improve is_valid_lrc

.gitignore

@@ -1 +1,2 @@
-test-dir*
+test-dir*
+*.json

add-synced-lyrics.sh

@@ -1,118 +1,10 @@
 #!/usr/bin/env bash
 
+# many functions are invoked via variables
+# shellcheck disable=SC2329
+
 set -u
 
-have_cmd() {
-    for cmd in "$@"; do
-        command -v "${cmd}" &>/dev/null || return 1
-    done
-}
-
-# shellcheck disable=SC2329
-void() {
-    echo "$@" &>/dev/null
-}
-
-# shellcheck disable=SC2329
-dry() {
-    local args=("$@")
-    local numArgs="${#args[@]}"
-    test "${numArgs}" -eq 0 && return 0
-    echo "'${args[0]}'"
-    local earlyStop=$((numArgs - 1))
-    for ((i = 1; i < earlyStop; i++)); do
-        echo "  '${args[${i}]}' \\"
-    done
-    echo "  '${args[${i}]}'"
-}
-
-check_required_utils() {
-    local utils=(
-        ffmpeg
-        jq
-        syncedlyrics
-        librelyrics
-        spotify # uv tool install --python 3.8 spotify-cli
-    )
-    local missing=false
-    for util in "${utils[@]}"; do
-        if ! have_cmd "${util}"; then
-            echo "missing ${util}!"
-            missing=true
-        fi
-    done
-
-    if [[ ${missing} == true ]]; then
-        return 1
-    else
-        return 0
-    fi
-}
-
-# shellcheck disable=SC2329
-get_spotify_url() {
-    local search="$1"
-    local response artistAlbumTitle url
-    response="$(
-        spotify \
-            search \
-            --track "${search}" \
-            --limit 1 \
-            --raw
-    )"
-
-    artistAlbumTitle="$(
-        jq -r '.items[0] | "\(.artists[0].name) - \(.album.name) - \(.name)"' \
-            <<<"${response}"
-    )"
-
-    if [[ "${artistAlbumTitle}" != "${search}" ]]; then
-        echo "${search} could not be found"
-        return 1
-    fi
-
-    url="$(
-        jq -r '.items[0] | "\(.external_urls.spotify)"' <<<"${response}"
-    )"
-
-    if [[ -z "${url}" ]]; then
-        echo "could not determine url for ${search}"
-        return 1
-    fi
-
-    echo "${url}"
-}
-
-output_eval_functions() {
-    while read -r line; do
-        IFS=' ' read -r _ _ function <<<"${line}"
-        [[ "${function}" == '_determine_inputs_'* ||
-            "${function}" == set_default_options ]] || continue
-        ${line}
-    done <<<"$(declare -F)"
-}
-
-get_artist_album_title() {
-    local file="$1"
-    local jqFilter='.streams[] | select(.codec_type == "audio") | .tags | "\(.ARTIST) - \(.ALBUM) - \(.TITLE)"'
-    ffprobe \
-        -v error \
-        -show_entries stream \
-        -of json \
-        "${file}" | jq \
-        -r "${jqFilter}"
-}
-
-set_lyric_file_name() {
-    local file="$1"
-    if [[ ! "${file}" =~ ${MUSIC_EXTENSION_REGEX} ]]; then
-        echo "${file} is not a music file"
-        return 1
-    fi
-
-    echo "${file%.opus}.lrc"
-}
-
 bash_basename() {
     local tmp
     path="$1"
@@ -125,245 +17,99 @@ bash_basename() {
     printf '%s\n' "${tmp:-/}"
 }
 
-readonly PROGNAME="$(bash_basename "$0")"
+bash_dirname() {
+    # Usage: dirname "path"
+    local tmp=${1:-.}
 
-usage() {
+    [[ $tmp != *[!/]* ]] && {
-    echo "${PROGNAME} [options]
+        printf '/\n'
+        return
+    }
 
-OPTIONS:
+    tmp=${tmp%%"${tmp##*[!/]}"}
-  -d, --dir       process files in directory
+
-  -r, --recurse   recursively process directory
+    [[ $tmp != */* ]] && {
-  -f, --file      process one file
+        printf '.\n'
-  -n, --dry-run   do not actually add synced lyrics,
+        return
-                  just show the files that would be processed
+    }
-  -e, --eval      output bash functions that can be directly processed
+
-                  by eval for use with testing this script.
+    tmp=${tmp%/*}
-  -i, --ignore    ignore errors, and continue attempting to find lyrics
+    tmp=${tmp%%"${tmp##*[!/]}"}
-                  even in the case of errors
+
-  -h, --help      show this output"
+    printf '%s\n' "${tmp:-/}"
-    exit ${EXIT_CODE:-1}
 }
 
-set_default_options() {
+PROGPATH="$(readlink -f "$0")"
-    DIR=${DIR:-}
+PROGDIR="$(bash_dirname "${PROGPATH}")"
-    FILE=${FILE:-}
+PROGNAME="$(bash_basename "${PROGPATH}")"
-    RECURSE=${RECURSE:-false}
+# shellcheck disable=SC2034
-    DRY_RUN=${DRY_RUN:-false}
+readonly PROGPATH PROGDIR PROGNAME || exit 1
-    IGNORE=${IGNORE:-false}
-    readonly MUSIC_EXTENSION_REGEX='.*\.(opus)$'
-}
 
-process_options() {
+for lib in "${PROGDIR}/lib/"*; do
-    while [[ $# -gt 0 ]]; do
+    # shellcheck disable=SC1090
-        option="$1"
+    source "${lib}" || exit 1
-        value="${2:-}"
+done
-        case "${option}" in
-        -d | --dir)
-            if [[ ! -d "${value}" ]]; then
-                echo "directory ${value} does not exist"
-                usage
-            fi
-            readonly DIR="${value}"
-            shift 2
-            ;;
-        -r | --recurse)
-            readonly RECURSE=true
-            shift 1
-            ;;
-        -n | --dry-run)
-            readonly DRY_RUN=true
-            shift 1
-            ;;
-        -i | --ignore)
-            readonly IGNORE=true
-            shift 1
-            ;;
-        -e | --eval)
-            output_eval_functions
-            exit 0
-            ;;
-        -f | --file)
-            if [[ ! -f "${value}" ]]; then
-                echo "file ${value} does not exist"
-                usage
-            fi
-            readonly FILE="${value}"
-            shift 2
-            ;;
-        -h | --help)
-            EXIT_CODE=0 usage
-            ;;
-        *)
-            echo "bad option"
-            usage
-            ;;
-        esac
-    done
-
-    if [[ "${DIR:-}${FILE:-}" == '' ]]; then
-        echo "either --dir or --file must be used"
-        usage
-    fi
-
-    if [[ -n "${DIR}" && -n "${FILE}" ]]; then
-        echo "cannot process both directory and file"
-        usage
-    fi
-
-    if [[ "${RECURSE}" == true && -n "${FILE}" ]]; then
-        echo "--recurse can only be used with --dir"
-        usage
-    fi
-}
-
-_determine_inputs_fd() {
-    local fdCmd=(
-        fd
-        --type f
-        "${MUSIC_EXTENSION_REGEX}"
-        "${DIR}"
-    )
-
-    if [[ "${RECURSE}" == false ]]; then
-        fdCmd+=(--max-depth 1)
-    fi
-
-    mapfile -t INPUTS < <("${fdCmd[@]}" | sort)
-}
-
-_determine_inputs_find() {
-    local findCmd=(
-        find
-        "${DIR}"
-    )
-
-    if [[ "${RECURSE}" == false ]]; then
-        findCmd+=(-maxdepth 1)
-    fi
-
-    findCmd+=(
-        -regextype posix-extended
-        -regex "${MUSIC_EXTENSION_REGEX}"
-        -type f
-    )
-
-    mapfile -t INPUTS < <("${findCmd[@]}" | sort)
-}
-
-_determine_inputs_bash() {
-    local unsortedInputs=()
-    if [[ "${RECURSE}" == true ]]; then
-        local preGlobstar="$(shopt -p globstar)"
-        shopt -s globstar
-        for f in "${DIR}"/**/*; do
-            unsortedInputs+=("${f}")
-        done
-        ${preGlobstar}
-    else
-        for f in "${DIR}"/**; do
-            unsortedInputs+=("${f}")
-        done
-    fi
-
-    local filteredInputs=()
-    for input in "${unsortedInputs[@]}"; do
-        [[ "${input}" =~ ${MUSIC_EXTENSION_REGEX} ]] || continue
-        filteredInputs+=("${input}")
-    done
-
-    mapfile -t INPUTS < <(printf '%s\n' "${filteredInputs[@]}" | sort)
-}
-
-determine_inputs() {
-    INPUTS=()
-    if [[ -n "${FILE}" ]]; then
-        INPUTS=("${FILE}")
-    elif have_cmd fd; then
-        _determine_inputs_fd || return 1
-    elif have_cmd find; then
-        _determine_inputs_find || return 1
-    else
-        _determine_inputs_bash || return 1
-    fi
-
-    if [[ "${#INPUTS[@]}" -eq 0 ]]; then
-        echo "no inputs found, something is wrong"
-        exit 1
-    fi
-
-    readonly INPUTS
-}
-
-create_tmp_dir() {
-    TMPDIR="$(mktemp -d)" || return 1
-    readonly TMPDIR
-    trap 'rm -rf ${TMPDIR}' EXIT
-}
 
 process_inputs() {
-    local dry='' void=''
+    local isrc output ret=0
-    if [[ "${DRY_RUN}" == true ]]; then
+    local downloadFuncs=(
-        dry=dry
+        download_with_lrclib
-        void=void
+        download_with_spotify
-    fi
+        download_with_deezer
+    )
 
-    local search='' output='' spotifyUrl='' ret=''
     for input in "${INPUTS[@]}"; do
         if [[ ${IGNORE} == false && ${ret} -ne 0 ]]; then
             return 1
         fi
 
-        if [[ "${input,,}" == *'instrumental'* ]]; then
+        if [[ "${input,,}" == *'instrumental'* ||
+            "${input,,}" == *'acoustic'* ]]; then
             echo "${input} is instrumental, skipping"
             continue
         fi
 
+        output=''
         output="$(set_lyric_file_name "${input}")"
-        if [[ ! -f "${output}" ]]; then
-            echo "processing ${input}"
-            search="$(get_artist_album_title "${input}")"
 
-            # try with syncedlyrics first
+        if [[ -f "${output}" ]]; then
-            ${dry} syncedlyrics \
+            if is_valid_lrc "${output}"; then
-                --synced-only \
-                --output "${output}" \
-                "${search}"
-
-            if ! ${void} test -f "${output}"; then
-                for f in "${TMPDIR}"/*; do
-                    if [[ -f "${f}" ]]; then
-                        echo "tempdir ${TMPDIR} is not empty!"
-                        echo "aborting operation"
-                        return 1
-                    fi
-                done
-
-                # try with librelyrics-spotify next
-                if ! spotifyUrl="$(${dry} get_spotify_url "${search}")"; then
-                    ret=1
-                    continue
-                fi
-
-                if ! ${dry} librelyrics \
-                    --directory "${TMPDIR}" \
-                    "${spotifyUrl}"; then
-                    ret=1
-                    continue
-                fi
-
-                if ! ${dry} mv "${TMPDIR}"/*.lrc "${output}"; then
-                    ret=1
-                    continue
-                fi
-            fi
-
-            if ! ${void} test -f "${output}"; then
-                echo "failed to get lyrics for ${input}"
-                ret=1
                 continue
+            else
+                rm "${output}" || return 1
             fi
         fi
+
+        echo "processing ${input}"
+        isrc=''
+        if ! isrc="$(get_file_isrc "${input}")"; then
+            ret=1
+            continue
+        fi
+
+        local tmpOutput="${TMPDIR}/tmp.lrc"
+        for func in "${downloadFuncs[@]}"; do
+            "${func}" "${isrc}" "${tmpOutput}" && break
+        done
+
+        if [[ -f "${tmpOutput}" ]]; then
+            if is_valid_lrc "${tmpOutput}"; then
+                mv "${tmpOutput}" "${output}" &>/dev/null || return 1
+            else
+                rm "${tmpOutput}" || return 1
+            fi
+        fi
+
+        if ! void test -f "${output}"; then
+            echo "failed to get lyrics for ${input}"
+            ret=1
+            continue
+        else
+            void echo "added lyrics for ${input}"
+        fi
     done
+
+    return ${ret}
 }
 
 check_required_utils || exit 1

lib/0-utils.sh

@@ -0,0 +1,261 @@
+#!/usr/bin/env bash
+
+# many functions are invoked via variables
+# shellcheck disable=SC2329
+
+# check commands exist
+# "$@" commands to check
+have_cmd() {
+    for cmd in "$@"; do
+        command -v "${cmd}" &>/dev/null || return 1
+    done
+}
+
+# validate results from `jq -r`
+jq_result_valid() {
+    local result="$1"
+    if [[ -z "${result}" || "${result}" == 'null' ]]; then
+        return 1
+    fi
+    return 0
+}
+
+stderr() { echo "$*" 1>&2; }
+info() { stderr "INFO [${FUNCNAME[1]}]: $*"; }
+error() { stderr "ERROR [${FUNCNAME[1]}]: $*"; }
+
+# only echo "$@" if ${DEBUG} is true
+debug() {
+    if [[ ${DEBUG} == false ]]; then
+        return 0
+    fi
+
+    stderr "$@"
+}
+
+# do not do anything
+# if ${DRY_RUN} is enabled
+void() {
+    local cmd=("$@")
+    if [[ ${DRY_RUN} == true ]]; then
+        return 0
+    else
+        "${cmd[@]}"
+        return $?
+    fi
+}
+
+# print out "$@" formatted for bash
+# if ${DRY_RUN} is enabled
+# otherwise, execute the actual command
+dry() {
+    local cmd=("$@")
+    if [[ ${DRY_RUN} == true ]]; then
+        local numCmd="${#cmd[@]}"
+        test "${numCmd}" -eq 0 && return 0
+        local firstLine="'${cmd[0]}'"
+        test "${numCmd}" -gt 1 && firstLine+=' \'
+        stderr "${firstLine}"
+        local earlyStop=$((numCmd - 1))
+        for ((i = 1; i < earlyStop; i++)); do
+            stderr "  '${cmd[${i}]}' \\"
+        done
+        stderr "  '${cmd[${i}]}'"
+    else
+        "${cmd[@]}"
+        return $?
+    fi
+}
+
+# check required utilities for this project
+check_required_utils() {
+    local utils=(
+        base64
+        cat
+        ffprobe
+        jq
+        librelyrics
+        spotify # uv tool install --python 3.8 spotify-cli
+    )
+    local missing=false
+    for util in "${utils[@]}"; do
+        if ! have_cmd "${util}"; then
+            error "missing ${util}!"
+            missing=true
+        fi
+    done
+
+    if [[ ${missing} == true ]]; then
+        return 1
+    else
+        return 0
+    fi
+}
+
+cache_command() {
+    local cmd=("$@")
+    local hash cacheFile cmdOut contents ret
+    hash="$(sha256sum <<<"${cmd[*]}")" || return 1
+    read -r cacheFile _ <<<"${hash}"
+    cacheFilePath="${CACHE_DIR}/${cacheFile}"
+    if [[ -f "${cacheFilePath}" && ${DRY_RUN} == false ]]; then
+        mapfile -t contents <"${cacheFilePath}"
+        ret=$?
+        # skip first line since it is the command
+        printf '%s\n' "${contents[@]:1}"
+    else
+        cmdOut="$(dry "${cmd[@]}")"
+        ret=$?
+        if [[ ${ret} -eq 0 && ${DRY_RUN} == false ]]; then
+            {
+                echo "${cmd[*]}"
+                echo "${cmdOut}"
+            } >"${cacheFilePath}" || return 1
+            echo "${cmdOut}"
+        fi
+    fi
+
+    return "${ret}"
+}
+
+create_tmp_dir() {
+    TMPDIR="$(mktemp -d)" || return 1
+    readonly TMPDIR
+    trap 'rm -rf ${TMPDIR}' EXIT
+}
+
+check_tmp_dir_empty() {
+    for f in "${TMPDIR}"/*; do
+        if [[ -f "${f}" ]]; then
+            error "tempdir ${TMPDIR} is not empty!"
+            error "aborting operation"
+            return 1
+        fi
+    done
+
+    return 0
+}
+
+# librelyrics only exposes a directory to download to
+# so this wrapper function downloads to a directory
+# and then outputs the contents of the downloaded file
+# to stdout so it can effectively be cached
+librelyrics_dl() {
+    local url="$1"
+    check_tmp_dir_empty || return 1
+    librelyrics \
+        --directory "${TMPDIR}" \
+        "${url}" 1>&2
+    local librelyricsRet=$?
+
+    local downloadedFile=''
+    for f in "${TMPDIR}/"*; do
+        if [[ -f "${f}" ]]; then
+            downloadedFile="${f}"
+            break
+        fi
+    done
+
+    if [[ ${librelyricsRet} -eq 0 && -z ${downloadedFile} ]]; then
+        error "failed to download file for ${url} despite no librelyrics error"
+        return 1
+    fi
+
+    local fileContents=''
+    if [[ -n "${downloadedFile}" ]]; then
+        fileContents="$(<"${downloadedFile}")"
+        rm "${downloadedFile}" || return 1
+    fi
+
+    if [[ ${librelyricsRet} -eq 0 && -z ${fileContents} ]]; then
+        error "failed to read file for ${url} despite no librelyrics error"
+        return 1
+    fi
+
+    echo "${fileContents}"
+}
+
+download_with_librelyrics() {
+    local isrc="$1"
+    local output="$2"
+    local urlType="$3"
+
+    if [[ ! "${urlType}" =~ spotify|deezer ]]; then
+        error "only spotify|deezer are supported"
+        return 1
+    fi
+
+    local url=''
+    url="$(get_"${urlType}"_url "${isrc}")" || return 1
+
+    local lyrics=''
+    lyrics="$(cache_command \
+        librelyrics_dl \
+        "${url}")"
+
+    if [[ -z "${lyrics}" ]]; then
+        error "could not get lyrics for ${isrc} using ${urlType}"
+        return 1
+    fi
+
+    info "found lyrics for ${isrc} with ${urlType}"
+    echo "${lyrics}" >"${output}"
+}
+
+output_eval_functions() {
+    while read -r line; do
+        IFS=' ' read -r _ _ function <<<"${line}"
+        [[ "${function}" == '_determine_inputs_'* ||
+            "${function}" == set_default_options ]] || continue
+        ${line}
+    done <<<"$(declare -F)"
+}
+
+get_file_isrc() {
+    local file="$1"
+    local probe='' jqResult=''
+
+    local probe=''
+    probe="$(
+        ffprobe \
+            -v error \
+            -show_entries stream \
+            -of json \
+            "${file}"
+    )" || return 1
+
+    local jqFilter='.streams[] | select(.codec_type == "audio") | .tags | with_entries(.key |= ascii_downcase) | .isrc'
+    jqResult="$(jq -r "${jqFilter}" <<<"${probe}")"
+
+    if [[ "${jqResult}" == 'null' ]]; then
+        error "failed to find ISRC for ${file}"
+        return 1
+    fi
+    echo "${jqResult}"
+}
+
+set_lyric_file_name() {
+    local file="$1"
+    if [[ ! "${file}" =~ ${MUSIC_EXTENSION_REGEX} ]]; then
+        echo "${file} is not a music file"
+        return 1
+    fi
+
+    echo "${file%.opus}.lrc"
+}
+
+is_valid_lrc() {
+    local file="$1"
+
+    local valid=1
+    while read -r line; do
+        [[ "${#line}" -eq 0 ]] && continue
+        if [[ "${line}" != '['* ]]; then
+            valid=1
+            break
+        fi
+        valid=0
+    done <"${file}"
+
+    return ${valid}
+}

lib/deezer.sh

@@ -0,0 +1,48 @@
+#!/usr/bin/env bash
+
+# many functions are invoked via variables
+# shellcheck disable=SC2329
+
+get_deezer_isrc_response() {
+    local isrc="$1"
+    if [[ -z "${isrc}" ]]; then
+        error "missing isrc"
+        return 1
+    fi
+
+    cache_command \
+        curl \
+        --silent \
+        --retry 3 \
+        "https://api.deezer.com/track/isrc:${isrc}"
+}
+
+get_deezer_url() {
+    local isrc="$1"
+    if [[ -z "${isrc}" ]]; then
+        error "missing isrc"
+        return 1
+    fi
+
+    local deezerResponse=''
+    deezerResponse="$(get_deezer_isrc_response "${isrc}")" || return 1
+
+    local jqResult=''
+    jqResult="$(jq -r .link <<<"${deezerResponse}")"
+
+    if ! jq_result_valid "${jqResult}"; then
+        error "could not get link from deezer for ${isrc}"
+        return 1
+    fi
+
+    echo "${jqResult}"
+}
+
+download_with_deezer() {
+    local isrc="$1"
+    local output="$2"
+    download_with_librelyrics \
+        "${isrc}" \
+        "${output}" \
+        deezer
+}

lib/lrclib.sh

@@ -0,0 +1,56 @@
+#!/usr/bin/env bash
+
+# many functions are invoked via variables
+# shellcheck disable=SC2329
+
+get_lrclib_api_response() {
+    local isrc="$1"
+    local deezerResponse=''
+    deezerResponse="$(get_deezer_isrc_response "${isrc}")" || return 1
+
+    # get metadata from deezer
+    local deezerMetadata=(
+        "track .title"
+        "artist .artist.name"
+        "album .album.title"
+        "duration .duration"
+    )
+    for data in "${deezerMetadata[@]}"; do
+        IFS=' ' read -r env jqFilter <<<"${data}"
+        jqResult="$(jq -r "${jqFilter}" <<<"${deezerResponse}")"
+        if ! jq_result_valid "${jqResult}"; then
+            error "could not determine lrclib ${env} for ${isrc}"
+            return 1
+        fi
+        declare "${env}=${jqResult}"
+        debug "${env}=${jqResult}"
+    done
+
+    # variables assigned above
+    # shellcheck disable=SC2154
+    cache_command \
+        curl \
+        "https://lrclib.net/api/get" \
+        --silent \
+        --get \
+        --data-urlencode "track_name=${track}" \
+        --data-urlencode "artist_name=${artist}" \
+        --data-urlencode "album_name=${album}" \
+        --data-urlencode "duration=${duration}"
+}
+
+download_with_lrclib() {
+    local isrc="$1"
+    local output="$2"
+
+    # get lrclib ID
+    local lrclibResponse syncedLyrics
+    lrclibResponse="$(get_lrclib_api_response "${isrc}")"
+    syncedLyrics="$(jq -r .syncedLyrics <<<"${lrclibResponse}")"
+    if ! jq_result_valid "${syncedLyrics}"; then
+        error "could not get lyrics for ${isrc}"
+        return 1
+    fi
+
+    echo "${syncedLyrics}" >"${output}"
+}

lib/options.sh

@@ -0,0 +1,178 @@
+#!/usr/bin/env bash
+
+# many functions are invoked via variables
+# shellcheck disable=SC2329
+
+usage() {
+    echo "${PROGNAME} [options]
+
+OPTIONS:
+  -d, --dir       process files in directory
+  -r, --recurse   recursively process directory
+  -f, --file      process one file
+  -n, --dry-run   do not actually add synced lyrics,
+                  just show the files that would be processed
+  -e, --eval      output bash functions that can be directly processed
+                  by eval for use with testing this script.
+  -i, --ignore    ignore errors, and continue attempting to find lyrics
+                  even in the case of errors
+  -h, --help      show this output
+  --debug         extra information useful for debugging"
+    exit "${EXIT_CODE:-1}"
+}
+
+set_default_options() {
+    DIR=${DIR:-}
+    FILE=${FILE:-}
+    RECURSE=${RECURSE:-false}
+    DRY_RUN=${DRY_RUN:-false}
+    IGNORE=${IGNORE:-false}
+    DEBUG=${DEBUG:-false}
+
+    # cache
+    CACHE_HOME="${XDG_CACHE_HOME:-"${HOME}/.cache"}"
+    CACHE_DIR="${CACHE_HOME}/add-synced-lyrics"
+    if [[ ! -d "${CACHE_DIR}" ]]; then
+        mkdir "${CACHE_DIR}" || return 1
+    fi
+
+    readonly MUSIC_EXTENSION_REGEX='.*\.(opus)$'
+}
+
+process_options() {
+    while [[ $# -gt 0 ]]; do
+        option="$1"
+        value="${2:-}"
+        case "${option}" in
+        -d | --dir)
+            if [[ ! -d "${value}" ]]; then
+                echo "directory ${value} does not exist"
+                usage
+            fi
+            readonly DIR="${value}"
+            shift 2
+            ;;
+        -r | --recurse)
+            readonly RECURSE=true
+            shift 1
+            ;;
+        -n | --dry-run)
+            readonly DRY_RUN=true
+            shift 1
+            ;;
+        -i | --ignore)
+            readonly IGNORE=true
+            shift 1
+            ;;
+        --debug)
+            readonly DEBUG=true
+            shift 1
+            ;;
+        -e | --eval)
+            output_eval_functions
+            exit 0
+            ;;
+        -f | --file)
+            if [[ ! -f "${value}" ]]; then
+                echo "file ${value} does not exist"
+                usage
+            fi
+            readonly FILE="${value}"
+            shift 2
+            ;;
+        -h | --help)
+            EXIT_CODE=0 usage
+            ;;
+        *)
+            echo "bad option"
+            usage
+            ;;
+        esac
+    done
+
+    if [[ "${DIR:-}${FILE:-}" == '' ]]; then
+        echo "either --dir or --file must be used"
+        usage
+    fi
+
+    if [[ -n "${DIR}" && -n "${FILE}" ]]; then
+        echo "cannot process both directory and file"
+        usage
+    fi
+
+    if [[ "${RECURSE}" == true && -n "${FILE}" ]]; then
+        echo "--recurse can only be used with --dir"
+        usage
+    fi
+}
+
+_determine_inputs_fd() {
+    local fdCmd=(
+        fd
+        --type f
+        "${MUSIC_EXTENSION_REGEX}"
+        "${DIR}"
+    )
+
+    if [[ "${RECURSE}" == false ]]; then
+        fdCmd+=(--max-depth 1)
+    fi
+
+    mapfile -t INPUTS < <("${fdCmd[@]}" | sort)
+}
+
+_determine_inputs_find() {
+    local findCmd=(
+        find
+        "${DIR}"
+    )
+
+    if [[ "${RECURSE}" == false ]]; then
+        findCmd+=(-maxdepth 1)
+    fi
+
+    findCmd+=(
+        -regextype posix-extended
+        -regex "${MUSIC_EXTENSION_REGEX}"
+        -type f
+    )
+
+    mapfile -t INPUTS < <("${findCmd[@]}" | sort)
+}
+
+_determine_inputs_bash() {
+    local unsortedInputs=()
+    local pattern="${DIR}/*"
+    shopt -s nullglob globstar || return 1
+
+    [[ "${RECURSE}" == true ]] && pattern="${DIR}/**/*"
+    mapfile -t unsortedInputs < <(printf '%s\n' ${pattern})
+
+    local filteredInputs=()
+    for input in "${unsortedInputs[@]}"; do
+        [[ "${input}" =~ ${MUSIC_EXTENSION_REGEX} ]] || continue
+        filteredInputs+=("${input}")
+    done
+
+    mapfile -t INPUTS < <(printf '%s\n' "${filteredInputs[@]}" | sort)
+}
+
+determine_inputs() {
+    INPUTS=()
+    if [[ -n "${FILE}" ]]; then
+        INPUTS=("${FILE}")
+    elif have_cmd fd; then
+        _determine_inputs_fd || return 1
+    elif have_cmd find; then
+        _determine_inputs_find || return 1
+    else
+        _determine_inputs_bash || return 1
+    fi
+
+    if [[ "${#INPUTS[@]}" -eq 0 ]]; then
+        echo "no inputs found, something is wrong"
+        exit 1
+    fi
+
+    readonly INPUTS
+}

lib/spotify.sh

@@ -0,0 +1,71 @@
+#!/usr/bin/env bash
+
+# many functions are invoked via variables
+# shellcheck disable=SC2329
+
+get_spotify_url() {
+    local isrc="$1"
+    if [[ -z "${isrc}" ]]; then
+        error "missing isrc"
+        return 1
+    fi
+
+    local search="isrc:${isrc}"
+    local response
+    response="$(
+        cache_command \
+            spotify \
+            search \
+            --track \
+            "${search}" \
+            --limit 1 \
+            --raw
+    )" || return 1
+
+    local tags=(
+        spotifyISRC
+        spotifyURL
+    )
+    # unset tag values
+    for tag in "${tags[@]}"; do
+        declare "${tag}="
+    done
+
+    local jqFilter='.items[] | "\(.external_ids.isrc)|\(.external_urls.spotify)"'
+    local jqOutput="$(jq -r "${jqFilter}" <<<"${response}")"
+
+    # compare tags versus the reference for each line
+    local foundMatching=false
+    while read -r line; do
+        IFS='|' read -r "${tags[@]}" <<<"${line}"
+
+        for tag in "${tags[@]}"; do
+            declare -n spotifyTagValue="${tag}"
+            debug "${tag}=${spotifyTagValue}"
+        done
+
+        # shellcheck disable=SC2154
+        if [[ "${spotifyISRC,,}" == "${isrc,,}" ]]; then
+            foundMatching=true
+            break
+        fi
+    done <<<"${jqOutput}"
+
+    if [[ "${foundMatching}" == false ]]; then
+        error "could not find matching spotify track for ${isrc}"
+        return 1
+    fi
+
+    # shellcheck disable=SC2154
+    echo "${spotifyURL}"
+    return 0
+}
+
+download_with_spotify() {
+    local isrc="$1"
+    local output="$2"
+    download_with_librelyrics \
+        "${isrc}" \
+        "${output}" \
+        spotify
+}

test-add-synced-lyrics.sh

@@ -7,8 +7,12 @@ set -u
 
 readonly THIS_DIR="$(dirname "$(readlink -f "$0")")"
 readonly TEST_DIR="${THIS_DIR}/test-dir"
-readonly TEST_FILE_1="${TEST_DIR}/03 - Back Burner.opus"
+# lyrics exist for this song
-readonly TEST_FILE_2="${TEST_DIR}/subdir/05 - Composure.opus"
+readonly GOOD_SONG="${TEST_DIR}/back burner.opus"
+readonly GOOD_LYRICS="${GOOD_SONG//.opus/.lrc}"
+# lyrics do not exist for this song
+readonly BAD_SONG="${TEST_DIR}/subdir/avalanche.opus"
+readonly BAD_LYRICS="${BAD_SONG//.opus/.lrc}"
 readonly PROG="${THIS_DIR}/add-synced-lyrics.sh"
 
 test_bad_input() {
@@ -59,31 +63,42 @@ test_determine_inputs_recurse() {
 }
 
 test_file_dry() {
-    "${PROG}" --file "${TEST_FILE_1}" --dry-run || return 1
+    "${PROG}" --file "${GOOD_SONG}" --dry-run
-
-    return 0
 }
 
 test_directory_dry() {
-    "${PROG}" --dir "${TEST_DIR}" --dry-run || return 1
+    "${PROG}" --dir "${TEST_DIR}" --dry-run
-
-    return 0
 }
 
 test_directory_recurse_dry() {
-    "${PROG}" --dir "${TEST_DIR}" --recurse --dry-run || return 1
+    "${PROG}" --dir "${TEST_DIR}" --recurse --dry-run
+}
+
+test_good_file() {
+    "${PROG}" --file "${GOOD_SONG}" || return 1
+    test -f "${GOOD_LYRICS}"
+}
+
+test_bad_file() {
+    "${PROG}" --file "${BAD_SONG}" && return 1
+    ! test -f "${BAD_LYRICS}"
+}
+
+test_directory_recurse() {
+    setup_test_data || return 1
+    # this test should fail since it includes the bad file
+    "${PROG}" --dir "${TEST_DIR}" --recurse && return 1
 
     return 0
 }
 
-test_file() {
+test_directory_recurse_ignore() {
-    "${PROG}" --file "${TEST_FILE_1}" || return 1
+    setup_test_data || return 1
-    test -f "${TEST_FILE_1//.opus/.lrc}"
+    "${PROG}" --dir "${TEST_DIR}" --recurse --ignore && return 1
-}
+    test -f "${GOOD_LYRICS}" || return 1
+    test -f "${BAD_LYRICS}" && return 1
 
-test_directory_recurse() {
+    return 0
-    "${PROG}" --dir "${TEST_DIR}" --recurse || return 1
-    test -f "${TEST_FILE_2//.opus/.lrc}"
 }
 
 setup_test_data() {
@@ -96,15 +111,13 @@ setup_test_data() {
         -i anullsrc=channel_layout=stereo:sample_rate=48000
         -c:a libopus
         -t 5
-        -metadata ALBUM="Messengers"
-        -metadata ARTIST="August Burns Red"
     )
     "${ffmpegCmd[@]}" \
-        -metadata TITLE="Back Burner" \
+        -metadata ISRC=USTN10700139 \
-        "${TEST_FILE_1}" || return 1
+        "${GOOD_SONG}" || return 1
     "${ffmpegCmd[@]}" \
-        -metadata TITLE="Composure" \
+        -metadata ISRC=US5261822978 \
-        "${TEST_FILE_2}" || return 1
+        "${BAD_SONG}" || return 1
 }
 
 TESTS=(
@@ -115,8 +128,10 @@ TESTS=(
     test_directory_dry
     test_directory_recurse_dry
     test_file_dry
-    test_file
+    test_good_file
+    test_bad_file
     test_directory_recurse
+    test_directory_recurse_ignore
 )
 
 # make sure no test is accidentally missed
@@ -135,6 +150,7 @@ for test in "${TESTS[@]}"; do
             "${test}"
         ) 2>&1
     )"; then
+        echo
         echo "!! ${test} failed !!"
         echo "${testOutput}"
         exit 1