#!/usr/bin/env bash

html=$(wget --quiet --output-document=- "$1")

page_count=$(echo "$html" |\
    grep --only-matching --perl-regexp 'pageCount":\K\d+')
[[ $page_count > 0 ]] || { echo 'no pages' && exit 1; }

publication_id=$(echo "$html" |\
    grep --only-matching --perl-regexp 'publicationId":"\K[a-z0-9]+"' |\
    grep --only-matching --perl-regexp '.+?(?=")' | head -n 1)
[[ -n $publication_id ]] || { echo 'no publication_id' && exit 1; }

revision_id=$(echo "$html" |\
    grep --only-matching --perl-regexp 'revisionId":"\K[0-9]+"' |\
    grep --only-matching --perl-regexp '.+?(?=")' | head -n 1)
[[ -n $revision_id ]] || { echo 'no revision_id' && exit 1; }

title=$(echo "$html" |\
    grep --only-matching --perl-regexp 'title":"\K.*?"' |\
    grep --only-matching --perl-regexp '.+?(?=")' | head -n 1)
[[ -z $title ]] && title=issuu

tmp_dir=$(mktemp --directory)
for ((i = 1; i <= page_count; i++)); do
    wget --quiet --output-document="${tmp_dir}/${i}.jpg" \
        "https://image.issuu.com/${revision_id}-${publication_id}/jpg/page_${i}.jpg" &
done

echo -n 'Downloading... '
wait
echo done!

echo Converting...
# convert doesn't like long filenames(252 bytes, I think).
tmp_file="${tmp_dir}/t.pdf"
convert \
    $(find "$tmp_dir" -type f -printf '%f\n' |\
    sort --numeric-sort |\
    awk -v dir="$tmp_dir" '{ printf dir "/" $1 " " }') \
    "$tmp_file"
mv "$tmp_file" "$title".pdf

exit 0

# vim: set ft=bash