#!/bin/bash
#
# rm2-make-pdf
# John Simpson <jms1@jms1.net> 2023-08-13
#
# Use Calibre's "ebook-convert" to convert an input file to a PDF, using
# settings that I think look good on a reMarkable 2 tablet.
#
# Requirements:
# - OS: macOS or Linux. This *might* also work on windows, if you install
#   whatever "Linux-ish" things you need to run it on.
# - Calibre.
#   https://calibre-ebook.com/
# - reMarkable tablet, or some other device or program to view the resulting
#   PDF file with.
#   https://remarkable.com/
#
# 2023-08-15 jms1 - fixed handling of title/author values containing spaces
#
# 2023-09-10 jms1 - show usage message if no input filename
#
###############################################################################
#
# The MIT License (MIT)
#
# Copyright (C) 2023 John Simpson
#
# Permission is hereby granted, free of charge, to any person obtaining a
# copy of this software and associated documentation files (the “Software”),
# to deal in the Software without restriction, including without limitation
# the rights to use, copy, modify, merge, publish, distribute, sublicense,
# and/or sell copies of the Software, and to permit persons to whom the
# Software is furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
# DEALINGS IN THE SOFTWARE.
#
###############################################################################

########################################
# Possible locations for the 'ebook-convert' executable. The first of these
# which exists will be used.

EBC_MAYBE="
/Applications/calibre.app/Contents/MacOS/ebook-convert
/opt/calibre/ebook-convert
/usr/local/bin/ebook-convert
/usr/bin/ebook-convert
"

###############################################################################
#
# usage

function usage {
    MSG="${1:-}"

    cat <<EOF
$0 [options] INFILE [OUTFILE]

Use Calibre's 'ebook-convert' to convert an input file to a PDF, using
settings that I think look good on a reMarkable 2 tablet.

-t ___  Specify the title in the PDF's metadata.

-a ___  Specify the author in the PDF's metadata.

-s ___  Specify the document's base font size. Default is 12.

-p      For input documents which have "H1" section headers (HTML, Markdown,
        etc.) start a new page for each H1 section.

If the input file has metadata, the '-t' and '-a' options will override the
values from the input file.

If OUTFILE is specified, it must end with '.pdf'.

EOF

    if [[ -n "$MSG" ]]
    then
        echo "$MSG"
        exit 1
    fi

    exit 0
}

###############################################################################
###############################################################################
###############################################################################
#
# Process the command line

SET_X=false
TITLE=''
AUTHOR=''
SIZE='12'
H1_NO_SPLIT=true

while getopts ':hxt:a:s:p' OPT
do
    case $OPT in
        h)  usage
            ;;
        x)  SET_X=true
            ;;
        t)  TITLE="$OPTARG"
            ;;
        a)  AUTHOR="$OPTARG"
            ;;
        s)  SIZE="$OPTARG"
            ;;
        p)  H1_NO_SPLIT=false
            ;;
        *)  usage "ERROR: unknown option '-$OPTARG'"
            ;;
    esac
done
shift $((OPTIND-1))

########################################
# Get the input filename

INFILE="${1:-}"
if [[ -z "$INFILE" ]]
then
    usage
fi

OUTFILE="${2:-.pdf}"
if [[ ! "$OUTFILE" =~ \.pdf$ ]]
then
    usage "ERROR: output filename must end with '.pdf'"
fi

########################################
# Find the 'ebook-convert' executable

for X in $EBC_MAYBE
do
    if [[ -x "$X" ]]
    then
        EBOOK_CONVERT="$X"
        continue
    fi
done

if [[ -z "$EBOOK_CONVERT" ]]
then
    echo "ERROR: unable to locate 'ebook-convert' executable, cannot continue"
    exit 1
fi

########################################
# Build a string containing options which may or may not need to be included
# in the final 'ebook-convert' command line.

# Array of options
OPTA=()

if [[ -n "$TITLE" ]]
then
    OPTA+=( '--title' )
    OPTA+=( "$TITLE" )
fi

if [[ -n "$AUTHOR" ]]
then
    OPTA+=( '--authors' )
    OPTA+=( "$AUTHOR" )
fi

if $H1_NO_SPLIT
then
    OPTA+=( '--page-breaks-before' '/' )
    OPTA+=( '--chapter' '/' )
fi

###############################################################################
#
# Do the deed
#
# 'ebook-convert' command line option reference:
#   https://manual.calibre-ebook.com/generated/en/ebook-convert.html

if $SET_X
then
    set -x
fi

"$EBOOK_CONVERT" "$INFILE" "$OUTFILE" \
    --input-profile                 default \
    --output-profile                generic_eink_hd \
    --base-font-size                $SIZE \
    --embed-all-fonts               \
    --subset-embedded-fonts         \
    --unsmarten-punctuation         \
    "${OPTA[@]}"                    \
    --custom-size                   1404x1872 \
    --unit                          devicepixel \
    --pdf-sans-family               'Liberation Sans' \
    --pdf-serif-family              'Liberation Serif' \
    --pdf-mono-family               'Liberation Mono' \
    --pdf-standard-font             serif \
    --pdf-mono-font-size            $SIZE \
    --pdf-page-margin-left          72 \
    --pdf-page-margin-right         18 \
    --pdf-page-margin-top           18 \
    --pdf-page-margin-bottom        18 \
    --preserve-cover-aspect-ratio