import { timingSafeEqual } from "node:crypto";
import { ShareHttpError } from "@/lib/share/http-error";

export type BotSenderProfile = {
  id: string;
  username: string;
  globalName: string | null;
  avatarUrl: string | null;
};

const FORBIDDEN_PROFILE_FIELDS = [
  "displayName",
  "avatarUrl",
  "authorName",
  "authorAvatarUrl",
] as const;

export function hasValidShareBotBearer(
  authorization: string | null,
  expected: string,
) {
  if (!authorization?.startsWith("Bearer ")) return false;
  const suppliedBytes = Buffer.from(authorization.slice("Bearer ".length));
  const expectedBytes = Buffer.from(expected);
  return suppliedBytes.length === expectedBytes.length &&
    timingSafeEqual(suppliedBytes, expectedBytes);
}

export function rejectSuppliedBotProfile(formData: FormData) {
  for (const field of FORBIDDEN_PROFILE_FIELDS) {
    if (formData.has(field)) {
      throw new ShareHttpError(
        `Profile field ${field} must not be supplied`,
        400,
      );
    }
  }
}

export async function resolveBotSenderProfile(
  discordId: string,
  lookup: (discordId: string) => Promise<BotSenderProfile | null>,
) {
  let profile: BotSenderProfile | null;
  try {
    profile = await lookup(discordId);
  } catch {
    throw new ShareHttpError("Discord profile lookup is unavailable", 503);
  }
  if (!profile) {
    throw new ShareHttpError(
      "Discord sender was not found in the configured guild",
      422,
    );
  }
  return profile;
}

export function buildBotShareResponse({
  baseUrl,
  share,
  displayName,
  avatarUrl,
  imagePath,
}: {
  baseUrl: string;
  share: { id: string; createdAt: Date };
  displayName: string;
  avatarUrl: string | null;
  imagePath: string | null;
}) {
  return {
    success: true as const,
    share: {
      id: share.id,
      url: `${baseUrl}/share/${share.id}`,
      author: { displayName, avatarUrl },
      imageUrl: imagePath ? `${baseUrl}${imagePath}` : null,
      createdAt: share.createdAt.toISOString(),
    },
  };
}