Refactor state functions into their own doodad

cmd/mothd/award.go

@@ -1,14 +1,13 @@
 package main
 
 import (
-	"encoding/json"
 	"fmt"
 	"strings"
-	"time"
 )
 
 type Award struct {
-	When     time.Time
+	// Unix epoch time of this event
+	When     int64
 	TeamId   string
 	Category string
 	Points   int
@@ -19,44 +18,18 @@ func ParseAward(s string) (*Award, error) {
 
 	s = strings.TrimSpace(s)
 
-	var whenEpoch int64
+	n, err := fmt.Sscanf(s, "%d %s %s %d", &ret.When, &ret.TeamId, &ret.Category, &ret.Points)
-
-	n, err := fmt.Sscanf(s, "%d %s %s %d", &whenEpoch, &ret.TeamId, &ret.Category, &ret.Points)
 	if err != nil {
 		return nil, err
 	} else if n != 4 {
 		return nil, fmt.Errorf("Malformed award string: only parsed %d fields", n)
 	}
 
-	ret.When = time.Unix(whenEpoch, 0)
-
 	return &ret, nil
 }
 
 func (a *Award) String() string {
-	return fmt.Sprintf("%d %s %s %d", a.When.Unix(), a.TeamId, a.Category, a.Points)
+	return fmt.Sprintf("%d %s %s %d", a.When, a.TeamId, a.Category, a.Points)
-}
-
-func (a *Award) MarshalJSON() ([]byte, error) {
-	if a == nil {
-		return []byte("null"), nil
-	}
-	jTeamId, err := json.Marshal(a.TeamId)
-	if err != nil {
-		return nil, err
-	}
-	jCategory, err := json.Marshal(a.Category)
-	if err != nil {
-		return nil, err
-	}
-	ret := fmt.Sprintf(
-		"[%d,%s,%s,%d]",
-		a.When.Unix(),
-		jTeamId,
-		jCategory,
-		a.Points,
-	)
-	return []byte(ret), nil
 }
 
 func (a *Award) Same(o *Award) bool {

cmd/mothd/state.go

@@ -0,0 +1,356 @@
+package main
+
+import (
+	"fmt"
+	"strconv"
+	"log"
+	"path/filepath"
+	"strings"
+	"os"
+	"io/ioutil"
+	"bufio"
+	"time"
+	"math/rand"
+)
+
+// Stuff people with mediocre handwriting could write down unambiguously, and can be entered without holding down shift
+const distinguishableChars = "234678abcdefhijkmnpqrtwxyz="
+
+func mktoken() string {
+	a := make([]byte, 8)
+	for i := range a {
+		char := rand.Intn(len(distinguishableChars))
+		a[i] = distinguishableChars[char]
+	}
+	return string(a)
+}
+
+type StateExport struct {
+	TeamNames map[string]string
+	PointsLog []Award
+	Messages  []string
+}
+
+// We use the filesystem for synchronization between threads.
+// The only thing State methods need to know is the path to the state directory.
+type State struct {
+	StateDir string
+	update   chan bool
+}
+
+func NewState(stateDir string) (*State) {
+	return &State{
+		StateDir: stateDir,
+		update:   make(chan bool, 10),
+	}
+}
+
+// Returns a cleaned up join of path parts relative to
+func (s *State) path(parts ...string) string {
+	rel := filepath.Clean(filepath.Join(parts...))
+	parts = filepath.SplitList(rel)
+	for i, part := range parts {
+		part = strings.TrimLeft(part, "./\\:")
+		parts[i] = part
+	}
+	rel = filepath.Join(parts...)
+	return filepath.Join(s.StateDir, rel)
+}
+
+// Check a few things to see if this state directory is "enabled".
+func (s *State) Enabled() bool {
+	if _, err := os.Stat(s.path("enabled")); os.IsNotExist(err) {
+		log.Print("Suspended: enabled file missing")
+		return false
+	}
+
+	untilspec, err := ioutil.ReadFile(s.path("until"))
+	if err == nil {
+		untilspecs := strings.TrimSpace(string(untilspec))
+		until, err := time.Parse(time.RFC3339, untilspecs)
+		if err != nil {
+			log.Printf("Suspended: Unparseable until date: %s", untilspec)
+			return false
+		}
+		if until.Before(time.Now()) {
+			log.Print("Suspended: until time reached, suspending maintenance")
+			return false
+		}
+	}
+
+	return true
+}
+
+// Returns team name given a team ID.
+func (s *State) TeamName(teamId string) (string, error) {
+	teamFile := s.path("teams", teamId)
+	teamNameBytes, err := ioutil.ReadFile(teamFile)
+	teamName := strings.TrimSpace(string(teamNameBytes))
+
+	if os.IsNotExist(err) {
+		return "", fmt.Errorf("Unregistered team ID: %s", teamId)
+	} else if err != nil {
+		return "", fmt.Errorf("Unregistered team ID: %s (%s)", teamId, err)
+	}
+	
+	return teamName, nil
+}
+
+// Write out team name. This can only be done once.
+func (s *State) SetTeamName(teamId string, teamName string) error {
+	teamFile := s.path("teams", teamId)
+	err := ioutil.WriteFile(teamFile, []byte(teamName), os.ModeExclusive | 0644)
+	return err
+}
+
+// Retrieve the current points log
+func (s *State) PointsLog() ([]*Award) {
+	pointsFile := s.path("points.log")
+	f, err := os.Open(pointsFile)
+	if err != nil {
+		log.Println(err)
+		return nil
+	}
+	defer f.Close()
+	
+	pointsLog := make([]*Award, 0, 200)
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		line := scanner.Text()
+		cur, err := ParseAward(line)
+		if err != nil {
+			log.Printf("Skipping malformed award line %s: %s", line, err)
+			continue
+		}
+		pointsLog = append(pointsLog, cur)
+	}
+	return pointsLog
+}
+
+// Return an exportable points log,
+// This anonymizes teamId with either an integer, or the string "self"
+// for the requesting teamId.
+func (s *State) Export(teamId string) (*StateExport) {
+	teamName, _ := s.TeamName(teamId)
+
+	pointsLog := s.PointsLog()
+
+	export := StateExport{
+		PointsLog: make([]Award, len(pointsLog)),
+		Messages: make([]string, 0, 10),
+		TeamNames: map[string]string{"self": teamName},
+	}
+	
+	// Read in messages
+	messagesFile := s.path("messages.txt")
+	if f, err := os.Open(messagesFile); err != nil {
+		log.Print(err)
+	} else {
+		defer f.Close()
+		scanner := bufio.NewScanner(f)
+		for scanner.Scan() {
+			message := scanner.Text()
+			if strings.HasPrefix(message, "#") {
+				continue
+			}
+			export.Messages = append(export.Messages, message)
+		}
+	}
+	
+	// Read in points
+	exportIds := map[string]string{teamId: "self"}
+	for logno, award := range pointsLog {
+		exportAward := award
+		if id, ok := exportIds[award.TeamId]; ok {
+			exportAward.TeamId = id
+		} else {
+			exportId := strconv.Itoa(logno)
+			exportAward.TeamId = exportId
+			exportIds[award.TeamId] = exportAward.TeamId
+			
+			name, err := s.TeamName(award.TeamId)
+			if err != nil {
+				name = "Rodney" // https://en.wikipedia.org/wiki/Rogue_(video_game)#Gameplay
+			}
+			export.TeamNames[exportId] = name
+		}
+		export.PointsLog[logno] = *exportAward
+	}
+	
+	return &export
+}
+
+// AwardPoints gives points to teamId in category.
+// It first checks to make sure these are not duplicate points.
+// This is not a perfect check, you can trigger a race condition here.
+// It's just a courtesy to the user.
+// The update task makes sure we never have duplicate points in the log.
+func (s *State) AwardPoints(teamId, category string, points int) error {
+	a := Award{
+		When:     time.Now().Unix(),
+		TeamId:   teamId,
+		Category: category,
+		Points:   points,
+	}
+
+	_, err := s.TeamName(teamId)
+	if err != nil {
+		return err
+	}
+
+	for _, e := range s.PointsLog() {
+		if a.Same(e) {
+			return fmt.Errorf("Points already awarded to this team in this category")
+		}
+	}
+
+	fn := fmt.Sprintf("%s-%s-%d", teamId, category, points)
+	tmpfn := s.path("points.tmp", fn)
+	newfn := s.path("points.new", fn)
+
+	if err := ioutil.WriteFile(tmpfn, []byte(a.String()), 0644); err != nil {
+		return err
+	}
+
+	if err := os.Rename(tmpfn, newfn); err != nil {
+		return err
+	}
+
+	s.update <- true
+	return nil
+}
+
+// collectPoints gathers up files in points.new/ and appends their contents to points.log,
+// removing each points.new/ file as it goes.
+func (s *State) collectPoints() {
+	files, err := ioutil.ReadDir(s.path("points.new"))
+	if err != nil {
+		log.Print(err)
+		return
+	}
+	for _, f := range files {
+		filename := s.path("points.new", f.Name())
+		awardstr, err := ioutil.ReadFile(filename)
+		if err != nil {
+			log.Print("Opening new points: ", err)
+			continue
+		}
+		award, err := ParseAward(string(awardstr))
+		if err != nil {
+			log.Print("Can't parse award file ", filename, ": ", err)
+			continue
+		}
+
+		duplicate := false
+		for _, e := range s.PointsLog() {
+			if award.Same(e) {
+				duplicate = true
+				break
+			}
+		}
+
+		if duplicate {
+			log.Print("Skipping duplicate points: ", award.String())
+		} else {
+			log.Print("Award: ", award.String())
+
+			logf, err := os.OpenFile(s.path("points.log"), os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+			if err != nil {
+				log.Print("Can't append to points log: ", err)
+				return
+			}
+			fmt.Fprintln(logf, award.String())
+			logf.Close()
+		}
+
+		if err := os.Remove(filename); err != nil {
+			log.Print("Unable to remove new points file: ", err)
+		}
+	}
+}
+
+
+func (s *State) maybeInitialize() {
+	// Are we supposed to re-initialize?
+	if _, err := os.Stat(s.path("initialized")); ! os.IsNotExist(err) {
+		return
+	}
+
+	log.Print("initialized file missing, re-initializing")
+
+	// Remove any extant control and state files
+	os.Remove(s.path("enabled"))
+	os.Remove(s.path("until"))
+	os.Remove(s.path("points.log"))
+	os.Remove(s.path("messages.txt"))
+	os.RemoveAll(s.path("points.tmp"))
+	os.RemoveAll(s.path("points.new"))
+	os.RemoveAll(s.path("teams"))
+
+	// Make sure various subdirectories exist
+	os.Mkdir(s.path("points.tmp"), 0755)
+	os.Mkdir(s.path("points.new"), 0755)
+	os.Mkdir(s.path("teams"), 0755)
+
+	// Preseed available team ids if file doesn't exist
+	if f, err := os.OpenFile(s.path("teamids.txt"), os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0644); err == nil {
+		defer f.Close()
+		for i := 0; i <= 100; i += 1 {
+			fmt.Fprintln(f, mktoken())
+		}
+	}
+
+	// Create some files
+	ioutil.WriteFile(
+		s.path("initialized"),
+		[]byte("Remove this file to re-initialized the contest\n"),
+		0644,
+	)
+	ioutil.WriteFile(
+		s.path("enabled"),
+		[]byte("Remove this file to suspend the contest\n"),
+		0644,
+	)
+	ioutil.WriteFile(
+		s.path("until"),
+		[]byte("3009-10-31T00:00:00Z\n"),
+		0644,
+	)
+	ioutil.WriteFile(
+		s.path("messages.txt"),
+		[]byte(fmt.Sprintf("[%s] Initialized.\n", time.Now())),
+		0644,
+	)
+	ioutil.WriteFile(
+		s.path("points.log"),
+		[]byte(""),
+		0644,
+	)
+}
+
+func (s *State) Run(updateInterval time.Duration) {
+	for {
+		s.maybeInitialize()
+		if s.Enabled() {
+			s.collectPoints()
+		}
+		
+		select {
+			case <-s.update:
+			case <-time.After(updateInterval):
+		}
+	}
+}
+
+
+func main() {
+	s := NewState("./state")
+	go s.Run(2 * time.Second)
+	for {
+		select {
+			case <-time.After(5 * time.Second):
+		}
+		
+		fmt.Println(s.Export(""))
+	}
+}