#!/usr/bin/env bash

# Maps a PR review comment node ID to its parent thread.
# Fetches thread IDs and first comment IDs to find the match,
# then returns the matching thread with full comment details.

set -euo pipefail

if [ $# -lt 2 ]; then
    echo "Usage: get-thread-for-comment PR_NUMBER COMMENT_NODE_ID [OWNER/REPO]"
    echo "Example: get-thread-for-comment 378 PRRC_kwDOP_gZVc6ySv89"
    exit 1
fi

PR_NUMBER=$1
COMMENT_NODE_ID=$2

if [ -n "${3:-}" ]; then
    OWNER=$(echo "$3" | cut -d/ -f1)
    REPO=$(echo "$3" | cut -d/ -f2)
else
    # `|| true` is load-bearing: under `set -e`, a failed command substitution
    # in an assignment aborts the script immediately. Run outside a git repo,
    # `gh repo view` exits 1, its stderr is swallowed by `2>/dev/null`, and the
    # script would die here with rc=1 and no output -- making the friendly error
    # below unreachable. Keep `|| true` so detection failure falls through to it.
    OWNER=$(gh repo view --json owner -q .owner.login 2>/dev/null || true)
    REPO=$(gh repo view --json name -q .name 2>/dev/null || true)
fi

if [ -z "$OWNER" ] || [ -z "$REPO" ]; then
    echo "Error: could not resolve owner/repo. Run get-thread-for-comment from inside the target git repository, or pass OWNER/REPO as the third argument (e.g., get-thread-for-comment $PR_NUMBER $COMMENT_NODE_ID OWNER/REPO)." >&2
    exit 1
fi

threads_pages=$(gh api graphql --paginate --slurp \
  -f owner="$OWNER" -f repo="$REPO" -F pr="$PR_NUMBER" \
  -f query='
query Threads($owner: String!, $repo: String!, $pr: Int!, $endCursor: String) {
  repository(owner: $owner, name: $repo) {
    pullRequest(number: $pr) {
      reviewThreads(first: 100, after: $endCursor) {
        nodes {
          id
          isResolved
          isOutdated
          path
          line
          originalLine
          startLine
          originalStartLine
          comments(first: 100) {
            nodes {
              id
              author { login }
              body
              createdAt
              url
            }
            pageInfo { hasNextPage endCursor }
          }
        }
        pageInfo { hasNextPage endCursor }
      }
    }
  }
}')

echo "$threads_pages" | jq -e --arg cid "$COMMENT_NODE_ID" '
  [.[].data.repository.pullRequest.reviewThreads.nodes[]] as $threads |
  [$threads[]
    | select(.comments.nodes | map(.id) | index($cid))] as $matches |
  [$threads[]
    | select(.comments.pageInfo.hasNextPage == true)
    | { thread_id: .id, path: .path, fetched_comments: (.comments.nodes | length) }] as $truncated |
  if ($matches | length) > 0 then
    $matches[0]
  elif ($truncated | length) > 0 then
    error("No thread found for comment \($cid); one or more review threads have more comments than the first 100 fetched by this script, so nested thread comment pagination is unsupported and absence is incomplete evidence.")
  else
    error("No thread found for comment \($cid)")
  end
'