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.remoteMethod('syncData', {
		description: 'Sync schema data from external provider',
		accessType: 'WRITE',
		returns: {
			type: 'object',
			root: true
		},
		http: {
			path: `/syncData`,
			verb: 'POST'
		}
	});

	Self.syncData = async options => {
		const models = Self.app.models;
		const myOptions = {};
		if (typeof options == 'object')
            Object.assign(myOptions, options);
		let tx, ws;
		try {
			const floricodeConfig = await models.FloricodeConfig.findOne({}, myOptions);
			if (!floricodeConfig) throw new UserError(`Floricode service is not configured`);

			const tables = await models.TableMultiConfig.find({}, myOptions);
			if (!tables?.length) throw new UserError(`No tables to sync`);

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

				if (!myOptions.transaction) {
					tx = await Self.beginTransaction({});
					myOptions.transaction = tx;
				}

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

				await fs.remove(ws.path);
				await table.updateAttribute('updated', Date.vnNew(), myOptions);
				if (tx) {
					await tx.commit();
					delete myOptions.transaction;
				}
			}
		} catch (e) {
			if (tx) await tx.rollback();
			if (await fs.pathExists(ws?.path))
				await fs.remove(ws?.path);
			throw e;
		}
	};

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

	Self.getData = async function (url, method, token) {
		let data = [];
		let count = 0;
		const maxCount = (await Self.get(`${url}/v2/${method}?$count=true`, token))["@odata.count"];
		 while (count < maxCount) {
			const response = await Self.get(`${url}/v2/${method}?$skip=${count}`, token)
			data.push(...response.value);
			count += response.value.length;
		}
		return data;
	};

	Self.get = async function get(url, token) {
		return (await axios.get(url, { headers: { Authorization: `Bearer ${token}` } })).data;
	};
};