#!/bin/sh
set -eu

usage() {
	printf 'Usage:	%s -p PROFILE -c "COMMAND"\n' "$0"
}

help() {
	echo '
Options:
 -p      profile to be used for gathering and storing data
 -c      command to be run, reading from STDIN, writing to STDOUT

See manpages for more information.'
}

missing() {
	printf 'Missing option: %s\n' "$1" >&2
}

# shellcheck disable=2068
for flag in $@; do
	if [ "$flag" = '--help' ]; then
		usage
		help
		exit 0
	fi
done

COMMANDFLAG=
PROFILEFLAG=
while getopts 'hc:p:' name; do
	case "$name" in
		c)
			COMMANDFLAG="$OPTARG"
			;;
		p)
			PROFILEFLAG="$OPTARG"
			;;
		h)
			usage
			help
			exit 0
			;;
		*)
			echo "Ignoring unrecognized flag '$name'" >&2
			;;
	esac
done

if [ -z "$COMMANDFLAG" ]; then
	missing '-c "COMMAND"'
	usage >&2
	exit 2
fi

if [ -z "$PROFILEFLAG" ]; then
	missing '-p PROFILE'
	usage >&2
	exit 2
fi

COMMAND="$COMMANDFLAG"
PROFILE="${XDG_DATA_HOME:-$HOME/.local/share/remembering}/$PROFILEFLAG"

if [ ! -e "$PROFILE" ]; then
	mkdir -p "$(dirname "$PROFILE")"
	touch "$PROFILE"
fi

MERGED="$(mktemp)"
FILTERED="$(mktemp)"
SORTED_STDIN="$(mktemp)"
cat | sort -u > "$SORTED_STDIN"

xargs printf '0:%s\n' < "$SORTED_STDIN" | \
	sort -t: -k2,2 -m - "$PROFILE" | \
	tac | \
	sort -t: -k2,2 -u > "$MERGED"

xargs printf 'filter_marker:%s\n' < "$SORTED_STDIN" | \
	cat - "$PROFILE" | \
	sort -t: -k2,2 | \
	awk '{
		split($0, l, ":")
		rank = l[1]
		entry = substr($0, length(rank) + 2)
		if (rank != "filter_marker") {
			prev_rank = rank
			prev_entry = entry
		} else {
			if (prev_entry == entry) {
				print prev_rank ":" entry
			} else {
				print "0:" entry
			}
		}
	}' > "$FILTERED"

CHOICE="$(sort -t: -k1nr,1 -k2,2 < "$FILTERED" | \
	cut -d: -f2- | \
	sh -c "$COMMAND")"

if [ -n "$CHOICE" ]; then
	NEW_PROFILE="$(mktemp)"
	awk -v choice="$CHOICE" '{
		split($0, l, ":")
		rank = l[1]
		entry = substr($0, length(rank) + 2)
		if (entry == choice) {
			# Naively increment ranking by one
			print rank + 1 ":" entry
		} else {
			print rank ":" entry
		}
	}' "$MERGED" > "$NEW_PROFILE"
	mv "$NEW_PROFILE" "$PROFILE"
	echo "$CHOICE"
fi