import { API, GraphQLResult, GRAPHQL_AUTH_MODE } from '@aws-amplify/api';
import { Auth } from '@aws-amplify/auth';
import { Cache } from '@aws-amplify/cache';
import {
	ConsoleLogger as Logger,
	Hub,
	HubCapsule,
	BackgroundProcessManager,
} from '@aws-amplify/core';
import { CONTROL_MSG as PUBSUB_CONTROL_MSG } from '@aws-amplify/pubsub';
import Observable, { ZenObservable } from 'zen-observable-ts';
import {
	InternalSchema,
	PersistentModel,
	SchemaModel,
	SchemaNamespace,
	PredicatesGroup,
	ModelPredicate,
	AuthModeStrategy,
	ErrorHandler,
	ProcessName,
	AmplifyContext,
} from '../../types';
import {
	buildSubscriptionGraphQLOperation,
	getAuthorizationRules,
	getModelAuthModes,
	getUserGroupsFromToken,
	TransformerMutationType,
	getTokenForCustomAuth,
	predicateToGraphQLFilter,
	dynamicAuthFields,
	filterFields,
	repeatedFieldInGroup,
	countFilterCombinations,
	RTFError,
	generateRTFRemediation,
} from '../utils';
import { ModelPredicateCreator } from '../../predicates';
import { validatePredicate, USER_AGENT_SUFFIX_DATASTORE } from '../../util';
import { getSubscriptionErrorType } from './errorMaps';

const logger = new Logger('DataStore');

export enum CONTROL_MSG {
	CONNECTED = 'CONNECTED',
}

export enum USER_CREDENTIALS {
	'none',
	'unauth',
	'auth',
}

type AuthorizationInfo = {
	authMode: GRAPHQL_AUTH_MODE;
	isOwner: boolean;
	ownerField?: string;
	ownerValue?: string;
};

class SubscriptionProcessor {
	private readonly typeQuery = new WeakMap<
		SchemaModel,
		[TransformerMutationType, string, string][]
	>();
	private buffer: [TransformerMutationType, SchemaModel, PersistentModel][] =
		[];
	private dataObserver!: ZenObservable.Observer<any>;

	private runningProcesses = new BackgroundProcessManager();

	constructor(
		private readonly schema: InternalSchema,
		private readonly syncPredicates: WeakMap<
			SchemaModel,
			ModelPredicate<any> | null
		>,
		private readonly amplifyConfig: Record<string, any> = {},
		private readonly authModeStrategy: AuthModeStrategy,
		private readonly errorHandler: ErrorHandler,
		private readonly amplifyContext: AmplifyContext = { Auth, API, Cache }
	) {}

	private buildSubscription(
		namespace: SchemaNamespace,
		model: SchemaModel,
		transformerMutationType: TransformerMutationType,
		userCredentials: USER_CREDENTIALS,
		cognitoTokenPayload: { [field: string]: any } | undefined,
		oidcTokenPayload: { [field: string]: any } | undefined,
		authMode: GRAPHQL_AUTH_MODE,
		filterArg: boolean = false
	): {
		opType: TransformerMutationType;
		opName: string;
		query: string;
		authMode: GRAPHQL_AUTH_MODE;
		isOwner: boolean;
		ownerField?: string;
		ownerValue?: string;
	} {
		const { aws_appsync_authenticationType } = this.amplifyConfig;
		const { isOwner, ownerField, ownerValue } =
			this.getAuthorizationInfo(
				model,
				userCredentials,
				aws_appsync_authenticationType,
				cognitoTokenPayload,
				oidcTokenPayload,
				authMode
			) || {};

		const [opType, opName, query] = buildSubscriptionGraphQLOperation(
			namespace,
			model,
			transformerMutationType,
			isOwner,
			ownerField!,
			filterArg
		);
		return { authMode, opType, opName, query, isOwner, ownerField, ownerValue };
	}

	private getAuthorizationInfo(
		model: SchemaModel,
		userCredentials: USER_CREDENTIALS,
		defaultAuthType: GRAPHQL_AUTH_MODE,
		cognitoTokenPayload: { [field: string]: any } = {},
		oidcTokenPayload: { [field: string]: any } = {},
		authMode: GRAPHQL_AUTH_MODE
	): AuthorizationInfo {
		const rules = getAuthorizationRules(model);

		// Return null if user doesn't have proper credentials for private API with IAM auth
		const iamPrivateAuth =
			authMode === GRAPHQL_AUTH_MODE.AWS_IAM &&
			rules.find(
				rule => rule.authStrategy === 'private' && rule.provider === 'iam'
			);

		if (iamPrivateAuth && userCredentials === USER_CREDENTIALS.unauth) {
			return null!;
		}

		// Group auth should take precedence over owner auth, so we are checking
		// if rule(s) have group authorization as well as if either the Cognito or
		// OIDC token has a groupClaim. If so, we are returning auth info before
		// any further owner-based auth checks.
		const groupAuthRules = rules.filter(
			rule =>
				rule.authStrategy === 'groups' &&
				['userPools', 'oidc'].includes(rule.provider)
		);

		const validGroup =
			(authMode === GRAPHQL_AUTH_MODE.AMAZON_COGNITO_USER_POOLS ||
				authMode === GRAPHQL_AUTH_MODE.OPENID_CONNECT) &&
			groupAuthRules.find(groupAuthRule => {
				// validate token against groupClaim
				const cognitoUserGroups = getUserGroupsFromToken(
					cognitoTokenPayload,
					groupAuthRule
				);
				const oidcUserGroups = getUserGroupsFromToken(
					oidcTokenPayload,
					groupAuthRule
				);

				return [...cognitoUserGroups, ...oidcUserGroups].find(userGroup => {
					return groupAuthRule.groups.find(group => group === userGroup);
				});
			});

		if (validGroup) {
			return {
				authMode,
				isOwner: false,
			};
		}

		// Owner auth needs additional values to be returned in order to create the subscription with
		// the correct parameters so we are getting the owner value from the Cognito token via the
		// identityClaim from the auth rule.
		const cognitoOwnerAuthRules =
			authMode === GRAPHQL_AUTH_MODE.AMAZON_COGNITO_USER_POOLS
				? rules.filter(
						rule =>
							rule.authStrategy === 'owner' && rule.provider === 'userPools'
				  )
				: [];

		let ownerAuthInfo: AuthorizationInfo;
		cognitoOwnerAuthRules.forEach(ownerAuthRule => {
			const ownerValue = cognitoTokenPayload[ownerAuthRule.identityClaim];

			// AuthZ for "list of owners" is handled dynamically in the subscription auth request
			// resolver. It doesn't rely on a subscription arg.
			// Only pass a subscription arg for single owner auth
			const singleOwner =
				model.fields[ownerAuthRule.ownerField]?.isArray !== true;
			const isOwnerArgRequired =
				singleOwner && !ownerAuthRule.areSubscriptionsPublic;

			if (ownerValue) {
				ownerAuthInfo = {
					authMode: GRAPHQL_AUTH_MODE.AMAZON_COGNITO_USER_POOLS,
					isOwner: isOwnerArgRequired,
					ownerField: ownerAuthRule.ownerField,
					ownerValue,
				};
			}
		});

		if (ownerAuthInfo!) {
			return ownerAuthInfo!;
		}

		// Owner auth needs additional values to be returned in order to create the subscription with
		// the correct parameters so we are getting the owner value from the OIDC token via the
		// identityClaim from the auth rule.
		const oidcOwnerAuthRules =
			authMode === GRAPHQL_AUTH_MODE.OPENID_CONNECT
				? rules.filter(
						rule => rule.authStrategy === 'owner' && rule.provider === 'oidc'
				  )
				: [];

		oidcOwnerAuthRules.forEach(ownerAuthRule => {
			const ownerValue = oidcTokenPayload[ownerAuthRule.identityClaim];

			const singleOwner =
				model.fields[ownerAuthRule.ownerField]?.isArray !== true;
			const isOwnerArgRequired =
				singleOwner && !ownerAuthRule.areSubscriptionsPublic;

			if (ownerValue) {
				ownerAuthInfo = {
					authMode: GRAPHQL_AUTH_MODE.OPENID_CONNECT,
					isOwner: isOwnerArgRequired,
					ownerField: ownerAuthRule.ownerField,
					ownerValue,
				};
			}
		});

		if (ownerAuthInfo!) {
			return ownerAuthInfo!;
		}

		// Fallback: return authMode or default auth type
		return {
			authMode: authMode || defaultAuthType,
			isOwner: false,
		};
	}

	private hubQueryCompletionListener(completed: Function, capsule: HubCapsule) {
		const {
			payload: { event },
		} = capsule;

		if (event === PUBSUB_CONTROL_MSG.SUBSCRIPTION_ACK) {
			completed();
		}
	}

	start(): [
		Observable<CONTROL_MSG>,
		Observable<[TransformerMutationType, SchemaModel, PersistentModel]>
	] {
		this.runningProcesses =
			this.runningProcesses || new BackgroundProcessManager();

		const ctlObservable = new Observable<CONTROL_MSG>(observer => {
			const promises: Promise<void>[] = [];

			// Creating subs for each model/operation combo so they can be unsubscribed
			// independently, since the auth retry behavior is asynchronous.
			let subscriptions: {
				[modelName: string]: {
					[TransformerMutationType.CREATE]: ZenObservable.Subscription[];
					[TransformerMutationType.UPDATE]: ZenObservable.Subscription[];
					[TransformerMutationType.DELETE]: ZenObservable.Subscription[];
				};
			} = {};
			let cognitoTokenPayload: { [field: string]: any },
				oidcTokenPayload: { [field: string]: any };
			let userCredentials = USER_CREDENTIALS.none;
			this.runningProcesses.add(async () => {
				try {
					// retrieving current AWS Credentials
					const credentials =
						await this.amplifyContext.Auth.currentCredentials();
					userCredentials = credentials.authenticated
						? USER_CREDENTIALS.auth
						: USER_CREDENTIALS.unauth;
				} catch (err) {
					// best effort to get AWS credentials
				}

				try {
					// retrieving current token info from Cognito UserPools
					const session = await this.amplifyContext.Auth.currentSession();
					cognitoTokenPayload = session.getIdToken().decodePayload();
				} catch (err) {
					// best effort to get jwt from Cognito
				}

				try {
					// Checking for the Cognito region in config to see if Auth is configured
					// before attempting to get federated token. We're using the Cognito region
					// because it will be there regardless of user/identity pool being present.
					const { aws_cognito_region, Auth: AuthConfig } = this.amplifyConfig;
					if (!aws_cognito_region || (AuthConfig && !AuthConfig.region)) {
						throw 'Auth is not configured';
					}

					let token;
					// backwards compatibility
					const federatedInfo = await this.amplifyContext.Cache.getItem(
						'federatedInfo'
					);
					if (federatedInfo) {
						token = federatedInfo.token;
					} else {
						const currentUser =
							await this.amplifyContext.Auth.currentAuthenticatedUser();
						if (currentUser) {
							token = currentUser.token;
						}
					}

					if (token) {
						const payload = token.split('.')[1];
						oidcTokenPayload = JSON.parse(
							Buffer.from(payload, 'base64').toString('utf8')
						);
					}
				} catch (err) {
					logger.debug('error getting OIDC JWT', err);
					// best effort to get oidc jwt
				}

				Object.values(this.schema.namespaces).forEach(namespace => {
					Object.values(namespace.models)
						.filter(({ syncable }) => syncable)
						.forEach(
							modelDefinition =>
								this.runningProcesses.isOpen &&
								this.runningProcesses.add(async () => {
									const modelAuthModes = await getModelAuthModes({
										authModeStrategy: this.authModeStrategy,
										defaultAuthMode:
											this.amplifyConfig.aws_appsync_authenticationType,
										modelName: modelDefinition.name,
										schema: this.schema,
									});

									// subscriptions are created only based on the READ auth mode(s)
									const readAuthModes = modelAuthModes.READ;

									subscriptions = {
										...subscriptions,
										[modelDefinition.name]: {
											[TransformerMutationType.CREATE]: [],
											[TransformerMutationType.UPDATE]: [],
											[TransformerMutationType.DELETE]: [],
										},
									};

									const operations = [
										TransformerMutationType.CREATE,
										TransformerMutationType.UPDATE,
										TransformerMutationType.DELETE,
									];

									const operationAuthModeAttempts = {
										[TransformerMutationType.CREATE]: 0,
										[TransformerMutationType.UPDATE]: 0,
										[TransformerMutationType.DELETE]: 0,
									};

									const predicatesGroup = ModelPredicateCreator.getPredicates(
										this.syncPredicates.get(modelDefinition)!,
										false
									);

									const addFilterArg = predicatesGroup !== undefined;

									// Retry subscriptions that failed for one of the following reasons:
									// 1. unauthorized - retry with next auth mode (if available)
									// 2. RTF error - retry without sending filter arg. (filtering will fall back to clientside)
									const subscriptionRetry = async (
										operation,
										addFilter = addFilterArg
									) => {
										const {
											opType: transformerMutationType,
											opName,
											query,
											isOwner,
											ownerField,
											ownerValue,
											authMode,
										} = this.buildSubscription(
											namespace,
											modelDefinition,
											operation,
											userCredentials,
											cognitoTokenPayload,
											oidcTokenPayload,
											readAuthModes[operationAuthModeAttempts[operation]],
											addFilter
										);

										const authToken = await getTokenForCustomAuth(
											authMode,
											this.amplifyConfig
										);

										const variables = {};

										if (addFilter && predicatesGroup) {
											variables['filter'] =
												predicateToGraphQLFilter(predicatesGroup);
										}

										if (isOwner) {
											if (!ownerValue) {
												observer.error(
													'Owner field required, sign in is needed in order to perform this operation'
												);
												return;
											}

											variables[ownerField!] = ownerValue;
										}

										logger.debug(
											`Attempting ${operation} subscription with authMode: ${
												readAuthModes[operationAuthModeAttempts[operation]]
											}`
										);

										const userAgentSuffix = USER_AGENT_SUFFIX_DATASTORE;

										const queryObservable = <
											Observable<{
												value: GraphQLResult<Record<string, PersistentModel>>;
											}>
										>(<unknown>this.amplifyContext.API.graphql({
											query,
											variables,
											...{ authMode },
											authToken,
											userAgentSuffix,
										}));

										let subscriptionReadyCallback: () => void;

										// TODO: consider onTerminate.then(() => API.cancel(...))

										subscriptions[modelDefinition.name][
											transformerMutationType
										].push(
											queryObservable
												.map(({ value }) => {
													return value;
												})
												.subscribe({
													next: ({ data, errors }) => {
														if (Array.isArray(errors) && errors.length > 0) {
															const messages = (<
																{
																	message: string;
																}[]
															>errors).map(({ message }) => message);

															logger.warn(
																`Skipping incoming subscription. Messages: ${messages.join(
																	'\n'
																)}`
															);

															this.drainBuffer();
															return;
														}

														const predicatesGroup =
															ModelPredicateCreator.getPredicates(
																this.syncPredicates.get(modelDefinition)!,
																false
															);

														// @ts-ignore
														const { [opName]: record } = data;

														// checking incoming subscription against syncPredicate.
														// once AppSync implements filters on subscriptions, we'll be
														// able to set these when establishing the subscription instead.
														// Until then, we'll need to filter inbound
														if (
															this.passesPredicateValidation(
																record,
																predicatesGroup!
															)
														) {
															this.pushToBuffer(
																transformerMutationType,
																modelDefinition,
																record
															);
														}
														this.drainBuffer();
													},
													error: async subscriptionError => {
														const {
															error: { errors: [{ message = '' } = {}] } = {
																errors: [],
															},
														} = subscriptionError;

														const isRTFError =
															// only attempt catch if a filter variable was added to the subscription query
															addFilter &&
															this.catchRTFError(
																message,
																modelDefinition,
																predicatesGroup
															);

														// Catch RTF errors
														if (isRTFError) {
															// Unsubscribe and clear subscription array for model/operation
															subscriptions[modelDefinition.name][
																transformerMutationType
															].forEach(subscription =>
																subscription.unsubscribe()
															);

															subscriptions[modelDefinition.name][
																transformerMutationType
															] = [];

															// retry subscription connection without filter
															subscriptionRetry(operation, false);
															return;
														}

														if (
															message.includes(
																PUBSUB_CONTROL_MSG.REALTIME_SUBSCRIPTION_INIT_ERROR
															) ||
															message.includes(
																PUBSUB_CONTROL_MSG.CONNECTION_FAILED
															)
														) {
															// Unsubscribe and clear subscription array for model/operation
															subscriptions[modelDefinition.name][
																transformerMutationType
															].forEach(subscription =>
																subscription.unsubscribe()
															);
															subscriptions[modelDefinition.name][
																transformerMutationType
															] = [];

															operationAuthModeAttempts[operation]++;
															if (
																operationAuthModeAttempts[operation] >=
																readAuthModes.length
															) {
																// last auth mode retry. Continue with error
																logger.debug(
																	`${operation} subscription failed with authMode: ${
																		readAuthModes[
																			operationAuthModeAttempts[operation] - 1
																		]
																	}`
																);
															} else {
																// retry with different auth mode. Do not trigger
																// observer error or error handler
																logger.debug(
																	`${operation} subscription failed with authMode: ${
																		readAuthModes[
																			operationAuthModeAttempts[operation] - 1
																		]
																	}. Retrying with authMode: ${
																		readAuthModes[
																			operationAuthModeAttempts[operation]
																		]
																	}`
																);
																subscriptionRetry(operation);
																return;
															}
														}

														logger.warn('subscriptionError', message);

														try {
															await this.errorHandler({
																recoverySuggestion:
																	'Ensure app code is up to date, auth directives exist and are correct on each model, and that server-side data has not been invalidated by a schema change. If the problem persists, search for or create an issue: https://github.com/aws-amplify/amplify-js/issues',
																localModel: null!,
																message,
																model: modelDefinition.name,
																operation,
																errorType:
																	getSubscriptionErrorType(subscriptionError),
																process: ProcessName.subscribe,
																remoteModel: null!,
																cause: subscriptionError,
															});
														} catch (e) {
															logger.error(
																'Subscription error handler failed with:',
																e
															);
														}

														if (
															typeof subscriptionReadyCallback === 'function'
														) {
															subscriptionReadyCallback();
														}

														if (
															message.includes('"errorType":"Unauthorized"') ||
															message.includes(
																'"errorType":"OperationDisabled"'
															)
														) {
															return;
														}
														observer.error(message);
													},
												})
										);

										promises.push(
											(async () => {
												let boundFunction: any;

												await new Promise(res => {
													subscriptionReadyCallback = res;
													boundFunction = this.hubQueryCompletionListener.bind(
														this,
														res
													);
													Hub.listen('api', boundFunction);
												});
												Hub.remove('api', boundFunction);
											})()
										);
									};

									operations.forEach(op => subscriptionRetry(op));
								})
						);
				});

				this.runningProcesses.isOpen &&
					this.runningProcesses.add(() =>
						Promise.all(promises).then(() => {
							observer.next(CONTROL_MSG.CONNECTED);
						})
					);
			}, 'subscription processor new subscriber');

			return this.runningProcesses.addCleaner(async () => {
				Object.keys(subscriptions).forEach(modelName => {
					subscriptions[modelName][TransformerMutationType.CREATE].forEach(
						subscription => subscription.unsubscribe()
					);
					subscriptions[modelName][TransformerMutationType.UPDATE].forEach(
						subscription => subscription.unsubscribe()
					);
					subscriptions[modelName][TransformerMutationType.DELETE].forEach(
						subscription => subscription.unsubscribe()
					);
				});
			});
		});

		const dataObservable = new Observable<
			[TransformerMutationType, SchemaModel, PersistentModel]
		>(observer => {
			this.dataObserver = observer;
			this.drainBuffer();

			return this.runningProcesses.addCleaner(async () => {
				this.dataObserver = null!;
			});
		});

		return [ctlObservable, dataObservable];
	}

	public async stop() {
		await this.runningProcesses.close();
		await this.runningProcesses.open();
	}

	private passesPredicateValidation(
		record: PersistentModel,
		predicatesGroup: PredicatesGroup<any>
	): boolean {
		if (!predicatesGroup) {
			return true;
		}

		const { predicates, type } = predicatesGroup;

		return validatePredicate(record, type, predicates);
	}

	private pushToBuffer(
		transformerMutationType: TransformerMutationType,
		modelDefinition: SchemaModel,
		data: PersistentModel
	) {
		this.buffer.push([transformerMutationType, modelDefinition, data]);
	}

	private drainBuffer() {
		if (this.dataObserver) {
			this.buffer.forEach(data => this.dataObserver.next!(data));
			this.buffer = [];
		}
	}

	/**
	 * @returns true if the service returned an RTF subscription error
	 * @remarks logs a warning with remediation instructions
	 *
	 */
	private catchRTFError(
		message: string,
		modelDefinition: SchemaModel,
		predicatesGroup: PredicatesGroup<any> | undefined
	): boolean {
		const header =
			'Backend subscriptions filtering error.\n' +
			'Subscriptions filtering will be applied clientside.\n';

		const messageErrorTypeMap = {
			'UnknownArgument: Unknown field argument filter': RTFError.UnknownField,
			'Filters exceed maximum attributes limit': RTFError.MaxAttributes,
			'Filters combination exceed maximum limit': RTFError.MaxCombinations,
			'filter uses same fieldName multiple time': RTFError.RepeatedFieldname,
			"The variables input contains a field name 'not'": RTFError.NotGroup,
			'The variables input contains a field that is not defined for input object type':
				RTFError.FieldNotInType,
		};

		const [_errorMsg, errorType] =
			Object.entries(messageErrorTypeMap).find(([errorMsg]) =>
				message.includes(errorMsg)
			) || [];

		if (errorType !== undefined) {
			const remediationMessage = generateRTFRemediation(
				errorType,
				modelDefinition,
				predicatesGroup
			);

			logger.warn(`${header}\n${message}\n${remediationMessage}`);
			return true;
		}

		return false;
	}
}

export { SubscriptionProcessor };