refactor(action): separate retrieving the old report

This makes the code easier to read

action.yml

@@ -77,59 +77,10 @@ runs:
         JOB_NAME: ${{ inputs.job-name }}
         PRIVATE_REPO: ${{ inputs.private-repo-workaround }}
       run: |
-        . "${GITHUB_ACTION_PATH}/utils.sh"
-
-        # USAGE: base_report_url
-        base_report_url() {
-          curl -X 'GET' \
-            "$GITHUB_API_URL/repos/$GITHUB_REPOSITORY/actions/tasks" \
-            -H "Authorization: token $GITHUB_TOKEN" \
-            -H 'accept: application/json' |
-              jq --raw-output \
-                --arg name "$JOB_NAME" \
-                --arg head_branch "$HEAD_BRANCH" \
-                '[.workflow_runs[] | select(.name == $name and .head_branch == $head_branch)] | first | .url'
-        }
-        # USAGE: has_report <REPORT_URL>
-        has_report() {
-          http_code=$(curl -X 'GET' -o /dev/null --silent -Iw '%{http_code}' \
-            "$1" -H "Authorization: token $GITHUB_TOKEN")
-          log "Got code $http_code for $1"
-          test "$http_code" = '200'
-        }
-
-        if [ "$PRIVATE_REPO" = 'true' ]; then 
-          log "In a private repo, downloading $HEAD_BRANCH to build the old report"
-
-          old=$(mktemp -d)
-          curl -X 'GET' \
-            "$GITHUB_API_URL/repos/$GITHUB_REPOSITORY/archive/$HEAD_BRANCH.tar.gz" \
-            -H "Authorization: token $GITHUB_TOKEN" |
-              tar -zvx --strip-components=1 -C "$old"
-
-          (cd "$old" && "$GITHUB_ACTION_PATH/create-report.sh") > old-report.json
-
-          log "Reporting on sizes and comparing to sizes in $HEAD_BRANCH"
+        if "$GITHUB_ACTION_PATH/retrieve-old-report.sh" && [ -f old-report.json ]; then
+           log "Reporting on sizes and comparing to sizes in $HEAD_BRANCH"
           "$GITHUB_ACTION_PATH/comment_on_pr.sh" report.json old-report.json
-          exit 0
-        # If we have a previous report compare against it
-        elif [ "$JOB_NAME" ] && [ "$HEAD_BRANCH" ]; then
-          url=$(base_report_url)
-          log "Found previous run at: $url"
-          report_url="$url/artifacts/$ARTIFACT_NAME"
-          if has_report "$report_url"; then
-            log 'Found previous report, downloading...'
-            curl -X 'GET' \
-              "$report_url" \
-              -H "Authorization: token $GITHUB_TOKEN" |
-              gunzip > old-report.json
-            log "Reporting on sizes and comparing to sizes in $HEAD_BRANCH"
-            "$GITHUB_ACTION_PATH/comment_on_pr.sh" report.json old-report.json
-            exit 0
-          else
-            log "Failed to find previous report, expected at: $report_url"
-          fi
+        else
+          log 'Reporting on sizes'
+          "$GITHUB_ACTION_PATH/comment_on_pr.sh" report.json
         fi
-
-        log 'Reporting on sizes'
-        "$GITHUB_ACTION_PATH/comment_on_pr.sh" report.json

retrieve-old-report.sh

@@ -0,0 +1,56 @@
+. "${GITHUB_ACTION_PATH}/utils.sh"
+
+# USAGE: base_report_url
+base_report_url() {
+	curl -X 'GET' \
+		"$GITHUB_API_URL/repos/$GITHUB_REPOSITORY/actions/tasks" \
+		-H "Authorization: token $GITHUB_TOKEN" \
+		-H 'accept: application/json' |
+		jq --raw-output \
+			--arg name "$JOB_NAME" \
+			--arg head_branch "$HEAD_BRANCH" \
+			'[.workflow_runs[] | select(.name == $name and .head_branch == $head_branch)] | first | .url'
+}
+# USAGE: has_report <REPORT_URL>
+has_report() {
+	http_code=$(curl -X 'GET' -o /dev/null --silent -Iw '%{http_code}' \
+		"$1" -H "Authorization: token $GITHUB_TOKEN")
+	log "Got code $http_code for $1"
+	test "$http_code" = '200'
+}
+
+# If we have a previous report compare against it
+if [ "$PRIVATE_REPO" = 'true' ]; then
+	log "In a private repo, downloading $HEAD_BRANCH to build the old report"
+
+	old=$(mktemp -d)
+	group 'Downloaded files'
+	curl -X 'GET' \
+		"$GITHUB_API_URL/repos/$GITHUB_REPOSITORY/archive/$HEAD_BRANCH.tar.gz" \
+		-H "Authorization: token $GITHUB_TOKEN" |
+		tar -zvx --strip-components=1 -C "$old"
+	endgroup
+
+	(cd "$old" && "$GITHUB_ACTION_PATH/create-report.sh") >old-report.json
+
+	exit 0
+elif [ "$JOB_NAME" ] && [ "$HEAD_BRANCH" ]; then
+	url=$(base_report_url)
+
+	log "Found previous run at: $url"
+	report_url="$url/artifacts/$ARTIFACT_NAME"
+
+	if has_report "$report_url"; then
+		log 'Found previous report, downloading...'
+		curl -X 'GET' \
+			"$report_url" \
+			-H "Authorization: token $GITHUB_TOKEN" |
+			gunzip >old-report.json
+		log "Reporting on sizes and comparing to sizes in $HEAD_BRANCH"
+		exit 0
+	else
+		log "Failed to find previous report, expected at: $report_url"
+	fi
+fi
+
+exit 1