entrypoint.sh

#!/bin/bash -l

# active bash options:
#   - stops the execution of the shell script whenever there are any errors from a command or pipeline (-e)
#   - option to treat unset variables as an error and exit immediately (-u)
#   - print each command before executing it (-x)
#   - sets the exit code of a pipeline to that of the rightmost command
#     to exit with a non-zero status, or to zero if all commands of the
#     pipeline exit successfully (-o pipefail)
set -euo pipefail

main() {

  prev_version="$1"; release_type="$2"

  if [[ "$prev_version" == "" ]]; then
    echo "could not read previous version"; exit 1
  fi

  possible_release_types="major feature bug alpha beta rc"

  if [[ ! ${possible_release_types[*]} =~ ${release_type} ]]; then
    echo "valid argument: [ ${possible_release_types[*]} ]"; exit 1
  fi

  major=0; minor=0; patch=0; pre=""; preversion=0

  # break down the version number into it's components
  regex="^([0-9]+).([0-9]+).([0-9]+)((-[a-z]+)([0-9]+))?$"
  if [[ $prev_version =~ $regex ]]; then
    major="${BASH_REMATCH[1]}"
    minor="${BASH_REMATCH[2]}"
    patch="${BASH_REMATCH[3]}"
    pre="${BASH_REMATCH[5]}"
    preversion="${BASH_REMATCH[6]}"
  else
    echo "previous version '$prev_version' is not a semantic version"
    exit 1
  fi

  # increment version number based on given release type
  case "$release_type" in
  "major")
    ((++major)); minor=0; patch=0; pre="";;
  "feature")
    ((++minor)); patch=0; pre="";;
  "bug")
    ((++patch)); pre="";;
  "alpha")
    if [[ -z "$preversion" ]];
      then
        preversion=0
      else
        if [[ "$pre" != "-alpha" ]];
          then
          preversion=1
          else ((++preversion))
        fi
    fi
    pre="-alpha$preversion";;
  "beta")
    if [[ -z "$preversion" ]];
      then
        preversion=0
      else
        if [[ "$pre" != "-beta" ]];
          then
          preversion=1
          else ((++preversion))
        fi
    fi
    pre="-beta$preversion";;
  "rc")
    if [[ -z "$preversion" ]];
      then
        preversion=0
      else
        if [[ "$pre" != "-rc" ]];
          then
          preversion=1
          else ((++preversion))
        fi
    fi
    pre="-rc$preversion";;
  esac

  next_version="${major}.${minor}.${patch}${pre}"
  echo "create $release_type-release version: $prev_version -> $next_version"

  echo "next-version=$next_version" >> $GITHUB_OUTPUT
}

main "$1" "$2"