From 6f6e4e23fe55ab08b893a287ea138b8a32bbe77c Mon Sep 17 00:00:00 2001
From: Bel LaPointe <breel@qualtrics.com>
Date: Wed, 25 Oct 2023 06:09:59 -0600
Subject: [PATCH] o it just werks that is sus

---
 ledger/file.go | 34 +++++++++++++++++++++++++++++++---
 1 file changed, 31 insertions(+), 3 deletions(-)

diff --git a/ledger/file.go b/ledger/file.go
index 4e150f9..b590b77 100644
--- a/ledger/file.go
+++ b/ledger/file.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"unicode"
 )
 
 var filesAppendDelim = "\t"
@@ -44,16 +45,43 @@ func (files Files) append(s string) error {
 }
 
 func (files Files) trimTrainlingWhitespace() error {
-	f, err := os.Open(string(files[0]))
-	if os.IsNotExist(err) {
+	idx, err := files._lastNonWhitespacePos()
+	if err != nil {
+		return err
+	}
+	if idx < 1 {
 		return nil
 	}
+
+	f, err := os.OpenFile(string(files[0]), os.O_CREATE|os.O_WRONLY, os.ModePerm)
 	if err != nil {
 		return err
 	}
 	defer f.Close()
 
-	return io.EOF
+	return f.Truncate(int64(idx + 1))
+}
+
+func (files Files) _lastNonWhitespacePos() (int, error) {
+	f, err := os.Open(string(files[0]))
+	if os.IsNotExist(err) {
+		return -1, nil
+	}
+	if err != nil {
+		return -1, err
+	}
+	defer f.Close()
+
+	b, err := io.ReadAll(f)
+	if err != nil {
+		return -1, err
+	}
+	for i := len(b) - 1; i >= 0; i-- {
+		if !unicode.IsSpace(rune(b[i])) {
+			return i, nil
+		}
+	}
+	return len(b) - 1, nil
 }
 
 func (files Files) Deltas(like ...Like) (Deltas, error) {