import React from 'react';
import AutocompleteProvider from './AutocompleteProvider';
import Q from 'q';
import 'whatwg-fetch';

import {TextualCompletion} from './Components';

const DDG_REGEX = /\/ddg\s+(.+)$/g;
const REFERRER = 'vector';

let instance = null;

export default class DuckDuckGoProvider extends AutocompleteProvider {
    constructor() {
        super(DDG_REGEX);
    }
    
    static getQueryUri(query: String) {
        return `https://api.duckduckgo.com/?q=${encodeURIComponent(query)}`
         + `&format=json&no_redirect=1&no_html=1&t=${encodeURIComponent(REFERRER)}`;
    }

    getCompletions(query: string, selection: {start: number, end: number}) {
        let {command, range} = this.getCurrentCommand(query, selection);
        if (!query || !command) {
            return Q.when([]);
        }

        return fetch(DuckDuckGoProvider.getQueryUri(command[1]), {
            method: 'GET',
        })
            .then(response => response.json())
            .then(json => {
                let results = json.Results.map(result => {
                    return {
                        completion: result.Text,
                        component: (
                            <TextualCompletion
                                title={result.Text}
                                description={result.Result} />
                        ),
                        range,
                    };
                });
                if (json.Answer) {
                    results.unshift({
                        completion: json.Answer,
                        component: (
                            <TextualCompletion
                                title={json.Answer}
                                description={json.AnswerType} />
                        ),
                        range,
                    });
                }
                if (json.RelatedTopics && json.RelatedTopics.length > 0) {
                    results.unshift({
                        completion: json.RelatedTopics[0].Text,
                        component: (
                            <TextualCompletion
                                title={json.RelatedTopics[0].Text} />
                        ),
                        range,
                    });
                }
                if (json.AbstractText) {
                    results.unshift({
                        completion: json.AbstractText,
                        component: (
                            <TextualCompletion
                                title={json.AbstractText} />
                        ),
                        range,
                    });
                }
                return results;
            });
    }

    getName() {
        return 'Results from DuckDuckGo';
    }

    static getInstance(): DuckDuckGoProvider {
        if (instance == null) {
            instance = new DuckDuckGoProvider();
        }
        return instance;
    }
}