threadwatcher/threadwatcher

#!/bin/bash
#A script that interacts with 4chans API to checks for media to download out of threads.
#It uses the file name used by the uploader.
#(and adds post no. to distinguish possible duplicate file names)
#consider using it in a cronjob intermittently with something like
#*/10 * * * * /usr/bin/threadwatcher scan
if [ -z "$TW_THREADWATCHER_DIR" ]; then
	THREADWATCHER_DIR=${XDG_DATA_HOME:-$HOME/.local/share}/threadwatcher
else
	THREADWATCHER_DIR="$TW_THREADWATCHER_DIR"
fi
URLFILE="$THREADWATCHER_DIR/threads"
AUTOPRUNE=${TW_AUTOPRUNE:-true} #automatically removes ended thread from threads list. Unreliable internet connections can mess up threads list.
AUTODEDUPE=${TW_AUTODEDUPE:-false} #automatically remove dupes after each scanned thread
TMP_URLFILE=/tmp/4chan_thread_watcher_tmp$$

[ -d "$THREADWATCHER_DIR" ] || mkdir -p "$THREADWATCHER_DIR"
[ -f "$URLFILE" ] || touch "$URLFILE"

#Cronjob Notifications
DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/$(id -u)/bus
export DBUS_SESSION_BUS_ADDRESS
export DISPLAY=:0.0

help="threadwatcher [add URL DL_LOCATION] [list] [edit] [clean] [help]

add URL DL_LOCATION
	downloads specified thread to given location. Paths can be relative to \$HOME or absolute.
list	lists all currently watched URLs and where they are downloading to
edit	open threads file in \$EDITOR/vim to manually edit.
clean	deletes threads file. This will not delete already downloaded material.
prune	manually prune list of threads. Deletes all finished threads from list.
dedupe	[DIR]
	remove all duplicate files from current download directories. (Comparing sha512 sums)
	If no DIR is given, will check all currently downloading directories.
help	display this help and exit."

#included personal prompt script here as function for portability.
prompt(){
	#use dmenu if installed
	if [ -n  "$(which dmenu)" ]; then
		# assumes a few dmenu patches to be installed, remove flags as needed
		[ "$(printf "No\\nYes" | dmenu -i -n -p "$1" -nb darkred -sb red -sf white -nf gray )" = "Yes" ] && $2
	#show terminal prompt otherwise
	else
		printf "%s (y/N):" "$1"
		read -r choice
		if [ "$choice" = "y" ]; then
			$2
		else
			exit
		fi
	fi
}

makepathabsolute(){
	if echo "$1" | grep -qE '^/'; then
		dl_location="$1"
	else
		dl_location="$HOME/$1"
	fi
	echo "$dl_location"
}

scan(){
	[ -f /tmp/threadwatcher.lock ] && [ "$(pgrep -c threadwatcher)" -gt 1 ] &&
		echo "Threadwatcher already scanning... waiting for it to finish before rescanning."
	while [ -f /tmp/threadwatcher.lock ] && [ "$(pgrep -c threadwatcher)" -gt 1 ]; do
		sleep 1
	done
	#Create lock file to stop override of URLFILE
	touch /tmp/threadwatcher.lock
	ping -q -c 1 4channel.org > /dev/null|| { echo "Cannot connect to 4chan."; exit 1;}
	if [ "$(wc -l < "$URLFILE")" -gt 0 ]; then
		echo "Scanning threads..."
	else
		echo "No threads to watch over currently."
		exit
	fi

	#tac used to prioritze newly added threads.
	tac "$URLFILE" | while read -r line; do
		running_dls=0
		url="$(echo "$line" | cut -f1)"
		dl_location="$(echo "$line" | cut -f2)"
		mkdir -p "$dl_location"
		json_url="$(echo "$url" | sed -E 's/boards\.(4chan|4channel)/a.4cdn/; s/$/.json/')"
		curl -s -L "$json_url" | jq . > /tmp/content$$
		thread_title="$(jq '.posts[0].sub' < /tmp/content$$ | tr -d '"')"
		# shellcheck disable=SC2001
		echo "$url ($thread_title) $(echo "$dl_location" | sed "s|$HOME|~|")"
		if [ -z "$(</tmp/content$$)" ]; then
			#check for internet again, in case something has changed during the download process
			if ping -q -c 1 4channel.org > /dev/null
			then
				if [ "$AUTOPRUNE" = "true" ]; then
					echo "Thread $url not found ($dl_location) pruning from cached list of threads to watch"
					# shellcheck disable=SC2001
					notify-send "threadwatcher" "Thread downloading to $(echo "$dl_location" | sed "s|$HOME|~|") is complete now."
				fi
			else
				echo "Cannot connect to 4chan."
				exit 1
			fi
			[ "$AUTOPRUNE" = 'false' ] &&
				echo "$line" >> "$TMP_URLFILE"
			continue
		else
			echo "$line" >> "$TMP_URLFILE"
			mkdir -p "$dl_location"
		fi
		files_json="$(jq '.posts[] | if has("filename") then {filename: "\(.no)_\(.filename)\(.ext)", location: "\(.tim)\(.ext)", md5: .md5} else empty end ' < /tmp/content$$ )"
		rm /tmp/content$$
		#pastes together a multiline var using process substitution with
		#layout: filename location md5
		#only real reason for bash here with process substitution
		#(gets messy with lots of temp files otherwise)
		files="$(paste <(paste <(echo "$files_json" | jq '.filename' | tr -d '"') <(echo "$files_json" | jq '.location' | tr -d '"')) <(echo "$files_json" | jq '.md5' | tr -d '"'))"
		echo "$files" | while read -r file_line; do
			#TODO: better cleanup like in booksplitter?
			filename="$(echo "$file_line" | cut -f1 | tr ' ' '_' |
				perl -C -MHTML::Entities -pe 'decode_entities($_);')" #recode html entities as UTF-8
			master_location="$(echo "$file_line" | cut -f2 | tr -d '"')"
			filelocation="$dl_location/$filename"
			correct_md5="$(echo "$file_line" | cut -f3)"
			[ -f "$filelocation" ] && slave_md5="$(openssl dgst -md5 -binary "$filelocation" | openssl enc -base64)"
			board="$(echo "$url" | cut -d '/' -f4)"
			file_url="https://i.4cdn.org/$board/$master_location"
			if [ -f "$filelocation" ]  && [ "$correct_md5" = "$slave_md5" ]; then
				true
			else
				if [ "$correct_md5" != "$slave_md5" ] && [ -f "$filelocation" ]; then
					rm "$filelocation"
					echo "[-] $filename because of incorrect checksum, redownloading."
				fi
				#limit concurrent dls
				if [ $running_dls -gt 25 ]; then
					wait
					running_dls=0
				fi
				curl -s -o "$filelocation" "$file_url" &
				echo "[+] $filelocation"
				((running_dls=running_dls+1))
			fi
		done
		wait
		if [ "$AUTODEDUPE" = "true" ]; then
			dedupe "$dl_location"
		fi
	done
	tac "$TMP_URLFILE" > "$URLFILE"
	cleanup
}

prune(){
	[ -f /tmp/threadwatcher.lock ] && [ "$(pgrep -c threadwatcher)" -gt 1 ] &&
	echo "Threadwatcher already scanning... waiting for it to finish before pruning"
	while [ -f /tmp/threadwatcher.lock ] && [ "$(pgrep -c threadwatcher)" -gt 1 ]; do
		sleep 1
	done
	#Create lock file to stop override of URLFILE
	touch /tmp/threadwatcher.lock
	ping -q -c 1 4channel.org > /dev/null|| { echo "Cannot connect to 4chan."; cleanup && exit 1;}
	if [ "$(wc -l < "$URLFILE")" -gt 0 ]; then
		echo "Pruning threads..."
	else
		echo "No threads to prune."
		cleanup && exit
	fi

	#tac used to prioritze newly added threads.
	tac "$URLFILE" | while read -r line; do
		url="$(echo "$line" | cut -f1)"
		dl_location="$(echo "$line" | cut -f2)"
		json_url="$(echo "$url" | sed -E 's/boards\.(4chan|4channel)/a.4cdn/; s/$/.json/')"
		curl -s -L "$json_url" | jq . > /tmp/content$$
		thread_title="$(jq '.posts[0].sub' < /tmp/content$$ | tr -d '"')"
		# shellcheck disable=SC2001
		echo "$url ($thread_title) $(echo "$dl_location" | sed "s|$HOME|~|")"
		if [ -z "$(</tmp/content$$)" ]; then
			#check for internet again, in case something has changed during the download process
			if ping -q -c 1 4channel.org > /dev/null
			then
				echo "Thread $url not found ($dl_location) pruning from cached list of threads to watch"
				# shellcheck disable=SC2001
				notify-send "threadwatcher" "Thread downloading to $(echo "$dl_location" | sed "s|$HOME|~|") is complete now."
			else
				echo "Cannot connect to 4chan."
				cleanup && exit 1
			fi
			continue
		else
			echo "Thread still running!"
			echo "$line" >> "$TMP_URLFILE"
		fi
		rm /tmp/content$$
	done
	tac "$TMP_URLFILE" > "$URLFILE"
	cleanup
}

dedupe(){
	if [ -n "$1" ]; then
		dirs="$1"
		echo "Deduping $1 manually..."
	else
		if [ "$(wc -l < "$URLFILE")" -gt 0 ]; then
			echo "Deduping download directories..."
		else
			echo "No download directories to dedupe."
			cleanup && exit
		fi
		#tac used to prioritze newly added threads.
		dirs="$( tac "$URLFILE" | cut -f2 | awk '!seen[$0]++' )"
	fi
	echo "$dirs" | while read -r dir; do
		echo "Generating checksums for $dir ..."
		#sort explanation: list roughly "human readable" names before just number strings.
		#thus this will result in probably better file names
		duplicates="$( sha512sum "$dir"/* | sort -r -t _ -k 2h | awk 'seen[$1]++' )"
		if [ -n "$duplicates" ]; then
			echo "Deleting duplicates..."
			echo "$duplicates" | cut -d' ' -f1,2 --complement |
				while read -r file; do
					rm -v "$file" | sed 's/^removed/[-]/' | tr -d "'"
				done
			echo "$(echo "$duplicates" | wc -l) duplicate files have been deleted in $dir"
		fi
	done
}

add() {
	dl_location="$(makepathabsolute "$2")"
		if grep -qP "^$1\t" "$URLFILE"; then
			dl_location_already="$(grep -P "^$1\t" "$URLFILE" | cut -f2)"
			# shellcheck disable=SC2001
			notify-send "threadwatcher" "Thread already being watched. currently downloads to $(echo "$dl_location_already" | sed "s|$HOME|~|")"

			if [ "$dl_location" != "$dl_location_already" ]; then
				prompt "Do you want to change download directory to $2?" &&
					new_location="$dl_location"
				[ -z "$new_location" ] && exit
				# Wait for last scan to finish in case of quick successive additions.
				# Otherwise there is a potential loss of threads
				[ -f /tmp/threadwatcher.lock ] && [ "$(pgrep -c threadwatcher)" -gt 1 ] &&
					echo "Threadwatcher currently scanning. Waiting for it to finish before adding new thread and rescanning."
				while [ -f /tmp/threadwatcher.lock ] && [ "$(pgrep -c threadwatcher)" -gt 1 ]; do
					sleep 1
				done

				sed -i "s|$dl_location_already|$new_location|" "$URLFILE"
			else
				echo "Already downloading thread to same location, exiting..."
				exit 0
			fi

			## Move already downloaded files to new location
			ping -q -c 1 1.1.1.1 > /dev/null || ping -q -c 1 1.0.0.1 > /dev/null || ping -q -c 1 4channel.org > /dev/null || { echo "No internet connection detected."; exit ;}
			mkdir -p "$new_location"
			url="$1"
			json_url="$(echo "$url" | sed -E 's/boards\.(4chan|4channel)/a.4cdn/; s/$/.json/')"
			curl -s -L "$json_url" | jq . > /tmp/content$$
			files_json="$(jq '.posts[] | if has("filename") then {filename: "\(.no)_\(.filename)\(.ext)", location: "\(.tim)\(.ext)"} else empty end ' < /tmp/content$$)"
			rm /tmp/content$$
			#only reason for bash here with process substitution
			files="$(paste <(echo "$files_json" | jq '.filename' | tr -d '"') <(echo "$files_json" | jq '.location' | tr -d '"'))"
			echo "$files" | while read -r file_line; do
				filename="$(echo "$file_line" | cut -f1 | tr ' ' '_' |
					perl -C -MHTML::Entities -pe 'decode_entities($_);')"
				mv -v "$dl_location_already/$filename" "$new_location"
			done
			rmdir --ignore-fail-on-non-empty "$dl_location_already"
			notify-send "threadwatcher" "already downloaded files moved to $new_location. New files will also be downloaded there"

		else
			# Wait for last scan to finish in case of quick successive additions.
			# Otherwise there is a potential loss of threads
			[ -f /tmp/threadwatcher.lock ] && [ "$(pgrep -c threadwatcher)" -gt 1 ] &&
				echo "Threadwatcher currently scanning. Waiting for it to finish before adding new thread and rescanning."
			while [ -f /tmp/threadwatcher.lock ] && [ "$(pgrep -c threadwatcher)" -gt 1 ]; do
				sleep 1
			done

			printf "%s\t%s\n" "$1" "$dl_location" | tee -ai "$URLFILE"
			echo "added $1 to threadwatcher list. Downloading to $dl_location"
		fi
}

cleanup(){
	rm -f /tmp/threadwatcher.lock
	rm -f "$TMP_URLFILE"
}

case "$1" in
	"add") 	add "$2" "$3"
		scan;;
	"scan") scan;;
	"list") printf "Thread:\t\t\t\t\t\tDownload location:\n"
		sed "s|$HOME|~|" "$URLFILE";;
	"clean")
		echo "Watchlist used up to now:"
		cat "$URLFILE"
		prompt "Do you want to stop watching over all current threads?" || exit 0
		echo "Deleting..."
		[ -f /tmp/threadwatcher.lock ] && [ "$(pgrep -c threadwatcher)" -gt 1 ] &&
			echo "Threadwatcher currently scanning. Waiting for it to finish before deleting file"
		while [ -f /tmp/threadwatcher.lock ] && [ "$(pgrep -c threadwatcher)" -gt 1 ]; do
			sleep 1
		done

		rm "$URLFILE"
		touch "$URLFILE";;
	"edit") #kill all other threadwatcher instances sine they could want to change $URLFILE
		pgrep threadwatcher | grep -v "^$$$" | xargs -r kill
		${EDITOR:-vim} "$URLFILE";;
	"prune") prune;;
	"dedupe") dedupe "$2";;
	"help") echo "$help";;
	*)echo "Incorrect usage. Correct usage:"
		echo "$help" && exit 1;;
esac