#!/bin/bash

die() {
    echo "$1" >&2
    exit 1
}

IMG_DEPTH=8
NUM_PAGES=$(find /dangerzone/page-*.rgb |wc -l)

echo "Document has $NUM_PAGES pages"
echo

# Convert rgb files to png files
for PAGE in $(seq 1 $NUM_PAGES); do
    FILENAME_BASE=/dangerzone/page-$PAGE
    RGB_FILENAME=${FILENAME_BASE}.rgb
    WIDTH_FILENAME=${FILENAME_BASE}.width
    HEIGHT_FILENAME=${FILENAME_BASE}.height
    PNG_FILENAME=/tmp/page-$PAGE.png
    OCR_FILENAME=/tmp/page-$PAGE
    PDF_FILENAME=/tmp/page-$PAGE.pdf

    IMG_WIDTH=$(cat $WIDTH_FILENAME)
    IMG_HEIGHT=$(cat $HEIGHT_FILENAME)

    if [ $OCR = "1" ]; then

        echo "Converting page $PAGE from pixels to searchable PDF"

        CONVERT_MSGS=$(convert -size "${IMG_WIDTH}x${IMG_HEIGHT}" -depth ${IMG_DEPTH} rgb:"$RGB_FILENAME" png:"$PNG_FILENAME" 2>&1)
        if [ $? -ne 0 ]; then
            die "Page $PAGE conversion failed: $CONVERT_MSGS"
        fi

        CONVERT_MSGS=$(tesseract $PNG_FILENAME $OCR_FILENAME pdf -l $OCR_LANGUAGE 2>&1)
        if [ $? -ne 0 ]; then
            die "Page $PAGE conversion failed: $CONVERT_MSGS"
        fi

    else

        echo "Converting page $PAGE from pixels to PDF"

        CONVERT_MSGS=$(convert -size "${IMG_WIDTH}x${IMG_HEIGHT}" -depth ${IMG_DEPTH} rgb:"$RGB_FILENAME" png:"$PNG_FILENAME" 2>&1)
        if [ $? -ne 0 ]; then
            die "Page $PAGE conversion failed: $CONVERT_MSGS"
        fi

        CONVERT_MSGS=$(convert $PNG_FILENAME $PDF_FILENAME 2>&1)
        if [ $? -ne 0 ]; then
            die "Page $PAGE conversion failed: $CONVERT_MSGS"
        fi

    fi
done

echo
echo "Merging $NUM_PAGES pages into a single PDF"

# Put PDF filenames into an array
declare -a args
for PAGE in $(seq 1 $NUM_PAGES); do
    args+=("/tmp/page-$PAGE.pdf")
done
args+=("/safezone/safe-output.pdf")

# Merge them
pdfunite "${args[@]}"

# Compress
echo "Compressing PDF"
ps2pdf /safezone/safe-output.pdf /safezone/safe-output-compressed.pdf