eval-helper

#!/usr/bin/env bash

function eval-helper() (
	source "$DOROTHY/sources/bash.bash"
	source "$DOROTHY/sources/tty.bash"

	# =====================================
	# Arguments

	function help {
		cat <<-EOF >/dev/stderr
			ABOUT:
			Helpers for working with commands.

			USAGE:
			eval-helper [...options] -- ...<command>

			OPTIONS:
			--[no-]wrap
			    Wrap the output of the command in the command itself.
			    Enabled by default.

			--[no-]confirm
			    Confirm execution of the command.
			    Disabled by default.

			--[no-]quiet
			    If enabled, only latest message will be kept, and command output will be cleared if successful.
			    If disabled, all messages and command output will be kept.

			--[no-]shapeshifter
			    Workaround for commands that clear themselves.
			    Disabled by default.

			--pending=<pending>
			    Message to display while the command is executing.

			--success=<success>
			    Message to display if the command succeeded.

			--failure=<failure>
			    Message to display if the command failed.
		EOF
		if test "$#" -ne 0; then
			echo-error "$@"
		fi
		return 22 # Invalid argument
	}

	# process
	local item cmd option_wrap option_confirm option_quiet option_pending option_success option_failure
	cmd=()
	option_wrap='yes'
	option_confirm='no'
	option_quiet="$(echo-quiet -- "$@")"
	option_shapeshifter='no'
	option_pending=''
	option_success=''
	option_failure=''
	while test "$#" -ne 0; do
		item="$1"
		shift
		case "$item" in
		'--help' | '-h') help ;;
		'--no-quiet'* | '--quiet'* | '--no-verbose'* | '--verbose'*) ;; # handled by echo-quiet
		'--pending='*) option_pending="${item#*--pending=}" ;;
		'--success='*) option_success="${item#*--success=}" ;;
		'--failure='*) option_failure="${item#*--failure=}" ;;
		'--no-confirm'* | '--confirm'*)
			option_confirm="$(
				get-flag-value confirm --missing="$option_confirm" -- "$item" | echo-affirmative
			)"
			;;
		'--no-shapeshifter'* | '--shapeshifter'*)
			option_shapeshifter="$(
				get-flag-value shapeshifter --missing="$option_shapeshifter" -- "$item" | echo-affirmative
			)"
			;;
		'--no-wrap'* | '--wrap'*)
			option_wrap="$(
				get-flag-value wrap --missing="$option_wrap" -- "$item" | echo-affirmative
			)"
			;;
		'--')
			cmd+=("$@")
			shift $#
			break
			;;
		'--'*) help "An unrecognised flag was provided: $item" ;;
		*) help "An unrecognised argument was provided: $item" ;;
		esac
	done

	# =====================================
	# Action

	# prepare
	local title
	title="$(echo-quote "${cmd[@]}" | echo-join ' ')"

	# confirm
	if test "$option_confirm" = 'yes' && ! confirm --positive --ppid=$$ -- 'Confirm execution of the command that is below:' "$(echo-style --code="$title")"; then
		echo-style --notice='Skipped execution of:' ' ' --code="$title"
		return 0
	fi

	# output everything if already inside a revolving door, or if in verbose mode
	local ec=0
	if test "${INSIDE_REVOLVING_DOOR-}" = 'yes' -o "$option_quiet" = 'no'; then
		# headers
		if test -n "$option_pending"; then
			echo "$option_pending"
		fi
		if test "$option_wrap" = 'yes'; then
			echo-element --open="$title"
		fi

		# body
		ec=0 && ("${cmd[@]}") || ec="$?"

		# footers
		if test "$option_wrap" = 'yes'; then
			echo-element --close="$title" --status="$ec"
		fi
		if test "$ec" -eq 0; then
			if test -n "$option_success"; then
				echo "$option_success"
			fi
		else
			if test -n "$option_failure"; then
				echo "$option_failure"
			fi
		fi
	else
		# not inside a revolving door, and not in verbose mode
		local headers body footer=''
		headers="$(mktemp)"
		body="$(mktemp)"

		# headers
		if test -n "$option_pending"; then
			echo "$option_pending" | tee -a "$headers"
		fi
		if test "$option_wrap" = 'yes'; then
			echo-element --open="$title" | tee -a "$headers"
		fi

		# body
		# NOTE |& is bash v4 only, and this script must work on Bash v3
		# https://github.com/bevry/dorothy/discussions/151
		local INSIDE_REVOLVING_DOOR_original="${INSIDE_REVOLVING_DOOR:-"no"}"
		export INSIDE_REVOLVING_DOOR='yes' # use export, as env doesn't work if cmd[0] was a function
		if test "$option_shapeshifter" = 'yes'; then
			# this is used if the command writes to TTY
			# in which case echo-revolving-door fails to clear
			tty_start
			cat "$headers" # redo headers inside alt tty while its active
			ec=0 && ("${cmd[@]}" 2>&1 | tee "$body") || ec="$?"
			tty_finish
		else
			ec=0 && ("${cmd[@]}" 2>&1 | tee "$body" | echo-revolving-door) || ec="$?"
		fi
		export INSIDE_REVOLVING_DOOR="$INSIDE_REVOLVING_DOOR_original"

		# clear headers, we can re-add them later if needed
		echo-clear-lines <"$headers"

		# generate footer
		if test "$ec" -eq 0; then
			if test -n "$option_success"; then
				footer+="$option_success"$'\n'
			fi
		else
			if test -n "$option_failure"; then
				footer+="$option_failure"$'\n'
			fi
		fi

		# if quiet and successful, dump footer and exit
		if test "$option_quiet" = 'yes' -a "$ec" -eq 0; then
			if test -n "$footer"; then
				echo -n "$footer"
			fi
			return "$ec"
		fi

		# if it didn't output anything, output self closing wrap, then footer, then exit
		if test -z "$(cat "$body")"; then
			echo-element --openclose="$title" --status="$ec"
			if test -n "$footer"; then
				echo -n "$footer"
			fi
			return "$ec"
		fi
		# the command outputted things

		# output wrap header
		if test "$option_wrap" = 'yes'; then
			echo-element --open="$title"
		fi
		# if verbose, or failure, output body
		if test "$option_quiet" = 'no' -o "$ec" -ne 0; then
			cat "$body"
		fi
		# outpout wrap footer
		if test "$option_wrap" = 'yes'; then
			echo-element --close="$title" --status="$ec"
		fi
		# output footer
		if test -n "$footer"; then
			echo -n "$footer"
		fi
	fi

	# done
	return "$ec"
)

# fire if invoked standalone
if test "$0" = "${BASH_SOURCE[0]}"; then
	eval-helper "$@"
fi