#!/usr/bin/env bash

# This is an old script of mine that I found again and updated
# to also allow for watching directories recursively.
# This script scans directories for webp files and converts them to
# png files. It can also be run as a daemon that runs whenever a file
# is created in the specified (sub)directories.

launch_daemon() {
    if [ -z "$(command -v inotifywait)" ]; then
        >&2 echo "inotify-tools are required for daemon mode"
        exit 1
    fi
    
    if [ -n "$RECURSE" ]; then
        scan_dirs=()
        for scan_dir in $(find "$SCAN_DIR" -type d); do
            scan_dirs+=("$scan_dir") 
        done

        inotifywait -mrq -e create --format %w%f "${scan_dirs[@]}" | while read -r FILE; do
            convert_if_webp "$FILE"
        done
    else
        inotifywait -mrq -e create --format %w%f "$SCAN_DIR" | while read -r FILE; do
            convert_if_webp "$FILE"
        done
    fi

}

scan_dir() {
    shopt -s globstar nullglob
    if [ "$RECURSE" ]; then
        for FILE in "$SCAN_DIR"**/**; do
            convert_if_webp "$FILE"
        done
    else
        for FILE in "$SCAN_DIR"/*; do
            convert_if_webp "$FILE"
        done
    fi
}

convert_if_webp() {
    if [ "$(file -b --mime-type "$FILE")" = "image/webp" ]; then
        out_file="${1%.*}"
        if [ -f "$out_file.png" ]; then
            sha1="$(echo -n "$1" | sha1sum | awk '{print $1}')"
            out_file+="-$sha1.png"
        else
            out_file+=".png"
        fi
        convert "$1" "$out_file"
        echo "Converted $1 to $out_file"
    fi
}

verify_option_with_argument() {
    if [ -z "$2" ] || [ "${2:0:1}" = "-" ]; then
        >&2 echo "Option $1 requires a parameter"
        exit 1
    fi
}

args() {
    while [ -n "$1" ]; do
        case "$1" in
            "" | "-h" | "--help")
                printf "\n\
arguments:\n\
    -c/--config         [config file]       (optional) <The configuration file>                 {default:~/.config/webpautoconv}\n\
    -d/--directory      [scan directory]    (optional) <The directory to convert files in>      {default:~/Downloads}\n\
    -w/--watch          [none]              (optional) <Launch in daemon mode and watch folder> {default:off}\n\
    -r/--recursive      [non]               (optional) <Also scan subdirectories>               {default:off}\n"
                exit 0
                ;;
            "-c" | "--config")
                verify_option_with_argument "$@"
                CONF_FILE="$2"
                shift 2
                ;;
            "-d" | "--directory")
                verify_option_with_argument "$@"
                SCAN_DIR="$2"
                shift 2
                ;;
            "-w" | "--watch")
                DAEMON="true"
                shift
                ;;
            "-r" | "--recursive")
                RECURSE="true"
                shift
                ;;
        esac
    done
}

config() {
    [ -z "$CONF_FILE" ] && CONF_FILE="$HOME/.config/webpautoconv"

    if [ -f "$CONF_FILE" ]; then
        # shellcheck source=/dev/null
        source "$CONF_FILE"
    fi

    # Default config options
    [ -z "$SCAN_DIR" ] && SCAN_DIR="$HOME/Downloads"
    [ -z "$DAEMON" ] && DAEMON="false"
    [ -z "$RECURSE" ] && RECURSE="false"
}

main() {
    config
    args "$@"
    scan_dir
    if [ "$DAEMON" = "true" ]; then
        launch_daemon
    fi
}

main "$@"