const https = require('https');
const fs = require('fs-extra');
const path = require('path');
const uuid = require('uuid');

module.exports = Self => {
    Self.remoteMethod('downloadImages', {
        description: 'Returns last entries',
        accessType: 'WRITE',
        returns: {
            type: ['Object'],
            root: true
        },
        http: {
            path: `/downloadImages`,
            verb: 'POST'
        }
    });

    Self.downloadImages = async() => {
        const models = Self.app.models;
        const container = await models.TempContainer.container('salix-image');
        const tempPath = path.join(container.client.root, container.name);
        const maxAttempts = 3;

        const images = await Self.find({
            where: {attempts: {eq: maxAttempts}}
        });

        for (let image of images) {
            const currentStamp = Date.vnNew().getTime();
            const updatedStamp = image.updated.getTime();
            const graceTime = Math.abs(currentStamp - updatedStamp);
            const maxTTL = 3600 * 48 * 1000; // 48 hours in ms;

            if (graceTime >= maxTTL)
                await Self.destroyById(image.itemFk);
        }

        download();

        async function download() {
            const image = await Self.findOne({
                where: {url: {neq: null}, attempts: {lt: maxAttempts}},
                order: 'priority, attempts, updated'
            });

            if (!image) return;

            const fileName = `${uuid.v4()}.png`;
            const filePath = path.join(tempPath, fileName);
            const imageUrl = image.url.replace('http://', 'https://');

            https.get(imageUrl, async response => {
                if (response.statusCode != 200) {
                    const error = new Error(`Could not download the image. Status code ${response.statusCode}`);

                    return await errorHandler(image.itemFk, error, filePath);
                }

                const writeStream = fs.createWriteStream(filePath);
                writeStream.on('open', () => response.pipe(writeStream));
                writeStream.on('error', async error =>
                    await errorHandler(image.itemFk, error, filePath));
                writeStream.on('finish', () => writeStream.end());

                writeStream.on('close', async function() {
                    try {
                        await models.Image.registerImage('catalog', filePath, fileName, image.itemFk);
                        await image.destroy();

                        download();
                    } catch (error) {
                        await errorHandler(image.itemFk, error, filePath);
                    }
                });
            }).on('error', async error => {
                await errorHandler(image.itemFk, error, filePath);
            });
        }

        async function errorHandler(rowId, error, filePath) {
            try {
                const row = await Self.findById(rowId);

                if (!row) return;

                if (row.attempts < maxAttempts) {
                    await row.updateAttributes({
                        error: error,
                        attempts: row.attempts + 1,
                        updated: Date.vnNew()
                    });
                }

                if (filePath && fs.existsSync(filePath))
                    await fs.unlink(filePath);

                download();
            } catch (err) {
                throw new Error(`Image download failed: ${err}`);
            }
        }
    };
};