From c208a0e00cbe2821054a2be4314a9b12e85f2150 Mon Sep 17 00:00:00 2001
From: Nick Thomas <me@ur.gs>
Date: Sat, 15 Oct 2016 01:31:11 +0100
Subject: [PATCH] Add a prefix adapter to implement ! commands and ignoring
 help in public channels

---
 adapters/prefix_adapter.go | 67 ++++++++++++++++++++++++++++++++++++++
 lysenko.go                 |  8 ++++-
 2 files changed, 74 insertions(+), 1 deletion(-)
 create mode 100644 adapters/prefix_adapter.go

diff --git a/adapters/prefix_adapter.go b/adapters/prefix_adapter.go
new file mode 100644
index 0000000..b020cf7
--- /dev/null
+++ b/adapters/prefix_adapter.go
@@ -0,0 +1,67 @@
+package adapters
+
+import (
+	"context"
+	"strings"
+
+	"github.com/tcolgate/hugot"
+)
+
+// Intercepts incoming messages. If they begin with a prefix, they are rewritten
+// so they appear to be to the bot. For example, "!foo" would become "foo". The
+// ToBot member of the Message struct is also set to true.
+//
+// The overall effect is to allow command handlers to be accessed via a !prefix
+//
+// You can also block the ubiquitous "help" handler outside of PMs by setting
+// PrivateHelpOnly to true. This should really be a separate adapter, but
+// overhead...
+type PrefixAdapter struct {
+	hugot.Adapter
+	Prefix          string
+	PrivateHelpOnly bool
+	c               chan *hugot.Message
+}
+
+func NewPrefixAdapter(around hugot.Adapter, prefix string) *PrefixAdapter {
+	return &PrefixAdapter{
+		Adapter: around,
+		Prefix:  prefix,
+		c:       make(chan *hugot.Message),
+	}
+}
+
+func (p *PrefixAdapter) Receive() <-chan *hugot.Message {
+	return p.c
+}
+
+func (p *PrefixAdapter) Run(ctx context.Context) {
+	for {
+		select {
+		case m := <-p.Adapter.Receive():
+			if m == nil {
+				return
+			}
+
+			m = p.fixup(m)
+			if !p.isBlacklisted(m) {
+				p.c <- m
+			}
+		case <-ctx.Done():
+			return
+		}
+	}
+}
+
+func (p *PrefixAdapter) fixup(m *hugot.Message) *hugot.Message {
+	if !m.ToBot && strings.HasPrefix(m.Text, p.Prefix) {
+		m.Text = strings.Replace(m.Text, p.Prefix, "", 1)
+		m.ToBot = true
+	}
+
+	return m
+}
+
+func (p *PrefixAdapter) isBlacklisted(m *hugot.Message) bool {
+	return p.PrivateHelpOnly && m.ToBot && strings.HasPrefix(m.Text, "help") && !m.Private
+}
diff --git a/lysenko.go b/lysenko.go
index af58af6..46c671f 100644
--- a/lysenko.go
+++ b/lysenko.go
@@ -14,6 +14,7 @@ import (
 	"github.com/tcolgate/hugot"
 	"github.com/tcolgate/hugot/adapters/irc"
 
+	"ur.gs/lysenko/adapters"
 	"ur.gs/lysenko/handlers/deadline"
 	"ur.gs/lysenko/handlers/quotedb"
 )
@@ -53,6 +54,11 @@ func main() {
 	}
 
 	adapter := irc.New(config, channelList...)
+	prefix_adapter := adapters.NewPrefixAdapter(adapter, "!")
+	prefix_adapter.PrivateHelpOnly = true
+
+	ctx := context.Background()
+	go prefix_adapter.Run(ctx)
 
 	db, err := quotedb.New(*quotes)
 	if err != nil {
@@ -67,5 +73,5 @@ func main() {
 	mux.HandleCommand(deadline.NewCommand(&quotedb.RandQuoteHandler{QuoteDB: db}))
 	mux.HandleCommand(deadline.NewCommand(&quotedb.QuoteHandler{QuoteDB: db}))
 
-	hugot.ListenAndServe(context.Background(), mux, adapter)
+	hugot.ListenAndServe(ctx, mux, prefix_adapter)
 }