#!/usr/bin/env bash

. /home/zgrep/offtopiabday/happybot/common.sh

segment() {
	sed 's/[a-zA-Z][a-zA-Z]*:\/\/\S*\|./&\n/g' | sed -n '/./p'
}

oldtopic="$(
	tac "$serv/$chan/out" \
	| awk '{if($3" "$5$6$7=="-!- changedtopicto"){print;exit}}' \
	| sed 's/^[^"]*"//;s/"$//'
)"

tail -n 0 -f "$serv/$chan/out" | gawk '{if($3" "$5$6$7=="-!- changedtopicto"){gsub(/^[^"]*"/,"");gsub(/"$/,"");print;fflush("/dev/stdout")}}' | while read -r t; do
	if [[ "$t" != "$oldtopic" ]]; then
		diff="(diff) "
		mode="_"
		diff="$(diff -a -d -U 1024 <(var "$oldtopic" | segment) <(var "$t" | segment) \
		| tail -n+4 | sed 's/^ /_/;s/^./& _/;s/$/_/' \
		| while read -r d l; do
			l="$(var "$l" | sed 's/^_//;s/_$//')"
			p=""
			if [[ "$mode" != "$d" ]]; then
				if [[ "$d" == "-" ]]; then
					if [[ "$mode" == "+" ]]; then
						p="$(echo -ne "\x0305,99")"
					else
						p="$(echo -ne "\x1f\x0305,99")"
					fi
				elif [[ "$d" == "+" ]]; then
					if [[ "$mode" == "-" ]]; then
						p="$(echo -ne "\x0303,99")"
					else
						p="$(echo -ne "\x1f\x0303,99")"
					fi
				elif [[ "$d" == "_" ]]; then
					p="$(echo -ne "\x0f")"
				fi
				mode="$d"
			fi
			diff="$diff$p$l"
			var "$diff"
		done | tail -n1)"
		var "$diff" | zwsp | say
		oldtopic="$t"
	fi
done