readonly EX_OK=0
readonly EX_GENERAL=1
readonly EX_USAGE=2
readonly EX_CONFIG=3
readonly EX_DEPENDENCY=4
readonly EX_PERMISSION=5
readonly EX_NOT_FOUND=6
readonly EX_COMMAND_FAILED=10
readonly EX_K8S=20
readonly EX_DB=30
readonly EX_BACKUP=40

# ERR_MSG=""
# ERR_CODE=0

# err_set() {
#     ERR_CODE="$1"
#     ERR_MSG="$2"
#     return "$ERR_CODE"
# }

# err_clear() {
#     ERR_CODE=0
#     ERR_MSG=""
# }

# m_a_riadbStatus() {
#     err_clear

#     local out err
#     if ! run out appError kubectl get pods -n mariadb; then
#         err_set 30 "Cannot get MariaDB pods: $err"
#         return $ERR_CODE
#     fi

#     log_table "$out"
# }


# Print an error message to stderr.
# $1 (message): error message text.
function appError() {
    printf '%s\n' "$*" >&2
}

# Print a fatal error message and exit the script.
# [$1] (code): optional numeric exit code (defaults to 1); if omitted, $1 is the message.
# $1 (message): error message text (all remaining args when code is provided).
function appFailure() {
    local code=1

    if [[ "${1:-}" =~ ^[0-9]+$ ]]; then
        code="$1"
        shift
    fi

    printf '%b\n' "\033[0;91mCrash: $*\033[0m"
    exit "$code"
}

# Source a shell file, exiting with failure if the file does not exist.
# $1 (file): path to the shell file to load.
function appLoadFile() {
    local file="$1"
    [[ -f "$file" ]] || appFailure  3 "File not found: $file"
    . "$file"
}

# Validate all required configuration variables and abort on any missing or malformed value.
function appCheckConfig() {
    local value

    local -a values=('hostName' 'hostIp' 'hostUuid' 'hostSalt' 'k3sNamespace' 'redisKube' 'mariadbKube' 'olsKube' 'postfixKube' 'workerKube' 'redisFileUsersAcl' 'postfixIp' 'postfixHost' 'postfixPostmaster' 'postfixDkimSelector' 'workerApiUrl' 'workerName' 'backupType' 'backupFirstDir')
    for value in "${values[@]}"; do
        [[ -n "${!value-}" ]] || appFailure 4 "$value: not specified"
    done

    values=('appAssetsPath' 'appDataPath' 'basePath' 'olsVhostsPath' 'domainsList' 'k3sCmd' 'redisPath' 'mariadbMasterPath' 'mariadbSlavePath' 'olsPath' 'olsAdminPath' 'olsPhpIniPath' 'olsLogsPath' 'olsConfigFile' 'olsPrivatePath' 'olsPublicPath' 'olsVhostsConfigPath' 'postfixPath' 'postfixDkimPath' 'workerPath' 'workerAgentPath' 'workerTasksPath' 'workerFilesPath' 'logPath' 'logFile' 'backupDailyPath' 'backupArchivePath' 'storagePath' 'rsyncPath' 'ftpPath' 'sshPath')
    for value in "${values[@]}"; do
        [[ "${!value-}" == /* ]] || appFailure 4 "$value: a variable must begin with /"
        [[ "${!value-}" != */ ]] || appFailure 4 "$value: a variable cannot end in /"
    done

    values=('backupParallelJobs' 'k3sReadyRetries' 'k3sReadySleep' 'workerApiGettingPause' 'workerApiSendingPause' 'backupDailyKeep' 'backupArchiveInterval' 'storageDailyKeep' 'storageArchiveKeep' 'olsQuotaBlockLimit' 'olsQuotaInodeLimit')
    for value in "${values[@]}"; do
        [[ "${!value-}" =~ ^[0-9]+$ ]] && (( ${!value} >= 1 )) || appFailure 4 "$value: incorrect number value"
    done

    if [[ "$backupDailySuffix" == "$backupArchiveSuffix" ]]; then
        appFailure 4 "backupDailySuffix = backupArchiveSuffix"
    fi
}

# Initialize the application by loading core libraries, config, modules, and commands.
function appBootstrap() {
    local file

    [[ "$EUID" -eq 0 ]] || appFailure 2 "You must run this script as root"

    # Core
    for file in \
        "$appPath/libs/main.sh" \
        "$appPath/libs/print.sh" \
        "$appPath/libs/file.sh"
    do
        appLoadFile "$file"
    done

    # Config
    appLoadFile "$appPath/config.sh"
    appCheckConfig

    # Modules
    for file in "$appPath/libs/modules/"*.sh; do
        appLoadFile "$file"
    done

    # Commands
    for file in "$appPath/libs/commands/"*.sh; do
        appLoadFile "$file"
    done
}

# Dispatch execution to the appropriate router based on the APP_MODE environment variable.
function appRouter() {
    local mode="${APP_MODE:-cmd}"

    case "$mode" in
        api) apiRouter "$@" ;;
        cmd|*) cmdRouter "$@" ;;
    esac
}