import type { ClientOAuth2Options } from '@n8n/client-oauth2';
import { ClientOAuth2 } from '@n8n/client-oauth2';
import Csrf from 'csrf';
import express from 'express';
import pkceChallenge from 'pkce-challenge';
import * as qs from 'querystring';
import get from 'lodash/get';
import omit from 'lodash/omit';
import set from 'lodash/set';
import split from 'lodash/split';
import unset from 'lodash/unset';
import { Credentials } from 'n8n-core';
import type { WorkflowExecuteMode, INodeCredentialsDetails } from 'n8n-workflow';
import { jsonStringify } from 'n8n-workflow';
import { resolve as pathResolve } from 'path';

import * as Db from '@/Db';
import * as ResponseHelper from '@/ResponseHelper';
import type { ICredentialsDb } from '@/Interfaces';
import { RESPONSE_ERROR_MESSAGES, TEMPLATES_DIR } from '@/constants';
import {
	CredentialsHelper,
	getCredentialForUser,
	getCredentialWithoutUser,
} from '@/CredentialsHelper';
import type { OAuthRequest } from '@/requests';
import { ExternalHooks } from '@/ExternalHooks';
import config from '@/config';
import { getInstanceBaseUrl } from '@/UserManagement/UserManagementHelper';
import { Container } from 'typedi';

import * as WorkflowExecuteAdditionalData from '@/WorkflowExecuteAdditionalData';
import { Logger } from '@/Logger';

export const oauth2CredentialController = express.Router();

const restEndpoint = config.getEnv('endpoints.rest');

/**
 * GET /oauth2-credential/auth
 *
 * Authorize OAuth Data
 */
oauth2CredentialController.get(
	'/auth',
	ResponseHelper.send(async (req: OAuthRequest.OAuth1Credential.Auth): Promise<string> => {
		const { id: credentialId } = req.query;

		if (!credentialId) {
			throw new ResponseHelper.BadRequestError('Required credential ID is missing');
		}

		const credential = await getCredentialForUser(credentialId, req.user);

		if (!credential) {
			Container.get(Logger).error('Failed to authorize OAuth2 due to lack of permissions', {
				userId: req.user.id,
				credentialId,
			});
			throw new ResponseHelper.NotFoundError(RESPONSE_ERROR_MESSAGES.NO_CREDENTIAL);
		}

		const additionalData = await WorkflowExecuteAdditionalData.getBase(req.user.id);

		const credentialType = credential.type;

		const mode: WorkflowExecuteMode = 'internal';
		const timezone = config.getEnv('generic.timezone');
		const credentialsHelper = Container.get(CredentialsHelper);
		const decryptedDataOriginal = await credentialsHelper.getDecrypted(
			additionalData,
			credential as INodeCredentialsDetails,
			credentialType,
			mode,
			timezone,
			true,
		);

		// At some point in the past we saved hidden scopes to credentials (but shouldn't)
		// Delete scope before applying defaults to make sure new scopes are present on reconnect
		// Generic Oauth2 API is an exception because it needs to save the scope
		const genericOAuth2 = ['oAuth2Api', 'googleOAuth2Api', 'microsoftOAuth2Api'];
		if (
			decryptedDataOriginal?.scope &&
			credentialType.includes('OAuth2') &&
			!genericOAuth2.includes(credentialType)
		) {
			delete decryptedDataOriginal.scope;
		}

		const oauthCredentials = credentialsHelper.applyDefaultsAndOverwrites(
			additionalData,
			decryptedDataOriginal,
			credentialType,
			mode,
			timezone,
		);

		const token = new Csrf();
		// Generate a CSRF prevention token and send it as an OAuth2 state string
		const csrfSecret = token.secretSync();
		const state = {
			token: token.create(csrfSecret),
			cid: req.query.id,
		};
		const stateEncodedStr = Buffer.from(JSON.stringify(state)).toString('base64');

		const scopes = get(oauthCredentials, 'scope', 'openid') as string;
		const oAuthOptions: ClientOAuth2Options = {
			clientId: get(oauthCredentials, 'clientId') as string,
			clientSecret: get(oauthCredentials, 'clientSecret', '') as string,
			accessTokenUri: get(oauthCredentials, 'accessTokenUrl', '') as string,
			authorizationUri: get(oauthCredentials, 'authUrl', '') as string,
			redirectUri: `${getInstanceBaseUrl()}/${restEndpoint}/oauth2-credential/callback`,
			scopes: split(scopes, ','),
			scopesSeparator: scopes.includes(',') ? ',' : ' ',
			state: stateEncodedStr,
		};
		const authQueryParameters = get(oauthCredentials, 'authQueryParameters', '') as string;
		if (authQueryParameters) {
			oAuthOptions.query = qs.parse(authQueryParameters);
		}

		await Container.get(ExternalHooks).run('oauth2.authenticate', [oAuthOptions]);

		const oAuthObj = new ClientOAuth2(oAuthOptions);

		// Encrypt the data
		const credentials = new Credentials(
			credential as INodeCredentialsDetails,
			credentialType,
			credential.nodesAccess,
		);
		decryptedDataOriginal.csrfSecret = csrfSecret;

		if (oauthCredentials.grantType === 'pkce') {
			const { code_verifier, code_challenge } = pkceChallenge();
			oAuthOptions.query = {
				...oAuthOptions.query,
				code_challenge,
				code_challenge_method: 'S256',
			};
			decryptedDataOriginal.codeVerifier = code_verifier;
		}

		credentials.setData(decryptedDataOriginal);
		const newCredentialsData = credentials.getDataToSave() as unknown as ICredentialsDb;

		// Add special database related data
		newCredentialsData.updatedAt = new Date();

		// Update the credentials in DB
		await Db.collections.Credentials.update(req.query.id, newCredentialsData);

		Container.get(Logger).verbose('OAuth2 authorization url created for credential', {
			userId: req.user.id,
			credentialId,
		});

		return oAuthObj.code.getUri();
	}),
);

const renderCallbackError = (res: express.Response, message: string, reason?: string) =>
	res.render('oauth-error-callback', { error: { message, reason } });

/**
 * GET /oauth2-credential/callback
 *
 * Verify and store app code. Generate access tokens and store for respective credential.
 */

oauth2CredentialController.get(
	'/callback',
	async (req: OAuthRequest.OAuth2Credential.Callback, res: express.Response) => {
		try {
			// realmId it's currently just use for the quickbook OAuth2 flow
			const { code, state: stateEncoded } = req.query;
			if (!code || !stateEncoded) {
				return renderCallbackError(
					res,
					'Insufficient parameters for OAuth2 callback.',
					`Received following query parameters: ${JSON.stringify(req.query)}`,
				);
			}

			let state;
			try {
				state = JSON.parse(Buffer.from(stateEncoded, 'base64').toString()) as {
					cid: string;
					token: string;
				};
			} catch (error) {
				return renderCallbackError(res, 'Invalid state format returned');
			}

			const credential = await getCredentialWithoutUser(state.cid);

			if (!credential) {
				const errorMessage = 'OAuth2 callback failed because of insufficient permissions';
				Container.get(Logger).error(errorMessage, {
					userId: req.user?.id,
					credentialId: state.cid,
				});
				return renderCallbackError(res, errorMessage);
			}

			const additionalData = await WorkflowExecuteAdditionalData.getBase(state.cid);

			const mode: WorkflowExecuteMode = 'internal';
			const timezone = config.getEnv('generic.timezone');
			const credentialsHelper = Container.get(CredentialsHelper);
			const decryptedDataOriginal = await credentialsHelper.getDecrypted(
				additionalData,
				credential as INodeCredentialsDetails,
				credential.type,
				mode,
				timezone,
				true,
			);
			const oauthCredentials = credentialsHelper.applyDefaultsAndOverwrites(
				additionalData,
				decryptedDataOriginal,
				credential.type,
				mode,
				timezone,
			);

			const token = new Csrf();
			if (
				decryptedDataOriginal.csrfSecret === undefined ||
				!token.verify(decryptedDataOriginal.csrfSecret as string, state.token)
			) {
				const errorMessage = 'The OAuth2 callback state is invalid!';
				Container.get(Logger).debug(errorMessage, {
					userId: req.user?.id,
					credentialId: state.cid,
				});
				return renderCallbackError(res, errorMessage);
			}

			let options: Partial<ClientOAuth2Options> = {};

			const scopes = get(oauthCredentials, 'scope', 'openid') as string;
			const oAuth2Parameters: ClientOAuth2Options = {
				clientId: get(oauthCredentials, 'clientId') as string,
				clientSecret: get(oauthCredentials, 'clientSecret', '') as string,
				accessTokenUri: get(oauthCredentials, 'accessTokenUrl', '') as string,
				authorizationUri: get(oauthCredentials, 'authUrl', '') as string,
				redirectUri: `${getInstanceBaseUrl()}/${restEndpoint}/oauth2-credential/callback`,
				scopes: split(scopes, ','),
				scopesSeparator: scopes.includes(',') ? ',' : ' ',
				ignoreSSLIssues: get(oauthCredentials, 'ignoreSSLIssues') as boolean,
			};

			if (oauthCredentials.grantType === 'pkce') {
				options = {
					body: { code_verifier: decryptedDataOriginal.codeVerifier },
				};
			} else if ((get(oauthCredentials, 'authentication', 'header') as string) === 'body') {
				options = {
					body: {
						client_id: get(oauthCredentials, 'clientId') as string,
						client_secret: get(oauthCredentials, 'clientSecret', '') as string,
					},
				};
				// @ts-ignore
				delete oAuth2Parameters.clientSecret;
			}

			await Container.get(ExternalHooks).run('oauth2.callback', [oAuth2Parameters]);

			const oAuthObj = new ClientOAuth2(oAuth2Parameters);

			const queryParameters = req.originalUrl.split('?').splice(1, 1).join('');

			const oauthToken = await oAuthObj.code.getToken(
				`${oAuth2Parameters.redirectUri as string}?${queryParameters}`,
				// @ts-ignore
				options,
			);

			if (Object.keys(req.query).length > 2) {
				set(oauthToken.data, 'callbackQueryString', omit(req.query, 'state', 'code'));
			}

			if (oauthToken === undefined) {
				const errorMessage = 'Unable to get OAuth2 access tokens!';
				Container.get(Logger).error(errorMessage, {
					userId: req.user?.id,
					credentialId: state.cid,
				});
				return renderCallbackError(res, errorMessage);
			}

			if (decryptedDataOriginal.oauthTokenData) {
				// Only overwrite supplied data as some providers do for example just return the
				// refresh_token on the very first request and not on subsequent ones.
				Object.assign(decryptedDataOriginal.oauthTokenData, oauthToken.data);
			} else {
				// No data exists so simply set
				decryptedDataOriginal.oauthTokenData = oauthToken.data;
			}

			unset(decryptedDataOriginal, 'csrfSecret');

			const credentials = new Credentials(
				credential as INodeCredentialsDetails,
				credential.type,
				credential.nodesAccess,
			);
			credentials.setData(decryptedDataOriginal);
			const newCredentialsData = credentials.getDataToSave() as unknown as ICredentialsDb;
			// Add special database related data
			newCredentialsData.updatedAt = new Date();
			// Save the credentials in DB
			await Db.collections.Credentials.update(state.cid, newCredentialsData);
			Container.get(Logger).verbose('OAuth2 callback successful for new credential', {
				userId: req.user?.id,
				credentialId: state.cid,
			});

			return res.sendFile(pathResolve(TEMPLATES_DIR, 'oauth-callback.html'));
		} catch (error) {
			return renderCallbackError(
				res,
				(error as Error).message,
				// eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
				'body' in error ? jsonStringify(error.body) : undefined,
			);
		}
	},
);