#!/bin/bash

set -e

GIT_FETCH_ARGS=""
GIT_CHECKOUT_ARGS=""

if [[ -n "${PLUGIN_DEPTH}" ]]; then
  GIT_FETCH_ARGS="${GIT_FETCH_ARGS} --depth=${PLUGIN_DEPTH}"
fi

if [ ! -d .git ]; then
  git init
  git remote add origin "${DRONE_REMOTE_URL}"
fi

# the branch may be empty for certain event types,
# such as github deployment events. If the branch
# is empty we checkout the sha directly. Note that
# we intentially omit depth flags to avoid failed
# clones due to lack of history.
if [[ -z "${DRONE_COMMIT_BRANCH}" ]] && [[ -n "${DRONE_COMMIT_SHA}" ]]; then
  GIT_CHECKOUT_ARGS="${GIT_CHECKOUT_ARGS} --quiet --force ${DRONE_COMMIT_SHA}"
  GIT_FETCH_ARGS="${GIT_FETCH_ARGS} origin"
fi

# the commit sha may be empty for builds that are
# manually triggered in Harness CI Enterprise. If
# the commit is empty we clone the branch.
if [[ -n "${DRONE_COMMIT_BRANCH}" ]] && [[ -z "${DRONE_COMMIT_SHA}" ]]; then
  GIT_CHECKOUT_ARGS="${GIT_CHECKOUT_ARGS} -b ${DRONE_COMMIT_BRANCH} refs/remotes/origin/${DRONE_COMMIT_BRANCH}"
  GIT_FETCH_ARGS="${GIT_FETCH_ARGS} origin +refs/heads/${DRONE_COMMIT_BRANCH}:refs/remotes/origin/${DRONE_COMMIT_BRANCH}"
fi

# if the commit sha and branch name not empty, fetch the branch even if a
# fast-forward is not possible. Checkout the specified commit sha which must be
# part of the branch.
if [[ -n "${DRONE_COMMIT_BRANCH}" ]] && [[ -n "${DRONE_COMMIT_SHA}" ]]; then
  GIT_CHECKOUT_ARGS="${GIT_CHECKOUT_ARGS} ${DRONE_COMMIT_SHA} -b refs/remotes/origin/${DRONE_COMMIT_BRANCH}"
  GIT_FETCH_ARGS="${GIT_FETCH_ARGS} origin +refs/heads/${DRONE_COMMIT_BRANCH}:refs/remotes/origin/${DRONE_COMMIT_BRANCH}"
fi

git fetch ${GIT_FETCH_ARGS}
git checkout ${GIT_CHECKOUT_ARGS}