entrypoint

#!/bin/sh

REPOSITORY_OWNER="$INPUT_REPOSITORY_OWNER"
REPOSITORY_NAME="$INPUT_REPOSITORY_NAME"
PULL_REQUEST="$INPUT_PULL_REQUEST"
ADD_LINKS_BY_CONTENT="$INPUT_ADD_LINKS_BY_CONTENT"

_RETRY_OPTS="--connect-timeout 15 --max-time 60 --retry 10 --retry-delay 1 --retry-max-time 600"

prepareInputs() {
  if [ -z "$REPOSITORY_OWNER" ]; then
    REPOSITORY_OWNER=$(< "$GITHUB_EVENT_PATH" jq -r ".repository.owner.login")
  fi

  if [ -z "$REPOSITORY_NAME" ]; then
    REPOSITORY_NAME=$(< "$GITHUB_EVENT_PATH" jq -r ".repository.name")
  fi

  if [ -z "$PULL_REQUEST" ]; then
    PULL_REQUEST=$(< "$GITHUB_EVENT_PATH" jq ".number")
    if [ "$PULL_REQUEST" = "null" ]; then
      printf "PR number can't be retrieved from event data.\n" >&2
      printf "You must define a pull request number using 'pr_number' input or" >&2
      printf " run the action against a pull request event.\n" >&2
      exit 1
    fi
  fi
}

get_issues() {
  # create a temporal directory to store unique pull request numbers
  linked_issues_tmpdir="/tmp/pr-linked-issues"
  rm -rf "$linked_issues_tmpdir"
  mkdir -p "$linked_issues_tmpdir"

  # get linked issued from GraphQL API
  script="query{repository(name:\\\"$REPOSITORY_NAME\\\",owner:\\\"$REPOSITORY_OWNER\\\"){pullRequest(number:$PULL_REQUEST){closingIssuesReferences(first:100){nodes{number}}}}}"
  linked_issues_response="$(
    curl -s -H 'Content-Type: application/json' \
    -H "authorization: Bearer $GITHUB_TOKEN" \
    -X POST -d "{ \"query\": \"$script\"}" https://api.github.com/graphql \
    $_RETRY_OPTS
  )"

  # iterate over PRs and create files for each one of them
  echo $linked_issues_response \
  | jq ".data.repository.pullRequest.closingIssuesReferences.nodes[].number?" \
  | while read linked_issue_number; do
    touch "$linked_issues_tmpdir/$linked_issue_number"
  done;

  # add links to other issues by content
  if [ -n "$ADD_LINKS_BY_CONTENT" ]; then
    if [ -z "$REPOSITORY_OWNER" ] || [ -z "$REPOSITORY_NAME" ] || [ -z "$PULL_REQUEST" ]; then
      # get body from event pull request
      pull_request_body="$(< "$GITHUB_EVENT_PATH" jq ".pull_request.body")"
    else
      # get body from Github API
      pull_request_body="$(
        curl -s \
          -H "Accept: application/vnd.github.v3+json" \
          -H "authorization: Bearer $GITHUB_TOKEN" \
          https://api.github.com/repos/$REPOSITORY_OWNER/$REPOSITORY_NAME/pulls/$PULL_REQUEST \
          $_RETRY_OPTS \
        | jq .body
      )"
    fi;

    # iterate over placeholder expressions
    echo "$ADD_LINKS_BY_CONTENT" | while read placeholder_line; do
      # ignore empty input lines and comments
      if [ -z "$placeholder_line" ] || [ "$(echo "$placeholder_line" | cut -c -1)" = "#" ]; then
        continue
      fi;

      # check that every line of 'add_links_by_content' input contains the '{issue_number}' placeholder
      if ! echo "$placeholder_line" | grep "{issue_number}" > /dev/null; then
        printf "The line '%s' of the input 'add_links_by_content'" "$placeholder_line" >&2
        printf " does not contains the '{issue_number}' placeholder.\n" >&2
        exit 1
      fi;

      # build regex replacing '{issue_number}' with digit matcher using Posix ERE and
      # escaping regex characters
      #
      # Current limitations:
      #   - '{{issue_number}}' placeholder does not work in Alpine (in Ubuntu is OK)
      #
      # Hexadecimal characters used in the following regexes
      # \x2b -> '+'
      # \x28 -> '('
      # \x29 -> ')'
      # \x7b -> '{'
      # \x7c -> '|'
      # \x7d -> '}'
      regex="$(
        echo "$placeholder_line" \
        | sed -e "s/\*/\\\\*/g" \
              -e "s/\x2b/\\\\+/g" \
              -e "s/\./\\\\./g" \
              -e "s/\[/\\\\[/g" \
              -e "s/\]/\\\\]/g" \
              -e "s/\\^/\\\\^/g" \
              -e "s/\\$/\\\\$/g" \
              -e "s/\x7c/\\\\\x7c/g" \
              -e "s/\x28/\\\\\x28/g" \
              -e "s/\x29/\\\\\x29/g" \
              -e "s/\x7b(?!?issue_number)/\\\x7b/g" \
              -e "s/\x7d(?<!?issue_number)/\\\x7d/g" \
              -e "s/{issue_number}/([[:digit:]]+)/"
      )"

      # if grep doesn't found any matchs, it exists with code 1,
      # which in combination with 'set -e' makes the program terminate
      # unexpectedly without printing any errors, so the part
      # '|| test $? = 1' makes it to only terminate if the grep exitcode
      # is different to 1
      more_linked_issues_by_content="$(
        echo "$pull_request_body" \
        | { grep -Eo "$regex" || test $? = 1; } \
        | { grep -Eo "[[:digit:]]+" || test $? = 1; }
      )"

      echo "$more_linked_issues_by_content" | while read linked_issue_by_content; do
        if [ -n "$linked_issue_by_content" ]; then
          linked_issue_filepath="$linked_issues_tmpdir/$linked_issue_by_content"
          if [ ! -f "$linked_issue_filepath" ]; then
            touch "$linked_issue_filepath"
          fi;
        fi;
      done;
    done;
  fi;

  # output issue numbers numerically ordered (-v)
  ls -v -1 "$linked_issues_tmpdir" | tr '\n' ',' | sed 's/,$//'
  rm -rf "$linked_issues_tmpdir"
}

main() {
  set -e
  prepareInputs
  issues="$(get_issues)"
  echo "issues=$issues" >> "$GITHUB_OUTPUT"

  # if we need don't need to get the issue owners, exit now
  if [ -z "$INPUT_OWNERS" ]; then
    return 0
  fi;

  PULL_REQUEST_OPENER="$(
    curl -s "https://api.github.com/repos/$REPOSITORY_OWNER/$REPOSITORY_NAME/pulls/$PULL_REQUEST" \
      -H "authorization: Bearer $GITHUB_TOKEN" \
      $_RETRY_OPTS \
    | jq -r .user.login
  )"

  touch /tmp/opener.txt /tmp/others.txt /tmp/null.txt

  # iterate through linked issues
  echo "$issues\n" | tr ',' '\n' | while read issue; do
    owner="$(
      curl -s "https://api.github.com/repos/$REPOSITORY_OWNER/$REPOSITORY_NAME/issues/$issue" \
        -H "authorization: Bearer $GITHUB_TOKEN" \
        $_RETRY_OPTS \
      | jq -r .user.login
    )"
    if [ "$owner" = "$PULL_REQUEST_OPENER" ]; then
      printf "$issue," >> /tmp/opener.txt
    elif [ "$owner" = "null" ] && [ -n "$ADD_LINKS_BY_CONTENT" ]; then
      # non existent issue
      printf "$issue," >> /tmp/null.txt
    else
      printf "$issue," >> /tmp/others.txt
    fi
  done

  echo "opener=$(< /tmp/opener.txt sed 's/[n,]\{1,\}$//')" >> "$GITHUB_OUTPUT"
  echo "others=$(< /tmp/others.txt sed 's/[n,]\{1,\}$//')" >> "$GITHUB_OUTPUT"
  rm -f /tmp/opener.txt /tmp/others.txt

  if [ -n "$ADD_LINKS_BY_CONTENT" ]; then
    # add null output
    echo "null=$(< /tmp/null.txt sed 's/[n,]\{1,\}$//')" >> "$GITHUB_OUTPUT"
    rm -rf /tmp/null.txt
  fi;
}

main