'use strict';

const fetch = require('node-fetch');
const mime = require('mime');

function scrapeGallery(data) {
    const oldestDate = Math.min(...data.gifs.map(gif => gif.createDate));

    return {
        album: {
            id: data.id,
            datetime: new Date(oldestDate * 1000),
        },
        items: data.gifs.map(gif => ({
            id: gif.id,
            url: gif.urls.hd,
            description: gif.tags.join(', '),
            type: mime.getType(gif.urls.hd),
            datetime: new Date(gif.createDate * 1000),
            original: gif,
        })),
    };
}

async function fetchGallery(galleryId) {
    const res = await fetch(`https://api.redgifs.com/v2/gallery/${galleryId}`);
    const data = await res.json();

    if (!data.gifs) {
        return null;
    }

    return scrapeGallery(data);
}

async function redgifs(host) {
    const res = await fetch(`https://api.redgifs.com/v2/gifs/${host.id.toLowerCase()}`);
    const data = await res.json();

    if (data.errorMessage) {
        throw new Error(`RedGifs API returned error for source '${host.url}' (${res.status}): ${data.errorMessage.description}`);
    }

    if (data.id && data.gifs) {
        return scrapeGallery(data);
    }

    if (!data.gif) {
        return null;
    }

    if (data.gif.gallery) {
        return fetchGallery(data.gif.gallery);
    }

    return {
        album: null,
        items: [{
            id: data.gif.id,
            url: data.gif.urls.hd,
            description: data.gif.tags.join(', '),
            type: mime.getType(new URL(data.gif.urls.hd).pathname),
            datetime: new Date(data.gif.createDate * 1000),
            original: data.gif,
        }],
    };
}

module.exports = redgifs;