logr

#!/bin/bash
# Courtesy of https://brettterpstra.com/projects/logr/

__logr_DEFAULT_LOG_DIR="${HOME}/logs"
__logr_DEFAULT_LOG="scripts"

unset __logr_LOG_NAME
unset __logr_SCRIPT_LOG
unset __logr_VERBOSE
logr() {
    [[ -z $__logr_LOG_DIR ]] && __logr_LOG_DIR=$__logr_DEFAULT_LOG_DIR
    # default to "user" facility, can be set to local[0-9], etc.
    [[ -z $__logr_FACILITY ]] && __logr_FACILITY=user
    # default to quiet, no output to STDERR
    [[ -z $__logr_VERBOSE ]] && __logr_VERBOSE=false
    # default log tag and filename to "scripts", changed via logr start command
    [[ -z "${__logr_LOG_NAME}" ]] && __logr_LOG_NAME=$__logr_DEFAULT_LOG
    [[ -z "${__logr_SCRIPT_LOG}" ]] && __logr_SCRIPT_LOG="${__logr_LOG_DIR%/}/${__logr_LOG_NAME}.log"
    
    local function_name="${FUNCNAME[1]}"
    local log_type=$1
    
    
    # start must be called first, initializes logging, sets global log file
    # param 1: (string, optional) [verbose|quiet], verbose echos to STDERR, defaults to quiet
    # param 2: (string, optional) name of log source, defaults to "scripts" (.log will be appended)
    if [[ $log_type == "start" ]]; then
        local should_clean=false
        mkdir -p "${__logr_LOG_DIR}"
        if [[ $2 =~ (^-v$|^verbose$) ]]; then
            __logr_VERBOSE=true
            shift
            elif [[ $2 =~ (^-q$|^quiet$) ]]; then
            __logr_VERBOSE=false
            shift
        else
            __logr_VERBOSE=false
        fi
        
        if [[ $2 =~ clea[nr] ]]; then
            should_clean=true
            shift
        fi
        
        if [[ -n "$2" ]]; then
            __logr_LOG_NAME=$2
        fi
        
        touch $__logr_SCRIPT_LOG
        $should_clean && logr clear
        __logr_exec info $__logr_LOG_NAME "====> BEGIN LOGGING"
        # logr quiet => disables STDERR output
        elif [[ $log_type == "quiet" ]]; then
        __logr_VERBOSE=false
        # logr verbose => enables STDERR output
        elif [[ $log_type == "verbose" ]]; then
        __logr_VERBOSE=true
        # logr clear => clears the log (unless it's the default log)
        elif [[ $log_type == "clear" && $__logr_LOG_NAME != $__logr_DEFAULT_LOG ]]; then
        [[ -n $__logr_SCRIPT_LOG && -f $__logr_SCRIPT_LOG ]] && echo -n > $__logr_SCRIPT_LOG
        # debug type shows full function stack
        elif [[ $log_type == "debug" ]]; then
        function_name=$(IFS="\\"; echo "${FUNCNAME[*]:1}")
        __logr_exec debug "${__logr_LOG_NAME}:${function_name}" "${*:2}"
        # log, notice, info, warn, error set logging level
        # warn and error go to /var/log/system.log as well as logfile
        elif [[ $log_type =~ ^(notice|log|info|warn(ing)?|err(or)?|emerg) ]]; then
        local level
        case $log_type in
            notice|log) level="notice" ;;
            info) level="info" ;;
            warn*) level="warning" ;;
            err*) level="err" ;;
            emerg) level="emerg" ;;
            *) level="info" ;;
        esac
        __logr_exec $level "${__logr_LOG_NAME}:${function_name}" "${*:2}"
        # if no type is given, assumes info level
    else
        __logr_exec info "${__logr_LOG_NAME}:${function_name}" "${*:1}"
    fi
}

# execute the logger command
# param 1: (string) [log|notice|info|debug|warn|error] log level
# param 2: (string) Tag
# param 3: (string) Message
__logr_exec() {
    local cmd
    if [[ $__logr_VERBOSE == true ]]; then
        logger -p ${__logr_FACILITY}.$1 -t $2 -s $3 2>&1 | tee -a ${__logr_SCRIPT_LOG} 1>&2
    else
        logger -p ${__logr_FACILITY}.$1 -t $2 -s $3 2>> ${__logr_SCRIPT_LOG}
    fi
}