tmcp

#!/usr/bin/env bash
# @file tmcp
# Simple switch TMC default provisioners
# @author Alister Lewis-Bowen <alister@lewis-bowen.org>
# Adapted for TMC from kubectx
# @ref https://github.com/ahmetb/kubectx

[[ -n $DEBUG ]] && set -x
set -eou pipefail

IFS=$'\n\t'
SELF_CMD="$0"
TMCP_DIR="$HOME/.config/tmcp"

usage() {
    cat <<EOF
USAGE:
  tmcp                    : list the provisioners in the current management cluster
  tmcp <NAME>             : change the active provisioner of current management cluster
  tmcp -                  : switch to the previous provisioner in this management cluster
  tmcp -c, --current      : show the current provisioner
  tmcp -h,--help          : show this message
EOF
}

exit_err() {
   echo >&2 "${1}"
   exit 1
}

current_context() {
    # Current context direct from tmc command...
    # !! Need to parse yaml, e.g. tmc system context current | yq e '.full_name.name' -
    grep name "$TMC_CONFIG_DIR/current-context" 2>/dev/null | \
        cut -d':' -f2 | \
        sed -e 's/^[ ]*//'
}

current_mgmt_cluster() {
    local cur_ctx mc

    cur_ctx="$(current_context)" || exit_err "error getting current context"
    # !! Only returns yaml so need to jump through hoops to get default values
    mc="$(tmc system context get "${cur_ctx}" | grep MANAGEMENT_CLUSTER_NAME | cut -d':' -f2 | sed -e 's/^[ ]*//')" \
        || exit_err "error getting current management cluster"

    if [[ -z "${mc}" ]]; then
        echo
    else
        echo "${mc}"
    fi
}

current_provisioner() {
    local cur_ctx p
    cur_ctx="$(current_context)" || exit_err "error getting current context"

    # !! Only returns yaml so need to jump through hoops to get default values
    p="$(tmc system context get "${cur_ctx}" | grep PROVISIONER_NAME | cut -d':' -f2 | sed -e 's/^[ ]*//')" \
        || exit_err "error getting current provisioner"

    if [[ -z "${p}" ]]; then
        echo
    else
        echo "${p}"
    fi
}

get_provisioners() {
    # !! Provisioner suncommand not shown in management cluster command help
    tmc mc prv list -m "${1}" | grep -v NAME | awk '{print $1}' | sort -n
}

escape_mgmt_cluster_name() {
    echo "${1//\//-}"
}

provisioner_file() {
    local mc
    mc="$(escape_mgmt_cluster_name "${1}")"
    echo "${TMCP_DIR}/${mc}"
}

read_provisioner() {
    local f
    f="$(provisioner_file "${1}")"

    [[ -f "${f}" ]] && cat "${f}"
    return 0
}

save_provisioner() {
    mkdir -p "${TMCP_DIR}"
    local f saved
    f="$(provisioner_file "${1}")"
    saved="$(read_provisioner "${1}")"

    if [[ "${saved}" != "${2}" ]]; then
        printf %s "${2}" > "${f}"
    fi
}

switch_provisioner() {
    local mc="${1}"
    # !! Unable to set defaults independenty from each other
    tmc configure -m "${mc}" -p "${2}"
    echo "Active provisioner is \"${2}\".">&2
}

choose_provisioner_interactive() {
    # directly calling tmcmc via fzf might fail with a cryptic error like
    # "$FZF_DEFAULT_COMMAND failed", so try to see if we can list 
    # provisioners locally first
    local p_list
    p_list="$(list_provisioners)"
    if [[ -z "$p_list" ]]; then
        echo >&2 "error: could not list provisioners"
        exit 1
    elif [[ "$(echo "${p_list}" | wc -l)" -eq 1 ]]; then
        set_provisioner "${p_list}"
        return 0
    fi

    local choice
    choice="$(_KUBECTX_FORCE_COLOR=1 \
        FZF_DEFAULT_COMMAND="${SELF_CMD}" \
        fzf --height=40% --layout=reverse --info=inline --border --ansi --no-preview || true)"
    if [[ -z "${choice}" ]]; then
        echo 2>&1 "error: you did not choose any of the options"
        exit 1
    else
        set_provisioner "${choice}"
    fi
}

set_provisioner() {
    local mc prev
    mc="$(current_mgmt_cluster)" || exit_err "error getting current management cluster"
    prev="$(current_provisioner)" || exit_error "error getting current provisioner"

    if grep -q ^"${1}"\$ <(get_provisioners "${mc}"); then
        switch_provisioner "${mc}" "${1}"

        if [[ "${prev}" != "${1}" ]]; then
        save_provisioner "${mc}" "${prev}"
        fi
    else
        echo "error: no provisioner exists with name \"${1}\".">&2
        exit 1
    fi
}

list_provisioners() {
    local yellow darkbg normal
    yellow=$(tput setaf 3 || true)
    darkbg=$(tput setab 0 || true)
    normal=$(tput sgr0 || true)

    local cur_ctx_fg cur_ctx_bg
    cur_ctx_fg=${TMCTX_CURRENT_FGCOLOR:-$yellow}
    cur_ctx_bg=${TMCTX_CURRENT_BGCOLOR:-$darkbg}

    local cur p_list
    cur="$(current_mgmt_cluster)" || exit_err "error getting current provisioner"
    p_list=$(get_provisioners "${cur}") || exit_err "error getting management cluster list"

    for c in $p_list; do
        if [[ -n "${_TMCTX_FORCE_COLOR:-}" || \
        -t 1 && -z "${NO_COLOR:-}" ]]; then
            # colored output mode
            if [[ "${c}" = "${cur}" ]]; then
            echo "${cur_ctx_bg}${cur_ctx_fg}${c}${normal}"
            else
            echo "${c}"
            fi
        else
            echo "${c}"
        fi
    done
}

swap_provisioner() {
    local mc p
    mc="$(current_mgmt_cluster)" || exit_err "error getting current management cluster"
    p="$(read_provisioner "${mc}")"
    if [[ -z "${p}" ]]; then
        echo "error: No previous provisioner found for current management cluster." >&2
        exit 1
    fi
    set_provisioner "${p}"
}

main() {
    if [[ "$#" -eq 0 ]]; then
        if [[ -t 1 && -z ${TMCTX_IGNORE_FZF:-} && "$(type fzf &>/dev/null; echo $?)" -eq 0 ]]; then
            choose_provisioner_interactive
        else
            list_provisioners
        fi
    elif [[ "$#" -eq 1 ]]; then
        if [[ "${1}" == '-h' || "${1}" == '--help' ]]; then
            usage
        elif [[ "${1}" == "-" ]]; then
            swap_provisioner
        elif [[ "${1}" == '-c' || "${1}" == '--current' ]]; then
            current_provisioner
        elif [[ "${1}" =~ ^-(.*) ]]; then
            echo "error: unrecognized flag \"${1}\"" >&2
            usage
            exit 1
        elif [[ "${1}" =~ (.+)=(.+) ]]; then
            alias_context "${BASH_REMATCH[2]}" "${BASH_REMATCH[1]}"
        else
            set_provisioner "${1}"
        fi
    else
        echo "error: too many flags" >&2
        usage
        exit 1
    fi
}

main "$@"