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 minor bug patch hotfix alpha beta pre rc stable)

  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 its components
  regex="^v?([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[7]}"
  else
    echo "previous version '$prev_version' is not a semantic version"
    exit 1
  fi

  # increment version number based on given release type
  case "$release_type" in
  "major")
    ((++major)); minor=0; patch=0; pre="";;
  "feature"|"minor")
    ((++minor)); patch=0; pre="";;
  "bug"|"patch"|"hotfix")
    ((++patch)); pre="";;
  "alpha"|"beta"|"pre"|"rc")
    if [[ -z "$pre" ]]; then
      # Increment patch if transitioning from stable to pre-release
      ((++patch))
      preversion=0
    elif [[ "$pre" != "$release_type" ]]; then
      preversion=1
    else
      ((++preversion))
    fi
    pre="-$release_type.$preversion";;
  "stable")
    # Remove pre-release tag
    pre=""; preversion=0;;
  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"