From eac59fd5a6e43a685e630f6304bb3ac72ed653aa Mon Sep 17 00:00:00 2001
From: Kyle Isom <kyle@imap.cc>
Date: Thu, 20 Nov 2025 18:20:00 -0800
Subject: [PATCH] msg: add new package for CLI output.

---
 README.md  |   1 +
 lib/lib.go |   4 ++
 msg/msg.go | 127 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 132 insertions(+)
 create mode 100644 msg/msg.go

diff --git a/README.md b/README.md
index fa5f18e..808a37f 100644
--- a/README.md
+++ b/README.md
@@ -84,6 +84,7 @@ Contents:
     lib/            Commonly-useful functions for writing Go programs.
     log/            A syslog library.
     logging/        A logging library.
+    msg/            Output library for command line programs.
     mwc/            MultiwriteCloser implementation.
     sbuf/           A byte buffer that can be wiped.
     seekbuf/        A read-seekable byte buffer.
diff --git a/lib/lib.go b/lib/lib.go
index 34a6bf5..57e8b0c 100644
--- a/lib/lib.go
+++ b/lib/lib.go
@@ -336,6 +336,10 @@ type DummyWriteCloser struct {
 	w io.Writer
 }
 
+func WithCloser(w io.Writer) io.WriteCloser {
+	return &DummyWriteCloser{w: w}
+}
+
 func (dwc *DummyWriteCloser) Write(p []byte) (int, error) {
 	return dwc.w.Write(p)
 }
diff --git a/msg/msg.go b/msg/msg.go
new file mode 100644
index 0000000..41eef08
--- /dev/null
+++ b/msg/msg.go
@@ -0,0 +1,127 @@
+// Package msg is a tool for handling commandline output based on
+// flags for quiet, verbose, and debug modes. The default is to
+// have all modes disabled.
+//
+// The QPrint messages will only output messages if quiet mode is
+// disabled
+// The VPrint messages will only output messages if verbose mode
+// is enabled.
+// The DPrint messages will only output messages if debug mode
+// is enabled.
+package msg
+
+import (
+	"fmt"
+	"io"
+
+	"git.wntrmute.dev/kyle/goutils/lib"
+
+	"git.wntrmute.dev/kyle/goutils/dbg"
+)
+
+var (
+	enableQuiet   bool
+	enableVerbose bool
+	debug         *dbg.DebugPrinter
+	w             io.Writer
+)
+
+func SetQuiet(q bool) {
+	enableQuiet = q
+}
+
+func SetVerbose(v bool) {
+	enableVerbose = v
+}
+
+func SetDebug(d bool) {
+	debug.Enabled = d
+}
+
+func Set(q, v, d bool) {
+	SetQuiet(q)
+	SetVerbose(v)
+	SetDebug(d)
+}
+
+func QPrint(a ...any) {
+	if enableQuiet {
+		return
+	}
+
+	fmt.Fprint(w, a...)
+}
+
+func QPrintf(format string, a ...any) {
+	if enableQuiet {
+		return
+	}
+
+	fmt.Fprintf(w, format, a...)
+}
+
+func QPrintln(a ...any) {
+	if enableQuiet {
+		return
+	}
+
+	fmt.Fprintln(w, a...)
+}
+
+func DPrint(a ...any) {
+	debug.Print(a...)
+}
+
+func DPrintf(format string, a ...any) {
+	debug.Printf(format, a...)
+}
+
+func DPrintln(a ...any) {
+	debug.Println(a...)
+}
+
+func StackTrace() {
+	debug.StackTrace()
+}
+
+func VPrint(a ...any) {
+	if !enableVerbose {
+		return
+	}
+
+	fmt.Fprint(w, a...)
+}
+
+func VPrintf(format string, a ...any) {
+	if !enableVerbose {
+		return
+	}
+
+	fmt.Fprintf(w, format, a...)
+}
+
+func VPrintln(a ...any) {
+	if !enableVerbose {
+		return
+	}
+
+	fmt.Fprintln(w, a...)
+}
+
+func Print(a ...any) {
+	fmt.Fprint(w, a...)
+}
+
+func Printf(format string, a ...any) {
+	fmt.Fprintf(w, format, a...)
+}
+
+func Println(a ...any) {
+	fmt.Fprintln(w, a...)
+}
+
+// SetWriter changes the output for messages.
+func SetWriter(dst io.Writer) {
+	w = dst
+	debug = dbg.To(lib.WithCloser(w))
+}