history: add history module

bot/history/history.go

@@ -0,0 +1,84 @@
+package history
+
+import (
+	"container/ring"
+	"fmt"
+
+	"github.com/velour/catbase/bot/msg"
+)
+
+// History is a ring buffer of messages
+type History struct {
+	r *ring.Ring
+}
+
+// New returns a history of sz size
+func New(sz int) *History {
+	return &History{ring.New(sz)}
+}
+
+// Edit looks for an entry and ammends it
+// returns error if the id is not found
+func (h *History) Edit(id string, update *msg.Message) error {
+	r := h.r
+	for i := 0; i < r.Len(); i++ {
+		m := r.Value.(*msg.Message)
+		if m != nil && m.ID == id {
+			r.Value = update
+			return nil
+		}
+		r = r.Next()
+	}
+	return fmt.Errorf("entry not found")
+}
+
+// Append adds a message to the history
+func (h *History) Append(m *msg.Message) {
+	h.r.Value = m
+	h.r = h.r.Next()
+}
+
+// Find looks for an entry by id and returns an error if not found
+func (h *History) Find(id string) (*msg.Message, error) {
+	r := h.r
+	for i := 0; i < r.Len(); i++ {
+		m := r.Value.(*msg.Message)
+		if m != nil && m.ID == id {
+			return m, nil
+		}
+		r = r.Next()
+	}
+	return nil, fmt.Errorf("entry not found")
+}
+
+// Last gets the last known message
+func (h *History) Last() *msg.Message {
+	return h.r.Prev().Value.(*msg.Message)
+}
+
+// LastInChannel searches backwards for the last message matching channel ch
+func (h *History) LastInChannel(ch string) (*msg.Message, error) {
+	r := h.r
+	for i := 0; i < r.Len(); i++ {
+		m := r.Value.(*msg.Message)
+		if m != nil && m.Channel == ch {
+			return m, nil
+		}
+		r = r.Prev()
+	}
+	return nil, fmt.Errorf("entry not found")
+}
+
+// InChannel returns all knows messages from channel ch in reverse order
+func (h *History) InChannel(ch string) []*msg.Message {
+	out := []*msg.Message{}
+	r := h.r
+	for i := 0; i < r.Len(); i++ {
+		m := r.Value.(*msg.Message)
+		if m != nil && m.Channel == ch {
+			out = append(out, m)
+		}
+		r = r.Prev()
+	}
+	return out
+}

bot/history/history_test.go

@@ -0,0 +1,82 @@
+package history
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/velour/catbase/bot/msg"
+)
+
+var sampleMessages []*msg.Message
+
+func init() {
+	sampleMessages = []*msg.Message{}
+	for i := 0; i < 100; i++ {
+		txt := fmt.Sprintf("Message #%d", i)
+		m := &msg.Message{
+			ID:   txt,
+			Body: txt,
+		}
+
+		sampleMessages = append(sampleMessages, m)
+	}
+}
+
+func TestAppend(t *testing.T) {
+	h := New(10)
+	for i := 0; i < 10; i++ {
+		h.Append(sampleMessages[i])
+	}
+	previous := h.r.Prev().Value.(*msg.Message)
+	assert.Equal(t, sampleMessages[9].ID, previous.ID)
+}
+
+func TestFindExists(t *testing.T) {
+	h := New(10)
+	for i := 0; i < 10; i++ {
+		h.Append(sampleMessages[i])
+	}
+	id := sampleMessages[5].ID
+	elt, err := h.Find(id)
+	assert.Nil(t, err)
+	assert.Equal(t, id, elt.ID)
+}
+
+func TestFindMissing(t *testing.T) {
+	h := New(10)
+	for i := 0; i < 10; i++ {
+		h.Append(sampleMessages[i])
+	}
+	id := sampleMessages[15].ID
+	elt, err := h.Find(id)
+	assert.NotNil(t, err)
+	assert.Nil(t, elt)
+}
+
+func TestEditExists(t *testing.T) {
+	h := New(10)
+	for i := 0; i < 10; i++ {
+		h.Append(sampleMessages[i])
+	}
+	id := sampleMessages[5].ID
+	m := sampleMessages[15]
+	m.ID = id
+	err := h.Edit(id, m)
+	assert.Nil(t, err)
+	actual, err := h.Find(id)
+	assert.Nil(t, err)
+	assert.Equal(t, m.Body, actual.Body)
+}
+
+func TestEditMissing(t *testing.T) {
+	h := New(10)
+	for i := 0; i < 10; i++ {
+		h.Append(sampleMessages[i])
+	}
+	id := sampleMessages[10].ID
+	m := sampleMessages[6]
+	t.Logf("id: %s, editID: %s", id, m.ID)
+	err := h.Edit(id, m)
+	assert.NotNil(t, err)
+}