'use strict';

const config = require('config');
const bhttp = require('bhttp');
const blake2 = require('blake2');

const logger = require('../logger')(__filename);
const limiter = require('../limiter').items;

async function fetchItem(url, attempt, post, host) {
    async function retry(error) {
        logger.warn(`Failed to fetch '${url}', ${attempt < config.fetch.retries ? 'retrying' : 'giving up'}: ${error.message} (${post ? post.permalink : 'no post'})`);

        if (attempt < config.fetch.retries) {
            return fetchItem(url, attempt + 1, post);
        }

        return null;
    }

    try {
        const res = await limiter.schedule(async () => bhttp.get(url));

        if (!res.statusCode === 200) {
            throw new Error(`Response not OK for '${url}', HTTP code '${res.status}'`);
        }

        if (!Buffer.isBuffer(res.body)) {
            throw new Error(`Unexpected response for '${url}' (${res.status}): ${res.body}`);
        }

        logger.debug(`Fetched '${host ? host.url : url}' (${post ? post.permalink : 'no post'})`);

        const hash = blake2.createHash('blake2b', { digestLength: 24 });
        hash.update(res.body);
        const contentHash = hash.digest('hex');

        return Object.assign(res.body, { hash: contentHash });
    } catch (error) {
        return retry(error);
    }
}

module.exports = fetchItem;