#!/usr/bin/env bash

# This code is thrown together lazily to just work and never be touched again.
# Do NOT try to learn from this piece of shit

check_dep() {
    if [ -z "$(command -v "$1")" ]; then
        echo "'$1' is required but not installed."
        exit 1
    fi
}

check_deps() {
    deps=("ffmpeg" "opusinfo" "xargs")
    for dep in "${deps[@]}"; do
        check_dep "$dep"
    done
}

args() {
    while [ -n "$1" ];do
        case "$1" in
            "help")
                printf "\n\
arguments:\n\
    in      [input directory]   (required)  <The flac directory> {default: none}\n\
    out     [output directory]  (required)  <The opus directory> {default: none}\n\
    verify  [on/off]            (optional)  <Check converted files for corruption> {default: on}
    vbr     [on/off]            (optional)  <Toggle variable bit rate> {default: on}
    bitrate [{bitrate}k]        (optional)  <Set the bitrate to be passed to ffmpeg> {default: 128k}\n\n"
                exit 0
                ;;
            "in")
                if [ -z "$2" ]; then
                    echo "option '$1' requires an additional argument."
                    exit 1
                fi

                INPUT_DIR="$(realpath "$2")"
                shift
                ;;
            "out")
                if [ -z "$2" ]; then
                    echo "option '$1' requires an additional argument."
                    exit 1
                fi

                OUTPUT_DIR="$(realpath "$2")"
                shift
                ;;
            "vbr")
                if [ -z "$2" ]; then
                    echo "option '$1' requires an additional argument."
                    exit 1
                fi

                if [ "$2" != "on" ] && [ "$2" != "off" ]; then
                    echo "Invalid option '$2' for $1. Only accepted options are 'on' or 'off'."
                    exit 1
                fi
                VBR="$2"
                shift
                ;;
            "verify")
                if [ -z "$2" ]; then
                    echo "option '$1' requires an additional argument."
                    exit 1
                fi

                if [ "$2" != "on" ] && [ "$2" != "off" ]; then
                    echo "Invalid option '$2' for $1. Only accepted options are 'on' or 'off'."
                    exit 1
                fi
                VERIFY="$2"
                shift
                ;;
            "bitrate")
                if [ -z "$2" ]; then
                    echo "option '$1' requires an additional argument."
                    exit 1
                fi

                BITRATE="$2"
                if [[ ! $2 =~ ^[0-9]+k$ ]]; then
                    echo "Invalid bitrate '$2', only accepts string matching pattern '[0-9]\\+k'"
                fi

                shift
                ;;
            *)
                echo "Invalid argument '$1', skipping"
                ;;
        esac
        shift
    done

    if [ -z "$INPUT_DIR" ]; then
        echo "Missing input directory"
        exit 1
    fi

    if [ -z "$OUTPUT_DIR" ]; then
        echo "Missing input directory"
        exit 1
    fi

    if [ -z "$BITRATE" ]; then
        BITRATE="128k"
    fi

    if [ -z "$VBR" ]; then
        VBR="on"
    fi

    if [ -z "$VERIFY" ]; then
        VERIFY="on"
    fi
}

get_total_count() {
    local -n ref_total_count="$2"
    total_count="$ref_total_count"

    local dir="$1"
    for item in "$dir"/*; do
        if [ -f "$item" ]; then
            new_file="${item/"$INPUT_DIR"/"$OUTPUT_DIR"}"
            new_file="${new_file/".flac"/".ogg"}"
            if [ ! -f "$new_file" ] && [[ "$item" == *".flac" ]]; then
                ((total_count+=1))
            elif [[ "$item" == *".flac" ]]; then
                if [ "$VERIFY" = "on" ]; then
                printf "Checking \e[93m'%s'\e[0m: " "$(basename "$new_file")"
                    if ! opusinfo "$new_file" > /dev/null 2>&1; then
                        ((total_count+=1))
                        printf "\e[31mbad\e[0m\n"
                        rm "$new_file"
                    else
                        printf "\e[32mgood\e[0m\n"
                    fi
                fi
            fi
        elif [ -d "$item" ]; then
            get_total_count "$item" "total_count"
        fi
    done
}

iterate_dirs() {
    local dir="$1"
    local conversions=()
    local -n ref_count="$2"
    local total_count="$3"
    count="$ref_count"
    for item in "$dir"/*; do
        local item="$(echo "$item" | sed "s/'/'\\\\'/g")"
        if [ -f "$item" ]; then
            new_file="${item/"$INPUT_DIR"/"$OUTPUT_DIR"}"
            if [ ! -f "$new_file" ]; then
                if [[ "$item" == *".flac" ]]; then
                    ((count+=1))
                    new_file="${new_file/".flac"/".ogg"}"
                    conversions+=("printf '[%s/%s] \e[92m%s\e[0m -> \e[93m%s\e[0m\n' $count $total_count \
                        '$item' '$new_file' && ffmpeg -hide_banner -loglevel error -i '$item' -c:a libopus -vbr \"$VBR\" -b:a \"$BITRATE\" '$new_file' > /dev/null")
                else
                    new_dir=$(dirname "${item/"$INPUT_DIR"/"$OUTPUT_DIR"}")
                    if [ ! -d "$new_dir" ]; then
                        mkdir -p "$new_dir"
                    fi
                    echo "Copied $(basename "$item")"
                    cp -f "$item" "$new_file"
                fi
            fi
        elif [ -d "$item" ]; then
            new_dir="${item/"$INPUT_DIR"/"$OUTPUT_DIR"}"
            mkdir -p "$new_dir"
            iterate_dirs "$item" "count" "$total_count"
        fi
    done

    if [ ${#conversions[@]} -gt 0 ]; then
        printf '%s\0' "${conversions[@]}" | xargs -0 -P "$(nproc)" -I {} bash -c '{}'
    fi
}

main () {
    check_deps

    args "$@"

    count="0"
    total_count="0"
    get_total_count "$INPUT_DIR" "total_count"
    iterate_dirs "$INPUT_DIR" "count" "$total_count"
}

# set -e
main "$@"