'use strict';

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

async function fetchPredata() {
    const data = {
        limit: 0,
        remaining: 0,
    };

    data.setRemaining = (remaining) => {
        data.remaining = remaining;
    };

    const res = await fetch('https://api.imgur.com/3/credits', {
        headers: {
            Authorization: `Client-ID ${config.methods.imgur.clientId}`,
        },
    });

    if (res.ok) {
        const body = await res.json();

        if (body.success) {
            data.limit = body.data.UserLimit;
            data.remaining = body.data.UserRemaining;
        }
    }

    return data;
}

async function imgurImageApi(host, post, { predata }) {
    if (predata.remaining === 10) { // keep a buffer
        throw new Error(`Reached Imgur API rate limit with source '${host.url}'`);
    }

    const res = await fetch(`https://api.imgur.com/3/image/${host.id}`, {
        headers: {
            Authorization: `Client-ID ${config.methods.imgur.clientId}`,
        },
    });

    const rateRemaining = Number(res.headers.get('x-ratelimit-userremaining'));

    if (rateRemaining) {
        predata.setRemaining(rateRemaining);
    }

    if (!res.ok) {
        throw new Error(`Imgur API returned HTTP ${res.status} for source '${host.url}'`);
    }

    const { data } = await res.json();

    if (res.status !== 200) {
        throw new Error(`Could not fetch info for imgur image '${host.id}': ${data.error}`);
    }

    return {
        album: null,
        items: [{
            id: data.id,
            url: data.animated ? data.mp4 : data.link,
            title: data.title,
            description: data.description,
            type: data.animated ? 'video/mp4' : data.type,
            datetime: new Date(data.datetime * 1000),
            original: data,
        }],
    };
}

async function imgurImage(host, post, context) {
    return imgurImageApi(host, post, context);
}

module.exports = {
    fetchInfo: imgurImage,
    fetchPredata,
};