Wordlists as new item's ID source

As also discussed in #34, it is now possible to specify a wordlist to be
used as source of the random ID for new items.

CHANGELOG.md

@@ -24,7 +24,7 @@ Types of changes:
 - Created Store RPC working on Unix domain sockets to allow a `fork`+`exec`ed daemon.
 - Configuration through YAML configuration file.
 - Configurable index template and static files, partially by [@riotbib](https://github.com/riotbib) in [#45](https://github.com/oxzi/gosh/pull/45).
-- Configurable ID length for generated items.
+- ID of new items is now configurable both in length as well as in source (random, wordlist).
 
 ### Changed
 - Dependency version bumps.

gosh.go

@@ -34,6 +34,7 @@ type Config struct {
 		IdGenerator struct {
 			Type   string `yaml:"type"`
 			Length int    `yaml:"length"`
+			File   string `yaml:"file"`
 		} `yaml:"id_generator"`
 	}
 

gosh.yml

@@ -11,13 +11,19 @@ store:
 
   # id_generator specifies how the ID resp. name of new elements is generated.
   id_generator:
-    # type defines the generator, currently only "random" which generates a
-    # base58-encoded string of length bytes.
+    # type specifies which generator to use:
+    # - "random" which generates a base58-encoded string of $length bytes.
+    # - "wordlist" picks $length words from $file where $file should contain
+    #   one word per line.
     type: "random"
     # length is the ID length.
-    # - For a "random" type, this is the byte length, resulting in
+    # - For the "random" type, this is the byte length, resulting in
     #   2^($length * 8) possible combinations.
+    # - For the "wordlist" type, this is the amount of words, resulting in
+    #   $wordlist_length^$length possible combinations.
     length: 8
+    # file is used as the source for type "wordlist".
+    # file: "/usr/share/dict/words"
 
 
 # The webserver section describes the web server's configuration.

gosh_store.go

@@ -44,6 +44,14 @@ func mainStore(conf Config) {
 	case "random":
 		idGenerator = randomIdGenerator(conf.Store.IdGenerator.Length)
 
+	case "wordlist":
+		var err error
+		idGenerator, err = wordlistIdGenerator(conf.Store.IdGenerator.File, conf.Store.IdGenerator.Length)
+		if err != nil {
+			slog.Error("Failed to create wordlist ID generator", slog.Any("error", err))
+			os.Exit(1)
+		}
+
 	default:
 		slog.Error("Failed to configure an ID generator as the type is unknown",
 			slog.String("type", conf.Store.IdGenerator.Type))

store.go

@@ -1,13 +1,16 @@
 package main
 
 import (
+	"bufio"
 	"crypto/rand"
 	"errors"
 	"fmt"
 	"io"
 	"log/slog"
+	"math/big"
 	"os"
 	"path/filepath"
+	"strings"
 	"time"
 
 	"github.com/akamensky/base58"
@@ -60,6 +63,39 @@ func randomIdGenerator(length int) func() (string, error) {
 	}
 }
 
+// wordlistIdGenerator returns an ID generator for the "wordlist" type.
+func wordlistIdGenerator(sourceFile string, length int) (func() (string, error), error) {
+	f, err := os.Open(sourceFile)
+	if err != nil {
+		return nil, err
+	}
+	defer func() { _ = f.Close() }()
+
+	scanner := bufio.NewScanner(f)
+
+	words := make([]string, 0, 1024)
+	for scanner.Scan() {
+		words = append(words, scanner.Text())
+	}
+	err = scanner.Err()
+	if err != nil {
+		return nil, err
+	}
+
+	return func() (string, error) {
+		parts := make([]string, length)
+		for i := 0; i < length; i++ {
+			n, err := rand.Int(rand.Reader, big.NewInt(int64(len(words))))
+			if err != nil {
+				return "", err
+			}
+			parts[i] = words[int(n.Int64())]
+		}
+
+		return strings.Join(parts, "-"), nil
+	}, nil
+}
+
 // Store stores an index of all Items as well as the pure files.
 type Store struct {
 	baseDir string