From a6aa63ed1f8cdaa5c6b0cbd2a997356cd3b46a4c Mon Sep 17 00:00:00 2001
From: Bruno Schaatsbergen <git@bschaatsbergen.com>
Date: Mon, 16 Dec 2024 12:42:59 -0800
Subject: [PATCH] Fix flaky tab writing behavior using text/tabwriter (#25)
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* fix flaky tab writing behavior

This fixes problems with tab writing caused by using a regular os.File writer. By standardizing the tab writer’s usage and ensuring consistent initialization, we improve the reliability and consistency of output formatting a lot.

* view: improve tabwriter documentation

* view: add the ability to debug the tabwriter

In the past, we’ve faced too many issues with flaky tab formatting. If the `debug` flag is specified, we should enable debugging for the tabwriter as well, leveraging its built-in support for this.

* view: move newline handling back to renderer

* view: preserve comment
---
 cmd/root.go             |  6 +++---
 internal/view/format.go | 22 +++++++++++++++++++++-
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/cmd/root.go b/cmd/root.go
index 95a506f..a985b03 100644
--- a/cmd/root.go
+++ b/cmd/root.go
@@ -2,7 +2,6 @@ package cmd
 
 import (
 	"fmt"
-	"io"
 	"os"
 	"sort"
 	"strings"
@@ -74,7 +73,7 @@ var (
 				vt = arguments.ViewHuman
 			}
 
-			var w io.Writer = os.Stdout
+			var w = view.NewTabWriter(os.Stdout, debug)
 			logFile := os.Getenv("ZNS_LOG_FILE")
 			if logFile != "" {
 				f, err := os.Create(logFile)
@@ -82,7 +81,7 @@ var (
 					panic(fmt.Sprintf("Failed to create log file: %v", err))
 				}
 				defer f.Close()
-				w = f
+				w = view.NewTabWriter(f, debug)
 			}
 
 			v := view.NewRenderer(vt, &view.View{
@@ -152,6 +151,7 @@ var (
 					v.Render(args[0], record)
 				}
 			}
+			w.Flush() // we need to flush the buffer to ensure all data is written to the underlying stream.
 		},
 	}
 )
diff --git a/internal/view/format.go b/internal/view/format.go
index 5ede329..72c7529 100644
--- a/internal/view/format.go
+++ b/internal/view/format.go
@@ -2,14 +2,34 @@ package view
 
 import (
 	"fmt"
+	"io"
 	"strconv"
 	"strings"
+	"text/tabwriter"
 	"time"
 
 	"github.com/fatih/color"
 	"github.com/miekg/dns"
 )
 
+// NewTabWriter initializes and returns a new tabwriter.Writer.
+// ZNS uses this writer to format DNS records into a clear, human-readable table.
+// See https://pkg.go.dev/text/tabwriter#Writer.Init for details.
+func NewTabWriter(w io.Writer, debug bool) *tabwriter.Writer {
+	flags := uint(0)
+	if debug {
+		flags = tabwriter.Debug
+	}
+	return tabwriter.NewWriter(
+		w,
+		0,   // Minwidth
+		8,   // Tabwidth
+		3,   // Padding
+		' ', // Padchar
+		flags,
+	)
+}
+
 // formatTTL converts TTL to a more readable format (hours, minutes, seconds).
 func formatTTL(ttl uint32) string {
 	duration := time.Duration(ttl) * time.Second
@@ -89,8 +109,8 @@ func formatRecord(domainName string, answer dns.RR) string {
 Unknown record type: %s
 
 We encountered an unsupported DNS record type: %s. 
-Please consider raising an issue on GitHub to add support for this record type.
 
+Please consider raising an issue on GitHub to add support for this record type.
 https://github.com/znscli/zns/issues/new
 
 Thank you for your contribution!