Add CodeOwners functionality

Inform responsible persons about merge requests in their directories.

.gitlab-ci.yml

 stages:
   - checkRepository
   - checkFormat
+  - finalise
   
 RebaseCheck:
   stage: checkRepository
@@ -97,3 +98,20 @@ FileMediaCheck:
     - ci_scripts/connect_upstream_repo.sh $CI_MERGE_REQUEST_PROJECT_URL
     - git fetch upstream
     - gawk -f ci_scripts/static_check.awk media.geo
+
+InformCodeOwners:
+  stage: finalise
+  tags:
+    - Code_Owners
+  only:
+    refs:
+      - merge_requests
+    variables:
+      - $CI_MERGE_REQUEST_PROJECT_PATH == "CbmSoft/cbmroot_geometry" && $CI_MERGE_REQUEST_TARGET_BRANCH_NAME == "master"
+  script:
+    # Get the upstream repository manually. I did not find any other way to have it for
+    # comparison
+    - apk update && apk add git bash
+    - ci_scripts/connect_upstream_repo.sh $CI_MERGE_REQUEST_PROJECT_URL
+    - git fetch upstream
+    - ci_scripts/inform_codeowners.sh upstream

CODEOWNERS

+# Ending a path in a `/` will specify the code owners for every file
+# nested in that directory, on any level
+/          @f.uhlig @p.-a.loizeau @d.emschermann
+
+## Detectors
+
+# TRD
+/trd/       @praisig
+
+# PSD
+/psd/ @karpushkin_AT_inr.ru
+
+# MUCH
+/much/         @v.singhal
+
+# TOF
+/tof/ @n.herrmann @i.deppner
+
+# RICH
+/rich/      @s.lebedev
+
+# STS
+/sts/ @v.friese @a.toia
+
+# MVD
+/mvd/ @c.muentz @m.deveaux
+
+# passive geometries
+/magnet/ @e.clerkin
+/passive/ @e.clerkin
+/pipe/ @e.clerkin
+
+#setups
+/setup/ @e.clerkin
\ No newline at end of file

ci_scripts/inform_codeowners.sh

+#!/bin/bash
+# Copyright (C) 2021 GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt
+# SPDX-License-Identifier: GPL-3.0-only
+# First commited by Florian Uhlig
+
+
+main () {
+  # get passead parameters
+  # 1. git name of the official repo
+  if [[ ! $# -eq 1 ]]; then
+    echo "Pass the name of the upstream repository as argument"
+    exit 1
+  fi
+
+  # Since bash only supports dictionaries from version 4
+  # the dictionary is implemented as list. The values in
+  # the list are the directory (key) and the list of users owning
+  # this directory separated by a colon. If there is more than one
+  # user owning a directory the list of users is separated by a
+  # semicolon.
+  # An example of such an entry is "/macro/:f.uhlig;v.friese"
+  declare -a dictionary
+  declare -a unique_users
+
+  parse_codeowners_file
+  #declare -p dictionary
+
+  CHANGED_FILES=""
+  generate_file_list "$1"
+
+  ALL_USERS=""
+  generate_codeowners_list "$CHANGED_FILES"
+
+  generate_comment
+}
+
+
+# Add a key value pair to the dictionary
+function add_hash () {
+  dictionary+=("$1":"$2")
+}
+
+# extract the directory (key) from the passed string
+function get_key () {
+  dir="${1%%:*}"
+}
+
+# extract the user list (value) from the passed string
+function get_value () {
+  users="${1##*:}"
+}
+
+# Parse the CODEOWNERS file and store the information of owned directories
+# in a dictionray with the directory as key and the code owners as value
+# read a file line by line
+# Parse the remaining lines, split them at the first blank
+# First entry of the array is the directory, all other entries
+# are the list of people to inform
+# We have to check that the CODEOWNERS file is properly formated since the
+# used parser is very simply
+function parse_codeowners_file () {
+  while read line; do
+    # exclude commented and empty lines
+    if [[ $line =~ ^\# || $line =~ ^$ ]]; then
+     dummy=$line
+    else
+      # split the line at blank characters and store the results in an array
+      IFS=' ' read -ra my_array <<< "$line"
+      # first entry is the directory
+      directory="${my_array[0]}"
+      # in case of two entries the second is the user
+      if [[ ${#my_array[@]} -eq 2 ]]; then
+        users="${my_array[1]}"
+      # in case of more entries the entries from the second to the last are a list of users
+      # Add the users to a semicolon separated list and store the list in the user array
+      else
+        arr2=("${my_array[@]:1:${#my_array[@]}}")
+        newUserList=""
+        for i in "${arr2[@]}"; do
+          newUserList="$newUserList;$i"
+        done
+        newUserList="${newUserList:1}"
+        users="$newUserList"
+      fi
+      add_hash "$directory" "$users"
+    fi
+  done < CODEOWNERS
+}
+
+function generate_codeowners_list () {
+  CHANGED_FILES=$1
+  all_users=""
+  for file in $CHANGED_FILES; do
+#    echo $file
+    file="/$file"
+    inform_users=""
+    longest_match=0
+    for entry in "${dictionary[@]}"; do
+      get_key $entry
+      if [[ $file =~ ^$dir ]]; then
+        get_value $entry
+        # echo "The length of the match is ${#dir}"
+        if [[ ${#dir} -gt $longest_match ]]; then
+          inform_users=$users
+        fi
+      fi
+    done
+#    echo "We have to inform user $inform_users for file $file"
+    all_users="$all_users;$inform_users"
+  done
+  ALL_USERS="${all_users:1}"
+
+  # remove duplications from string
+  IFS=';'
+  read -ra users <<< "$ALL_USERS"
+
+  for user in "${users[@]}"; do   # access each element of array
+    if [[ ! " ${unique_users[@]} " =~ " ${user} " ]]; then
+      unique_users+=("$user")
+    fi
+  done
+  OWNERS_LIST=${unique_users[@]}
+
+  echo "We have to inform the following users about the code ownership: $OWNERS_LIST"
+}
+
+function generate_file_list() {
+
+  if [[ $# -eq 1 ]]; then
+    UPSTREAM=$1
+  else
+    if [ -z $UPSTREAM ]; then
+      UPSTREAM=$(git remote -v | grep git.cbm.gsi.de[:/]computing/cbmroot | cut -f1 | uniq)
+      if [ -z $UPSTREAM ]; then
+        echo "Error: Name of upstream repository not provided and not found by automatic means"
+        echo 'Please provide if by checking your remotes with "git remote -v" and exporting UPSTREAM'
+        echo "or passing as an argument"
+        exit -1
+      fi
+    fi
+  fi
+  echo "Upstream name is :" $UPSTREAM
+
+  # Rebase the MR to extract the changed files properly
+  # If upstream/master was changed while the pipline was running one would otherwise get
+  # a wrong list of files
+  git rebase $UPSTREAM/master
+  BASE_COMMIT=$UPSTREAM/master
+  CHANGED_FILES=$(git diff --name-only $BASE_COMMIT)
+}
+
+function generate_comment() {
+
+  # Get Information about the MR in JSON format
+  # Check if the returned string contains the signature that the CodeOwners label is set
+  # Only create GitLab comment if there is no comment yet (CodeOwners label not set)
+  MRInfo=$(curl -s --request GET --header "PRIVATE-TOKEN: $COMMENT_TOKEN" "https://git.cbm.gsi.de/api/v4/projects/$CI_MERGE_REQUEST_PROJECT_ID/merge_requests/$CI_MERGE_REQUEST_IID" | grep labels.*\\[.*CodeOwners.*\\])
+  if [[ -z $MRInfo ]]; then
+
+    comment="Dear "
+    for user in "${unique_users[@]}"; do
+      comment="$comment $user,"
+    done
+    comment="$comment
+
+you have been identified as code owner of at least one file which was changed with this merge request.
+
+Please check the changes and approve them or request changes."
+
+
+    # Add a comment to the merge request which informs code owners about their duty to review
+    curl -s --request POST \
+       -d "body=$comment" \
+       --header "PRIVATE-TOKEN: $COMMENT_TOKEN" \
+       "https://git.cbm.gsi.de/api/v4/projects/$CI_MERGE_REQUEST_PROJECT_ID/merge_requests/$CI_MERGE_REQUEST_IID/notes"
+
+    # On first call set a label which can be checked later on to avoid sending the comment over and over again
+    curl -s --request PUT \
+       --header "PRIVATE-TOKEN: $COMMENT_TOKEN" \
+       "https://git.cbm.gsi.de/api/v4/projects/$CI_MERGE_REQUEST_PROJECT_ID/merge_requests/$CI_MERGE_REQUEST_IID?add_labels=CodeOwners"
+  else
+    echo "Information message already exits, so there is no need to create another one."
+  fi
+}
+
+main "$@"