const UserError = require('vn-loopback/util/user-error');
const fs = require('fs-extra');
const fastCsv = require("fast-csv");
const axios = require('axios');
const path = require('path');
const { pipeline } = require('stream/promises');

module.exports = Self => {
	Self.remoteMethodCtx('syncData', {
		description: 'Sync schema data from external provider',
		accessType: 'WRITE',
		returns: {
			type: 'object',
			root: true
		},
		http: {
			path: `/syncData`,
			verb: 'POST'
		}
	});
	
	Self.syncData = async ctx => {
		const models = Self.app.models;
		let tx;
		try {
			const tables = await models.TableMultiConfig.find();
			if (!tables?.length) throw new UserError(`No tables to sync`);

			const floricodeConfig = await models.FloricodeConfig.findOne();
			if (!floricodeConfig) throw new UserError(`Floricode service is not configured`);

			const token = await getToken(floricodeConfig);
			for (const table of tables) {
				const data = await getData(floricodeConfig.url, table.method, token);
				if (!data) continue;

				tx = await Self.beginTransaction({});
				const options = {transaction: tx, userId: ctx.req.accessToken.userId};

				await Self.rawSql(`DELETE FROM edi.??`, [table.toTable]);

				const ws = fs.createWriteStream(path.join(__dirname, `/${table.toTable}.csv`));
				await pipeline(fastCsv.write(data, { delimiter: ';' }), ws);
				const templatePath = path.join(__dirname, `./syncSql/${table.toTable}.sql`);
				const sqlTemplate = await fs.readFile(templatePath, 'utf8');
				await Self.rawSql(sqlTemplate, [ws.path], options);
				await fs.remove(ws.path);
				await table.updateAttribute('updated', Date.vnNew(), options);
				await tx.commit();
			}
		} catch (e) {
			if (tx) await tx.rollback();
			throw e;
		}
	};

	async function getToken(floricodeConfig) {
		const response = await axios.post(`${floricodeConfig.url}/oauth/token`, {
			grant_type: 'client_credentials',
			client_id: floricodeConfig.user,
			client_secret: floricodeConfig.password
		}, {
			headers: {
				'Content-Type': 'application/x-www-form-urlencoded'
			}
		});
		return response.data.access_token;
	}

	async function getData(url, method, token) {
		let data = [];
		let count = 0;
		const maxCount = await getCount(url, method, token);
		 while (count < maxCount) {
			const request = await axios.get(`${url}/v2/${method}?$skip=${count}`, {
				headers: {
					'Authorization': `Bearer ${token}`
				}
			});
			data.push(...request.data.value);
			count += request.data.value.length;
		}
		return data;
	}

	async function getCount(url, method, token) {
		const request = await axios.get(`${url}/v2/${method}?$count=true`, {
			headers: {
				'Authorization': `Bearer ${token}`
			}
		});
		return request.data["@odata.count"];
	}
};