'use strict';

const fs = require('fs-extra');
const path = require('path');
const fetch = require('node-fetch');

function saveToDisk(buffer, item, index, filename, post, user) {
    const stream = fs.createWriteStream(filename);

    return new Promise((resolve, reject) => {
        buffer.body.pipe(stream).on('error', error => {
            reject(error);
        }).on('finish', () => {
            console.log(`Fetched and saved ${filename}`);

            resolve(filename);
        });
    });
};

function fetchItem(item, index, post, user) {
    return fetch(item.url).then(res => {
        return res.ok ? res : Promise.reject(`Failed to fetch ${item.url}`);
    });
};

module.exports = function(posts, user) {
    return Promise.all(posts.map(post => {
        const filepath = post.content.album ? `output/${user}/${post.content.album.datetime} - ${post.content.album.id} - ${post.title}/` : `output/${user}/`;

        return Promise.resolve().then(() => {
            if(post.content.album) {
                return fs.ensureDir(filepath);
            };
        }).then(() => {
            return Promise.all(post.content.items.map((item, index) => {
                return fetchItem(item, index, post, user).then(buffer => Object.assign(item, {buffer}));
            }));
        }).then(items => {
            return Promise.all(items.map((item, index) => {
                const filename = post.content.album ? `${filepath}${index + 1} - ${item.id}.jpg` : `${filepath}${item.datetime} - ${item.id}.jpg`;

                return saveToDisk(item.buffer, item, index, filename, post, user)
            }));
        });
    }));
};