Rewrite server update script (#148)

* refactor!: rewrite update script

* refactor: split common URL logic into download_with_args

* feat: add skip_404 arg to url/zip download type

scripts/update.sh

@@ -0,0 +1,56 @@
+#!/bin/sh
+# shellcheck disable=SC1091 # Included files should be manually checked
+set -e
+
+# Pipefail is part of POSIX.1-2024, however some shells haven't
+# implemented it yet. Turn it on only if it's available.
+# shellcheck disable=SC3040
+if (set -o pipefail 2>/dev/null); then
+    set -o pipefail
+fi
+
+_SCRIPT_PATH="$(dirname "$(readlink -f -- "$0")")"
+. "$_SCRIPT_PATH"/_common.sh
+. "$_SCRIPT_PATH"/_sources/_index.sh
+
+_FILTER="$1"
+if [ "$_FILTER" = "help" ]; then
+    cat <<USAGE
+Usage: scripts/update.sh [FILTER]
+Downloads all files contained in scripts/downloads.json. If FILTER
+is specified, only files whose JSON paths start with FILTER will be
+downloaded.
+
+Examples:
+    scripts/update.sh server
+    scripts/update.sh plugins/internal
+USAGE
+    exit 1
+fi
+
+_parse_downloads() {
+    exitcode=0
+
+    jq --null-input --raw-output --exit-status \
+        --arg arg1 "$_FILTER" \
+        --from-file "$_SCRIPT_PATH"/_parser.jq \
+        --stream "$_SCRIPT_PATH"/downloads.json || exitcode=$?
+    if [ $exitcode = 4 ]; then
+        echo 'No downloads matched the filter.'>&2
+        return $exitcode
+    fi
+
+    return $exitcode
+}
+
+echo "Downloading with filter ${_FILTER:-"<none>"}..."
+_parse_downloads | while read -r path; read -r type; read -r args; do
+    echo "> $path"
+    if ! check_path "$path"; then
+        echo "Bailing!"
+        exit 1
+    fi
+
+    debug "download_type: type=$type; args=$args"
+    echo "$args" | download_type "$type" "$path"
+done