refactor(discord): split send pipeline

src/discord/send.permissions.ts

@@ -0,0 +1,169 @@
+import { RequestClient } from "@buape/carbon";
+import type {
+  APIChannel,
+  APIGuild,
+  APIGuildMember,
+  APIRole,
+} from "discord-api-types/v10";
+import {
+  ChannelType,
+  PermissionFlagsBits,
+  Routes,
+} from "discord-api-types/v10";
+
+import { loadConfig } from "../config/config.js";
+import type { RetryConfig } from "../infra/retry.js";
+import { resolveDiscordAccount } from "./accounts.js";
+import type {
+  DiscordPermissionsSummary,
+  DiscordReactOpts,
+} from "./send.types.js";
+import { normalizeDiscordToken } from "./token.js";
+
+const PERMISSION_ENTRIES = Object.entries(PermissionFlagsBits).filter(
+  ([, value]) => typeof value === "bigint",
+) as Array<[string, bigint]>;
+
+type DiscordClientOpts = {
+  token?: string;
+  accountId?: string;
+  rest?: RequestClient;
+  retry?: RetryConfig;
+  verbose?: boolean;
+};
+
+function resolveToken(params: {
+  explicit?: string;
+  accountId: string;
+  fallbackToken?: string;
+}) {
+  const explicit = normalizeDiscordToken(params.explicit);
+  if (explicit) return explicit;
+  const fallback = normalizeDiscordToken(params.fallbackToken);
+  if (!fallback) {
+    throw new Error(
+      `Discord bot token missing for account "${params.accountId}" (set discord.accounts.${params.accountId}.token or DISCORD_BOT_TOKEN for default).`,
+    );
+  }
+  return fallback;
+}
+
+function resolveRest(token: string, rest?: RequestClient) {
+  return rest ?? new RequestClient(token);
+}
+
+function resolveDiscordRest(opts: DiscordClientOpts) {
+  const cfg = loadConfig();
+  const account = resolveDiscordAccount({ cfg, accountId: opts.accountId });
+  const token = resolveToken({
+    explicit: opts.token,
+    accountId: account.accountId,
+    fallbackToken: account.token,
+  });
+  return resolveRest(token, opts.rest);
+}
+
+function addPermissionBits(base: bigint, add?: string) {
+  if (!add) return base;
+  return base | BigInt(add);
+}
+
+function removePermissionBits(base: bigint, deny?: string) {
+  if (!deny) return base;
+  return base & ~BigInt(deny);
+}
+
+function bitfieldToPermissions(bitfield: bigint) {
+  return PERMISSION_ENTRIES.filter(([, value]) => (bitfield & value) === value)
+    .map(([name]) => name)
+    .sort();
+}
+
+export function isThreadChannelType(channelType?: number) {
+  return (
+    channelType === ChannelType.GuildNewsThread ||
+    channelType === ChannelType.GuildPublicThread ||
+    channelType === ChannelType.GuildPrivateThread
+  );
+}
+
+async function fetchBotUserId(rest: RequestClient) {
+  const me = (await rest.get(Routes.user("@me"))) as { id?: string };
+  if (!me?.id) {
+    throw new Error("Failed to resolve bot user id");
+  }
+  return me.id;
+}
+
+export async function fetchChannelPermissionsDiscord(
+  channelId: string,
+  opts: DiscordReactOpts = {},
+): Promise<DiscordPermissionsSummary> {
+  const rest = resolveDiscordRest(opts);
+  const channel = (await rest.get(Routes.channel(channelId))) as APIChannel;
+  const channelType = "type" in channel ? channel.type : undefined;
+  const guildId = "guild_id" in channel ? channel.guild_id : undefined;
+  if (!guildId) {
+    return {
+      channelId,
+      permissions: [],
+      raw: "0",
+      isDm: true,
+      channelType,
+    };
+  }
+
+  const botId = await fetchBotUserId(rest);
+  const [guild, member] = await Promise.all([
+    rest.get(Routes.guild(guildId)) as Promise<APIGuild>,
+    rest.get(Routes.guildMember(guildId, botId)) as Promise<APIGuildMember>,
+  ]);
+
+  const rolesById = new Map<string, APIRole>(
+    (guild.roles ?? []).map((role) => [role.id, role]),
+  );
+  const everyoneRole = rolesById.get(guildId);
+  let base = 0n;
+  if (everyoneRole?.permissions) {
+    base = addPermissionBits(base, everyoneRole.permissions);
+  }
+  for (const roleId of member.roles ?? []) {
+    const role = rolesById.get(roleId);
+    if (role?.permissions) {
+      base = addPermissionBits(base, role.permissions);
+    }
+  }
+
+  let permissions = base;
+  const overwrites =
+    "permission_overwrites" in channel
+      ? (channel.permission_overwrites ?? [])
+      : [];
+  for (const overwrite of overwrites) {
+    if (overwrite.id === guildId) {
+      permissions = removePermissionBits(permissions, overwrite.deny ?? "0");
+      permissions = addPermissionBits(permissions, overwrite.allow ?? "0");
+    }
+  }
+  for (const overwrite of overwrites) {
+    if (member.roles?.includes(overwrite.id)) {
+      permissions = removePermissionBits(permissions, overwrite.deny ?? "0");
+      permissions = addPermissionBits(permissions, overwrite.allow ?? "0");
+    }
+  }
+  for (const overwrite of overwrites) {
+    if (overwrite.id === botId) {
+      permissions = removePermissionBits(permissions, overwrite.deny ?? "0");
+      permissions = addPermissionBits(permissions, overwrite.allow ?? "0");
+    }
+  }
+
+  return {
+    channelId,
+    guildId,
+    permissions: bitfieldToPermissions(permissions),
+    raw: permissions.toString(),
+    isDm: false,
+    channelType,
+  };
+}