Android: Add comment with manifest diff script

bin/comment_with_manifest_diff

@@ -0,0 +1,105 @@
+#!/bin/bash
+
+# This script is used in a Buildkite CI pipeline to analyze and comment on manifest changes in a
+# GitHub pull request (PR). It compares the project manifest between the
+# trunk version and the PR version to identify changes caused by updates to the project.
+#
+# Usage:
+#    ./comment_with_manifest_diff <MODULE>
+#
+# Parameters:
+#    <MODULE>        : The project module whose manifest will be checked.
+#
+# Steps:
+# 1. It copies the manifest reports for both the trunk and PR versions.
+# 2. The script compares these reports to detect any changes in the project's manifest.
+# 3. If changes are found, the script creates a comment on the GitHub PR with the results.
+# 4. If no changes are detected, the script exits without posting any comment.
+#
+# Notes:
+# - The comment on the PR will include a detailed list of changes.
+#
+# Example:
+#    ./comment_with_manifest_diff app
+#
+# This will analyze the `app` module and post the result to the PR.
+
+set -euo pipefail
+
+MODULE="${1:-}"
+
+ANDROID_MERGED_MANIFEST="${HOME}/.android/merged_manifest/${MODULE}"
+TRUNK_MANIFEST_PATH="${ANDROID_MERGED_MANIFEST}/jalapenoDebug/processJalapenoDebugMainManifest/AndroidManifest.xml"
+PR_MANIFEST_PATH="${MODULE}/build/intermediates/merged_manifest/jalapenoDebug/processJalapenoDebugMainManifest/AndroidManifest.xml"
+
+if [ -z "$MODULE" ]; then
+  echo "Not enough arguments provided. Usage: ./comment_with_manifest_diff <MODULE>"
+  exit 1
+fi
+
+if [ "${BUILDKITE_PULL_REQUEST:-false}" == "false" ]; then
+  echo "This script should only be called on pull requests. Be sure to set \`if: build.pull_request.id != null\` on the step invoking it in your Buildkite pipeline"
+  exit 2
+fi
+
+DIFF_MANIFEST_FOLDER="./build/reports/diff_manifest"
+TRUNK_MANIFEST_FILE="$DIFF_MANIFEST_FOLDER/trunk_AndroidManifest.txt"
+PR_MANIFEST_FILE="$DIFF_MANIFEST_FOLDER/pr_AndroidManifest.txt"
+DIFF_MANIFEST_FILE="$DIFF_MANIFEST_FOLDER/diff_manifest.txt"
+
+mkdir -p "$DIFF_MANIFEST_FOLDER"
+
+# Get trunk and PR manifest
+cp "$TRUNK_MANIFEST_PATH" "$TRUNK_MANIFEST_FILE"
+cp "$PR_MANIFEST_PATH" "$PR_MANIFEST_FILE"
+
+# Generate diff
+echo "--> Generating manifest diff"
+diff -u "$TRUNK_MANIFEST_FILE" "$PR_MANIFEST_FILE" > "$MANIFEST_DIFF_FILE" || true
+
+generate_manifest_comment_body() {
+  cat <<EOF
+
+The following changes in \`$MODULE\` AndroidManifest.xml were detected (configuration ):
+
+\`\`\`diff
+$(cat "$DIFF_MANIFEST_FILE")
+\`\`\`
+
+EOF
+}
+
+if [ -n "$DIFF_MANIFEST_FILE" ]; then
+  echo "--> Commenting manifest diff to GitHub"
+
+  # Create or clear the comment body file
+  COMMENT_FILE="$DIFF_MANIFEST_FOLDER/comment_body.txt"
+  true > $COMMENT_FILE  # 'true' used to clear the file as a no-op
+
+  append_content() {
+    local header="$1"
+    local content="$2"
+    local github_comment_max_size=65400 # GitHub constraint is 65536, but we decrease this value slightly to reserve for hidden comment_on_pr content and line breaks
+    local warning_message="Content exceeds $github_comment_max_size characters. [Navigate to Buildkite build artifacts](${BUILDKITE_BUILD_URL}#${BUILDKITE_JOB_ID}) to see details."
+
+    local current_size
+    current_size=$(wc -c < "$COMMENT_FILE")
+
+    # Calculate if there's enough space for the content and header
+    if (( current_size + ${#header} + ${#content} > github_comment_max_size - ${#header} - ${#warning_message})); then
+      printf "\n%s\n%s\n" "$header" "$warning_message" > $COMMENT_FILE
+      return
+    fi
+
+    printf "\n%s\n" "$header" >> $COMMENT_FILE
+    printf "%s\n" "$content" >> $COMMENT_FILE
+  }
+
+  if [ -s "$DIFF_MANIFEST_FILE" ]; then
+    append_content "## Project manifest changes" "$(generate_manifest_comment_body)"
+  fi
+
+  comment_on_pr --id "manifest-diff" --if-exist update "$COMMENT_FILE"
+else
+  comment_on_pr --id "manifest-diff" --if-exist delete
+fi