given a GitHub issue number prints "fix-<number>-<title-slug>"

git-slug.sh

#!/usr/bin/env bash
#
# git-slug — given a GitHub issue URL, prints "fix-<number>-<title-slug>"
#
# Usage: ./git-slug [-q] <github-issue-url | issue-number>
#        -q  quiet: print only the slug, without the git command
#        if the parameter is just a number, the default base URL (MapStore2) is used
#
# Usage with pipe, create new branch immediatly
#  git-slug 1123 | sh
#  

set -euo pipefail

DEFAULT_BASE_URL="https://github.com/geosolutions-it/MapStore2/issues/"

usage() {
    echo "Uso: $(basename "$0") [-q] <url-issue-github | numero-issue>" >&2
    echo "Es.: $(basename "$0") https://github.com/owner/repo/issues/123" >&2
    echo "     $(basename "$0") 123   # usa ${DEFAULT_BASE_URL}123" >&2
    echo "  -q  stampa solo lo slug, senza il comando git" >&2
    exit 1
}

command -v curl >/dev/null || { echo "Errore: curl non trovato" >&2; exit 1; }

quiet=0
if [ "${1:-}" = "-q" ] || [ "${1:-}" = "--quiet" ]; then
    quiet=1
    shift
fi

[ $# -eq 1 ] || usage

url="$1"

# Number only → issue of the default repo
if [[ "$url" =~ ^[0-9]+$ ]]; then
    url="${DEFAULT_BASE_URL}${url}"
fi

if [[ "$url" =~ ^https?://github\.com/[^/]+/[^/]+/issues/([0-9]+) ]]; then
    num="${BASH_REMATCH[1]}"
else
    echo "Errore: URL issue GitHub non valido: $url" >&2
    usage
fi

html=$(curl -fsSL "$url") \
    || { echo "Errore: impossibile scaricare la pagina della issue" >&2; exit 1; }

# Prefer og:title (always populated) over <title>, which is sometimes generic ("Issue · GitHub")
html_title=$(printf '%s' "$html" | grep -oP '<meta[^>]*property="og:title"[^>]*content="\K[^"]*' | head -1)
[ -n "$html_title" ] || html_title=$(printf '%s' "$html" | grep -oP '(?<=<title>).*?(?=</title>)' | head -1)

[ -n "$html_title" ] || { echo "Errore: titolo non trovato nella pagina" >&2; exit 1; }

# The title has format: "TITLE · Issue #123 · owner/repo[ · GitHub]" → strip the suffix
title=$(printf '%s' "$html_title" | sed -E 's/ · [A-Za-z ]+ #[0-9]+ · .*$//')

# Slugification: HTML entities dropped, accents → ASCII, lowercase, non-alphanumerics → "-"
slug=$(printf '%s' "$title" \
    | sed -E 's/&[a-zA-Z]+;|&#[0-9]+;/ /g' \
    | iconv -f utf-8 -t ascii//TRANSLIT \
    | tr '[:upper:]' '[:lower:]' \
    | sed -E 's/[^a-z0-9]+/-/g; s/^-+//; s/-+$//')

[ -n "$slug" ] || { echo "Errore: slug vuoto dopo la pulizia del titolo" >&2; exit 1; }

branch="fix-${num}-${slug}"

if [ "$quiet" -eq 1 ]; then
    echo "$branch"
else
    echo "git checkout -b $branch"
fi