web/src/decrypt/utils.ts

import {IAudioMetadata} from "music-metadata-browser";
import ID3Writer from "browser-id3-writer";
import MetaFlac from "metaflac-js";

export const FLAC_HEADER = [0x66, 0x4C, 0x61, 0x43];
export const MP3_HEADER = [0x49, 0x44, 0x33];
export const OGG_HEADER = [0x4F, 0x67, 0x67, 0x53];
export const M4A_HEADER = [0x66, 0x74, 0x79, 0x70];
export const WMA_HEADER = [
    0x30, 0x26, 0xB2, 0x75, 0x8E, 0x66, 0xCF, 0x11,
    0xA6, 0xD9, 0x00, 0xAA, 0x00, 0x62, 0xCE, 0x6C,
]
export const WAV_HEADER = [0x52, 0x49, 0x46, 0x46]
export const AAC_HEADER = [0xFF, 0xF1]
export const AudioMimeType: { [key: string]: string } = {
    mp3: "audio/mpeg",
    flac: "audio/flac",
    m4a: "audio/mp4",
    ogg: "audio/ogg",
    wma: "audio/x-ms-wma",
    wav: "audio/x-wav"
};


export function BytesHasPrefix(data: Uint8Array, prefix: number[]): boolean {
    if (prefix.length > data.length) return false
    return prefix.every((val, idx) => {
        return val === data[idx];
    })
}


export function SniffAudioExt(data: Uint8Array, fallback_ext: string = "mp3"): string {
    if (BytesHasPrefix(data, MP3_HEADER)) return "mp3"
    if (BytesHasPrefix(data, FLAC_HEADER)) return "flac"
    if (BytesHasPrefix(data, OGG_HEADER)) return "ogg"
    if (data.length >= 4 + M4A_HEADER.length &&
        BytesHasPrefix(data.slice(4), M4A_HEADER)) return "m4a"
    if (BytesHasPrefix(data, WAV_HEADER)) return "wav"
    if (BytesHasPrefix(data, WMA_HEADER)) return "wma"
    if (BytesHasPrefix(data, AAC_HEADER)) return "aac"
    return fallback_ext;
}

export function GetArrayBuffer(obj: Blob): Promise<ArrayBuffer> {
    if (!!obj.arrayBuffer) return obj.arrayBuffer()
    return new Promise((resolve, reject) => {
        const reader = new FileReader();
        reader.onload = (e) => {
            const rs = e.target?.result
            if (!rs) {
                reject("read file failed")
            } else {
                resolve(rs as ArrayBuffer)
            }
        };
        reader.readAsArrayBuffer(obj);
    });
}

export function GetCoverFromFile(metadata: IAudioMetadata): string {
    if (metadata.common?.picture && metadata.common.picture.length > 0) {
        return URL.createObjectURL(new Blob(
            [metadata.common.picture[0].data],
            {type: metadata.common.picture[0].format}
        ));
    }
    return "";
}

export interface IMusicMetaBasic {
    title: string
    artist?: string
}

export function GetMetaFromFile(filename: string, exist_title?: string, exist_artist?: string, separator = "-")
    : IMusicMetaBasic {
    const meta: IMusicMetaBasic = {title: exist_title ?? "", artist: exist_artist}

    const items = filename.split(separator);
    if (items.length > 1) {
        if (!meta.artist) meta.artist = items[0].trim();
        if (!meta.title) meta.title = items[1].trim();
    } else if (items.length === 1) {
        if (!meta.title) meta.title = items[0].trim();
    }
    return meta
}

export async function GetImageFromURL(src: string):
    Promise<{ mime: string; buffer: ArrayBuffer; url: string } | undefined> {
    try {
        const resp = await fetch(src);
        const mime = resp.headers.get("Content-Type");
        if (mime?.startsWith("image/")) {
            const buffer = await resp.arrayBuffer();
            const url = URL.createObjectURL(new Blob([buffer], {type: mime}))
            return {buffer, url, mime}
        }
    } catch (e) {
        console.warn(e)
    }
}


export interface IMusicMeta {
    title: string
    artists?: string[]
    album?: string
    picture?: ArrayBuffer
    picture_desc?: string
}

export function WriteMetaToMp3(audioData: Buffer, info: IMusicMeta, original: IAudioMetadata) {
    const writer = new ID3Writer(audioData);

    // reserve original data
    const frames = original.native['ID3v2.4'] || original.native['ID3v2.3'] || original.native['ID3v2.2'] || []
    frames.forEach(frame => {
        if (frame.id !== 'TPE1' && frame.id !== 'TIT2' && frame.id !== 'TALB') {
            try {
                writer.setFrame(frame.id, frame.value)
            } catch (e) {
            }
        }
    })

    const old = original.common
    writer.setFrame('TPE1', old?.artists || info.artists || [])
        .setFrame('TIT2', old?.title || info.title)
        .setFrame('TALB', old?.album || info.album || "");
    if (info.picture) {
        writer.setFrame('APIC', {
            type: 3,
            data: info.picture,
            description: info.picture_desc || "Cover",
        })
    }
    return writer.addTag();
}

export function WriteMetaToFlac(audioData: Buffer, info: IMusicMeta, original: IAudioMetadata) {
    const writer = new MetaFlac(audioData)
    const old = original.common
    if (!old.title && !old.album && old.artists) {
        writer.setTag("TITLE=" + info.title)
        writer.setTag("ALBUM=" + info.album)
        if (info.artists) {
            writer.removeTag("ARTIST")
            info.artists.forEach(artist => writer.setTag("ARTIST=" + artist))
        }
    }

    if (info.picture) {
        writer.importPictureFromBuffer(Buffer.from(info.picture))
    }
    return writer.save()
}