From 1c44c714e68e097325bad2879642b9a5615d1287 Mon Sep 17 00:00:00 2001
From: Andrey Petrov <andrey.petrov@shazow.net>
Date: Sat, 16 Mar 2019 15:27:43 -0400
Subject: [PATCH] chat: Sort NamesPrefix by recently active

---
 chat/message/user.go | 13 +++++++++++++
 chat/room.go         | 18 ++++++++++++++----
 chat/room_test.go    | 42 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 69 insertions(+), 4 deletions(-)

diff --git a/chat/message/user.go b/chat/message/user.go
index d094bde..43da001 100644
--- a/chat/message/user.go
+++ b/chat/message/user.go
@@ -238,3 +238,16 @@ func init() {
 
 	// TODO: Seed random?
 }
+
+// RecentActiveUsers is a slice of *Users that knows how to be sorted by the time of the last message.
+type RecentActiveUsers []*User
+
+func (a RecentActiveUsers) Len() int      { return len(a) }
+func (a RecentActiveUsers) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
+func (a RecentActiveUsers) Less(i, j int) bool {
+	a[i].mu.Lock()
+	defer a[i].mu.Unlock()
+	a[j].mu.Lock()
+	defer a[j].mu.Unlock()
+	return a[i].lastMsg.After(a[j].lastMsg)
+}
diff --git a/chat/room.go b/chat/room.go
index 71e3171..851d0e3 100644
--- a/chat/room.go
+++ b/chat/room.go
@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"sort"
 	"sync"
 
 	"github.com/shazow/ssh-chat/chat/message"
@@ -227,12 +228,21 @@ func (r *Room) SetTopic(s string) {
 }
 
 // NamesPrefix lists all members' names with a given prefix, used to query
-// for autocompletion purposes.
+// for autocompletion purposes. Sorted by which user was last active.
 func (r *Room) NamesPrefix(prefix string) []string {
 	items := r.Members.ListPrefix(prefix)
-	names := make([]string, len(items))
-	for i, item := range items {
-		names[i] = item.Value().(*Member).User.Name()
+
+	// Sort results by recently active
+	users := make([]*message.User, 0, len(items))
+	for _, item := range items {
+		users = append(users, item.Value().(*Member).User)
+	}
+	sort.Sort(message.RecentActiveUsers(users))
+
+	// Pull out names
+	names := make([]string, 0, len(items))
+	for _, user := range users {
+		names = append(names, user.Name())
 	}
 	return names
 }
diff --git a/chat/room_test.go b/chat/room_test.go
index e30c170..77c77f7 100644
--- a/chat/room_test.go
+++ b/chat/room_test.go
@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"github.com/shazow/ssh-chat/chat/message"
+	"github.com/shazow/ssh-chat/set"
 )
 
 // Used for testing
@@ -362,3 +363,44 @@ func TestRoomNames(t *testing.T) {
 		t.Errorf("Got: %q; Expected: %q", actual, expected)
 	}
 }
+
+func TestRoomNamesPrefix(t *testing.T) {
+	r := NewRoom()
+
+	s := &MockScreen{}
+	members := []*Member{
+		&Member{User: message.NewUserScreen(message.SimpleID("aaa"), s)},
+		&Member{User: message.NewUserScreen(message.SimpleID("aab"), s)},
+		&Member{User: message.NewUserScreen(message.SimpleID("aac"), s)},
+		&Member{User: message.NewUserScreen(message.SimpleID("foo"), s)},
+	}
+
+	for _, m := range members {
+		if err := r.Members.Add(set.Itemize(m.ID(), m)); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	// Inject some activity
+	members[2].HandleMsg(message.NewMsg("hi")) // aac
+	members[0].HandleMsg(message.NewMsg("hi")) // aaa
+	members[3].HandleMsg(message.NewMsg("hi")) // foo
+	members[1].HandleMsg(message.NewMsg("hi")) // aab
+
+	if got, want := r.NamesPrefix("a"), []string{"aab", "aaa", "aac"}; !reflect.DeepEqual(got, want) {
+		t.Errorf("got: %q; want: %q", got, want)
+	}
+
+	members[2].HandleMsg(message.NewMsg("hi")) // aac
+	if got, want := r.NamesPrefix("a"), []string{"aac", "aab", "aaa"}; !reflect.DeepEqual(got, want) {
+		t.Errorf("got: %q; want: %q", got, want)
+	}
+
+	if got, want := r.NamesPrefix("f"), []string{"foo"}; !reflect.DeepEqual(got, want) {
+		t.Errorf("got: %q; want: %q", got, want)
+	}
+
+	if got, want := r.NamesPrefix("bar"), []string{}; !reflect.DeepEqual(got, want) {
+		t.Errorf("got: %q; want: %q", got, want)
+	}
+}