import { betterFetch } from "@better-fetch/fetch";
import { APIError } from "better-call";
import { decodeJwt, decodeProtectedHeader, importJWK, jwtVerify } from "jose";
import type { OAuthProvider, ProviderOptions } from "@better-auth/core/oauth2";
import {
	refreshAccessToken,
	createAuthorizationURL,
	validateAuthorizationCode,
} from "@better-auth/core/oauth2";
export interface AppleProfile {
	/**
	 * The subject registered claim identifies the principal that’s the subject
	 * of the identity token. Because this token is for your app, the value is
	 * the unique identifier for the user.
	 */
	sub: string;
	/**
	 * A String value representing the user's email address.
	 * The email address is either the user's real email address or the proxy
	 * address, depending on their status private email relay service.
	 */
	email: string;
	/**
	 * A string or Boolean value that indicates whether the service verifies
	 * the email. The value can either be a string ("true" or "false") or a
	 * Boolean (true or false). The system may not verify email addresses for
	 * Sign in with Apple at Work & School users, and this claim is "false" or
	 * false for those users.
	 */
	email_verified: true | "true";
	/**
	 * A string or Boolean value that indicates whether the email that the user
	 * shares is the proxy address. The value can either be a string ("true" or
	 * "false") or a Boolean (true or false).
	 */
	is_private_email: boolean;
	/**
	 * An Integer value that indicates whether the user appears to be a real
	 * person. Use the value of this claim to mitigate fraud. The possible
	 * values are: 0 (or Unsupported), 1 (or Unknown), 2 (or LikelyReal). For
	 * more information, see ASUserDetectionStatus. This claim is present only
	 * in iOS 14 and later, macOS 11 and later, watchOS 7 and later, tvOS 14
	 * and later. The claim isn’t present or supported for web-based apps.
	 */
	real_user_status: number;
	/**
	 * The user’s full name in the format provided during the authorization
	 * process.
	 */
	name: string;
	/**
	 * The URL to the user's profile picture.
	 */
	picture: string;
	user?: AppleNonConformUser;
}

/**
 * This is the shape of the `user` query parameter that Apple sends the first
 * time the user consents to the app.
 * @see https://developer.apple.com/documentation/signinwithapplerestapi/request-an-authorization-to-the-sign-in-with-apple-server./
 */
export interface AppleNonConformUser {
	name: {
		firstName: string;
		lastName: string;
	};
	email: string;
}

export interface AppleOptions extends ProviderOptions<AppleProfile> {
	clientId: string;
	appBundleIdentifier?: string;
	audience?: string | string[];
}

export const apple = (options: AppleOptions) => {
	const tokenEndpoint = "https://appleid.apple.com/auth/token";
	return {
		id: "apple",
		name: "Apple",
		async createAuthorizationURL({ state, scopes, redirectURI }) {
			const _scope = options.disableDefaultScope ? [] : ["email", "name"];
			options.scope && _scope.push(...options.scope);
			scopes && _scope.push(...scopes);
			const url = await createAuthorizationURL({
				id: "apple",
				options,
				authorizationEndpoint: "https://appleid.apple.com/auth/authorize",
				scopes: _scope,
				state,
				redirectURI,
				responseMode: "form_post",
				responseType: "code id_token",
			});
			return url;
		},
		validateAuthorizationCode: async ({ code, codeVerifier, redirectURI }) => {
			return validateAuthorizationCode({
				code,
				codeVerifier,
				redirectURI,
				options,
				tokenEndpoint,
			});
		},
		async verifyIdToken(token, nonce) {
			if (options.disableIdTokenSignIn) {
				return false;
			}
			if (options.verifyIdToken) {
				return options.verifyIdToken(token, nonce);
			}
			const decodedHeader = decodeProtectedHeader(token);
			const { kid, alg: jwtAlg } = decodedHeader;
			if (!kid || !jwtAlg) return false;
			const publicKey = await getApplePublicKey(kid);
			const { payload: jwtClaims } = await jwtVerify(token, publicKey, {
				algorithms: [jwtAlg],
				issuer: "https://appleid.apple.com",
				audience:
					options.audience && options.audience.length
						? options.audience
						: options.appBundleIdentifier
							? options.appBundleIdentifier
							: options.clientId,
				maxTokenAge: "1h",
			});
			["email_verified", "is_private_email"].forEach((field) => {
				if (jwtClaims[field] !== undefined) {
					jwtClaims[field] = Boolean(jwtClaims[field]);
				}
			});
			if (nonce && jwtClaims.nonce !== nonce) {
				return false;
			}
			return !!jwtClaims;
		},
		refreshAccessToken: options.refreshAccessToken
			? options.refreshAccessToken
			: async (refreshToken) => {
					return refreshAccessToken({
						refreshToken,
						options: {
							clientId: options.clientId,
							clientKey: options.clientKey,
							clientSecret: options.clientSecret,
						},
						tokenEndpoint: "https://appleid.apple.com/auth/token",
					});
				},
		async getUserInfo(token) {
			if (options.getUserInfo) {
				return options.getUserInfo(token);
			}
			if (!token.idToken) {
				return null;
			}
			const profile = decodeJwt<AppleProfile>(token.idToken);
			if (!profile) {
				return null;
			}
			const name = token.user
				? `${token.user.name?.firstName} ${token.user.name?.lastName}`
				: profile.name || profile.email;
			const emailVerified =
				typeof profile.email_verified === "boolean"
					? profile.email_verified
					: profile.email_verified === "true";
			const enrichedProfile = {
				...profile,
				name,
			};
			const userMap = await options.mapProfileToUser?.(enrichedProfile);
			return {
				user: {
					id: profile.sub,
					name: enrichedProfile.name,
					emailVerified: emailVerified,
					email: profile.email,
					...userMap,
				},
				data: enrichedProfile,
			};
		},
		options,
	} satisfies OAuthProvider<AppleProfile>;
};

export const getApplePublicKey = async (kid: string) => {
	const APPLE_BASE_URL = "https://appleid.apple.com";
	const JWKS_APPLE_URI = "/auth/keys";
	const { data } = await betterFetch<{
		keys: Array<{
			kid: string;
			alg: string;
			kty: string;
			use: string;
			n: string;
			e: string;
		}>;
	}>(`${APPLE_BASE_URL}${JWKS_APPLE_URI}`);
	if (!data?.keys) {
		throw new APIError("BAD_REQUEST", {
			message: "Keys not found",
		});
	}
	const jwk = data.keys.find((key) => key.kid === kid);
	if (!jwk) {
		throw new Error(`JWK with kid ${kid} not found`);
	}
	return await importJWK(jwk, jwk.alg);
};
