#!/usr/bin/env bash
# Summary: Show the currently-selected terraform version

set -uo pipefail;

####################################
# Ensure we can execute standalone #
####################################

function early_death() {
  echo "[FATAL] ${0}: ${1}" >&2;
  exit 1;
};

if [ -z "${TFENV_ROOT:-""}" ]; then
  # http://stackoverflow.com/questions/1055671/how-can-i-get-the-behavior-of-gnus-readlink-f-on-a-mac
  readlink_f() {
    local target_file="${1}";
    local file_name;

    while [ "${target_file}" != "" ]; do
      cd "$(dirname ${target_file})" || early_death "Failed to 'cd \$(dirname ${target_file})' while trying to determine TFENV_ROOT";
      file_name="$(basename "${target_file}")" || early_death "Failed to 'basename \"${target_file}\"' while trying to determine TFENV_ROOT";
      target_file="$(readlink "${file_name}")";
    done;

    echo "$(pwd -P)/${file_name}";
  };

  TFENV_ROOT="$(cd "$(dirname "$(readlink_f "${0}")")/.." && pwd)";
  [ -n "${TFENV_ROOT}" ] || early_death "Failed to 'cd \"\$(dirname \"\$(readlink_f \"${0}\")\")/..\" && pwd' while trying to determine TFENV_ROOT";
else
  TFENV_ROOT="${TFENV_ROOT%/}";
fi;
export TFENV_ROOT;

if [ -n "${TFENV_HELPERS:-""}" ]; then
  log 'debug' 'TFENV_HELPERS is set, not sourcing helpers again';
else
  [ "${TFENV_DEBUG:-0}" -gt 0 ] && echo "[DEBUG] Sourcing helpers from ${TFENV_ROOT}/lib/helpers.sh";
  if source "${TFENV_ROOT}/lib/helpers.sh"; then
    log 'debug' 'Helpers sourced successfully';
  else
    early_death "Failed to source helpers from ${TFENV_ROOT}/lib/helpers.sh";
  fi;
fi;

# Ensure libexec and bin are in $PATH
for dir in libexec bin; do
  case ":${PATH}:" in
    *:${TFENV_ROOT}/${dir}:*) log 'debug' "\$PATH already contains '${TFENV_ROOT}/${dir}', not adding it again";;
    *)
      log 'debug' "\$PATH does not contain '${TFENV_ROOT}/${dir}', prepending and exporting it now";
      export PATH="${TFENV_ROOT}/${dir}:${PATH}";
      ;;
  esac;
done;

#####################
# Begin Script Body #
#####################

if [[ -z "${TFENV_TERRAFORM_VERSION:-""}" ]]; then
  TFENV_VERSION_FILE="$(tfenv-version-file)" \
    && log 'debug' "TFENV_VERSION_FILE retrieved from tfenv-version-file: ${TFENV_VERSION_FILE}" \
    || log 'error' 'Failed to retrieve TFENV_VERSION_FILE from tfenv-version-file';

  TFENV_VERSION="$(cat "${TFENV_VERSION_FILE}" || true)" \
    && log 'debug' "TFENV_VERSION specified in TFENV_VERSION_FILE: ${TFENV_VERSION}";

  TFENV_VERSION_SOURCE="${TFENV_VERSION_FILE}";
else
  TFENV_VERSION="${TFENV_TERRAFORM_VERSION}" \
    && log 'debug' "TFENV_VERSION specified in TFENV_TERRAFORM_VERSION: ${TFENV_VERSION}";

  TFENV_VERSION_SOURCE='TFENV_TERRAFORM_VERSION';
fi;

if [[ "${TFENV_VERSION}" =~ ^latest.*$ ]]; then
  log 'debug' "TFENV_VERSION uses 'latest' keyword: ${TFENV_VERSION}";

  [ -d "${TFENV_CONFIG_DIR}/versions" ] \
    || log 'error' 'No versions of terraform installed. Please install one with: tfenv install';

  if [[ "${TFENV_VERSION}" =~ ^latest\:.*$ ]]; then
    regex="${TFENV_VERSION##*\:}";
    log 'debug' "'latest' keyword uses regex: ${regex}";
  else
    regex="^[0-9]\+\.[0-9]\+\.[0-9]\+$";
    log 'debug' "Version uses latest keyword alone. Forcing regex to match stable versions only: ${regex}";
  fi;

  declare local_version='';
  if [[ -d "${TFENV_CONFIG_DIR}/versions" ]]; then
    local_version="$(\find "${TFENV_CONFIG_DIR}/versions/" -type d -exec basename {} \; \
      | tail -n +2 \
      | sort -t'.' -k 1nr,1 -k 2nr,2 -k 3nr,3 \
      | grep -e "${regex}" \
      | head -n 1)";
  fi;

  if [[ "${TFENV_AUTO_INSTALL:-true}" == "true" ]]; then
    log 'debug' "Trying to find the remote version using the regex: ${regex}";
    remote_version="$(tfenv-list-remote | grep -e "${regex}" | head -n 1)";
    if [[ -n "${remote_version}" ]]; then
        if [[ "${local_version}" != "${remote_version}" ]]; then
          log 'debug' "The installed version '${local_version}' does not much the remote version '${remote_version}'";
          TFENV_VERSION="${remote_version}";
        else
          TFENV_VERSION="${local_version}";
        fi;
    else
      log 'error' "No versions matching '${requested}' found in remote";
    fi;
  else
    if [[ -n "${local_version}" ]]; then
      TFENV_VERSION="${local_version}";
    else
      log 'error' "No installed versions of terraform matched '${TFENV_VERSION}'";
    fi;
  fi;
else
  log 'debug' 'TFENV_VERSION does not use "latest" keyword';

  # Accept a v-prefixed version, but strip the v.
  if [[ "${TFENV_VERSION}" =~ ^v.*$ ]]; then
    log 'debug' "Version Requested is prefixed with a v. Stripping the v."
    TFENV_VERSION="${TFENV_VERSION#v*}";
  fi;
fi;

if [[ -z "${TFENV_VERSION}" ]]; then
  log 'error' "Version could not be resolved (set by ${TFENV_VERSION_SOURCE} or tfenv use <version>)";
fi;

if [[ ! -d "${TFENV_CONFIG_DIR}/versions/${TFENV_VERSION}" ]]; then
  log 'debug' "version '${TFENV_VERSION}' is not installed (set by ${TFENV_VERSION_SOURCE})";
fi;

echo "${TFENV_VERSION}";
