#!/usr/bin/env sh

USAGE="ssync-index [options] ROOT_DIR
    OPTIONS
	-b index basename only
	-k KEY_FILE (optional: if indexing local)
	   ssh-key file to use (needs to be non-interactive)
	   optional: will use default session key
	   or key set in ssh_config for HOST
	-o OUTPUT_FILE
	-r REMOTE_HOST (optional)
	   remote host to index from such as user@hostname
	   username can be omitted if identical to $USER
	   or if set in ssh_config
        -v verbose logging
	-w NUM_SECONDS
	   index all files newer than NOW - NUM_SECONDS
        -h print this message"

# HELPER METHODS
verbose_log() {
    if [ ! -z "$VERBOSE_FLAG" ]; then
	echo "$1"
    fi
}
lines() {
    wc -l $1 | cut -d' ' -f1
}

# GLOBAL VALUES
BASENAME_ONLY_FLAG=
KEY_FILE_FLAG=
KEY_FILE_ARG=
OUTPUT_FILE_FLAG=
OUTPUT_FILE_ARG=
REMOTE_HOST_FLAG=
REMOTE_HOST_ARG=
WINDOW_FLAG=
WINDOW_ARG=
VERBOSE_FLAG=

# OPTIONS PARSING
while getopts "hvbr:k:o:w:" opt; do
    case "${opt}" in
	h) echo "$USAGE"
	   exit 1
	   ;;
	b) BASENAME_ONLY_FLAG=1
	   ;;
	k) KEY_FILE_FLAG=1
	   KEY_FILE_ARG="$OPTARG"
	   ;;
	o) OUTPUT_FILE_FLAG=1
	   OUTPUT_FILE_ARG="$OPTARG"
	   ;;
	r) REMOTE_HOST_FLAG=1
	   REMOTE_HOST_ARG="$OPTARG"
	   ;;
	v) VERBOSE_FLAG=1
	   ;;
	w) WINDOW_FLAG=1
	   WINDOW_ARG="$OPTARG"
	   ;;
    esac
done

shift $(($OPTIND -1))

if [ $# -ne 1 ]; then
    echo "$USAGE"
    exit 1

fi

# ROOT_DIR validation

ROOT_DIR=$1

if [ -z "$ROOT_DIR" ]; then
    echo "ROOT_DIR is missing."
    exit 1
fi
if [ -z "$REMOTE_HOST_ARG" ]; then
    # local so check if directory exists
    if [ ! -d "$ROOT_DIR" ]; then
	echo "$ROOT_DIR does not exist."
	exit 1
    fi
fi

# Option Validation
if [ -z "$OUTPUT_FILE_FLAG" ]; then
    echo "-o output file required"
    exit 1
fi

keyfile_cmd=""
if [ ! -z "$KEY_FILE_FLAG" ]; then
    if [ ! -f "$KEY_FILE_ARG" ]; then
	echo "Identity file '$KEY_FILE_ARG' does not exist"
	exit 1
    fi
    keyfile_cmd="-i $KEY_FILE_ARG"
fi

windowing_flag=""
if [ ! -z "$WINDOW_FLAG" ]; then
    if [ "$WINDOW_ARG" -gt 0 ]; then
	newermt=$(date -d "$WINDOW_ARG seconds ago" -u -Is)
	windowing_flag="-newermt $newermt"
	verbose_log "Targetting files from $WINDOW_ARG seconds ago: $newermt"
    else
	echo "Invalid window value: $WINDOW_ARG"
	exit 1
    fi
fi

index_value_cmd=
if [ ! -z "$BASENAME_ONLY_FLAG" ]; then
    index_value_cmd="basename {}"
else
    index_value_cmd="realpath {}"
fi

if [ -z "$REMOTE_HOST_FLAG" ]; then
    verbose_log "Generate local index from ${ROOT_DIR} to ${OUTPUT_FILE_ARG}"
    find ${ROOT_DIR} -type f ${windowing_flag} -exec ${index_value_cmd} \; > $OUTPUT_FILE_ARG
    verbose_log "Indexed $(lines $OUTPUT_FILE_ARG) files"
else
    verbose_log "Generate remote index from $REMOTE_HOST_ARG:${ROOT_DIR} to ${OUTPUT_FILE_ARG}"
    ssh $keyfile_cmd $REMOTE_HOST_ARG \
        "find ${ROOT_DIR} -type f ${windowing_flag} -exec ${index_value_cmd} \;" > $OUTPUT_FILE_ARG
    verbose_log "Indexed $(lines $OUTPUT_FILE_ARG) files"
fi