wikipediaIntent.js

'use strict';
var https = require('https');

/**
 * URL prefix to download history content from Wikipedia
 */
var urlPrefix = 'https://en.wikipedia.org/w/api.php?action=query&prop=extracts&format=json&explaintext=&exsectionformat=plain&redirects=&titles=';

/**
 * Variable defining number of events to be read at one time
 */
var paginationSize = 3;

/**
 * Variable defining the length of the delimiter between events
 */
var delimiterSize = 2;




/**
 * Gets a poster prepares the speech to reply to the user.
 */
function handleFirstEventRequest(intent, session, response) {
    var daySlot = intent.slots.day;
    var repromptText = "With History Buff, you can get historical events for any day of the year.  For example, you could say today, or August thirtieth. Now, which day do you want?";
    var monthNames = ["January", "February", "March", "April", "May", "June",
                      "July", "August", "September", "October", "November", "December"
    ];
    var sessionAttributes = {};
    // Read the first 3 events, then set the count to 3
    sessionAttributes.index = paginationSize;
    var date = "";

    // If the user provides a date, then use that, otherwise use today
    // The date is in server time, not in the user's time zone. So "today" for the user may actually be tomorrow
    if (daySlot && daySlot.value) {
        date = new Date(daySlot.value);
    } else {
        date = new Date();
    }

    var prefixContent   = "For " + monthNames[date.getMonth()] + " " + date.getDate() + " ";
    var cardContent     = "For " + monthNames[date.getMonth()] + " " + date.getDate() + " ";
    var cardTitle = "Events on " + monthNames[date.getMonth()] + " " + date.getDate();

    getJsonEventsFromWikipedia(monthNames[date.getMonth()], date.getDate(), function (events) {
        var speechText = "",
            i;
        sessionAttributes.text = events;
        session.attributes = sessionAttributes;
        if (events.length == 0) {
            speechText = "There is a problem connecting to Wikipedia at this time. Please try again later.";
            cardContent = speechText;
            response.tell(speechText);
        } else {
            for (i = 0; i < paginationSize; i++) {
                cardContent = cardContent + events[i];
                speechText  = speechText + events[i];
            }
            speechText = speechText + "Wanna go deeper in history?";
            var speechOutput   = prefixContent + speechText;
            var repromptOutput = repromptText;
            response.askWithCard(speechOutput, cardTitle, cardContent);
        }
    });
}

/**
 * Gets a poster prepares the speech to reply to the user.
 */
function handleNextEventRequest(intent, session, response) {
    var cardTitle = "More events on this day in history",
        sessionAttributes = session.attributes,
        result = sessionAttributes.text,
        speechText = "",
        cardContent = "",
        repromptText = "Do you want to know more about what happened on this date?",
        i;
    if (!result) {
        speechText = "With History Buff, you can get historical events for any day of the year.  For example, you could say today, or August thirtieth. Now, which day do you want?";
        cardContent = speechText;
    } else if (sessionAttributes.index >= result.length) {
        speechText = "There are no more events for this date. Try another date by saying  get events for august thirtieth.";
        cardContent = "There are no more events for this date. Try another date by saying, get events for august thirtieth.";
    } else {
        for (i = 0; i < paginationSize; i++) {
            if (sessionAttributes.index>= result.length) {
                break;
            }
            speechText = speechText + result[sessionAttributes.index];
            cardContent = cardContent + result[sessionAttributes.index];
            sessionAttributes.index++;
        }
        if (sessionAttributes.index < result.length) {
            speechText = speechText + " Wanna go deeper in history?";
            cardContent = cardContent + " Wanna go deeper in history?";
        }
    }
    var speechOutput = speechText;
    var repromptOutput = repromptText;
    response.askWithCard(speechOutput, repromptOutput, cardTitle, cardContent);
}

function getJsonEventsFromWikipedia(day, date, eventCallback) {
    var url = urlPrefix + day + '_' + date;
    console.log("yippee requestId: " + url);

    https.get(url, function(res) {
        var body = '';

        res.on('data', function (chunk) {
            body += chunk;
        });

        res.on('end', function () {
            var stringResult = parseJson(body);
            eventCallback(stringResult);
        });
    }).on('error', function (e) {
        console.log("Got error: ", e);
    });
}

function parseJson(inputText) {
    // sizeOf (/nEvents/n) is 10
    var text = inputText.substring(inputText.indexOf("\\nEvents\\n")+10, inputText.indexOf("\\n\\n\\nBirths")),
        retArr = [],
        retString = "",
        endIndex,
        startIndex = 0;

    if (text.length == 0) {
        return retArr;
    }

    while(true) {
        endIndex = text.indexOf("\\n", startIndex+delimiterSize);
        var eventText = (endIndex == -1 ? text.substring(startIndex) : text.substring(startIndex, endIndex));
        // replace dashes returned in text from Wikipedia's API
        eventText = eventText.replace(/\\u2013\s*/g, '');
        // add comma after year so Alexa pauses before continuing with the sentence
        eventText = eventText.replace(/(^\d+)/,'$1,');
        eventText = 'In ' + eventText;
        startIndex = endIndex+delimiterSize;
        retArr.push(eventText);
        if (endIndex == -1) {
            break;
        }
    }
    if (retString != "") {
        retArr.push(retString);
    }
    retArr.reverse();
    return retArr;
}
module.exports = handleFirstEventRequest;
module.exports = handleNextEventRequest;