ini𝖔 𝕞𝐚𝔢 b𝖁𝖘𝖋𝖗𝖆𝕊t commit

src/downloader/song.ts

@@ -0,0 +1,128 @@
+import { appleMusicApi } from "../api/index.js";
+import * as log from "../log.js";
+import type { SongAttributes } from "../api/types/appleMusic/attributes.js";
+import hls, { Item } from "parse-hls";
+import axios from "axios";
+// TODO: remove
+import { select } from "@inquirer/prompts";
+
+// ugliest type ever
+// this library is so bad
+// i wish pain on the person who wrote this /j :smile:
+type HLS = ReturnType<typeof hls.default.parse>;
+
+// TODO: whole big thing, and a somewhat big issue
+// some files can just Not be downloaded
+// this is because only the fairplay (com.apple.streamingkeydelivery) key is present
+// and no other drm schemes exist..
+// however... there is still widevine ones ???? just tucked away... REALLY WELL
+// https://github.com/glomatico/gamdl/blob/main/gamdl/downloader_song_legacy.py#L27
+// bullshit, i tell you.
+// havent had this issue with the small pool i tested before late 2024. what ????
+// i don't get it.
+// i just tried another thing from 2022 ro 2023 and it worked fine
+
+// SUPER TODO: turn this all into a streaminfo class
+
+// this typing is dubious...
+// TODO: possibly just stop using an array; use union type on generic
+// TODO: add "legacy" fallback
+async function getStreamInfo(trackMetadata: SongAttributes<["extendedAssetUrls"]>): Promise<void> {
+    const m3u8Url = trackMetadata.extendedAssetUrls.enhancedHls;
+    const m3u8 = await axios.get(m3u8Url, { responseType: "text" });
+    const m3u8Parsed = hls.default.parse(m3u8.data);
+
+    const drmInfos = getDrmInfos(m3u8Parsed);
+    const assetInfos = getAssetInfos(m3u8Parsed);
+    const playlist = await getPlaylist(m3u8Parsed);
+    const variantId = playlist.properties[0].attributes.stableVariantId;
+    if (typeof variantId !== "string") { throw "variant id does not exist or is not a string!"; }
+    const drmIds = assetInfos[variantId]["AUDIO-SESSION-KEY-IDS"];
+
+    const widevinePssh = getWidevinePssh(drmInfos, drmIds);
+    const playreadyPssh = getPlayreadyPssh(drmInfos, drmIds);
+    const fairplayKey = getFairplayKey(drmInfos, drmIds);
+
+    log.debug("widevine pssh", widevinePssh);
+    log.debug("playready pssh", playreadyPssh);
+    log.debug("fairplay key", fairplayKey);
+}
+
+// i don't think i wanna write all of the values we need. annoying !
+type DrmInfos = { [key: string]: { [key: string]: { "URI": string } }; };
+function getDrmInfos(m3u8Data: HLS): DrmInfos {
+    // see `getAssetInfos` for the reason why this is so bad
+    // filthy. i should write my own m3u8 library that doesn't suck balls
+    for (const line of m3u8Data.lines) {
+        if (
+            line.name === "sessionData" &&
+            line.content.includes("com.apple.hls.AudioSessionKeyInfo")
+        ) {
+            const value = line.content.match(/VALUE="([^"]+)"/);
+            if (!value) { throw "could not match for value!"; }
+
+            return JSON.parse(Buffer.from(value[1], "base64").toString("utf-8"));
+        }
+    }
+
+    throw "m3u8 missing audio session key info!";
+}
+
+// TODO: remove inquery for the codec, including its library, this is for testing
+// add a config option for preferred codec ?
+async function getPlaylist(m3u8Data: HLS): Promise<Item> {
+    const masterPlaylists = m3u8Data.streamRenditions;
+    const masterPlaylist = await select({
+        message: "codec ?",
+        choices: masterPlaylists.map((playlist) => ({
+            name: playlist.properties[0].attributes.audio as string,
+            value: playlist
+        }))
+    });
+
+    return masterPlaylist;
+}
+
+// TODO: check type more strictly
+// does it really exist? we never check,,
+// i don't think i wanna write all of the values we need. annoying !
+type AssetInfos = { [key: string]: { "AUDIO-SESSION-KEY-IDS": string[]; }; }
+function getAssetInfos(m3u8Data: HLS): AssetInfos {
+    // LOL??? THIS LIBRARY IS SO BAD
+    // YOU CAN'T MAKE THIS SHIT UP
+    // https://files.catbox.moe/ac0ps4.jpg
+    for (const line of m3u8Data.lines) {
+        if (
+            line.name === "sessionData" &&
+            line.content.includes("com.apple.hls.audioAssetMetadata")
+        ) {
+            const value = line.content.match(/VALUE="([^"]+)"/);
+            if (!value) { throw "could not match for value!"; }
+
+            return JSON.parse(Buffer.from(value[1], "base64").toString("utf-8"));
+        }
+    }
+
+    throw "m3u8 missing audio asset metadata!";
+}
+
+function getDrmData(drmInfos: DrmInfos, drmIds: string[], drmKey: string): string {
+    const drmInfoEntry = drmIds.find((drmId) => {
+        const entry = drmInfos[drmId];
+        return drmId !== "1" && entry?.[drmKey];
+    });
+
+    if (drmInfoEntry === undefined) { throw `requested drm key (${drmKey}) not found!`; }
+
+    const drmInfo = drmInfos[drmInfoEntry];
+    return drmInfo[drmKey].URI; // afaik this index is 100% safe?
+}
+
+const getWidevinePssh = (drmInfos: DrmInfos, drmIds: string[]): string => getDrmData(drmInfos, drmIds, "urn:uuid:edef8ba9-79d6-4ace-a3c8-27dcd51d21ed");
+const getPlayreadyPssh = (drmInfos: DrmInfos, drmIds: string[]): string => getDrmData(drmInfos, drmIds, "com.microsoft.playready");
+const getFairplayKey = (drmInfos: DrmInfos, drmIds: string[]): string => getDrmData(drmInfos, drmIds, "com.apple.streamingkeydelivery");
+
+// TODO: remove later, this is just for testing
+log.debug(await appleMusicApi.getWebplayback("1758429584"));
+await getStreamInfo((await appleMusicApi.getSong("1758429584")).data[0].attributes);
+