// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
import { Hub } from '@aws-amplify/core';
import {
	CustomMutations,
	CustomQueries,
	CustomSubscriptions,
	EnumTypes,
	ModelTypes,
	addSchemaToClient,
} from '@aws-amplify/data-schema/runtime';

import {
	V6Client,
	__amplify,
	__apiKey,
	__authMode,
	__authToken,
	__endpoint,
	__headers,
	getInternals,
} from '../types';

import { isApiGraphQLConfig } from './utils/runtimeTypeGuards/isApiGraphQLProviderConfig';
import { isConfigureEventWithResourceConfig } from './utils/runtimeTypeGuards/isConfigureEventWithResourceConfig';
import { cancel, graphql, isCancelError } from './v6';
import { ClientGenerationParams } from './types';

/**
 * @private
 *
 * Creates a client that can be used to make GraphQL requests, using a provided `AmplifyClassV6`
 * compatible context object for config and auth fetching.
 *
 * @param params
 * @returns
 */
export function generateClient<
	T extends Record<any, any> = never,
	Options extends ClientGenerationParams = ClientGenerationParams,
>(params: Options): V6Client<T, Options> {
	const client = {
		[__amplify]: params.amplify,
		[__authMode]: params.authMode,
		[__authToken]: params.authToken,
		[__apiKey]: 'apiKey' in params ? params.apiKey : undefined,
		[__endpoint]: 'endpoint' in params ? params.endpoint : undefined,
		[__headers]: params.headers,
		graphql,
		cancel,
		isCancelError,
		models: emptyProperty as ModelTypes<never>,
		enums: emptyProperty as EnumTypes<never>,
		queries: emptyProperty as CustomQueries<never>,
		mutations: emptyProperty as CustomMutations<never>,
		subscriptions: emptyProperty as CustomSubscriptions<never>,
	} as any;

	const apiGraphqlConfig = params.amplify.getConfig().API?.GraphQL;

	if (client[__endpoint]) {
		if (!client[__authMode]) {
			throw new Error(
				'generateClient() requires an explicit `authMode` when `endpoint` is provided.',
			);
		}
		if (client[__authMode] === 'apiKey' && !client[__apiKey]) {
			throw new Error(
				"generateClient() requires an explicit `apiKey` when `endpoint` is provided and `authMode = 'apiKey'`.",
			);
		}
	}

	if (!client[__endpoint]) {
		if (isApiGraphQLConfig(apiGraphqlConfig)) {
			addSchemaToClient(client, apiGraphqlConfig, getInternals);
		} else {
			// This happens when the `Amplify.configure()` call gets evaluated after the `generateClient()` call.
			//
			// Cause: when the `generateClient()` and the `Amplify.configure()` calls are located in
			// different source files, script bundlers may randomly arrange their orders in the production
			// bundle.
			//
			// With the current implementation, the `client.models` instance created by `generateClient()`
			// will be rebuilt on every `Amplify.configure()` call that's provided with a valid GraphQL
			// provider configuration.
			//
			// TODO: revisit, and reverify this approach when enabling multiple clients for multi-endpoints
			// configuration.
			generateModelsPropertyOnAmplifyConfigure(client);
		}
	}

	return client as any;
}

const generateModelsPropertyOnAmplifyConfigure = (clientRef: any) => {
	Hub.listen('core', coreEvent => {
		if (!isConfigureEventWithResourceConfig(coreEvent.payload)) {
			return;
		}

		const apiGraphQLConfig = coreEvent.payload.data.API?.GraphQL;

		if (isApiGraphQLConfig(apiGraphQLConfig)) {
			addSchemaToClient(clientRef, apiGraphQLConfig, getInternals);
		}
	});
};

const emptyProperty = new Proxy(
	{},
	{
		get() {
			throw new Error(
				'Client could not be generated. This is likely due to `Amplify.configure()` not being called prior to `generateClient()` or because the configuration passed to `Amplify.configure()` is missing GraphQL provider configuration.',
			);
		},
	},
);