#!/usr/bin/env sh

# Description: Browse Project Gutenberg catalogue by popularity, then download
#              and read a book of your choice.
#
# Details: Set the variable EBOOK_ID to download in html format and read in w3m.
#          Clear EBOOK_ID to browse available ebooks by popularity and set it to
#          the ID once you find an interesting one.
#          To download and read in epub format set READER to an epub reader like
#          epr: https://github.com/wustho/epr
#
#          More on EBOOK_ID:
#          Wuthering Heights by Emily Brontë is at https://www.gutenberg.org/ebooks/768
#          So EBOOK_ID would be 768
#
#          Downloaded ebooks are at ${XDG_CACHE_HOME:-$HOME/.cache}/nnn/gutenbooks/
#
# Shell: POSIX compliant
# Author: Arun Prakash Jana

EBOOK_ID="${EBOOK_ID:-""}"
DIR="${XDG_CACHE_HOME:-$HOME/.cache}/nnn/gutenbooks/$EBOOK_ID"
BROWSE_LINK="https://www.gutenberg.org/ebooks/search/?sort_order=downloads"
BROWSER="${BROWSER:-w3m}"
READER="${READER:-""}"

if [ -n "$EBOOK_ID" ]; then
    if [ ! -e "$DIR" ]; then
        mkdir -p "$DIR"
        cd "$DIR" || exit 1

        if [ -z "$READER" ]; then
            curl -L -O "https://www.gutenberg.org/files/$EBOOK_ID/$EBOOK_ID-h.zip"
            unzip "$EBOOK_ID"-h.zip
        else
            curl -L -o "$EBOOK_ID".epub "https://www.gutenberg.org/ebooks/$EBOOK_ID.epub.noimages"
        fi
    fi

    if [ -d "$DIR" ]; then
        if [ -z "$READER" ]; then
            "$BROWSER" "$DIR/$EBOOK_ID-h/$EBOOK_ID-h.htm"
        else
            "$READER" "$DIR/$EBOOK_ID.epub"
        fi
    fi
else
    "$BROWSER" "$BROWSE_LINK"
fi