#!/usr/bin/env bash
set -o errexit
set -o pipefail

readonly ENVIRONMENT="${1:-}"
readonly USE_IAP="${2:-false}"
readonly PROJECT="domain-${ENVIRONMENT}"

append() {
    touch ${SCRIPTDIR}/inventory.yml
    printf "%s\n" "${1}" >> ${SCRIPTDIR}/inventory.yml
}

generateHeader() {
    append '---'
}
generateJumphostEntry() {
    append 'group_jumphost:'
    append '  hosts:'
    append '    jumphost:'
    append "      ansible_user: ${SSH_USER}"
    append "      ansible_host: jumphost.${ENVIRONMENT}.domain.com"
    append "      ansible_ssh_private_key_file: ${SSH_KEY_FILE}"
    append '      ansible_python_interpreter: "/usr/bin/python3"'
    append ''
}
generateHostEntry() {
    local prior_group=${1:-}
    local entry_group=${2:-}
    local entry_host=${3:-}
    local header_group=${4:-true}

  if [[ "$prior_group" != "$entry_group" ]]; then
    append "$entry_group:"
    append '  hosts:'
  fi
    append "    $entry_host:"
    append '      ansible_python_interpreter: "/usr/bin/python3"'
  if [ ${USE_IAP} == "false" ]; then
    local address_host=$(gcloud compute instances list --filter="name=($entry_host)" --format="value(INTERNAL_IP)")
    append "      ansible_user: ${SSH_USER}"
    append "      ansible_host: $address_host"
    append "      ansible_ssh_private_key_file: ${SSH_KEY_FILE}"
    append "      ansible_ssh_common_args: ${SSH_JUMPHOST_SETTINGS}"
  fi
    append ''
}

main() {
    gcloud config set project ${PROJECT}

    if [ "${CI}" == "true" ]; then
        declare SCRIPTDIR=$GITHUB_WORKSPACE
        readonly SSH_USER="deploy"
        readonly SSH_KEY_FILE="/home/runner/.ssh/ssh-priv-key"
    else
        declare SCRIPTDIR=$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )
        read -p "Enter SSH_USER ($USER if empty): " SSH_USER; SSH_USER=${SSH_USER:-$USER}
        read -ep "Enter absolute path of SSH_KEY_FILE: " SSH_KEY_FILE # has tab completion, much wow
    fi

    declare SSH_JUMPHOST_CON_STR="${SSH_USER}@jumphost.${ENVIRONMENT}.domain.com"
    declare SSH_JUMPHOST_SETTINGS='-o ProxyCommand="ssh -W %h:%p -q '${SSH_JUMPHOST_CON_STR}'"'

    rm -f ${SCRIPTDIR}/inventory.yml
    generateHeader
    [ ${USE_IAP} == "false" ] && generateJumphostEntry

    last_group=
    declare header_group
    declare -a HOSTS=$(gcloud compute instances list --format='value(name)')
    for host in ${HOSTS}; do
        [ $(echo $host | cut -f1 -d "-") == "gke" ] && continue # exclude legacy, testing and gke infra
        [ $(echo $host | cut -f1 -d "-") == "staging" ] && continue
        [ $(echo $host | cut -f1 -d "-") == "stage" ] && continue
        [ $(echo $host | cut -f1 -d "-") == "test" ] && continue
        [ $(echo $host | cut -f1 -d "-") == "jumphost" ] && continue
        group=group_$(echo $host | cut -f1 -d "-")

        generateHostEntry "$last_group" "$group" "$host" "$header_group"
        last_group="$group"
    done

    cat ${SCRIPTDIR}/inventory.yml
}
time main