logging

#!/bin/bash

[[ ${__LOGS_LOADED__} -eq 1 ]] && return 0
export __LOGS_LOADED__=1

shopt -s extglob # required to consistently extract the verbosity from positional parameters

__JOB__="$(basename "$0" '.sh')"

_black_='\033[0;30m'
_red_='\033[0;31m'
_green_='\033[0;32m'
_yellow_='\033[0;33m'
_purple_='\033[0;35m'
_white_='\033[0;97m'
_cyan_='\033[0;36m'
_lgreen_='\033[0;92m'
_reset_='\033[0m'

function ecrit()   { __verb__=1 elog "_purple_" "FATAL" "$*" ;}
function eerror()  { __verb__=2 elog "_red_"    "ERROR" "$*" ;}
function ewarn()   { __verb__=2 elog "_yellow_" "WARN"	"$*" ;}
function einfo()   { __verb__=2 elog "_white_"  "INFO"	"$*" ;}
function edebug()  { __verb__=3 elog "_green_"  "DEBUG" "$*" ;}
function etrace()  { __verb__=4 elog "_cyan_"   "TRACE" "$*" ;}

## eprint outputs irrespective of verbosity
function eprint() { __verb__=0 elog "_lgreen_" "*" "$*" ;}
function edumpvar() { local -a a=(); for var in "$@"; do a+=("$var = '${!var}' "); done; etrace "${FUNCNAME[1]} :::: ${a[*]}"; }

function elog() {
#	if ! [[ -v cccombo_breaker ]]; then
#			local cccombo_breaker=1
#			edebug "${FUNCNAME[2]} called ${FUNCNAME[1]} and __L_O__ is '${__LOG_OPEN__}' & __L_L__ is '${__LOG_LEVEL__}' & __v__ is '${__verb__}' FUNCNAME is '${#FUNCNAME[@]}' long"
#			edumpvar __LOG_OPEN__ __LOG_LEVEL__ __verb__
#	fi
	if [[ ${FUNCNAME[1]} == "eprint" ]]; then
		local fd=${__STOUTFD__}
	else
		local fd=${__STERRFD__}
	fi

	if [[ ${verbosity:-2} -ge ${__verb__} ]]; then
		printf "${!1}%5s${_reset_}  %s\n" "$2" "$3" >&$fd
	fi

	if [[ -n ${__LOG_OPEN__} && ${__LOG_LEVEL__} -ge ${__verb__} ]]; then
		printf "%(%Y-%m-%d %H:%M:%S)T  ${!1}%5s${_reset_}  %s\n" -1 "$2" "$3" >>"${__LOG__}"
	fi
}

function dlog() {
	if [[ -n ${__LOG_OPEN__} ]]; then
		if [[ -n ${__LOG_STOUT__} ]]; then
			dd if="${__STOUT_PIPE__}" iflag=nonblock status=none 2>/dev/null
		fi
		printf "%(%Y-%m-%d %H:%M:%S)T  ${!1}%-7s${_reset_}%b\n" -1 "$2" "$3" >>"${__LOG__}"
	else
		edebug "Failed to write '$3' to file because the Log File is Closed."
	fi
}

function __init_messages__() {
	exec {__STOUTFD__}>&1
	exec {__STERRFD__}>&2
	extract_verbosity "$@"
	trap __end_messages__ EXIT
}

extract_verbosity() {
    local arg
    local -i next_positional=2
	local rtn=0
    for arg in "$@"; do
        case $arg in
			-!(-)*v|--verb)
                if [[ -n ${!next_positional} && ${!next_positional} =~ ^[0-4]$ ]]; then
                    export verbosity=${!next_positional}
					rtn=2
                    break
                fi
                ;;
            -!(-)*v[0-4]|--verb=[0-4])
                export verbosity=${arg: -1}
				rtn=1
                break
                ;;
        esac
        (( next_positional++))
    done
	return $rtn
}

function __open_logfile__() {
	edumpvar __LOG_OPEN__ __LOGPATH__
	if [[ -z ${__LOG_OPEN__} ]]; then
		if [[ -d ${__LOGPATH__} ]]; then
			__LOG__="${__LOGPATH__}/LOG_${__JOB__}.txt"
			if ! [[ -e ${__LOG__} ]]; then
				local user=$(awk -F':' -v uid=$EUID '$3 == uid {print $1}' /etc/passwd)
				install -o "$user" -g "$user" -m 660 /dev/null "${__LOG__}"
			fi
			
			exec {__LOGFD__}>>"${__LOG__}" # only used to keep the file open...

			__LOG_OPEN__=1	
			dlog "_white_" "LOGS" "SESSION OPENED"

			if [[ -n ${__LOG_STOUT__} ]]; then
				local user=$(awk -F':' -v uid=$EUID '$3 == uid {print $1}' /etc/passwd)
				install -o "$user" -g "$user" -m 700 -d "/run/${__JOB__}/$$"
				__SO_PIPE_PATH__="/run/${__JOB__}/$$"
				__STOUT_PIPE__="${__SO_PIPE_PATH__}/somessages.pipe"
				mkfifo -m 700 "${__STOUT_PIPE__}" 
				exec {__SO_PIPE_FD__}<>"${__STOUT_PIPE__}"

				sed -u 's/^/   /' "${__STOUT_PIPE__}" > >(tee -a "${__LOG__}" >&"${__STOUTFD__}") &
				__SED_SO_PID__=$!
				exec 1>>"${__STOUT_PIPE__}"
				
				etrace "${FUNCNAME[0]} inherited stout from __init_messages__ on FD: '${__STOUTFD__}'"
				etrace "Pipe initialized on FD: '${__SO_PIPE_FD__}' pointing to '${__STOUT_PIPE__}'"
				etrace "Sed filtering '${__STOUT_PIPE__}' on PID: '${__SED_SO_PID__}.' Appending output to: '${__LOG__}' and FD: '${__STOUTFD__}'"
				edumpvar user __STOUT_PIPE__ __SO_PIPE_FD__ __SED_SO_PID__
			fi

			if [[ -n ${__LOG_STERR__} ]]; then
				local user=$(awk -F':' -v uid=$EUID '$3 == uid {print $1}' /etc/passwd)
				install -o "$user" -g "$user" -m 700 -d "/run/${__JOB__}/$$"
				__SE_PIPE_PATH__="/run/${__JOB__}/$$"
				__STERR_PIPE__="${__SE_PIPE_PATH__}/semessages.pipe"
				mkfifo -m 700 "${__STERR_PIPE__}"
				exec {__SE_PIPE_FD__}<>"${__STERR_PIPE__}"

				sed -u -r -e "s/^/	\x1b\[0;31m/" -e "s/$/\x1b\[0m/" "${__STERR_PIPE__}" > >(tee -a "${__LOG__}" >&"${__STERRFD__}") &
				__SED_SE_PID__=$!
				exec 2>>"${__STERR_PIPE__}"

				etrace "${FUNCNAME[0]} inherited sterr from __init_messages__ on FD: '${__STERRFD__}'"
				etrace "Pipe initialized on FD: '${__SE_PIPE_FD__}' pointing to '${__STERR_PIPE__}'"
				etrace "Sed filtering '${__STERR_PIPE__}' on PID: '${__SED_SE_PID__}.' Appending output to: '${__LOG__}' and FD: '${__STERRFD__}'"
				edumpvar user __STERR_PIPE__ __SE_PIPE_FD__ __SED_SE_PID__
			fi

			if [[ ${__LOG_LEVEL__} -ge 4 || ${verbosity} -ge 4 ]]; then
				ls -Alh /proc/$$/fd | awk '{ print $(NF-2), $(NF-1), $NF}' | tail -n +2 >&2 # "${__STOUT_PIPE__}"
			fi
			trap __end_messages__ EXIT
			edebug "Logging to '${__LOG__}'"
			edumpvar __LOG_OPEN__ __LOGPATH__ __LOG__
			edumpvar __LOG_STOUT__ __LOGFD__ __STOUTFD__ __STERRFD__
		else
			ewarn "__LOGPATH__ is not a directory. Logging disabled."
			return 1
		fi
	else
		edebug "Log File: '${__LOG__}' already open."
		return 1
	fi
}

function __end_messages__() {
	[[ -n "${__LOG_OPEN__}" ]] && dlog "_white_" "LOGS" "SESSION CLOSED\n" && unset __LOG_OPEN__
	[[ -v __LOGFD__ ]] && exec {__LOGFD__}>&-
	exec 1>&${__STOUTFD__}-
	exec 2>&${__STERRFD__}-
	if [[ -n ${__LOG_STOUT__} ]]; then
		kill ${__SED_SO_PID__} 
		exec {__SO_PIPE_FD__}>&-
		rm -r "${__SO_PIPE_PATH__}"
		unset __LOG_STOUT__
	fi
	if [[ -n ${__LOG_STERR__} ]]; then
		kill ${__SED_SE_PID__}
		exec {__SE_PIPE_FD__}>&-
		[[ -d ${__SE_PIPE_PATH__} ]] && rm -r "${__SE_PIPE_PATH__}"
		unset __LOG_STERR__
	fi
	unset __LOG_OPEN__	__STOUTFD__ __STERRFD__ __LOG__ __LOGPATH__ __LOGFD__ __SED_SO_PID__ __SO_PIPE_PATH__ __SE_PIPE_PATH__ __SED_SE_PID__
	trap - EXIT
}

# relevant information... i think?

# https://unix.stackexchange.com/questions/522877/how-to-cat-named-pipe-without-waiting/522881#522881 # see GNU dd's remark for info
# https://technotes.adelerhof.eu/bash/logging/ # rough template of this library
# https://stackoverflow.com/questions/6834347/named-pipe-closing-prematurely-in-script
# https://stackoverflow.com/questions/5376489/how-do-i-use-exec-3myfifo-in-a-script-and-not-have-echo-foo3-close-the-pipe
# https://stackoverflow.com/questions/2776994/tee-a-pipe-asynchronously
# https://catonmat.net/bash-one-liners-explained-part-three - SEE ITEM 13??
# https://github.com/miguelmota/bash-streams-handbook#send-commands-to-terminal-through-a-named-pipe
# https://github.com/codeforester/base/blob/master/lib/stdlib.sh