xkcdlock/xkcdlock

#!/usr/bin/env bash
#
# xkcdlock v1
#
# A wrapper around screen lockers to display xkcd images on the lock screen
#
# Depending on the given arguments xkcdlock shows a random image, the latest
# image or an image of choice.
#
# Note that 'latest' needs an internet connection for the download!
# If the download fails it falls back to a specific hard-coded image
#
# Builtin is a function to download all images.
#
# Dependencies: rbash, i3lock/swaylock, xrandr, awk, curl, recode,
#               convert (from imagick)
#
# © 2016 Björn Busse (see also: LICENSE)
# bbusse@baerlin.eu
#
# Thanks to Randall Patrick Munroe! BTC 1FhCLQK2ZXtCUQDtG98p6fVH7S6mxAsEey
# Thanks to Michael Stapelberg for an awesome window manager - i3
#
# TODO:
# - Make sure we do not exceed screen boundaries in x and y
# - Improve tooltip text border overflow prevention
#   wrt display resolution (and font size?)
# - Add support for other screen lockers
# - Parallelize downloads

[[ "$TRACE" ]] && set -x
set -eo pipefail

readonly SCRIPT_NAME=$(basename $0)

# screensaver executable
LOCK_BIN="swaylock"
# verbosity
VERBOSE=0
# "latest" or "random"
IMG_CHOICE="random"
# path to images
IMG_PATH="${HOME}/Pictures/xkcd"
# default / fallback image
IMG_DEFAULT="not_really_into_pokemon.png"
# background colour
BG_COLOUR="white"
# Break tooltip every x char to prevent border overflow
TOOLTIP_MAX_LINE_LEN=100

FONT="xkcd Script"
FONT_FILE="xkcd-script.ttf"
FONT_PATH="${HOME}/.local/share/fonts/${FONT_FILE}"
URL_FONT="https://github.com/ipython/xkcd-font/raw/master/xkcd-script/font/xkcd-script.ttf"

declare -a DEPS=("xrandr" "awk" "curl" "convert" "recode" "sed")
declare -a DEPS_LOCKER=("i3lock" "swaylock")

DOWNLOAD_DISCLAIMER="\nThe downloaded images will end up in your current working directory.\n\
Since we are using restricted bash, we can not change path.\n\
Use '-y' instead of '-d' to really start the download to the current working directory.\n"

log() {
    if (( 1=="${VERBOSE}" )); then
        echo "$@" >&2
    fi

    logger -p user.notice -t $SCRIPT_NAME "$@"
}

error() {
    echo "$@" >&2
    logger -p user.error -t $SCRIPT_NAME "$@"
}

# does not work with restricted bash (bash -r/rbash)
get_script_path() {
    echo $(dirname $(readlink -f $0))
}

show_help() {
    printf "\n xkcd_lock v1\n\n\
 Available options are:\n\n \
   -d  download images to current working directory\n \
   -h  show this help\n \
   -i  show specific image file - overrides '-m'\n \
   -l  lock program: one of i3lock/swaylock\n \
   -m  latest|random                                   default: random\n \
   -v  be verbose\n\n"
}

check_dependencies() {
    for i in "${DEPS[@]}"
    do
        if [[ -z $(which "${i}") ]]; then
            error "Could not find ${i}"
            exit 1
        fi
    done

    if fc-list -q "${FONT}"; then
        log "Font exists"
    else
        log "Downloading font"
        curl -o "${HOME}/${FONT_PATH}" -sLO "${URL_FONT}"
    fi
}

xkcd_get_latest_image() {
    log "Looking for latest image"
    local img_url=$(curl -s https://xkcd.com/index.html | \
                    awk '/Image URL \(for hotlinking\/embedding\): / {print $5}' | \
                    awk 'BEGIN{FS="<";} {print $1}')

    if [[ -z $img_url ]]; then
        error "Can not download latest image, using fallback image"
        local img_fn="${IMG_DEFAULT}"
    else
        log "Downloading: $img_url"
        curl -sO --max-time 6 "$img_url"

        if [[ 0="$?" ]]; then
            local img_fn=$(echo "$img_url" | awk 'BEGIN{FS="/";} {print $5}')
        else
            error "Can not download latest image, using fallback image"
            local img_fn="${IMG_DEFAULT}"
        fi
    fi

    echo "$img_fn"
}

xkcd_get_img_name() {
    local fn=$(echo "$img_url_hotlink" | awk 'BEGIN{FS="/";} {print $5}')
    IFS='.' read -r -a array <<< "${fn}"
    fn="${array[0]}"_"${i}"."${array[-1]}"
    echo "$fn"
}

xkcd_get_img_name_from_file() {
    IFS='/' read -r -a array <<< "$img_fn"
    IFS='.' read -r -a array <<< "${array[-1]}"
    IFS='_' read -r -a array <<< "${array[0]}"
    local fn=${array[-1]}
    echo "$fn"
}

xkcd_get_img_nr() {
    IFS='.' read -r -a array <<< "$img_name"
    IFS='_' read -r -a array <<< "${array[0]}"
    echo "${array[-1]}"
}

xkcd_get_all_images() {
    VERBOSE="1"
    log "Looking for latest image"
    local nimg_latest=$(curl -s https://xkcd.com/index.html | \
                        awk '/Permanent link to this comic: / {print $6}' | \
                        awk 'BEGIN{FS="/";} {print $4}')

    if [[ -z "$nimg_latest" ]]; then
        VERBOSE=1
        error "Failed to find latest image number, not downloading anything"
        exit 1
    else
        log "Found: $nimg_latest"
    fi

    for ((i=1; i<=$nimg_latest; i++)); do
        local img_url_hotlink=$(xkcd_get_hotlink_url $i)
        local img_name=$(xkcd_get_img_name $img_url_hotlink $i)

        if [[ -e "$img_name" ]]; then
            log "$img_name exists. Skipping download"
            continue
        fi

        log "Downloading #${i} ${img_url_hotlink} (${img_name})"
        $(curl -s $img_url_hotlink -o $img_name)
        if (( 0 != "$?" )); then
            error "Failed to download ${i}"
        fi

        if [ "${img_name: -3}" == "jpg" ]; then
            convert_image $img_name
        fi
    done

    echo 0
}

xkcd_get_hotlink_url() {
    local url="https://xkcd.com/$i"
    local url_hotlink="$(curl -sL $url | awk '/Image URL \(for hotlinking\/embedding\): / {print $5}')"
    echo $url_hotlink
}

xkcd_get_img_tooltip() {
    local url="https://xkcd.com/$1"
    echo $(curl -sL $url | grep -A 1 '<div id=\"comic\">' | awk -F "\"" '/src=/ {print $4}' | recode html..UTF8)
}

xkcd_format_tooltip() {
    local text=$(echo $text | fold -s -w  $TOOLTIP_MAX_LINE_LEN)
    echo "$text"
}

get_nscreens() {
    local nscreens=$(xrandr -q | awk '/ connected/ {count++} END {print count}')
    echo "$nscreens"
}

screen_get_smallest_resolution() {
    local res=$(xrandr -q | awk '/*/ {print $1}' \
                | awk 'BEGIN{FS="x";} NR==1 || $1<min {line=$0; min=$1}; END {print line}')

    echo "$res"
}

screen_get_highest_resolution() {
    local res=$(xrandr -q | awk '/\*/ {print $1}' \
                          | awk 'BEGIN{FS="x";} NR==1 || $1>max {line=$0; max=$1}; END {print line}')

    echo "$res"
}

get_random_image() {
    local img_fn="$(find $IMG_PATH -type f | sort -R | head -n1 )"

    if ! [[ -e "$img_fn" ]]; then
        error "Could not find image to display"
    fi

    echo "$img_fn"
}

convert_image() {
    local img_name_len=$((${#img_name} - 4))
    local img_name_png=${img_name:0:$img_name_len}".png"
    log "Converting $img_name to $img_name_png"
    $(convert $img_name $img_name_png)
    $(rm -f $img_name)
}

image_add_text() {
    local tmp_file=$(mktemp)

    log "Adding \""${2}"\" to ${1} and saving image to ${tmp_file}"
    $(convert "${1}" -font "${5}" -gravity "${3}" -pointsize "${7}" -fill "${4}" $8 -annotate "${6}" "${2}" "${tmp_file}")

    if ! [[ -e "$tmp_file" ]]; then
        error "Could not find image with text overlay"
        exit 1
    fi

    echo "$tmp_file"
}

resize_image() {
    local tmp_file=$(mktemp)

    log "Resizing $img_fn to $res and saving image to $tmp_file"
    convert -adaptive-resize $res $img_fn $tmp_file

    if ! [[ -e "$tmp_file" ]]; then
        error "Could not find resized image"
        exit 1
    fi

    echo "$tmp_file"
}

center_image() {
    local tmp_file=$(mktemp)

    log "Centering $tmp_file and saving image to $tmp_file"
    $(convert $tmp_file_r -gravity center -background $BG_COLOUR -extent $res $tmp_file)

    if ! [[ -e "$tmp_file" ]]; then
        error "Could not find centered image"
        exit 1
    fi

    echo "$tmp_file"
}

prepare_image() {
    local res=$(screen_get_highest_resolution)
    local img_name=$(xkcd_get_img_name_from_file $img_fn)
    local img_nr=$(xkcd_get_img_nr $img_name)
    local text=$(xkcd_get_img_tooltip $img_nr)
    img_tooltip=$(xkcd_format_tooltip $text)

    local tmp_file_r=$(resize_image $img_fn $res)
    local tmp_file_c=$(center_image $tmp_file_r $res)
    local tmp_file_t1=$(image_add_text "${tmp_file_c}" "${img_nr}" "Northeast" "green" "${FONT_PATH}" "+50+50" "50")
    local tmp_file_t2=$(image_add_text "${tmp_file_t1}" "${img_tooltip}" "Southwest" "red" "${FONT_PATH}" "+0+0" "30" " -undercolor '#00000080' ")

    echo "$tmp_file_t2"
}

screen_lock() {
    local img_fn_final=$(prepare_image $img_fn)

    log "Locking screen with $img_fn"
    $LOCK_BIN -i $img_fn_final
}

main() {
    local locker=$(which $LOCK_BIN)
    local OPTIND

    while getopts "h?i:l:vm:dy" opt; do
        case "$opt" in
        d)
            printf "%s${DOWNLOAD_DISCLAIMER}"
            printf "%s\nCurrent working directory: ${PWD}\n\n"
            exit 0
            ;;
        h|\?)
            show_help
            exit 0
            ;;
        i)
            local img_fn="${OPTARG}"
            local r=$(screen_lock $img_fn)
            exit 0
            ;;
        l)
            if [[ "sway"="${OPTARG}" ]]; then
               LOCK_BIN="swaylock"
               echo "Not yet implemented since we have no xrandr with wayland"
               exit 1
            fi
            ;;
        m)
            IMG_CHOICE="${OPTARG}"
            ;;
        v)
            VERBOSE=1
            ;;
        y)
            r=$(xkcd_get_all_images)
            exit 0
        esac
    done

    check_dependencies

    if ! [[ -d "$IMG_PATH" ]]; then
        error "Image directory does not exist: $IMG_PATH"
        exit 1
    fi

    case "$IMG_CHOICE" in
        "latest")   local img_fn=$(xkcd_get_latest_image);;
        "random")   local img_fn=$(get_random_image);;
    esac

    screen_lock $img_fn
}

main "$@"