bin/walls

#!/bin/bash
# Author: https://github.com/skiqqy
# This script will fetch pictures from a thread from 4chan and test them for wallpapers.

# Our variables
VERSION="v1.0"
declare -A threads # Hashmap of title to thread id
titles=() # Array containing titles from the catalog

usage ()
{
	cat << EOF
walls $VERSION ~ The easy way to browse 4chan wallpapers.

Usage: walls [options]

options
-------

-h                 Shows this message.
-b <board>         Specify the board.
-t <n>             Only fetch the top n threads.
-a                 Fetch all threads.
-u                 Test wallpapers using setwp (found here https://github.com/skiqqy/bin/blob/master/setwp).
-o <number>        Open the first n wallpapers in your browser.
-s <thread>        Specify a thread to use.

Written by skiqqy.
EOF
}

# Fetch links to pictures from a thread.
# Usage: thread_pics <board> <thread_nr>
# TODO: Improve thise regex, grep was being wierd with \w etc, hence the scuffed version below.
thread_pics ()
{
	res=$(curl -s https://boards.4chan.org/"$1"/thread/"$2" | \
		grep -o -E "href=\"[/\.a-zA-Z0-9]*\.(jpg|png)\"" | uniq)
	for l in $res
	do
		url=$(echo "$l" | cut -d= -f 2)
		url="https:${url//\"}"
		echo "$url"
	done
}

# Get the title of a thread from a board
# Usage: thread_title <board> <thread>
# Prints: <Thread Title>:
# TODO: Improve thise regex, grep was being wierd with \w etc, hence the scuffed version below.
thread_title ()
{
	res=$(curl -s https://boards.4chan.org/"$1"/thread/"$2" | \
		grep -o -E "<span class=\"subject\">[/\\\.a-zA-Z0-9\ ]*</span>" | head -1)
	res=$(echo "$res" | cut -d ">" -f 2 | cut -d "<" -f 1)
	[ -n "$res" ] && echo "$res:$2"
}

# Fetch threads from a board
# Usage: board_threads <board>
board_threads ()
{
	curl -s https://a.4cdn.org/"$1"/catalog.json | jq '.[].threads[].no'
}

print_tui ()
{
	clear # Clear the screen so that the printing looks nice
	echo "To exit type 'EXIT'"
	echo -e "-------------------\n"

	i=0
	for title in "${titles[@]}"
	do
		echo "$i. $title"
		((i++))
	done
	echo
}

# Print the list of threads with thier title, ask the user which thread they want, and return the result
get_thread ()
{
	read -r -p "Index: " index
	if [[ "$index" =~ ^(exit)|(EXIT)$ ]]
	then
		return 1
	fi
	# We check that the input is a number and it is in the correct range, else we exit.
	if [[ ! "$index" =~ ^[0-9]+$ ]] || [ "$index" -lt 0 ] || [ "$index" -ge "$cnt" ] # Short circuiting
	then
		return 2
	fi

	index=${titles[$index]}
	echo "${threads[$index]}"
}

# Iterate over the links found in $links
use_links ()
{
	# Safety stuff I dont nuke my ram by opening alot of links.
	if [ -n "$open" ]
	then
		tmp=( $links ) # I want splitting
		n=$((${#tmp[@]} - 1))

		if [ "$open" -gt "$n" ]
		then
			open="$n"
		fi

		read -r -p "[WARNING] This will open $open link(s), proceed Y/N? " input
		[[ ! $input =~ ^y|Y(es)?$ ]] && exit
	fi

	i=0
	for link in $links
	do
		if [ -n "$open" ]
		then
			[ "$i" -eq "$open" ] && exit
			echo "Opening $link"
			xdg-open "$link"
			((i++))
		elif [ -n "$apply" ]
		then
			setwp "$link"
		else
			echo "$link" # This is just for debugging.
		fi
	done
}

# Spawn the tui
tui ()
{
	print_tui

	thread=$(get_thread)
	case $? in
		1)
			echo "Goodbye!"
			exit
			;;
		2)
			if [ "$cnt" -eq 1 ]
			then
				range="{0}"
			else
				range="[0 , $((cnt-1))]"
			fi
			echo "Invalid input, expecting an integer in the set $range."
			exit 2
		;;
	esac

	links=$(thread_pics "$board" "$thread")
	use_links
}

# Entry point
main ()
{
	# Vars
	board=wg
	top=3 # Fetch top 3 by default.
	cnt=0
	open=
	apply=
	thread=

	while getopts "hb:t:auo:s:" opt
	do
		case $opt in
			h)
				usage
				exit 0
				;;
			b)
				board="$OPTARG"
				;;
			t)
				top="$OPTARG"
				;;
			a)
				top=
				;;
			u)
				apply=1
				;;
			o)
				open="$OPTARG"
				;;
			s)
				thread="$OPTARG"
				;;
			*)
				usage
				exit 1
				;;
		esac
	done

	if [ -z "$thread" ]
	then
		# First we map thread titles to thier respective threads for later use.
		res=$(board_threads "$board")

		for r in $res
		do
			if [ -n "$top" ] && [ "$cnt" -ge "$top" ]
			then
				break # We have fetched the top n, hence exit
			fi
			res=$(thread_title "$board" "$r")
			title=$(echo "$res" | cut -d ":" -f 1)
			thread=$(echo "$res" | cut -d ":" -f 2)
			if [ -z "$thread" ] || [ -z "$title" ]
			then
				continue
			fi
			titles+=( "$title" )
			threads[$title]="$thread"
			((cnt++))
		done

		for ((;;))
		do
			tui
		done
	else
		links=$(thread_pics "$board" "$thread")
		use_links
	fi
}

main "$@"