#!/usr/bin/env zsh

setopt NULL_GLOB

print_usage() {
    name="$(basename "$1")"
    print "Usage:"
    print "$name (watch | convert_all | clean) <source_dir> <output_dir>"
    print "$name --help"
}

new_path() {
    old_path="$1"
    rel_path="$(realpath --canonicalize-missing \
                                 --relative-to="$source_dir" "$old_path")"
    print "$output_dir/$rel_path"
}

pdf_path() {
    xoj_path="$1"
    new_path="$(new_path "$xoj_path")"
    print "${new_path%.(xoj|xopp)}.pdf"
}

fail_path() {
    pdf_path="$1"
    print "$pdf_path.fail"
}

convert() {
    xoj_path="$1"
    pdf_path="$(pdf_path "$xoj_path")"
    new_dirpath="$(dirname "$pdf_path")"
    fail_path="$(fail_path "$pdf_path")"

    print "Converting $xoj_path -> $pdf_path"
    # Create the directory if it does not exist
    mkdir --verbose --parents "$new_dirpath"
    if xournalpp --create-pdf "$pdf_path" "$xoj_path"; then
        # Delete a fail notice if it exists
        rm --force "$fail_path"
    else
        # Create a fail notice
        print >&2 "Conversion failed. Creating $fail_path"
        touch "$fail_path"
    fi
}

delete() {
    del_path="$1"
    del_dirpath="$(dirname "$del_path")"
    fail_path="$(fail_path "$del_path")"

    print "Deleting $del_path"
    rm "$del_path"
    # Delete a fail notice if it exists
    rm --force "$fail_path"
    # Try deleting the directory; only succeeds if it is empty
    rmdir --verbose --parents --ignore-fail-on-non-empty "$del_dirpath"
}

watch() {
    last_time=""
    last_event=""
    last_path=""

    inotifywait --monitor --recursive \
        --event modify --event delete --event move \
        --format "%T %e %w%f" \
        --timefmt "%s" \
        "$source_dir" |
    # This works even if the directory or filename contain spaces
    while read t event file_path
    do
        [[ "$t" == "$last_time"
        && "$event" == "$last_event"
        && "$file_path" == "$last_path"
        ]] && continue

        last_time="$t"
        last_event="$event"
        last_path="$file_path"

        [[ "$file_path" == (*.xoj|*.xopp)  && "$file_path" != (*autosave*) ]]; is_xoj=$(( !$? ))
        [[ -d "$file_path" ]]; is_dir=$(( !$? ))

        case "$event" in
        MODIFY | MOVED_TO)
            (( is_xoj )) && sleep 1s && convert "$file_path";;
        DELETE | MOVED_FROM)
            if (( is_xoj )); then
                pdf_path="$(pdf_path "$file_path")"
                [[ -e "$pdf_path" ]] && delete "$pdf_path"
            fi;;
        MOVED_TO,ISDIR)
            convert_all "$file_path"
            ;;
        MOVED_FROM,ISDIR)
            rm -r "$(new_path "$file_path")"
            ;;
        *)
            print >&2 "Unhandled event: $event $file_path";;
        esac
    done
}

convert_all() {
    subdir="$1"

    for xoj_path in "$subdir"/**/*.(xoj|xopp)
    do
        pdf_path="$(pdf_path "$xoj_path")"
        if [[ ! -e "$pdf_path" || "$pdf_path" -ot "$xoj_path" ]]; then
            convert "$xoj_path"
        fi
    done
}

clean() {
    subdir="$1"

    for pdf_path in "$subdir"/**/*.pdf
    do
        rel_path="$(realpath --canonicalize-missing \
                                 --relative-to="$output_dir" "$pdf_path")"
        xoj_path="$source_dir/${rel_path%.pdf}.xoj"
        xopp_path="$source_dir/${rel_path%.pdf}.xopp"
        if [[ ! -e "$xoj_path" && ! -e "$xopp_path" ]]; then
            print "Neither $xoj_path nor $xopp_path exist."
            delete "$pdf_path"
        fi
    done
}


case "$1" in
    --help)
        print_usage "$0";;
    watch|convert_all|clean)
        if (( $# == 3 )); then
            source_dir="$2"
            output_dir="$3"
        else
            print_usage "$0" >&2
            exit 1
        fi
        ;|
    watch)
        watch;;
    convert_all)
        convert_all "$source_dir";;
    clean)
        clean "$output_dir";;
    *)
        print_usage "$0" >&2
        exit 1;;
esac