample(0, notWAV) }},
		{"tune a pad whose layer is not an object", func() error { return p.SetTune(1, 3, 0) }},
		{"mute group on a pad that is not an object", func() error { return p.SetMuteGroup(20, 2) }},
		{"sequence whose clip has no value", func() error { return p.SetSequence(seq.Slot, "Renamed", 99, 8) }},
		{"bad slot", func() error { return p.SetTune(Pads, 0, 0) }},
	} {
		t.Run(c.name, func(t *testing.T) {
			if err := c.edit(); err == nil {
				t.Fatal("no error")
			}
			unchanged(t, p, before, sources)
		})
	}

	// The sample limit: a full pool refuses a new file and changes nothing.
	full := newProject(t)
	for i := range MaxSamples - 1 {
		must(t, full.AssignSample(i, writeWAV(t, filepath.Join(dir, fmt.Sprintf("g%03d.wav", i)), 4)))
	}
	full.addPoolEntry("unused.wav") // a 128th entry no pad uses
	full.MarkExported()
	before = encode(t, full)
	sources = map[string]string{}
	for k, v := range full.sources {
		sources[k] = v
	}
	if err := full.AssignSample(MaxSamples-1, good); err == nil {
		t.Fatal("129th sample accepted")
	}
	unchanged(t, full, before, sources)
}

func TestAssignReplacesBrokenPad(t *testing.T) {
	// AssignSample starts from the blank pad, so a pad with no layers is
	// replaced whole rather than failing halfway.
	p := loadDemo(t, func(d *xpj.Node) {
		must(t, d.Set("tracks[0].program.drum.instruments[5].layersv", xpj.NewArray()))
	})
	kick := writeWAV(t, filepath.Join(t.TempDir(), "kick.wav"), 100)
	must(t, p.AssignSample(5, kick))
	if v := padOf(t, p, 5); v.File != "kick.wav" || v.End != 99 {
		t.Errorf("pad A6 = %+v", v)
	}
}

func TestAssignReusesFreedName(t *testing.T) {
	// Replacing a pad's only sample frees its name for the new file, as
	// before edits were made all-or-nothing.
	dir := t.TempDir()
	p := newProject(t)
	must(t, p.AssignSample(0, writeWAV(t, filepath.Join(dir, "a", "kick.wav"), 10)))
	must(t, p.AssignSample(0, writeWAV(t, filepath.Join(dir, "b", "kick.wav"), 20)))
	if got := p.PoolFiles(); len(got) != 1 || got[0] != "kick.wav" {
		t.Errorf("pool %q, want [kick.wav]", got)
	}
}