#!/bin/bash
set -e

TMP_DIR="`mktemp -d`"

## Args
OPTIONAL_FLAGS=( \
    "-v" "--verbose" \
    "-c" "--config" \
    "-h" "-?" "--help" \
)

verbose () {
    [[ $VERBOSE = 1 ]] && echo "$1"
}


pdf_to_jpg () {
    verbose "Converting the scan '$1' to jpg"

    convert -density 300 -quality 100 "$1" "$TMP_DIR/out-%05d.jpg"
}

tesseract_jpgs () {
    verbose "Applying tesseract to the jpgs"

    for file in $TMP_DIR/out-*.jpg; do
        tesseract "$file" "$TMP_DIR/$(basename "$file" .jpg)" -l deu PDF
    done
}

concat_pdfs () {
    new_pdf_name="$(basename "$1" .pdf) - EDITABLE.pdf"
    verbose "Concatenating all the pdfs into '$new_pdf_name'"

    pdfunite "$TMP_DIR"/out-*.pdf ./"$new_pdf_name"
}

usage () {
    cat << EOF
scantopdf - A quick bash script that wraps around tesseract to make book scans "editable"

Usage:  scantopdf [-v|--verbose] file.pdf
        scantopdf [-v|--verbose] "file with spaces.pdf"
        scantopdf [-h|-?|--help]

Options:
    file.pdf                            the file you want to make editable (make
                                        sure to put quotes " around the file
                                        name if the filename has spaces)

Optional arguments:
    -v, --verbose                       print each step the script passes through
    -h, -?, --help                      show this message
EOF
}

while [[ " ${OPTIONAL_FLAGS[@]} " =~ " $1 " ]]; do
    verbose && echo "Checking for optional arguments"

    case $1 in 
        -v|--verbose)
            VERBOSE=1
            echo "Setting \$VERBOSE to true (\$VERBOSE=$VERBOSE)"
            shift
            ;;
        -h|-\?|--help)
            verbose "Detected -h, -? or --help"
            usage
            exit
            ;;
    esac
done

export TESSDATA_PREFIX="$HOME/tesseract/tessdata"

if [[ "$1" ]]; then
    if [[ "$1" =~ \.pdf$ ]] && [[ -f "$1" ]]; then
        pdf_to_jpg "$1"
        tesseract_jpgs 
        concat_pdfs "$1"
    else
        echo "The file you gave me isn't a pdf or doesn't exist, so I can't perform the convertion."
    fi
else
    echo "You have to give me the name of the pdf you want to make editable."
fi