[I18N] Add Locale merger script

(cherry picked from commit ecc3dae2ac)
(cherry picked from commit c6c3fc6ace)
(cherry picked from commit 4833bd594a)

[I18N] in the home page replace GitHub with Forgejo

The english string that shows on the home page to encourage for
contribution no longer reference GitHub. But some translations still
do. In this context, and this context only, replace it with Forgejo
even though it may not be correct in some cases.

Refs: https://codeberg.org/forgejo/forgejo/pulls/450
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build/merge-forgejo-locales.go

@@ -0,0 +1,97 @@
+// Copyright 2022 The Forgejo Authors c/o Codeberg e.V.. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+//go:build ignore
+
+package main
+
+import (
+	"bufio"
+	"os"
+	"regexp"
+	"strings"
+
+	"gopkg.in/ini.v1"
+)
+
+const (
+	trimPrefix   = "gitea_"
+	sourceFolder = "options/locales/"
+)
+
+// returns list of locales, still containing the file extension!
+func generate_locale_list() []string {
+	localeFiles, _ := os.ReadDir(sourceFolder)
+	locales := []string{}
+	for _, localeFile := range localeFiles {
+		if !localeFile.IsDir() && strings.HasPrefix(localeFile.Name(), trimPrefix) {
+			locales = append(locales, strings.TrimPrefix(localeFile.Name(), trimPrefix))
+		}
+	}
+	return locales
+}
+
+// replace all occurrences of Gitea with Forgejo
+func renameGiteaForgejo(filename string) []byte {
+	file, err := os.Open(filename)
+	if err != nil {
+		panic(err)
+	}
+
+	replacer := strings.NewReplacer(
+		"Gitea", "Forgejo",
+		"https://docs.gitea.io/en-us/install-from-binary/", "https://forgejo.org/download/#installation-from-binary",
+		"https://github.com/go-gitea/gitea/tree/master/docker", "https://forgejo.org/download/#container-image",
+		"https://docs.gitea.io/en-us/install-from-package/", "https://forgejo.org/download",
+		"https://code.gitea.io/gitea", "https://forgejo.org/download",
+		"code.gitea.io/gitea", "Forgejo",
+		`<a href="https://github.com/go-gitea/gitea/issues" target="_blank">GitHub</a>`, `<a href="https://codeberg.org/forgejo/forgejo/issues" target="_blank">Codeberg</a>`,
+		"https://github.com/go-gitea/gitea", "https://codeberg.org/forgejo/forgejo",
+		"https://blog.gitea.io", "https://forgejo.org/news",
+	)
+
+	out := make([]byte, 0, 1024)
+	scanner := bufio.NewScanner(file)
+	scanner.Split(bufio.ScanLines)
+	for scanner.Scan() {
+		line := scanner.Text()
+
+		if strings.HasPrefix(line, "license_desc=") {
+			line = strings.Replace(line, "GitHub", "Forgejo", 1)
+		}
+
+		if strings.HasPrefix(line, "[") && strings.HasSuffix(line, "]") {
+			out = append(out, []byte("\n"+line+"\n")...)
+		} else if strings.HasPrefix(line, "settings.web_hook_name_gitea") {
+			out = append(out, []byte("\n"+line+"\n")...)
+			out = append(out, []byte("settings.web_hook_name_forgejo = Forgejo\n")...)
+		} else if strings.HasPrefix(line, "migrate.gitea.description") {
+			re := regexp.MustCompile(`(.*Gitea)`)
+			out = append(out, []byte(re.ReplaceAllString(line, "${1}/Forgejo")+"\n")...)
+		} else {
+			out = append(out, []byte(replacer.Replace(line)+"\n")...)
+		}
+	}
+	file.Close()
+	return out
+}
+
+func main() {
+	locales := generate_locale_list()
+	var err error
+	var localeFile *ini.File
+	for _, locale := range locales {
+		giteaLocale := sourceFolder + "gitea_" + locale
+		localeFile, err = ini.LoadSources(ini.LoadOptions{
+			IgnoreInlineComment: true,
+		}, giteaLocale, renameGiteaForgejo(giteaLocale))
+		if err != nil {
+			panic(err)
+		}
+		err = localeFile.SaveTo("options/locale/locale_" + locale)
+		if err != nil {
+			panic(err)
+		}
+	}
+}