RestLibraryUtils.kt

    /**
     * For given track/album/etc. parameters or just artist or just title, build a filename to store AA:<br></br>
     * - for streams return path<br></br>
     * - for just title, returns getNameWithoutNumber for path if > 10 (thus, title is ignored)<br></br>
     * - if we have title + artists, returns "artist - title"<br></br>
     * - if we have just artist, returns "artist"<br></br>
     * - if we have just album, return "album"<br></br>
     * - otherwise returns "artist - album"<br></br>
     * @param artistOrName either artist name or any entity name as needed. This may be the album name for Unknown album (album=null in this case)
     * @param fileType used to check if this is stream
     * @param sb should be set to zero length and should be returned with sanitization
     * @return sanitized base filename, or null on failures
     */
    // THREADING: any
    fun buildAAFileName(
        title: CharSequence?, album: CharSequence?, artistOrName: CharSequence?, path: String?,
        fileType: Int, sb: StringBuilder
    ): StringBuilder? {
        if(LOG) Log.w(TAG, "buildAAFileName title=$title album=$album artistOrName=$artistOrName path=$path fileType=$fileType")

        sb.setLength(0)

        if(isStream(fileType)) { // Streams always use own art name approach (sanitized uri)
            if(aa_per_stream_track && !title.isNullOrEmpty() && !artistOrName.isNullOrEmpty()) {
                // Use track based logic
            } else {
                if(path.isNullOrEmpty()) {
                    if(LOG) Log.e(TAG, "buildAAFileName FAIL isStream !path")
                    return null
                }
                sb.append(path)
                if(LOG) Log.w(TAG, "buildAAFileName isStream =>$sb")
                return PathUtils.sanitizeFilenameMutate(sb)
            }
        }

        val albumEmpty = album.isNullOrEmpty()
        val artistOrNameEmpty = artistOrName.isNullOrEmpty()
        val titleEmpty = title.isNullOrEmpty()

        if(albumEmpty && artistOrNameEmpty) {
            if(titleEmpty && path.isNullOrEmpty()) {
                if(LOG) Log.e(TAG, "buildAAFileName FAIL albumEmpty artistOrNameEmpty titleEmpty path is empty")
                return null
            }

            // Try to extract larger name from path as we have nothing in album/artist
            // NOTE: title is ignored here. Keeping it this way for legacy
            val pathWithoutNumber = PathUtils.getNameWithoutNumber(path)
            if(!pathWithoutNumber.isNullOrEmpty()) {
                sb.append(title)
                return PathUtils.sanitizeFilenameMutate(sb)
            }

            // We may have path made just from numbers. In this case use it as is. It's guaranteed to be non-empty
            sb.append(path)
            return PathUtils.sanitizeFilenameMutate(sb)
        } else if(albumEmpty) {
            //  artistEmpty=true can't be here
            if(titleEmpty) { // We have just artist. It's pointless to add " - " to just artist
                sb.append(artistOrName)
                return PathUtils.sanitizeFilenameMutate(sb)
            }
            sb.append(artistOrName).append(" - ").append(title) // REVISIT: title may be empty
            return PathUtils.sanitizeFilenameMutate(sb)
        } else if(artistOrNameEmpty) {
            sb.append(album)
            return PathUtils.sanitizeFilenameMutate(sb)
        }
        sb.append(artistOrName).append(" - ").append(album) // Album is not empty - checked above

        return PathUtils.sanitizeFilenameMutate(sb)
    }