sumdir

#!/bin/bash
# Author: Christopher Lovejoy <c@lovejoy.io>


## PLUMBING

yell() { echo "$@" >&2; }
die() { yell "$@"; exit 111; }
must() { "$@" || die "cannot $*"; }
whisper() { local volume=$1; shift; [[ $opt_verbose -ge $volume ]] && yell "$@"; }
getValueIfDefined() {
	varName="$1";
	eval "[ -n \"\${${varName}+v}\" ] && echo -en \"\$${varName}\"";
	local status=$?;
	return $status;
}
toLowerCase() {
	#perl -C -lne 'print uc';
	tr '[:upper:]' '[:lower:]';
}
toUpperCase() {
	#perl -C -lne 'print uc';
	tr '[:lower:]' '[:upper:]';
}
getArrayFromColonList() {
	local varName="$1";
	local colonValue="$2";
	local listValue=();
	local singleValue='';
	while [[ "$colonValue" =~ : ]]; do
		singleValue="${colonValue%%:*}";
		colonValue="${colonValue#*:}"; # Remove first segment from colon-delimited list.
		if [[ -z "$singleValue" ]]; then
			continue;
		fi
		listValue+=("$singleValue");
	done
	listValue+=("${colonValue}");
	eval "${opt}=(\"\${listValue[@]}\")"
}
fullPath() {
	local inputPath="$1";
	echo "$(cd "${inputPath%/*}" &>/dev/null && echo -n "${PWD}/${inputPath##*/}")";
}
dereferenceSymlink() {
	local linkPath="$1";
	local realPath;
	while [ -L "$linkPath" ]; do
		realPath="$(readlink "${linkPath}")";
		if [ ${realPath:0:1} != '/' ]; then
			realPath="$(dirname "${linkPath}")/${realPath}";
		fi
		linkPath="${realPath}";
	done
	fullPath "${linkPath}";
}
sumCommand=();
checkCommand=();
g_algoUpper='';
initializeSumCommand() {
	case "$(echo -n "$opt_algorithm" | toLowerCase)" in
		sha*) opt_algorithm=sha256;
			sumCommand=(sha256sum);
			if ! command -v ${sumCommand[0]} &>/dev/null; then
				if command -v shasum &>/dev/null; then
					sumCommand=(shasum -a 256);
				else
					die "Missing checksum software: sha256sum or shasum.";
				fi
			fi
			checkCommand=("${sumCommand[@]}");
			if [[ ${#opt_list_sha_opts[@]} -gt 0 ]]; then
				sumCommand+=("${opt_list_sha_opts[@]}");
			fi
			;;
		b2*|blake*) opt_algorithm=b2;
			sumCommand=(b2sum);
			checkCommand=("${sumCommand[@]}");
			if [[ ${#opt_list_b2_opts[@]} -gt 0 ]]; then
				sumCommand+=("${opt_list_b2_opts[@]}");
			fi
			;;
		*) die "Unknown sum algorithm '${opt_algorithm}'. Aborting for safety.";;
	esac
	if command -v "${sumCommand[0]}" &>/dev/null; then
		whisper 1 "Using $(which "${sumCommand[0]}")";
	else
		die "Missing selected checksum software: ${sumCommand[0]}.";
	fi
	g_algoUpper="$(echo "$opt_algorithm" | toUpperCase)";
}


## CONFIGURATION OPTIONS
## See functions: getDefaultOptName, getEnvOptName, getValueIfDefined

DEFAULT_ALGORITHM='sha256';
DEFAULT_DATE_FORMAT='+%Y%m%dT%H%M%SZ';
DEFAULT_LIST_EXCLUDE_NAME='.DS_Store:.thumbnails';
DEFAULT_LIST_EXCLUDE_PATH='*/.git/*:*/node_modules/*';
DEFAULT_OUTPUT_FILE_TEMPLATE='.SUM%A--%d'; # previously '.SHA256SUM--{}'
DEFAULT_SHOULD_DEREFERENCE=false;
DEFAULT_SHOULD_INCLUDE_LOCATION_IN_OUTPUT=false;
DEFAULT_SHOULD_RECURSE=false;
DEFAULT_SHOULD_SINGLE_HASH_FILE=false;
DEFAULT_TIMEZONE=UTC;
DEFAULT_VERBOSE=0;

SCRIPT_NAME="${0##*/}";
CALLED_AS_WITH_ARGS="${SCRIPT_NAME} $*";
OPT_OUTPUT_FILE_TEMPLATE_BK='%d..%ASUM';
OPT_VAR_NAMES=(
opt_algorithm
opt_date_format
opt_list_exclude_name
opt_list_exclude_path
opt_list_b2_opts
opt_list_sha_opts
opt_output_file_template
opt_should_dereference
opt_should_include_location_in_output
opt_should_recurse
opt_should_single_hash_file
opt_timezone
opt_verbose # check verbose first
);
getDefaultOptName() {
	local opt="$1";
	echo -n "DEFAULT${opt#opt}" | toUpperCase;
}
getEnvOptName() {
	local opt="$1";
	echo -n "SUMDIR${opt#opt}" | toUpperCase;
}


## DOCUMENTATION

SCRIPT_USAGE="${0##*/} [OPTIONS] [PATH...]"
SCRIPT_OPTIONS=(
	"-h,--help,help"
	"    Show this help"
	""
	"-a CMD"
	"    Hashing algorithm to use. Currently supported: 'sha256', 'b2'. env: SUMDIR_ALGORITHM."
	""
	"-r                "
	"    into directory. env: SUMDIR_SHOULD_RECURSE"
	""
	"-L                "
	"    symlinks. env: SUMDIR_SHOULD_DEREFERENCE"
	""
	"-1,--single"
	"    Remove existing *SUM* sumfiles in this directory (trash-cli, falls back to rm). Only this directory, even with -r. env: SUMDIR_SHOULD_SINGLE_HASH_FILE"
	""
	"-o,--out TEMPLATE"
	"    Output file name template. See 'TEMPLATES' below for substitution patterns. env: SUMDIR_OUTPUT_FILE_TEMPLATE"
	""
	"-l                "
	"    hostname and PWD in output sumfile. Affected by -L. env: SUMDIR_SHOULD_INCLUDE_LOCATION_IN_OUTPUT"
	""
	"-z,--tz TZ"
	"    Set timezone for timestamp; default 'UTC'. env: SUMDIR_TIMEZONE"
	""
	"-f,--dateformat"
	"    Set format for timestamp (per GNU coreutils date). env: SUMDIR_DATE_FORMAT"
	""
	"-v,--verbose[=N]  "
	"    the detail of the info output to STDERR. env: SUMDIR_VERBOSE"
	""
	"-x,--exclude PATTERN"
	"    Exclude files by name, per find '! -name PATTERN'. env: SUMDIR_LIST_EXCLUDE_NAME"
	""
	"-X,--exclude-path PATTERN"
	"    Exclude files by name, per find '! -path PATTERN'; usually of form '*PATTERN*'. env: SUMDIR_LIST_EXCLUDE_PATH"
	""
	"--length N        "
	"    length in bits (b2sum only). Digests appear 1/4 this length in hexadecimal."
	"     Default and maximum is 512 (for an output 128 chars long)."
	"     This is the same as setting the env var SUMDIR_LIST_B2_OPTS='--length:N'."
	"     env: SUMDIR_LIST_%A_OPTS, where %A is the algorithm in upper case (SHA256 or B2)."
	"--"
	"    After this, all further arguments are passed to 'find'"
	""
	"--bk"
	"    Same as -f '${OPT_OUTPUT_FILE_TEMPLATE_BK}'"
	""
	"--version"
	"    Output version information"
);
SCRIPT_DESCRIPTION_LINES=(
	"If no PATH is specified, the current directory (\$PWD) is used."
	""
	"If no SUMFILE is specified, .*SUM* and *SUM* is globbed, and the newest one is used."
	""
	"TEMPLATES"
	" The following strings are substituted for dynamic values:"
	" '%d' or '{}'  =>  Datetime as formatted by -f"
	" '%a'  =>  Algorithm ('sha256', 'b2', …)"
	" '%A'  =>  Algorithm uppercase ('SHA256', 'B2', …)"
	" "
	""
	"ENVIRONMENT VARIABLES"
	" *_SHOULD_* options expect 'true' or 'false' values."
	" *_LIST_* options must be colon-separated like PATH."
	""
	" You may set any of the options above by using the following environment variables."
	" They are shown here with their default values, if available."
);
for opt in "${OPT_VAR_NAMES[@]}"; do
	line=" $(getEnvOptName "$opt")";
	defaultValue="$(getValueIfDefined $(getDefaultOptName "$opt"))" && line+="='${defaultValue}'";
	SCRIPT_DESCRIPTION_LINES+=("$line");
done
SCRIPT_VERSIONS=(
	"0.1.4  @1695831187  Improved documentation, esp. environment variables.  b2sum=ad161516&size=11916" #nosum
	"0.1.3  @1681229730  Sort digest output by file path.  b2sum=af60835a&size=11528" #nosum
	"0.1.2  @1670970402  Improving BSD/POSIX portability (Don't use perl, Support Bash 3.2.x).  b2sum=5252a8b4&b2_length=32&size=11500" #nosum
	"0.1.1  @1669932673  Add '--length N' option (currently for b2sum only).  b2sum=f6a28dc2&b2_length=32&size=12099" #nosum
	"0.1.0  @1669925986  Add '-a CMD' to choose sum command ('a' for 'algorithm', similar to 'shasum' command). Removed _OPT from env var names." #nosum
	"0.0.9  @1669844764  Improve overriding options default + env + arg. (Some) defaults are now explicitly separate from the initial option value." #nosum
	"0.0.8  @1669653009  Add support for multiple optional PATH arguments." #nosum
	"0.0.7  @1666203994  BSD/macOS support (Bash 3.2, shasum -a 256). Tests PASS @1666203994 with GNU bash, version 3.2.57(1)-release (x86_64-apple-darwin20)" #nosum
	"0.0.6  @1664219098  Adding SUMDIR_* env config. Put directory path in output file, with option '-l'." #nosum
	"0.0.4  @1664178613  Exclude .git contents." #nosum
	"0.0.3  @1664177599  '-r' To let find go deep; args after -- go to find." #nosum
	"0.0.2  @1664175862  Added --exclude PATTERN option." #nosum
	"0.0.1  @1664175274" #nosum
);
## <data:application/vim+macro,mx%2FSCRIPT_VERSIONS%3D%0Dj%24F%22hvT%20c%12%3DTrim%28system%28%27sum-stream%27%2C%20join%28getline%281%2C%27%24%27%29%2C%22%5Cn%22%29%29%29%0D%1B%60x> ref:1670969781
SCRIPT_VERSION="${SCRIPT_VERSIONS[0]}";
SCRIPT_VERSION_NICE="v${SCRIPT_VERSION%%  *}";

showHelp() {
	echo "USAGE: $SCRIPT_USAGE";
	echo "";
	echo "OPTIONS:";
	local opt;
	for opt in "${SCRIPT_OPTIONS[@]}"; do
		echo "  ${opt}"
	done
	echo "";
	echo "DESCRIPTION:";
	for line in "${SCRIPT_DESCRIPTION_LINES[@]}"; do
		echo "  ${line}"
	done
}

removeFilesByTemplate() {
	local template="$1";

	whisper 2 "Output filename template: ${template}";
	local templateStar="${template//\{\}/*}";
	templateStar="${templateStar//%d/*}";
	templateStar="${templateStar//%a/$opt_algorithm}";
	templateStar="${templateStar//%A/${g_algoUpper}}";
	whisper 2 "Pattern for files to remove: ${templateStar}";
	local oIFS="$IFS";
	local IFS='*';
	local templateParts=($templateStar);
	local idxLastTemplatePart=$(( ${#templateParts[@]} - 1 )); # For Bash 3.2.x compatibility, rather than using index -1.
	if [[ -n ${templateParts[$idxLastTemplatePart]} && $templateStar =~ \*$ ]]; then
		templateParts+=("");
	fi
	IFS="$oIFS";

	local removeCommand=trash;
	command -v "$removeCommand" &>/dev/null || removeCommand=rm;

	whisper 1 "$ $removeCommand $templateStar";

	case ${#templateParts[@]} in
		0) whisper 1 "No non-wildcard part of name template to glob by, for removing previous output sum files."; return 1;;
		1) whisper 2 "No wildcards in template. Searching for literal name"; $removeCommand "${templateParts[0]}";;
		2) $removeCommand "${templateParts[0]}"*"${templateParts[1]}";;
		3) $removeCommand "${templateParts[0]}"*"${templateParts[1]}"*"${templateParts[2]}";;
		4) $removeCommand "${templateParts[0]}"*"${templateParts[1]}"*"${templateParts[2]}"*"${templateParts[3]}";;
	esac
}


## ARGUMENT OPTIONS


setOptsFromEnvAndDefaults() {
	local missingEnv=();
	for opt in "${OPT_VAR_NAMES[@]}"; do
		## Get environment variable.
		fromVarName="$(getEnvOptName "$opt")";
		if ! newValue="$(getValueIfDefined "$fromVarName")"; then
			missingEnv+=("${fromVarName}");

			## Get default.
			fromVarName="$(getDefaultOptName "$opt")";
			if ! newValue="$(getValueIfDefined "$fromVarName")"; then
				whisper 2 "✗ Missing env and default values for '${opt}'";
				continue;
			fi
		fi

		if [[ $opt =~ ^opt_list_ ]]; then
			if getArrayFromColonList $opt "$newValue"; then
				whisper 1 "✓ ${opt}: (${#listValue[@]})[${listValue[*]}] # from ${fromVarName}";
			else
				yell "✗ Unable to parse colon-separated list from env var '${fromVarName}'.";
			fi
		else
			eval "${opt}=\"\$newValue\"";
			whisper 1 "✓ ${opt}: \"${newValue}\" # from ${fromVarName}";
		fi
	done
	[[ ${#missingEnv[@]} -gt 0 ]] && whisper 2 "✗ No env vars for options: ${missingEnv[*]}";
}


## EXECUTION

inputDirectories=();

setOptsFromEnvAndDefaults;

while [[ $# -gt 0 ]]; do
	case "$1" in
		-h|--help|help) showHelp | less; exit;;
		-a) opt_algorithm="$2"; shift;;
		-r) opt_should_recurse=true;;
		-L) opt_should_dereference=true;;
		-1|--single) opt_should_single_hash_file=true;;
		-o|--out) opt_output_file_template="$2"; shift;;
		-l) opt_should_include_location_in_output=true;;
		-z|--tz) opt_timezone="$2"; shift;;
		-f|--dateformat) opt_date_format="$2"; shift;;
		-v|--verbose) let opt_verbose++;;
		--verbose=*) opt_verbose=${1#*=};;
		--length) opt_list_b2_opts+=(--length $2); shift;;
		-x|--exclude) opt_list_exclude_name+=("$2"); shift;;
		-X|--exclude-path) opt_list_exclude_path+=("$2"); shift;;
		--) shift; break;;
		--bk) opt_output_file_template="$OPT_OUTPUT_FILE_TEMPLATE_BK";;
		--version) echo "${SCRIPT_VERSION_NICE} ($0)"; whisper 1 "${SCRIPT_VERSION#*  }" 2>&1; exit;;
		*) inputDirectories+=("$1");;
	esac
	shift;
done
whisper 1 "(Verbose output level: ${opt_verbose})"

initializeSumCommand;

[[ ${#inputDirectories[@]} -eq 0 ]] && inputDirectories=("$PWD");



## LOOP THROUGH INPUT DIRECTORIES
dStackHeight=0
for dir in "${inputDirectories[@]}"; do
	while [[ $dStackHeight -gt 0 ]]; do
		popd &>/dev/null \
			&& let dStackHeight--;
	done

	if pushd "$dir" &>/dev/null; then
		let dStackHeight++;
	else
		yell "Unable to access directory '$dir'. Skipping.";
		continue;
	fi

	if [[ $opt_should_single_hash_file == true ]]; then
		removeFilesByTemplate "$opt_output_file_template";
	fi

	date="$(TZ="$opt_timezone" date "$opt_date_format")";

	outputFilename="${opt_output_file_template/\{\}/$date}";
	outputFilename="${outputFilename/\%d/$date}";
	outputFilename="${outputFilename/\%a/$opt_algorithm}";
	outputFilename="${outputFilename/\%A/${g_algoUpper}}";

	findArgs=();
	if [[ $opt_should_dereference == true ]]; then
		findArgs+=(-L);
	fi
	findArgs+=(.);
	if [[ $opt_should_recurse != true ]]; then
		findArgs+=(-maxdepth 1);
	fi
	findArgs+=(-type f);
	findArgs+=(\! -name "$outputFilename");
	if [[ ${#opt_list_exclude_path[@]} -gt 0 ]]; then
		for pattern in "${opt_list_exclude_path[@]}"; do
			findArgs+=(\! -path "$pattern");
		done
	fi
	if [[ ${#opt_list_exclude_name[@]} -gt 0 ]]; then
		for pattern in "${opt_list_exclude_name[@]}"; do
			findArgs+=(\! -name "$pattern");
		done
	fi
	if [[ $# -gt 0 ]]; then
		findArgs+=("$@");
	fi
	findArgs+=(-print0);

	whisper 1 "\$ find ${findArgs[*]}";
	{
		echo "# Generated ${date} by ${SCRIPT_NAME} ${SCRIPT_VERSION_NICE}  (called as \`${CALLED_AS_WITH_ARGS}\`)";
		echo "# Same as:  ${sumCommand[*]} FILENAMES";
		echo "# To check file integrity, run:  ${checkCommand[*]} -c ${outputFilename}";
		if [[ $opt_should_include_location_in_output == true ]]; then
			dirPath="${PWD}"
			if [[ $opt_should_dereference == true ]]; then
				dirPath="$(dereferenceSymlink "${PWD}")";
			else
				dirPath="${PWD}"
			fi
			echo "# Location:  $(hostname):${dirPath}";
		fi

		## Removing leading  `./` in paths.
			#| sed -z 's/^\.\///' \ # BSD sed doesn't have `-z` (sed --version)
			#| perl -pe 's/^\.\///' \ # untested @1666202382 # Pulling this convenience out for now, since it breaks compatibility.
			#| perl -pe 's/(^|\x00)\.\//\1/g' \
		must find "${findArgs[@]}" \
			| sed -E 's/(^|\x00)\.\//\1/g' \
			| parallel -0 "${sumCommand[@]}" \
			| sort -k2;
	} > "${outputFilename}";
	sumStatus=$?;
	yell "Generated ${dir}/${outputFilename}";

	if [[ $sumStatus != 0 ]]; then
		exit $sumStatus;
	fi

done