#! /usr/bin/env dash

# shellcheck source=/dev/null
SHELL_LIBRARY_VERSION="1.7.1" . %SHELL_LIBRARY_PATH


# needed for help() and version
# shellcheck disable=2034
AUTHORS="Soispha";
# shellcheck disable=2034
YEARS="2023";
# shellcheck disable=2034
VERSION="1.0.0";

help() {
cat << EOF
Scan images and turn them into a pdf.

Usage:
    $NAME [OPTIONS] --name --device

OPTIONS:
    --out-dir | -o [FILE]
                            Path to place the generated pdf files (default: ./pdf).

    --name | -n NAME
                            Name for the pdf files (e.g. <NAME>_1.pdf).

    --num-pages | -p NUM
                            Number of pages to merge into one pdf (default: 1).

    --device | -d DEVICE
                            Device used for scanning.

    --method | -m METHOD
                            Method to use for scanning (default: ADF).

    --help | -h
                            Display this help and exit.

    --version | -v
                            Display version and copyright information and exit.
ARGUMENTS:
    FILE := [[fd . --max-depth 3]]
                            A name of a file to store, default is: ./pdf

    NAME | * := [[fd . --max-depth 3]]
                            The basename of the generated files

    NUM | *([0-9]) := 0 | 1 | 2 | 3 | 4
                            Possible numbers of pages, can be more than 4

    DEVICE := [[$(cat %DEVICE_FUNCTION)]]
                            Possible scanner names

    METHOD := ADF | Flatbed
                            The scanning method to use, not all scanners support both of
                            these. The default is ADF
EOF
}

scan() {
    number_of_pages="$1";
    device="$2";
    output_directory="$(readlink -f "$3")";
    name="$4";
    method="$5";

    [ -z "$number_of_pages" ] && die "Parameter 'number_of_pages' is not set!"
    [ -z "$device" ] && die "Parameter 'device' is not set!"
    [ -z "$output_directory" ] && die "Parameter 'output_directory' is not set!"
    [ -z "$name" ] && die "Parameter 'name' is not set!"
    [ -z "$method" ] && die "Parameter 'method' is not set!"

    tiff_temp_path="$(mktmp -d)";
    cd "$tiff_temp_path" || die "Bug"

    msg "Started scanning...";
    if [ "$method" = "Flatbed" ]; then
        for i in $(seq "$number_of_pages"); do
            do_until_success \
                "scanimage --format=tiff --progress --source='$method' --device='$device' --output-file=$i.tiff" \
                "warn 'Retrying scan, as we assume a network error!'"
            if [ "$number_of_pages" -ne 1 ];then
                msg "Finished turn, please change side!";
                readp "Press enter to continue" noop
            fi
        done
    else
        for i in $(seq "$number_of_pages");do
            do_until_success \
                "scanimage --format=tiff --progress --source='$method' --device='$device' --batch=%d.tif --batch-increment='$number_of_pages' --batch-start='$i'" \
                "warn 'Retrying scan, as we assume a network error!'"


            if [ "$number_of_pages" -ne 1 ];then
                msg "Finished turn, please change side!";
                readp "Press enter to continue" noop
            fi
        done
    fi

    msg "Creating output directory...";
    mkdir "$output_directory";
    cd "$output_directory" || die "Bug"

    counter=0;
    image_cache="$(mktmp)"
    msg "Converting images to pdfs...";
    while read -r scanned_image; do
        echo "$scanned_image" >> "$image_cache"
        : $((counter += 1))
        if [ "$counter" = "$number_of_pages" ]; then
            counter=0;
            process_images "$image_cache" "$name" "$output_directory"
            echo "" > "$image_cache"
        fi
    done < "$(tmp_pipe fd . "$tiff_temp_path" "|" sort -n)"
}

process_images() {
    image_cache="$1";
    name="$2";
    output_dir="$3";

    set --
    while read -r image; do
        set -- "$@" "$image"
    done < "$image_cache"

    while [ -e "$output_dir/${name}.pdf" ]; do
        name="${name}_$(tr -dc 'A-Za-z0-9!"#$%&'\''()*+,-./:;<=>?@[\]^_`{|}~' </dev/urandom | head -c 25)"
    done

    convert "$@" -compress jpeg -quality 100 "$output_dir/${name}.pdf"
}

for input in "$@"; do
    case "$input" in
        "--help" | "-h")
            help;
            exit 0;
            ;;
        "--version" | "-v")
            version;
            exit 0;
            ;;
    esac
done

number_of_pages="1";
unset device;
output_directory="$(pwd)/pdf";
unset name;
method="ADF";

while [ "$#" -ne 0 ]; do
    case "$1" in
        "--help" | "-h")
            ;;
        "--version" | "-v")
            ;;
        "--out-dir" | "-o")
            shift 1;
            output_directory="$1";
            ;;
        "--name" | "-n")
            shift 1;
            name="$1";
            ;;
        "--num-pages" | "-p")
            shift 1;
            number_of_pages="$1";
            ;;
        "--device" | "-d")
            shift 1;
            device="$1";
            ;;
        "--method" | "-m")
            shift 1;
            method="$1";
            ;;
        *)
            die "Command line arg $1 does not exist. See --help for a list.";
            ;;
    esac
    shift 1;
done
scan "$number_of_pages" "$device" "$output_directory" "$name" "$method";