From e0e1a775bcf1a42e5a220cae1f07e466f87d444c Mon Sep 17 00:00:00 2001
From: Gustavo Maronato <gustavo@maronato.dev>
Date: Sat, 19 Aug 2023 12:04:28 -0300
Subject: [PATCH] reduce default short values

---
 internal/service/short/shortservice.go |  4 ++--
 internal/util/short/alphabet.go        |  3 ---
 internal/util/short/generator.go       | 14 ++++++++++----
 3 files changed, 12 insertions(+), 9 deletions(-)
 delete mode 100644 internal/util/short/alphabet.go

diff --git a/internal/service/short/shortservice.go b/internal/service/short/shortservice.go
index bc2a5f0..bbcf0ed 100644
--- a/internal/service/short/shortservice.go
+++ b/internal/service/short/shortservice.go
@@ -15,11 +15,11 @@ import (
 
 const (
 	// DefaultShortLength is the default length of the short URL.
-	DefaultShortLength = 8
+	DefaultShortLength = 5
 	// MinShortLength is the minimum length of the short URL.
 	MinShortLength = 4
 	// MaxShortLength is the maximum length of the short URL.
-	MaxShortLength = 32
+	MaxShortLength = 20
 )
 
 type ShortService struct {
diff --git a/internal/util/short/alphabet.go b/internal/util/short/alphabet.go
deleted file mode 100644
index 29e47f6..0000000
--- a/internal/util/short/alphabet.go
+++ /dev/null
@@ -1,3 +0,0 @@
-package shortutil
-
-const alphabet = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_-" // 64 possibilities
diff --git a/internal/util/short/generator.go b/internal/util/short/generator.go
index 6718568..a2e27c6 100644
--- a/internal/util/short/generator.go
+++ b/internal/util/short/generator.go
@@ -3,16 +3,22 @@ package shortutil
 
 import (
 	"math/rand"
+	"strconv"
 	"strings"
 	"time"
 )
 
-const (
-	letterIdxBits = 7                    // 7 bits to represent a letter index
-	letterIdxMask = 1<<letterIdxBits - 1 // All 1-bits, as many as letterIdxBits
-	letterIdxMax  = 63 / letterIdxBits   // # of letter indices fitting in 63 bits
+// These are the characters that can be used in shorts
+const alphabet = "abcdefghijklmnopqrstuvwxyz0123456789" // 36 possibilities
+const alphabetLen = int64(len(alphabet))
+
+var (
+	letterIdxBits = len(strconv.FormatInt(alphabetLen, 2)) // number of bits to represent alphabetLen
+	letterIdxMask = int64(1<<letterIdxBits - 1)            // All 1-bits, as many as letterIdxBits
+	letterIdxMax  = 63 / letterIdxBits                     // # of letter indices fitting in 63 bits
 )
 
+// src is the random source for generating shorts
 var src = rand.NewSource(time.Now().UnixNano())
 
 func GenerateRandomShort(n int) string {