2 files changed, 77 insertions, 30 deletions
diff --git a/app.go b/app.go
index a10c665..569fe8a 100644
--- a/app.go
+++ b/app.go
@@ -455,36 +455,10 @@ func (app *App) completions(cursorIdx int, text []rune) []ui.Completion {
 		return cs
 	}
 
-	var start int
-	for start = cursorIdx - 1; 0 <= start; start-- {
-		if text[start] == ' ' {
-			break
-		}
-	}
-	start++
-	word := text[start:cursorIdx]
-	if len(word) == 0 {
-		return cs
-	}
-	wordCf := app.s.Casemap(string(word))
-	for _, name := range app.s.Names(app.win.CurrentBuffer()) {
-		if strings.HasPrefix(app.s.Casemap(name.Name.Name), wordCf) {
-			nickComp := []rune(name.Name.Name)
-			if start == 0 {
-				nickComp = append(nickComp, ':')
-			}
-			nickComp = append(nickComp, ' ')
-			c := make([]rune, len(text)+len(nickComp)-len(word))
-			copy(c[:start], text[:start])
-			if cursorIdx < len(text) {
-				copy(c[start+len(nickComp):], text[cursorIdx:])
-			}
-			copy(c[start:], nickComp)
-			cs = append(cs, ui.Completion{
-				Text:      c,
-				CursorIdx: start + len(nickComp),
-			})
-		}
+	buffer := app.win.CurrentBuffer()
+	if app.s.IsChannel(buffer) {
+		cs = app.completionsChannelTopic(cs, cursorIdx, text)
+		cs = app.completionsChannelMembers(cs, cursorIdx, text)
 	}
 
 	if cs != nil {
diff --git a/completions.go b/completions.go
new file mode 100644
index 0000000..6fac5e8
--- /dev/null
+++ b/completions.go
@@ -0,0 +1,73 @@
+package senpai
+
+import (
+	"strings"
+
+	"git.sr.ht/~taiite/senpai/ui"
+)
+
+func (app *App) completionsChannelMembers(cs []ui.Completion, cursorIdx int, text []rune) []ui.Completion {
+	var start int
+	for start = cursorIdx - 1; 0 <= start; start-- {
+		if text[start] == ' ' {
+			break
+		}
+	}
+	start++
+	word := text[start:cursorIdx]
+	if len(word) == 0 {
+		return cs
+	}
+	wordCf := app.s.Casemap(string(word))
+	for _, name := range app.s.Names(app.win.CurrentBuffer()) {
+		if strings.HasPrefix(app.s.Casemap(name.Name.Name), wordCf) {
+			nickComp := []rune(name.Name.Name)
+			if start == 0 {
+				nickComp = append(nickComp, ':')
+			}
+			nickComp = append(nickComp, ' ')
+			c := make([]rune, len(text)+len(nickComp)-len(word))
+			copy(c[:start], text[:start])
+			if cursorIdx < len(text) {
+				copy(c[start+len(nickComp):], text[cursorIdx:])
+			}
+			copy(c[start:], nickComp)
+			cs = append(cs, ui.Completion{
+				Text:      c,
+				CursorIdx: start + len(nickComp),
+			})
+		}
+	}
+	return cs
+}
+
+func (app *App) completionsChannelTopic(cs []ui.Completion, cursorIdx int, text []rune) []ui.Completion {
+	if !hasPrefix(text, []rune("/topic ")) {
+		return cs
+	}
+	topic, _, _ := app.s.Topic(app.win.CurrentBuffer())
+	if cursorIdx == len(text) {
+		compText := append(text, []rune(topic)...)
+		cs = append(cs, ui.Completion{
+			Text:      compText,
+			CursorIdx: len(compText),
+		})
+	}
+	return cs
+}
+
+func hasPrefix(s, prefix []rune) bool {
+	return len(prefix) <= len(s) && equal(prefix, s[:len(prefix)])
+}
+
+func equal(a, b []rune) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i := 0; i < len(a); i++ {
+		if a[i] != b[i] {
+			return false
+		}
+	}
+	return true
+}