print-changelog.sh

#!/usr/bin/env bash

# Writes changelog in markdown format to std out.
# Example usage:
#   local changelog
#   if ! changelog=$(bash "print-changelog.sh" --repository "undergroundwires/privacy.sexy"); then
#     echo "Could not create changelog"
#   fi
# Prerequisites:
#   - Ensure your current folder is the repository root
#   - Ensure all tags are fetched
# Dependencies:
#   - External: git
#   - Local: ./log-commits.sh, ./shared/utilities.sh

# Globals
readonly SCRIPTS_DIRECTORY="$(cd "$(dirname -- "${BASH_SOURCE[0]}")" >/dev/null 2>&1 && pwd -P)"
readonly LOG_COMMITS_SCRIPT_PATH="${SCRIPTS_DIRECTORY}/shared/log-commits.sh"

# Import dependencies
# shellcheck source=shared/utilities.sh
source "${SCRIPTS_DIRECTORY}/shared/utilities.sh"

print_title() {
  local -r tag="$1"
  local tag_date
  if ! tag_date=$(git log -1 --pretty=format:'%ad' --date=short "${tag}") ||
    utilities::is_empty_or_null "${tag_date}"; then
    echo "Cannot get tag date for ${tag}"
    exit 1
  fi
  printf "\n## %s (%s)\n\n" "${tag}" "${tag_date}"
}

print_all_versions_from_latest() {
  git tag | sort -V -r
}

print_tags_except_first() {
  local -r repository="$1"
  local tags
  if ! tags=$(print_all_versions_from_latest); then
    echo "Could not list & sort tags"
    exit 1
  fi
  local current_tag=0
  for next_tag in ${tags}; do
    if [[ ${current_tag} != 0 ]]; then
      print_title "${current_tag}"
      local changes
      if ! changes=$(bash "${LOG_COMMITS_SCRIPT_PATH}" \
        --repository "${repository}" \
        --current "${current_tag}" \
        --previous "${next_tag}"); then
        echo "${LOG_COMMITS_SCRIPT_PATH} has failed:"
        echo "${changes}"
        exit 1
      fi
      if [[ -n ${changes} ]]; then
        printf "%s\n\n" "${changes}"
      fi
      printf "[compare](https://github.com/%s/compare/%s...%s)" "${repository}" "${next_tag}" "${current_tag}"
      printf "\n"
    fi
    current_tag=${next_tag}
  done
}

print_initial_commit_sha() {
  git rev-list --max-parents=0 HEAD
}

print_first_version() {
  git tag | sort -V | head -1
}

print_commit_sha_of_tag() {
  local -r tag="$1"
  git rev-list -n 1 "${tag}" ||
    {
      echo "Cannot get the comit for tag ${tag}"
      exit 1
    }
}

print_first_tag() {
  local -r repository="$1"
  local first_tag
  if ! first_tag=$(print_first_version) ||
    utilities::is_empty_or_null "${first_tag}"; then
    echo "Cannot get the first tag"
    exit 1
  fi
  print_title "${first_tag}"
  local first_commit_with_tag_sha
  if ! first_commit_with_tag_sha=$(print_commit_sha_of_tag "${first_tag}") ||
    utilities::is_empty_or_null "${first_commit_with_tag_sha}"; then
    echo "Cannot get first commit with tag: ${first_tag}"
    exit 1
  fi
  local initial_commit_sha
  if ! initial_commit_sha=$(print_initial_commit_sha) ||
    utilities::is_empty_or_null "${initial_commit_sha}"; then
    echo "Cannot get initial commit"
    exit 1
  fi
  if [[ ${first_commit_with_tag_sha} == "${initial_commit_sha}" ]]; then
    printf "%s | [commits](https://github.com/%s/commit/%s)" \
      "Initial release" "${repository}" "${initial_commit_sha}"
    return 0
  fi
  local changes
  if ! changes=$(bash "${LOG_COMMITS_SCRIPT_PATH}" \
    --repository "${repository}" \
    --current "${first_commit_with_tag_sha}" \
    --previous "${initial_commit_sha}"); then
    echo "${LOG_COMMITS_SCRIPT_PATH} has failed"
    exit 1
  fi
  if ! utilities::is_empty_or_null "${changes}"; then
    printf "%s\n" "${changes}"
  fi
  printf "[compare](https://github.com/%s/compare/%s...%s)" \
    "${repository}" "${initial_commit_sha}" "${first_commit_with_tag_sha}"
}

main() {
  local -r repository="$1"
  if utilities::is_empty_or_null "${repository}"; then
    echo "Repository name is not set."
    exit 1
  fi
  printf "# Changelog\n"
  print_tags_except_first "${repository}"
  print_first_tag "${repository}"
  printf "\n\n"
}

while [[ $# -gt 0 ]]; do
  case $1 in
  --repository)
    REPOSITORY="$2"
    shift
    ;;
  *)
    echo "Unknown parameter passed: $1"
    exit 1
    ;;
  esac
  shift
done

main "${REPOSITORY}"