#!/bin/bash
# Downloads and converts an article to EPUB

ok="yes"
if ! command -v mercury-parser >/dev/null; then
    echo 'Could not find mercury-parser. Get it from:' >&2
    echo '    https://mercury.postlight.com/web-parser/' >&2
    ok="no"
fi

if ! command -v jq >/dev/null; then
    echo 'Could not find jq. Get it from:' >&2
    echo '    https://stedolan.github.io/jq/' >&2
    ok="no"
fi

if ! command -v pandoc >/dev/null; then
    echo 'Could not find pandoc. Get it from:' >&2
    echo '    https://pandoc.org/' >&2
    ok="no"
fi

if ! command -v hxcopy >/dev/null; then
    echo 'Could not find hxcopy. Get it from:' >&2
    echo '    brew install hxml-xml-utils' >&2
    echo ' or apt-get install hxml-xml-utils' >&2
    ok="no"
fi

if [ "$ok" != "yes" ]; then
    exit 1
fi

if [ -z "$1" ]; then
    echo 'You must specify at least one URL.' >&2
    exit 1
fi

echo "Parsing $1" >&2
json=$(mercury-parser $1)
title=$(echo $json | jq -r '.title // "Untitled"')
author=$(echo $json | jq -r '.author // "Unknown"')
pubdate=$(echo $json | jq -r '.date_published')
description=$(echo $json | jq -r '.excerpt // ""')
description="${description}<br><br><a href=\"${1}\">${1}</a>"
content=$(echo $json | jq -r .content | hxcopy -i "$1" -o "file:///")
shift
for url in "$@"; do
    echo "Parsing and appending $url" >&2
    content="${content}$(mercury-parser $url | jq -r .content)"
    description="${description}<br><a href=\"${url}\">${url}</a>"
done
filename="${author} - ${title}.epub"
pandoc -f html -o "${filename}" \
    --metadata title="${title}" \
    --metadata author="${author}" \
    --metadata date="${pubdate}" \
    --metadata description="${description}" \
    <(echo $content) \
    && echo "Wrote ${filename}" >&2