Server can now be a devel server

cmd/mothd/httpd_test.go

@@ -94,7 +94,7 @@ func TestHttpd(t *testing.T) {
 
 	if r := hs.TestRequest("/answer", map[string]string{"cat": "pategory", "points": "1", "answer": "moo"}); r.Result().StatusCode != 200 {
 		t.Error(r.Result())
-	} else if r.Body.String() != `{"status":"fail","data":{"short":"not accepted","description":"Invalid answer"}}` {
+	} else if r.Body.String() != `{"status":"fail","data":{"short":"not accepted","description":"Incorrect answer"}}` {
 		t.Error("Unexpected body", r.Body.String())
 	}
 
@@ -119,7 +119,7 @@ func TestHttpd(t *testing.T) {
 
 	if r := hs.TestRequest("/answer", map[string]string{"cat": "pategory", "points": "1", "answer": "answer123"}); r.Result().StatusCode != 200 {
 		t.Error(r.Result())
-	} else if r.Body.String() != `{"status":"fail","data":{"short":"not accepted","description":"Points already awarded to this team in this category"}}` {
+	} else if r.Body.String() != `{"status":"fail","data":{"short":"not accepted","description":"Error awarding points: Points already awarded to this team in this category"}}` {
 		t.Error("Unexpected body", r.Body.String())
 	}
 }

cmd/mothd/main.go

@@ -24,6 +24,11 @@ func main() {
 		"mothballs",
 		"Path to mothball files",
 	)
+	puzzlePath := flag.String(
+		"puzzles",
+		"",
+		"Path to puzzles tree; if specified, enables development mode",
+	)
 	refreshInterval := flag.Duration(
 		"refresh",
 		2*time.Second,
@@ -41,9 +46,18 @@ func main() {
 	)
 	flag.Parse()
 
-	theme := NewTheme(afero.NewBasePathFs(afero.NewOsFs(), *themePath))
-	state := NewState(afero.NewBasePathFs(afero.NewOsFs(), *statePath))
-	puzzles := NewMothballs(afero.NewBasePathFs(afero.NewOsFs(), *mothballPath))
+	osfs := afero.NewOsFs()
+	theme := NewTheme(afero.NewBasePathFs(osfs, *themePath))
+	state := NewState(afero.NewBasePathFs(osfs, *statePath))
+
+	config := Configuration{}
+
+	var provider PuzzleProvider
+	provider = NewMothballs(afero.NewBasePathFs(osfs, *mothballPath))
+	if *puzzlePath != "" {
+		provider = NewTranspilerProvider(afero.NewBasePathFs(osfs, *puzzlePath))
+		config.Devel = true
+	}
 
 	// Add some MIME extensions
 	// Doing this avoids decompressing a mothball entry twice per request
@@ -52,9 +66,9 @@ func main() {
 
 	go theme.Maintain(*refreshInterval)
 	go state.Maintain(*refreshInterval)
-	go puzzles.Maintain(*refreshInterval)
+	go provider.Maintain(*refreshInterval)
 
-	server := NewMothServer(puzzles, theme, state)
+	server := NewMothServer(config, theme, state, provider)
 	httpd := NewHTTPServer(*base, server)
 
 	httpd.Run(*bindStr)

cmd/mothd/mothballs.go

@@ -88,15 +88,15 @@ func (m *Mothballs) Inventory() []Category {
 }
 
 // CheckAnswer returns an error if the provided answer is in any way incorrect for the given category and points
-func (m *Mothballs) CheckAnswer(cat string, points int, answer string) error {
+func (m *Mothballs) CheckAnswer(cat string, points int, answer string) (bool, error) {
 	zfs, ok := m.getCat(cat)
 	if !ok {
-		return fmt.Errorf("No such category: %s", cat)
+		return false, fmt.Errorf("No such category: %s", cat)
 	}
 
 	af, err := zfs.Open("answers.txt")
 	if err != nil {
-		return fmt.Errorf("No answers.txt file")
+		return false, fmt.Errorf("No answers.txt file")
 	}
 	defer af.Close()
 
@@ -104,11 +104,11 @@ func (m *Mothballs) CheckAnswer(cat string, points int, answer string) error {
 	scanner := bufio.NewScanner(af)
 	for scanner.Scan() {
 		if scanner.Text() == needle {
-			return nil
+			return true, nil
 		}
 	}
 
-	return fmt.Errorf("Invalid answer")
+	return false, nil
 }
 
 // refresh refreshes internal state.

cmd/mothd/mothballs_test.go

@@ -81,16 +81,16 @@ func TestMothballs(t *testing.T) {
 		t.Error("This file shouldn't exist")
 	}
 
-	if err := m.CheckAnswer("pategory", 1, "answer"); err == nil {
+	if ok, _ := m.CheckAnswer("pategory", 1, "answer"); ok {
 		t.Error("Wrong answer marked right")
 	}
-	if err := m.CheckAnswer("pategory", 1, "answer123"); err != nil {
+	if _, err := m.CheckAnswer("pategory", 1, "answer123"); err != nil {
 		t.Error("Right answer marked wrong", err)
 	}
-	if err := m.CheckAnswer("pategory", 1, "answer456"); err != nil {
+	if _, err := m.CheckAnswer("pategory", 1, "answer456"); err != nil {
 		t.Error("Right answer marked wrong", err)
 	}
-	if err := m.CheckAnswer("nealegory", 1, "moo"); err == nil {
+	if ok, err := m.CheckAnswer("nealegory", 1, "moo"); ok {
 		t.Error("Checking answer in non-existent category should fail")
 	} else if err.Error() != "No such category: nealegory" {
 		t.Error("Wrong error message")

cmd/mothd/providercommand.go

@@ -4,7 +4,6 @@ package main
 import (
 	"bytes"
 	"context"
-	"fmt"
 	"io"
 	"log"
 	"os"
@@ -15,14 +14,14 @@ import (
 	"time"
 )
 
-// PuzzleCommand specifies a command to run for the puzzle API
-type PuzzleCommand struct {
+// ProviderCommand specifies a command to run for the puzzle API
+type ProviderCommand struct {
 	Path string
 	Args []string
 }
 
 // Inventory runs with "action=inventory", and parses the output into a category list.
-func (pc PuzzleCommand) Inventory() (inv []Category) {
+func (pc ProviderCommand) Inventory() (inv []Category) {
 	ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
 	defer cancel()
 
@@ -62,16 +61,18 @@ func (pc PuzzleCommand) Inventory() (inv []Category) {
 	return
 }
 
+// NullReadSeekCloser wraps a no-op Close method around an io.ReadSeeker.
 type NullReadSeekCloser struct {
 	io.ReadSeeker
 }
 
+// Close does nothing.
 func (f NullReadSeekCloser) Close() error {
 	return nil
 }
 
 // Open passes its arguments to the command with "action=open".
-func (pc PuzzleCommand) Open(cat string, points int, path string) (ReadSeekCloser, time.Time, error) {
+func (pc ProviderCommand) Open(cat string, points int, path string) (ReadSeekCloser, time.Time, error) {
 	ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
 	defer cancel()
 
@@ -91,7 +92,7 @@ func (pc PuzzleCommand) Open(cat string, points int, path string) (ReadSeekClose
 // CheckAnswer passes its arguments to the command with "action=answer".
 // If the command exits successfully and sends "correct" to stdout,
 // nil is returned.
-func (pc PuzzleCommand) CheckAnswer(cat string, points int, answer string) error {
+func (pc ProviderCommand) CheckAnswer(cat string, points int, answer string) (bool, error) {
 	ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
 	defer cancel()
 
@@ -105,9 +106,9 @@ func (pc PuzzleCommand) CheckAnswer(cat string, points int, answer string) error
 	stdout, err := cmd.Output()
 	if ee, ok := err.(*exec.ExitError); ok {
 		log.Printf("%s: %s", pc.Path, string(ee.Stderr))
-		return err
+		return false, err
 	} else if err != nil {
-		return err
+		return false, err
 	}
 	result := strings.TrimSpace(string(stdout))
 
@@ -115,12 +116,12 @@ func (pc PuzzleCommand) CheckAnswer(cat string, points int, answer string) error
 		if result == "" {
 			result = "Nothing written to stdout"
 		}
-		return fmt.Errorf("Wrong answer: %s", result)
+		return false, nil
 	}
 
-	return nil
+	return true, nil
 }
 
-// Maintain does nothing: a command puzzle provider has no housekeeping
-func (pc PuzzleCommand) Maintain(updateInterval time.Duration) {
+// Maintain does nothing: a command puzzle ProviderCommand has no housekeeping
+func (pc ProviderCommand) Maintain(updateInterval time.Duration) {
 }

cmd/mothd/providercommand_test.go

@@ -6,8 +6,8 @@ import (
 	"testing"
 )
 
-func TestPuzzleCommand(t *testing.T) {
-	pc := PuzzleCommand{
+func TestProviderCommand(t *testing.T) {
+	pc := ProviderCommand{
 		Path: "testdata/testpiler.sh",
 	}
 
@@ -34,14 +34,14 @@ func TestPuzzleCommand(t *testing.T) {
 		}
 	}
 
-	if err := pc.CheckAnswer("pategory", 1, "answer"); err != nil {
+	if ok, err := pc.CheckAnswer("pategory", 1, "answer"); !ok {
 		t.Errorf("Correct answer for pategory: %v", err)
 	}
-	if err := pc.CheckAnswer("pategory", 1, "wrong"); err == nil {
+	if ok, _ := pc.CheckAnswer("pategory", 1, "wrong"); ok {
 		t.Errorf("Wrong answer for pategory judged correct")
 	}
 
-	if err := pc.CheckAnswer("pategory", 2, "answer"); err == nil {
+	if _, err := pc.CheckAnswer("pategory", 2, "answer"); err == nil {
 		t.Errorf("Internal error not returned")
 	} else if ee, ok := err.(*exec.ExitError); ok {
 		if string(ee.Stderr) != "Internal error\n" {

cmd/mothd/server.go

@@ -22,11 +22,14 @@ type ReadSeekCloser interface {
 	io.Closer
 }
 
+// Configuration stores information about server configuration.
+type Configuration struct {
+	Devel bool
+}
+
 // StateExport is given to clients requesting the current state.
 type StateExport struct {
-	Config struct {
-		Devel bool
-	}
+	Config    Configuration
 	Messages  string
 	TeamNames map[string]string
 	PointsLog award.List
@@ -37,7 +40,7 @@ type StateExport struct {
 type PuzzleProvider interface {
 	Open(cat string, points int, path string) (ReadSeekCloser, time.Time, error)
 	Inventory() []Category
-	CheckAnswer(cat string, points int, answer string) error
+	CheckAnswer(cat string, points int, answer string) (bool, error)
 	Maintainer
 }
 
@@ -68,17 +71,19 @@ type Maintainer interface {
 
 // MothServer gathers together the providers that make up a MOTH server.
 type MothServer struct {
-	Puzzles PuzzleProvider
-	Theme   ThemeProvider
-	State   StateProvider
+	PuzzleProviders []PuzzleProvider
+	Theme           ThemeProvider
+	State           StateProvider
+	Config          Configuration
 }
 
 // NewMothServer returns a new MothServer.
-func NewMothServer(puzzles PuzzleProvider, theme ThemeProvider, state StateProvider) *MothServer {
+func NewMothServer(config Configuration, theme ThemeProvider, state StateProvider, puzzleProviders ...PuzzleProvider) *MothServer {
 	return &MothServer{
-		Puzzles: puzzles,
-		Theme:   theme,
-		State:   state,
+		Config:          config,
+		PuzzleProviders: puzzleProviders,
+		Theme:           theme,
+		State:           state,
 	}
 }
 
@@ -99,15 +104,52 @@ type MothRequestHandler struct {
 }
 
 // PuzzlesOpen opens a file associated with a puzzle.
-func (mh *MothRequestHandler) PuzzlesOpen(cat string, points int, path string) (ReadSeekCloser, time.Time, error) {
+// BUG(neale): Multiple providers with the same category name are not detected or handled well.
+func (mh *MothRequestHandler) PuzzlesOpen(cat string, points int, path string) (r ReadSeekCloser, ts time.Time, err error) {
 	export := mh.ExportState()
+	found := false
 	for _, p := range export.Puzzles[cat] {
 		if p == points {
-			return mh.Puzzles.Open(cat, points, path)
+			found = true
+		}
+	}
+	if !found {
+		return nil, time.Time{}, fmt.Errorf("Category not found")
+	}
+
+	// Try every provider until someone doesn't return an error
+	for _, provider := range mh.PuzzleProviders {
+		r, ts, err = provider.Open(cat, points, path)
+		if err != nil {
+			return r, ts, err
 		}
 	}
 
-	return nil, time.Time{}, fmt.Errorf("Puzzle locked")
+	return
+}
+
+// CheckAnswer returns an error if answer is not a correct answer for puzzle points in category cat
+func (mh *MothRequestHandler) CheckAnswer(cat string, points int, answer string) error {
+	correct := false
+	for _, provider := range mh.PuzzleProviders {
+		if ok, err := provider.CheckAnswer(cat, points, answer); err != nil {
+			return err
+		} else if ok {
+			correct = true
+		}
+	}
+	if !correct {
+		return fmt.Errorf("Incorrect answer")
+	}
+
+	msg := fmt.Sprintf("GOOD %s %s %s %d", mh.participantID, mh.teamID, cat, points)
+	mh.State.LogEvent(msg)
+
+	if err := mh.State.AwardPoints(mh.teamID, cat, points); err != nil {
+		return fmt.Errorf("Error awarding points: %s", err)
+	}
+
+	return nil
 }
 
 // ThemeOpen opens a file from a theme.
@@ -124,29 +166,13 @@ func (mh *MothRequestHandler) Register(teamName string) error {
 	return mh.State.SetTeamName(mh.teamID, teamName)
 }
 
-// CheckAnswer returns an error if answer is not a correct answer for puzzle points in category cat
-func (mh *MothRequestHandler) CheckAnswer(cat string, points int, answer string) error {
-	if err := mh.Puzzles.CheckAnswer(cat, points, answer); err != nil {
-		msg := fmt.Sprintf("BAD %s %s %s %d %s", mh.participantID, mh.teamID, cat, points, err.Error())
-		mh.State.LogEvent(msg)
-		return err
-	}
-
-	if err := mh.State.AwardPoints(mh.teamID, cat, points); err != nil {
-		msg := fmt.Sprintf("GOOD %s %s %s %d", mh.participantID, mh.teamID, cat, points)
-		mh.State.LogEvent(msg)
-		return err
-	}
-
-	return nil
-}
-
 // ExportState anonymizes team IDs and returns StateExport.
 // If a teamID has been specified for this MothRequestHandler,
 // the anonymized team name for this teamID has the special value "self".
 // If not, the puzzles list is empty.
 func (mh *MothRequestHandler) ExportState() *StateExport {
 	export := StateExport{}
+	export.Config = mh.Config
 
 	teamName, _ := mh.State.TeamName(mh.teamID)
 
@@ -182,20 +208,22 @@ func (mh *MothRequestHandler) ExportState() *StateExport {
 		// but then we got a bad reputation on some secretive blacklist,
 		// and now the Navy can't register for events.
 
-		for _, category := range mh.Puzzles.Inventory() {
-			// Append sentry (end of puzzles)
-			allPuzzles := append(category.Puzzles, 0)
+		for _, provider := range mh.PuzzleProviders {
+			for _, category := range provider.Inventory() {
+				// Append sentry (end of puzzles)
+				allPuzzles := append(category.Puzzles, 0)
 
-			max := maxSolved[category.Name]
+				max := maxSolved[category.Name]
 
-			puzzles := make([]int, 0, len(allPuzzles))
-			for i, val := range allPuzzles {
-				puzzles = allPuzzles[:i+1]
-				if val > max {
-					break
+				puzzles := make([]int, 0, len(allPuzzles))
+				for i, val := range allPuzzles {
+					puzzles = allPuzzles[:i+1]
+					if !mh.Config.Devel && (val > max) {
+						break
+					}
 				}
+				export.Puzzles[category.Name] = puzzles
 			}
-			export.Puzzles[category.Name] = puzzles
 		}
 	}
 

cmd/mothd/server_test.go

@@ -24,7 +24,7 @@ func NewTestServer() *MothServer {
 	afero.WriteFile(theme.Fs, "/index.html", []byte("index.html"), 0644)
 	go theme.Maintain(TestMaintenanceInterval)
 
-	return NewMothServer(puzzles, theme, state)
+	return NewMothServer(Configuration{Devel: true}, theme, state, puzzles)
 }
 
 func TestServer(t *testing.T) {

cmd/mothd/state/enabled

@@ -0,0 +1 @@
+enabled: remove or rename to suspend the contest.

cmd/mothd/state/hours

@@ -0,0 +1,11 @@
+# hours: when the contest is enabled
+#
+# Enable:  + timestamp
+# Disable: - timestamp
+#
+# You can have multiple start/stop times.
+# Whatever time is the most recent, wins.
+# Times in the future are ignored.
+
++ 2020-09-08T23:43:53Z
+- 3019-10-31T00:00:00Z

cmd/mothd/state/initialized

@@ -0,0 +1,3 @@
+initialized: remove to re-initialize the contest.
+
+This instance was initaliazed at 2020-09-08T23:43:53Z

cmd/mothd/state/messages.html

@@ -0,0 +1 @@
+<!-- messages.html: put client broadcast messages here. -->

cmd/mothd/state/teamids.txt

@@ -0,0 +1,100 @@
+ywf3=a32
+c4hp2dxx
+brb4r4t2
+ybyen862
+8mfqd834
+yk788pqx
+ymf6idk3
+4qiwfar7
+h2m7=nf7
+nzbz=pzx
+ddmd=m8p
+87ahkr28
+7rbq3=pd
+y2xix7ep
+37h86=64
+7ey32edn
+=f4rrhrr
+4k2i2rzz
+cie2p7ed
+zcydpq44
+riqxziqa
+ptqqwh2k
+=8=3q3kd
+c8na=qix
+reqhwkca
+fkm3tkm7
+6etm6kh7
+pwd2p=fi
+ryz7t4xe
+qy3azp2k
+h3rweqd8
+d=2f3r=q
+zha7t6rp
+=nh6ncz4
+kbabkwaq
+7z4dmdbz
+it8iddbb
+dtwptqn8
+anwhemzw
+etptmc8w
+c=pa3hz2
+pe4r=ede
+=cw23dhe
+yw3xaw3n
+=a7yz2f3
+q6dqamia
+4x8e6c8c
+3tt88hkx
+6crqe=kn
+dhnprc4r
+kdczyz7q
+y=z8pkpk
+6h3i6p=i
+mipx4dmh
+b6rdhb2z
+kpqt8th2
+mqwa=b3f
+hzzr7dwa
+x8833aa4
+in327p7t
+it=dnyh=
+kr2pftrh
+zahqwz32
+66wkyc8q
+8amz4ehy
+ct37zri6
+rd2zpp67
+6hczfmpt
+4dckadbz
+7wx3r4hf
+8p6aynxm
+=xwanh=4
+fw4y2qdf
+6qz7k8ee
+7z7neebn
+a3mi3m3a
+bhftc6dt
+hhm3b4qd
+hddy=t2c
+cqi32enq
+xnmknai4
+=a24=2ci
+fnfc322r
+fzb62kmk
+w8kenc7y
+q8=y=pf4
+=ry46dd8
+tz=bp4kw
+amwwfaqy
+2fan2phi
+73=387fb
+ye==8i2w
+r2zznx=e
+nn83t4ni
+dzxpi4ae
+ef6reizk
+4q8e8kbq
+wwyq2=x7
+y7db2nty
+6222=fpb

cmd/mothd/testdata/cat0/1/puzzle.md

@@ -0,0 +1,3 @@
+author: neale
+
+Hello, world.

cmd/mothd/transpiler.go

@@ -0,0 +1,75 @@
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"io"
+	"log"
+	"time"
+
+	"github.com/dirtbags/moth/pkg/transpile"
+	"github.com/spf13/afero"
+)
+
+// NewTranspilerProvider returns a new TranspilerProvider.
+func NewTranspilerProvider(fs afero.Fs) TranspilerProvider {
+	return TranspilerProvider{fs}
+}
+
+// TranspilerProvider provides puzzles generated from source files on disk
+type TranspilerProvider struct {
+	fs afero.Fs
+}
+
+// Inventory returns a Category list for this provider.
+func (p TranspilerProvider) Inventory() []Category {
+	ret := make([]Category, 0)
+	inv, err := transpile.FsInventory(p.fs)
+	if err != nil {
+		log.Print(err)
+		return ret
+	}
+	for name, points := range inv {
+		ret = append(ret, Category{name, points})
+	}
+	return ret
+}
+
+type nopCloser struct {
+	io.ReadSeeker
+}
+
+func (c nopCloser) Close() error {
+	return nil
+}
+
+// Open returns a file associated with the given category and point value.
+func (p TranspilerProvider) Open(cat string, points int, filename string) (ReadSeekCloser, time.Time, error) {
+	c := transpile.NewFsCategory(p.fs, cat)
+	switch filename {
+	case "", "puzzle.json":
+		p, err := c.Puzzle(points)
+		if err != nil {
+			return nopCloser{new(bytes.Reader)}, time.Time{}, err
+		}
+		jp, err := json.Marshal(p)
+		if err != nil {
+			return nopCloser{new(bytes.Reader)}, time.Time{}, err
+		}
+		return nopCloser{bytes.NewReader(jp)}, time.Now(), nil
+	default:
+		r, err := c.Open(points, filename)
+		return r, time.Now(), err
+	}
+}
+
+// CheckAnswer checks whether an answer si correct.
+func (p TranspilerProvider) CheckAnswer(cat string, points int, answer string) (bool, error) {
+	c := transpile.NewFsCategory(p.fs, cat)
+	return c.Answer(points, answer), nil
+}
+
+// Maintain performs housekeeping.
+func (p TranspilerProvider) Maintain(updateInterval time.Duration) {
+	// Nothing to do here.
+}

cmd/mothd/transpiler_test.go

@@ -0,0 +1,19 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/spf13/afero"
+)
+
+func TestTranspiler(t *testing.T) {
+	fs := afero.NewBasePathFs(afero.NewOsFs(), "testdata")
+	p := NewTranspilerProvider(fs)
+
+	inv := p.Inventory()
+	if len(inv) != 1 {
+		t.Error("Wrong inventory:", inv)
+	} else if len(inv[0].Puzzles) != 1 {
+		t.Error("Wrong inventory:", inv)
+	}
+}

cmd/transpile/main.go

@@ -9,25 +9,11 @@ import (
 	"os"
 	"sort"
 
-	"github.com/GoBike/envflag"
+	"github.com/dirtbags/moth/pkg/transpile"
+
 	"github.com/spf13/afero"
 )
 
-// Category defines the functionality required to be a puzzle category.
-type Category interface {
-	// Inventory lists every puzzle in the category.
-	Inventory() ([]int, error)
-
-	// Puzzle provides a Puzzle structure for the given point value.
-	Puzzle(points int) (Puzzle, error)
-
-	// Open returns an io.ReadCloser for the given filename.
-	Open(points int, filename string) (io.ReadCloser, error)
-
-	// Answer returns whether the given answer is correct.
-	Answer(points int, answer string) bool
-}
-
 // T contains everything required for a transpilation invocation (across the nation).
 type T struct {
 	// What action to take
@@ -39,7 +25,8 @@ type T struct {
 	Fs       afero.Fs
 }
 
-// ParseArgs parses command-line arguments into T, returning the action to take
+// ParseArgs parses command-line arguments into T, returning the action to take.
+// BUG(neale): CLI arguments are not related to how the CLI will be used.
 func (t *T) ParseArgs() string {
 	action := flag.String("action", "inventory", "Action to take: must be 'inventory', 'open', 'answer', or 'mothball'")
 	flag.StringVar(&t.Cat, "cat", "", "Puzzle category")
@@ -47,7 +34,7 @@ func (t *T) ParseArgs() string {
 	flag.StringVar(&t.Answer, "answer", "", "Answer to check for correctness, for 'answer' action")
 	flag.StringVar(&t.Filename, "filename", "", "Filename, for 'open' action")
 	basedir := flag.String("basedir", ".", "Base directory containing all puzzles")
-	envflag.Parse()
+	flag.Parse()
 
 	osfs := afero.NewOsFs()
 	t.Fs = afero.NewBasePathFs(osfs, *basedir)
@@ -130,7 +117,7 @@ func (t *T) Open() error {
 // Mothball writes a mothball to the writer.
 func (t *T) Mothball() error {
 	c := t.NewCategory(t.Cat)
-	mb, err := Mothball(c)
+	mb, err := transpile.Mothball(c)
 	if err != nil {
 		return err
 	}
@@ -141,8 +128,8 @@ func (t *T) Mothball() error {
 }
 
 // NewCategory returns a new Fs-backed category.
-func (t *T) NewCategory(name string) Category {
-	return NewFsCategory(t.Fs, name)
+func (t *T) NewCategory(name string) transpile.Category {
+	return transpile.NewFsCategory(t.Fs, name)
 }
 
 func main() {

cmd/transpile/main_test.go

@@ -6,6 +6,7 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/dirtbags/moth/pkg/transpile"
 	"github.com/spf13/afero"
 )
 
@@ -78,7 +79,7 @@ func TestEverything(t *testing.T) {
 		t.Error(err)
 	}
 
-	p := Puzzle{}
+	p := transpile.Puzzle{}
 	if err := json.Unmarshal(stdout.Bytes(), &p); err != nil {
 		t.Error(err)
 	}

pkg/transpile/basepath.go

@@ -1,4 +1,4 @@
-package main
+package transpile
 
 import (
 	"os"

pkg/transpile/category.go

@@ -1,11 +1,9 @@
-package main
+package transpile
 
 import (
 	"bytes"
 	"context"
 	"encoding/json"
-	"io"
-	"io/ioutil"
 	"log"
 	"os/exec"
 	"strconv"
@@ -15,6 +13,21 @@ import (
 	"github.com/spf13/afero"
 )
 
+// Category defines the functionality required to be a puzzle category.
+type Category interface {
+	// Inventory lists every puzzle in the category.
+	Inventory() ([]int, error)
+
+	// Puzzle provides a Puzzle structure for the given point value.
+	Puzzle(points int) (Puzzle, error)
+
+	// Open returns an io.ReadCloser for the given filename.
+	Open(points int, filename string) (ReadSeekCloser, error)
+
+	// Answer returns whether the given answer is correct.
+	Answer(points int, answer string) bool
+}
+
 // NopReadCloser provides an io.ReadCloser which does nothing.
 type NopReadCloser struct {
 }
@@ -81,7 +94,7 @@ func (c FsCategory) Puzzle(points int) (Puzzle, error) {
 }
 
 // Open returns an io.ReadCloser for the given filename.
-func (c FsCategory) Open(points int, filename string) (io.ReadCloser, error) {
+func (c FsCategory) Open(points int, filename string) (ReadSeekCloser, error) {
 	return NewFsPuzzle(c.fs, points).Open(filename)
 }
 
@@ -149,18 +162,13 @@ func (c FsCommandCategory) Puzzle(points int) (Puzzle, error) {
 }
 
 // Open returns an io.ReadCloser for the given filename.
-func (c FsCommandCategory) Open(points int, filename string) (io.ReadCloser, error) {
+func (c FsCommandCategory) Open(points int, filename string) (ReadSeekCloser, error) {
 	ctx, cancel := context.WithTimeout(context.Background(), c.timeout)
 	defer cancel()
 
 	cmd := exec.CommandContext(ctx, c.command, "file", strconv.Itoa(points), filename)
 	stdout, err := cmd.Output()
-	buf := ioutil.NopCloser(bytes.NewBuffer(stdout))
-	if err != nil {
-		return buf, err
-	}
-
-	return buf, nil
+	return nopCloser{bytes.NewReader(stdout)}, err
 }
 
 // Answer checks whether an answer is correct.

pkg/transpile/category_test.go

@@ -1,4 +1,4 @@
-package main
+package transpile
 
 import (
 	"bytes"

pkg/transpile/common_test.go

@@ -0,0 +1,53 @@
+package transpile
+
+import (
+	"github.com/spf13/afero"
+)
+
+var testMothYaml = []byte(`---
+answers:
+  - YAML answer
+pre:
+  authors:
+    - Arthur
+    - Buster
+    - DW
+  attachments:
+    - filename: moo.txt
+---
+YAML body
+`)
+var testMothRfc822 = []byte(`author: test
+Author: Arthur
+author: Fred Flintstone
+answer: RFC822 answer
+
+RFC822 body
+`)
+
+func newTestFs() afero.Fs {
+	fs := afero.NewMemMapFs()
+	afero.WriteFile(fs, "cat0/1/puzzle.md", testMothYaml, 0644)
+	afero.WriteFile(fs, "cat0/1/moo.txt", []byte("Moo."), 0644)
+	afero.WriteFile(fs, "cat0/2/puzzle.md", testMothRfc822, 0644)
+	afero.WriteFile(fs, "cat0/3/puzzle.moth", testMothYaml, 0644)
+	afero.WriteFile(fs, "cat0/4/puzzle.md", testMothYaml, 0644)
+	afero.WriteFile(fs, "cat0/5/puzzle.md", testMothYaml, 0644)
+	afero.WriteFile(fs, "cat0/10/puzzle.md", []byte(`---
+Answers:
+  - moo
+Authors:
+  - bad field
+---
+body
+`), 0644)
+	afero.WriteFile(fs, "cat0/20/puzzle.md", []byte("Answer: no\nBadField: yes\n\nbody\n"), 0644)
+	afero.WriteFile(fs, "cat0/21/puzzle.md", []byte("Answer: broken\nSpooon\n"), 0644)
+	afero.WriteFile(fs, "cat0/22/puzzle.md", []byte("---\nanswers:\n  - pencil\npre:\n unused-field: Spooon\n---\nSpoon?\n"), 0644)
+	afero.WriteFile(fs, "cat1/93/puzzle.md", []byte("Answer: no\n\nbody"), 0644)
+	afero.WriteFile(fs, "cat1/barney/puzzle.md", testMothYaml, 0644)
+	afero.WriteFile(fs, "unbroken/1/puzzle.md", testMothYaml, 0644)
+	afero.WriteFile(fs, "unbroken/1/moo.txt", []byte("Moo."), 0644)
+	afero.WriteFile(fs, "unbroken/2/puzzle.md", testMothRfc822, 0644)
+	return fs
+}

pkg/transpile/inventory.go

@@ -0,0 +1,36 @@
+package transpile
+
+import (
+	"log"
+	"sort"
+
+	"github.com/spf13/afero"
+)
+
+// Inventory maps category names to lists of point values.
+type Inventory map[string][]int
+
+// FsInventory returns a mapping of category names to puzzle point values.
+func FsInventory(fs afero.Fs) (Inventory, error) {
+	dirEnts, err := afero.ReadDir(fs, ".")
+	if err != nil {
+		log.Print(err)
+		return nil, err
+	}
+
+	inv := make(Inventory)
+	for _, ent := range dirEnts {
+		if ent.IsDir() {
+			name := ent.Name()
+			c := NewFsCategory(fs, name)
+			puzzles, err := c.Inventory()
+			if err != nil {
+				return nil, err
+			}
+			sort.Ints(puzzles)
+			inv[name] = puzzles
+		}
+	}
+
+	return inv, nil
+}

pkg/transpile/inventory_test.go

@@ -0,0 +1,16 @@
+package transpile
+
+import "testing"
+
+func TestInventory(t *testing.T) {
+	fs := newTestFs()
+	inv, err := FsInventory(fs)
+	if err != nil {
+		t.Error(err)
+	}
+	if c, ok := inv["cat0"]; !ok {
+		t.Error("No cat0")
+	} else if len(c) != 9 {
+		t.Error("Wrong category length", c)
+	}
+}

pkg/transpile/mothball.go

@@ -1,4 +1,4 @@
-package main
+package transpile
 
 import (
 	"archive/zip"

pkg/transpile/mothball_test.go

@@ -1,4 +1,4 @@
-package main
+package transpile
 
 import (
 	"archive/zip"

pkg/transpile/puzzle.go

@@ -1,4 +1,4 @@
-package main
+package transpile
 
 import (
 	"bufio"
@@ -8,7 +8,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"log"
 	"net/mail"
 	"os/exec"
@@ -92,13 +91,20 @@ type StaticAttachment struct {
 	Listed         bool   // Whether this file is listed as an attachment
 }
 
+// ReadSeekCloser provides io.Reader, io.Seeker, and io.Closer.
+type ReadSeekCloser interface {
+	io.Reader
+	io.Seeker
+	io.Closer
+}
+
 // PuzzleProvider establishes the functionality required to provide one puzzle.
 type PuzzleProvider interface {
 	// Puzzle returns a Puzzle struct for the current puzzle.
 	Puzzle() (Puzzle, error)
 
 	// Open returns a newly-opened file.
-	Open(filename string) (io.ReadCloser, error)
+	Open(filename string) (ReadSeekCloser, error)
 
 	// Answer returns whether the provided answer is correct.
 	Answer(answer string) bool
@@ -160,8 +166,8 @@ func (fp FsPuzzle) Puzzle() (Puzzle, error) {
 }
 
 // Open returns a newly-opened file.
-func (fp FsPuzzle) Open(name string) (io.ReadCloser, error) {
-	empty := ioutil.NopCloser(new(bytes.Buffer))
+func (fp FsPuzzle) Open(name string) (ReadSeekCloser, error) {
+	empty := nopCloser{new(bytes.Reader)}
 	static, _, err := fp.staticPuzzle()
 	if err != nil {
 		return empty, err
@@ -343,15 +349,23 @@ func (fp FsCommandPuzzle) Puzzle() (Puzzle, error) {
 	return puzzle, nil
 }
 
+type nopCloser struct {
+	io.ReadSeeker
+}
+
+func (c nopCloser) Close() error {
+	return nil
+}
+
 // Open returns a newly-opened file.
-func (fp FsCommandPuzzle) Open(filename string) (io.ReadCloser, error) {
+// BUG(neale): FsCommandPuzzle.Open() reads everything into memory, and will suck for large files.
+func (fp FsCommandPuzzle) Open(filename string) (ReadSeekCloser, error) {
 	ctx, cancel := context.WithTimeout(context.Background(), fp.timeout)
 	defer cancel()
 
 	cmd := exec.CommandContext(ctx, fp.command, "-file", filename)
-	// BUG(neale): FsCommandPuzzle.Open() reads everything into memory, and will suck for large files.
 	out, err := cmd.Output()
-	buf := ioutil.NopCloser(bytes.NewBuffer(out))
+	buf := nopCloser{bytes.NewReader(out)}
 	if err != nil {
 		return buf, err
 	}

pkg/transpile/puzzle_test.go

@@ -1,4 +1,4 @@
-package main
+package transpile
 
 import (
 	"bytes"