Alexa Skill Shopping List- Python

The following Python code asks for user consent to access the Alexa Shopping List.
Once permission is granted in the companion app, the skill can get the items in customer's Shopping List and add items to the Shopping List.

def build_speechlet_response(title, output, reprompt_text, should_end_session):
    return {
        'outputSpeech': {
            'type': 'PlainText',
            'text': output
        },
        'card': {
            'type': 'Simple',
            'title': "SessionSpeechlet - " + title,
            'content': "SessionSpeechlet - " + output
        },
        'reprompt': {
            'outputSpeech': {
                'type': 'PlainText',
                'text': reprompt_text
            }
        },
        'shouldEndSession': should_end_session
    }

def build_permissions_consent_response(title, output, reprompt_text, should_end_session):
    return {
        'outputSpeech': {
            'type': 'PlainText',
            'text': output
        },
        'card': {
            'type': 'AskForPermissionsConsent',
            'permissions': [
           "read::alexa:household:list",
     "write::alexa:household:list"
     ]
        },
        'reprompt': {
            'outputSpeech': {
                'type': 'PlainText',
                'text': reprompt_text
            }
        },
        'shouldEndSession': should_end_session
    }

def build_response(session_attributes, speechlet_response):
    return {
        'version': '1.0',
        'sessionAttributes': session_attributes,
        'response': speechlet_response
    }

def handle_get_shopping_list_intent(intent, session, context):
    session_attributes = {}
    if "attributes" in session and "userInfo" in session["attributes"]:
        session_attributes["userInfo"] = session["attributes"]["userInfo"]
    card_title = "Get Shopping List Intent"
    reprompt_text = "Please ask me product question"
    should_end_session = False
    try:
        url = "https://api.amazonalexa.com:443/v2/householdlists/"
        request = urllib2.Request(url, \
                  headers = {"Authorization": "Bearer " + context["System"]["apiAccessToken"]})
        response = json.loads(urllib2.urlopen(request).read())
        alexaList = response["lists"]
        shoppingList = {}
        for item in response["lists"]:
            print(item)
            if item["name"] == "Alexa shopping list":
                shoppingList = item
        print(shoppingList)
        url = "https://api.amazonalexa.com:443"
        for item in shoppingList["statusMap"]:
            if item["status"] == "active":
                url += item["href"]
        request = urllib2.Request(url, \
                  headers = {"Authorization": "Bearer " + context["System"]["apiAccessToken"]})
        response = json.loads(urllib2.urlopen(request).read())
        print(response)
        if len(response["items"]) == 0:
            speech_output = "Currently there are no items in your Alexa Shopping List"
        else:
            item_set = Set([])
            speech_output = "Currently the following items are in your Alexa Shopping List: "
            for i in range(0, len(response["items"])):
                item_set.add(response["items"][i]["value"])
            for item in item_set:
                speech_output += item + ", "
    except urllib2.HTTPError as err:
        if err.code == 403:
            speech_output = "Please grant shopping list permissions to this skill in your Alexa app."
            return build_response({}, build_permissions_consent_response(
        card_title, speech_output, reprompt_text, should_end_session))
        else:
            speech_output = "Something went wrong while getting your shopping list"
    except:
        speech_output = "Something went wrong while getting your shopping list"
    return build_response({}, build_speechlet_response(
        card_title, speech_output, reprompt_text, should_end_session))

def handle_add_shopping_list_intent(intent, session, context):
    session_attributes = {}
    if "attributes" in session and "userInfo" in session["attributes"]:
        session_attributes["userInfo"] = session["attributes"]["userInfo"]
    card_title = "Add to Shopping List Intent"
    reprompt_text = "Please ask me product question"
    should_end_session = False
    if "value" not in intent["slots"]["product"]:
        return build_response(session_attributes, build_speechlet_response_with_directive_nointent())
    product_name = intent["slots"]["product"]["value"]
    product_name = spell_check(product_name)
    try:
        url = "https://api.amazonalexa.com:443/v2/householdlists/"
        request = urllib2.Request(url, \
                  headers = {"Authorization": "Bearer " + context["System"]["apiAccessToken"]})
        response = json.loads(urllib2.urlopen(request).read())
        alexaList = response["lists"]
        shoppingList = {}
        for item in response["lists"]:
            print(item)
            if item["name"] == "Alexa shopping list":
                shoppingList = item
        print(shoppingList)
        url = "https://api.amazonalexa.com:443"
        for item in shoppingList["statusMap"]:
            if item["status"] == "active":
                href = item["href"].replace("active", "items")
                url += href
        print(url)
        data = {"value": product_name, "status": "active"}
        #data = urllib.urlencode(data)
        request = urllib2.Request(url)
        headers = {"Authorization": "Bearer " + context["System"]["apiAccessToken"], "Content-Type": "application/json"}
        request.add_header("Content-Type", "application/json")
        request.add_header("Authorization", "Bearer " + context["System"]["apiAccessToken"])
        result = urllib2.urlopen(request, json.dumps(data))
        response = json.loads(result.read())
        print(response)
        if result.getcode() >= 200 and result.getcode() < 300:
            speech_output = product_name + " is added to your Alexa Shopping List"
        else:
            speech_output = "Something went wrong while adding " + product_name + " to your Shopping List"
    except urllib2.HTTPError as err:
        if err.code == 403:
            speech_output = "Please grant shopping list permissions to this skill in your Alexa app."
            return build_response({}, build_permissions_consent_response(
        card_title, speech_output, reprompt_text, should_end_session))
        else:
            speech_output = "Something went wrong while adding " + product_name + " to your shopping list"
    except:
        speech_output = "Something went wrong while adding " + product_name + " to your Shopping List"
    return build_response({}, build_speechlet_response(
        card_title, speech_output, reprompt_text, should_end_session))

def on_intent(intent_request, session, context):
    """ Called when the user specifies an intent for this skill """

    print("on_intent requestId=" + intent_request['requestId'] +
          ", sessionId=" + session['sessionId'])

    intent = intent_request['intent']
    intent_name = intent_request['intent']['name']

    # Dispatch to your skill's intent handlers
    if intent_name == "GetShoppingListIntent":
        return handle_get_shopping_list_intent(intent, session, context)
    elif intent_name == "AddToShoppingList":
        return handle_add_shopping_list_intent(intent, session, context)


# --------------- Main handler ------------------

def lambda_handler(event, context):
    """ Route the incoming request based on type (LaunchRequest, IntentRequest,
    etc.) The JSON body of the request is provided in the event parameter.
    """
    print("event.session.application.applicationId=" + 
          event['session']['application']['applicationId'])

    """
    Uncomment this if statement and populate with your skill's application ID to
    prevent someone else from configuring a skill that sends requests to this
    function.
    """
    # if (event['session']['application']['applicationId'] !=
    #         "amzn1.echo-sdk-ams.app.[unique-value-here]"):
    #     raise ValueError("Invalid Application ID")

    

    if event['request']['type'] == "LaunchRequest":
        return on_launch(event['request'], event['session'])
    elif event['request']['type'] == "IntentRequest":
        return on_intent(event['request'], event['session'], event['context'])
    elif event['request']['type'] == "SessionEndedRequest":
        return on_session_ended(event['request'], event['session'])

Alexa Skill Account Linking- Python

For setting up account linking in Alexa Skill, follow the steps here.
Once setup is done, and intent handler needs to be implemented in the Python code: 

# --------------- Helpers that build all of the responses ----------------------

def build_user_authentication_response():
    return {
        "version": "1.0",
        "response": {
            "outputSpeech": {
                "type": "PlainText",
                "text": " Please use the companion app to authenticate on Amazon to start using this skill"
            },
            "card": {
                "type": "LinkAccount"
            },
            "shouldEndSession": false
        },
        "sessionAttributes": {}
    }

# --------------- Method that gets called when there is an intent request ----------------------

def on_intent(intent_request, session, context):
    """ Called when the user specifies an intent for this skill """

    print("on_intent requestId=" + intent_request['requestId'] +
          ", sessionId=" + session['sessionId'])

    intent = intent_request['intent']
    intent_name = intent_request['intent']['name']
    if intent_name == "SayHello":
        return build_user_authentication_response()


# --------------- Main handler ------------------

def lambda_handler(event, context):
    """ Route the incoming request based on type (LaunchRequest, IntentRequest,
    etc.) The JSON body of the request is provided in the event parameter.
    """
    print("event.session.application.applicationId=" + 
          event['session']['application']['applicationId'])

    """
    Uncomment this if statement and populate with your skill's application ID to
    prevent someone else from configuring a skill that sends requests to this
    function.
    """
    # if (event['session']['application']['applicationId'] !=
    #         "amzn1.echo-sdk-ams.app.[unique-value-here]"):
    #     raise ValueError("Invalid Application ID")

    if event['request']['type'] == "LaunchRequest":
        return on_launch(event['request'], event['session'])
    elif event['request']['type'] == "IntentRequest":
        return on_intent(event['request'], event['session'], event['context'])
    elif event['request']['type'] == "SessionEndedRequest":
        return on_session_ended(event['request'], event['session'])

This will open a Login with Amazon screen where customers can sign in using their Amazon Account Credentials. Once logged-in successfully, the account is linked and next time onwards the user token comes as part of the session request.

Sample Request after Account Linking:

{
    "version": "1.0",
    "session": {
        "new": true,
        "sessionId": "session-id",
        "application": {
            "applicationId": "application-id"
        },
        "user": {
            "userId": "user-id",
            "accessToken": "access-token",
            "permissions": {
                "consentToken": "consent-token"
            }
        }
    },
    "context": {
        "AudioPlayer": {
            "playerActivity": "IDLE"
        },
        "Display": {},
        "System": {
            "application": {
                "applicationId": "application-id"
            },
            "user": {
                "userId": "user-id",
                "accessToken": "access-token",
                "permissions": {
                    "consentToken": "consent-token"
                }
            },
            "device": {
                "deviceId": "device-id",
                "supportedInterfaces": {
                    "AudioPlayer": {},
                    "Display": {
                        "templateVersion": "1.0",
                        "markupVersion": "1.0"
                    }
                }
            },
            "apiEndpoint": "https://api.eu.amazonalexa.com",
            "apiAccessToken": "api-access-token"
        }
    },
    "request": {
        "type": "LaunchRequest",
        "requestId": "request-id",
        "timestamp": "2018-06-03T05:22:36Z",
        "locale": "en-US",
        "shouldLinkResultBeReturned": false
    }
}

Number of ways to have breakfast

Problem:
Find the number of ways you can have breakfast in ‘n’ days, given Bread-butter can be eaten every day, Pizza can be eaten every alternate day and Burger can be eaten every two days. Only one item can be eaten on a given day.

Solution:
Let us call the sequence of breakfast item on the days as timetable. And the condition of whether a particular item can be consumed on a given day as constraint.

Approach 1:
Create the timetable while checking that the constraints are met.

Approach 2:
Generate all possible timetables and eliminate the timetables that do not meet the constraints.

Java Program:

package com.sourabh.practice;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class Breakfast {
    public static void main(String[] args) {
        String[] menu = new String[]{"Bread-butter", "Pizza", "Burger"};
        int[] constraint = new int[]{1, 2, 3};
        List<List<String>> timeTableList = new ArrayList<>();
        List<String> timeTable = new ArrayList<>();
        int n = 3;
        Breakfast breakfast = new Breakfast();
        breakfast.countNumberOfWaysEvaluationApproach(menu, constraint, timeTableList, timeTable, n);
        System.out.println(timeTableList.size());
    }
    
    public void countNumberOfWaysEvaluationApproach(String[] menu, int[] constraint, List<List<String>> timeTableList, List<String> timeTable, int n) {
        if(timeTable.size() == n) {
            // For unit-testing purpose
            List<String> output = new ArrayList<>();
            for(String food : timeTable) {
                System.out.print(food + " ");
                output.add(food);
            }
            System.out.println();
            timeTableList.add(output);
        } else {
            List<String> possibilities = new ArrayList<>();
            boolean found = false;
            for(int i=0; i<constraint.length; i++) {
                for(int j=1; j<constraint[i]; j++) {
                    if(timeTable.size() - j >=0 && timeTable.get(timeTable.size() - j).equals(menu[i])) {
                        found = true;
                    }
                }
                if(!found) {
                    possibilities.add(menu[i]);
                } else {
                    found = false;
                }
            }
            for(String possibility : possibilities) {
                timeTable.add(possibility);
                countNumberOfWaysEvaluationApproach(menu, constraint, timeTableList, timeTable, n);
                timeTable.remove(timeTable.size() - 1);
            }
        }
    }
    
    public void countNumberOfWaysExhaustiveApproach(String[] menu, int[] constraint, List<List<String>> timeTableList, List<String> timeTable, int n) {
        generatePermutation(menu, timeTableList, timeTable, n);
        Iterator<List<String>> iterator = timeTableList.iterator();
        while(iterator.hasNext()) {
            List<String> output = iterator.next();
            boolean passed = true;
            for(int i=0; i<menu.length; i++) {
                int occ1 = -1;
                int occ2 = -1;
                for(int j = 0; j < output.size(); j++) {
                    if(output.get(j).equals(menu[i])) {
                        if(occ1 < 0) {
                            occ1 = j;
                        } else {
                            occ2 = occ1;
                            occ1 = j;
                        }
                    }
                    if(occ1 >= 0 && occ2 >= 0 && occ1 > occ2 && occ1 - occ2 < constraint[i]) {
                        passed = false;
                    }
                }
            }
            if(!passed) {
                iterator.remove();
            }
        }
        for(List<String> output : timeTableList) {
            for(String food : output) {
                System.out.print(food + " ");
            }
            System.out.println();
        }
        System.out.println(timeTableList.size());
    }
    
    public void generatePermutation(String[] menu, List<List<String>> timeTableList, List<String> timeTable, int n) {
        if(timeTable.size() == n) {
            // For unit-testing purpose
            List<String> output = new ArrayList<>();
            for(String food : timeTable) {
                output.add(food);
            }
            timeTableList.add(output);
        } else {
            for(int i=0; i<menu.length; i++) {
                timeTable.add(menu[i]);
                generatePermutation(menu, timeTableList, timeTable, n);
                timeTable.remove(timeTable.size() - 1);
            }
        }
    }
} 

Sample Output:

Bread-butter Bread-butter Bread-butter 
Bread-butter Bread-butter Pizza 
Bread-butter Bread-butter Burger 
Bread-butter Pizza Bread-butter 
Bread-butter Pizza Burger 
Bread-butter Burger Bread-butter 
Bread-butter Burger Pizza 
Pizza Bread-butter Bread-butter 
Pizza Bread-butter Pizza 
Pizza Bread-butter Burger 
Pizza Burger Bread-butter 
Pizza Burger Pizza 
Burger Bread-butter Bread-butter 
Burger Bread-butter Pizza 
Burger Pizza Bread-butter 
15

Unit Tests:

package com.sourabh.practice;

import static org.junit.Assert.*;

import java.util.ArrayList;
import java.util.List;

import org.junit.Assert;
import org.junit.Test;

public class BreakfastTests {
    Breakfast breakfast = new Breakfast();
    @Test
    public void testCountNumberOfWaysInTermsOfFrequency() {
        String[] menu = new String[]{"Bread-butter", "Pizza", "Burger"};
        int[] constraint = new int[]{1, 2, 3};
        List<List<String>> timeTableList = new ArrayList<>();
        List<String> timeTable = new ArrayList<>();
        int n = 3;
        Breakfast breakfast = new Breakfast();
        breakfast.countNumberOfWaysEvaluationApproach(menu, constraint, timeTableList, timeTable, n);
        boolean passed = true;
        for(List<String> output : timeTableList) {
            for(int i=0; i<menu.length; i++) {
                int occ1 = -1;
                int occ2 = -1;
                for(int j = 0; j < output.size(); j++) {
                    if(output.get(j).equals(menu[i])) {
                        if(occ1 < 0) {
                            occ1 = j;
                        } else {
                            occ2 = occ1;
                            occ1 = j;
                        }
                    }
                    if(occ1 >= 0 && occ2 >= 0 && occ1 > occ2 && occ1 - occ2 < constraint[i]) {
                        passed = false;
                    }
                }
            }
        }
        Assert.assertTrue(passed);
    }
    
    @Test
    public void testCountNumberOfWaysInTermsOfExhaustiveness() {
        String[] menu = new String[]{"Bread-butter", "Pizza", "Burger"};
        int[] constraint = new int[]{1, 2, 3};
        List<List<String>> timeTableList = new ArrayList<>();
        List<String> timeTable = new ArrayList<>();
        int n = 3;
        Breakfast breakfast = new Breakfast();
        breakfast.countNumberOfWaysExhaustiveApproach(menu, constraint, timeTableList, timeTable, n);
        boolean passed = true;
        for(List<String> output : timeTableList) {
            for(int i=0; i<menu.length; i++) {
                int occ1 = -1;
                int occ2 = -1;
                for(int j = 0; j < output.size(); j++) {
                    if(output.get(j).equals(menu[i])) {
                        if(occ1 < 0) {
                            occ1 = j;
                        } else {
                            occ2 = occ1;
                            occ1 = j;
                        }
                    }
                    if(occ1 >= 0 && occ2 >= 0 && occ1 > occ2 && occ1 - occ2 < constraint[i]) {
                        passed = false;
                    }
                }
            }
        }
        Assert.assertTrue(passed);
    }
    
    @Test
    public void testCountNumberOfWaysInTermsOfAccuracy() {
        String[] menu = new String[]{"Bread-butter", "Pizza", "Burger"};
        int[] constraint = new int[]{1, 2, 3};
        List<List<String>> timeTableList = new ArrayList<>();
        List<String> timeTable = new ArrayList<>();
        int n = 3;
        Breakfast breakfast = new Breakfast();
        Long start1 = System.currentTimeMillis();
        breakfast.countNumberOfWaysEvaluationApproach(menu, constraint, timeTableList, timeTable, n);
        Long end1 = System.currentTimeMillis();
        int size1 = timeTableList.size();
        timeTableList = new ArrayList<>();
        timeTable = new ArrayList<>();
        Long start2 = System.currentTimeMillis();
        breakfast.countNumberOfWaysExhaustiveApproach(menu, constraint, timeTableList, timeTable, n);
        Long end2 = System.currentTimeMillis();
        int size2 = timeTableList.size();
        Assert.assertEquals(size1, size2);
        System.out.println(end1 - start1);
        System.out.println(end2 - start2);;
    }
}