comments wip

comments/comments.go

@@ -0,0 +1,243 @@
+package comments
+
+import (
+	"bytes"
+	"crypto/subtle"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"sync"
+	"time"
+
+	"github.com/peterbourgon/diskv"
+)
+
+type Comment struct {
+	Name, Text string
+	IP         string
+	Date       time.Time
+	Spam       bool
+}
+
+func MarshalJSON(c Comment) ([]byte, error) {
+	buf := new(bytes.Buffer)
+	err := json.NewEncoder(buf).Encode(c)
+	return buf.Bytes(), err
+}
+
+func UnmarshalJSON(b []byte) (Comment, error) {
+	var c Comment
+	err := json.NewDecoder(bytes.NewBuffer(b)).Decode(&c)
+	return c, err
+}
+
+func Default() *Service {
+	return WithStorage(NewDiskv("comments"))
+}
+
+func WithStorage(storage Storage) *Service {
+	return &Service{Storage: storage}
+}
+
+type Service struct {
+	Storage  Storage
+	Password string
+}
+
+type Storage interface {
+	Store(post string, c Comment) error
+	Retreive(post string) ([]Comment, error)
+	ReadAll(post string) (io.Reader, error)
+}
+
+func (cs *Service) User(r *http.Request) (string, bool) {
+	if cs.Password == "" {
+		return "", true
+	}
+
+	user, providedPass, ok := r.BasicAuth()
+	if ok && subtle.ConstantTimeCompare([]byte(cs.Password), []byte(providedPass)) == 1 {
+		return user, true
+	}
+
+	return "", false
+}
+
+func (cs *Service) ServeComments(post string, w http.ResponseWriter, r *http.Request) error {
+	user, allowed := cs.User(r)
+	if !allowed {
+		w.WriteHeader(401)
+		return nil
+	}
+
+	if r.Method == "POST" {
+		return cs.Comment(post, Comment{
+			Name: user,
+			Text: r.FormValue("Text"),
+			IP:   r.RemoteAddr,
+			Date: time.Now(),
+		})
+	}
+
+	_, err := cs.WriteTo(post, w)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (cs *Service) Comment(post string, c Comment) error {
+	return cs.Storage.Store(post, c)
+}
+
+func (cs *Service) Load(post string) ([]Comment, error) {
+	return cs.Storage.Retreive(post)
+}
+
+func (cs *Service) WriteTo(post string, w io.Writer) (int64, error) {
+	r, err := cs.Storage.ReadAll(post)
+	if err != nil {
+		return 0, err
+	}
+
+	return io.Copy(w, r)
+}
+
+type diskvStorage struct {
+	*diskv.Diskv
+
+	keyMtx       sync.Mutex
+	keyLastKnown int64
+}
+
+func (d *diskvStorage) nextKey(post string) (string, error) {
+	d.keyMtx.Lock()
+	defer d.keyMtx.Unlock()
+
+	var i uint64
+
+	prefix := post + "-"
+
+	keys := d.KeysPrefix(prefix, nil)
+	for range keys {
+		i++
+	}
+
+	key := prefix + fmt.Sprint(i)
+	err := d.WriteStream(key, &bytes.Buffer{}, true)
+
+	return key, err
+}
+
+func (d *diskvStorage) Store(post string, c Comment) error {
+	b, err := MarshalJSON(c)
+	if err != nil {
+		return fmt.Errorf("error marshaling comment for storage: %v", err)
+	}
+
+	key, err := d.nextKey(post)
+	if err != nil {
+		return fmt.Errorf("error recording comment: %v", err)
+	}
+
+	err = d.Write(key, b)
+	if err != nil {
+		return fmt.Errorf("error writing comment to storage: %v", err)
+	}
+
+	return nil
+}
+
+type multiReadCloser struct {
+	rcs []io.ReadCloser
+}
+
+func (mrc *multiReadCloser) Read(b []byte) (int, error) {
+	if len(mrc.rcs) == 0 {
+		return 0, io.EOF
+	}
+
+	n, err := mrc.rcs[0].Read(b)
+	if n == len(b) { // we read enough
+		return n, err
+	}
+
+	for (err == nil || err == io.EOF) && len(mrc.rcs) > 1 {
+		var n2 int
+		closeErr := mrc.rcs[0].Close()
+		if closeErr != nil {
+			return n, closeErr
+		}
+
+		mrc.rcs = mrc.rcs[1:]
+		n2, err = mrc.rcs[0].Read(b[n:])
+		n += n2
+	}
+
+	return n, err
+}
+
+func (mrc *multiReadCloser) Close() error {
+	var err error
+
+	for _, rc := range mrc.rcs {
+		err2 := rc.Close()
+		if err2 != nil {
+			err = err2
+		}
+	}
+
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (d *diskvStorage) ReadAll(post string) (io.Reader, error) {
+	prefix := post + "-"
+
+	var rcs []io.ReadCloser
+
+	keys := d.KeysPrefix(prefix, nil)
+	for key := range keys {
+		rc, err := d.ReadStream(key, false)
+		if err != nil {
+			return nil, err
+		}
+		rcs = append(rcs, rc)
+	}
+
+	return &multiReadCloser{rcs}, nil
+}
+
+func (d *diskvStorage) Retreive(post string) ([]Comment, error) {
+	var comments []Comment
+
+	r, err := d.ReadAll(post)
+	if err != nil {
+		return comments, fmt.Errorf("error reading comment from storage: %v", err)
+	}
+
+	dec := json.NewDecoder(r)
+	for dec.More() {
+		comment := Comment{}
+		err := dec.Decode(&comment)
+		if err != nil {
+			return comments, fmt.Errorf("error unmarshaling comment: %v", err)
+		}
+	}
+
+	return comments, nil
+}
+
+func NewDiskv(path string) Storage {
+	return &diskvStorage{
+		Diskv: diskv.New(diskv.Options{
+			BasePath:     path,
+			CacheSizeMax: 1024 * 1024,
+		}),
+	}
+}