Rework action.sh script

action.sh

@@ -1,33 +1,28 @@
 #!/bin/bash
 
 if [[ -z "${ACTIONS_ID_TOKEN_REQUEST_URL}" ]] && [[ -z "${ACTIONS_ID_TOKEN_REQUEST_TOKEN}" ]]; then
-    echo "==> No GitHub OIDC token found, skipping..."
+    echo "::error:: The job or workflow run requires a permissions setting with id-token: write.\nYou won't be able to request the OIDC JWT ID token if the permissions setting for id-token is set to read or none.\nThe \`id-token: write\` setting allows the JWT to be requested from GitHub's OIDC provider."
     exit 0
 fi
 
+if [ ! "$(command -v dart)" ] && [ ! "$(command -v flutter)" ]; then
+    echo "::error::Flutter is not installed,"
+    echo "See https://github.com/flutter-actions/setup-flutter for more details."
+    exit 1
+fi
+
 log_group_start() {
     echo "::group::${1}"
 }
 log_group_end() {
     echo "::endgroup::"
 }
 
-jwtd() {
-    log_group_start "Decoding JWT data..."
-    jq -R 'split(".") | .[0],.[1] | @base64d | fromjson' <<< "${1}"
-    echo "Signature: $(echo "${1}" | awk -F'.' '{print $3}')"
-    log_group_end
-}
-
-INPUT_GITHUB_OIDC_AUDIENCE="https://pub.dev"
-
 echo "Create the OIDC token used for pub.dev publishing..."
+INPUT_GITHUB_OIDC_AUDIENCE="https://pub.dev"
 GITHUB_OIDC_RESPONSE=$(curl -s -H "Authorization: bearer $ACTIONS_ID_TOKEN_REQUEST_TOKEN" "$ACTIONS_ID_TOKEN_REQUEST_URL&audience=${INPUT_GITHUB_OIDC_AUDIENCE}")
 GITHUB_OIDC_IDTOKEN=$(jq -r '.value' <<< "${GITHUB_OIDC_RESPONSE}")
 export PUB_TOKEN=${GITHUB_OIDC_IDTOKEN}
 echo "PUB_TOKEN=${GITHUB_OIDC_IDTOKEN}" >> $GITHUB_ENV
-
-jwtd "$GITHUB_OIDC_IDTOKEN"
-
 echo "The Dart CLI successfully authenticated with the GitHub OIDC token,"
 dart pub token add ${INPUT_GITHUB_OIDC_AUDIENCE} --env-var PUB_TOKEN