the-pizza-fun

the-pizza-fun.go

package main

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"sort"
)

type Pizza struct {
	Toppings []string `json:"toppings"`
}

// String - Stringer interface
func (thisRef Pizza) String() string {
	data, err := json.Marshal(thisRef)
	if err != nil {
		log.Println(err)

		return ""
	}

	return string(data)
}

const TOP_N = 20

func main() {
	orders, err := fetchData()
	if err != nil {
		log.Fatal(err)
	}

	data := map[string]int{}

	for _, pizza := range orders {
		for _, topping := range pizza.Toppings {
			if _, ok := data[topping]; ok {
				data[topping]++
			} else {
				data[topping] = 0
			}
		}
	}

	sortedData := rankByWordCount(data)
	topN := len(sortedData)
	if topN > TOP_N {
		topN = TOP_N
	}
	for i := 0; i < TOP_N; i++ {
		log.Println(fmt.Sprintf("%s - %d", sortedData[i].Key, sortedData[i].Value))
	}
}

func fetchData() ([]Pizza, error) {
	const url = "http://files.olo.com/pizzas.json"

	req, err := http.NewRequest(http.MethodGet, url, nil)
	if err != nil {
		return nil, err
	}

	client := http.Client{}
	res, err := client.Do(req)
	if err != nil {
		return nil, err
	}

	data, err := ioutil.ReadAll(res.Body)
	if err != nil {
		return nil, err
	}

	pizzas := []Pizza{}
	err = json.Unmarshal(data, &pizzas)
	if err != nil {
		return nil, err
	}

	return pizzas, nil
}

func rankByWordCount(wordFrequencies map[string]int) PairList {
	pl := make(PairList, len(wordFrequencies))
	i := 0
	for k, v := range wordFrequencies {
		pl[i] = Pair{k, v}
		i++
	}
	sort.Sort(sort.Reverse(pl))
	return pl
}

type Pair struct {
	Key   string
	Value int
}

type PairList []Pair

func (p PairList) Len() int           { return len(p) }
func (p PairList) Less(i, j int) bool { return p[i].Value < p[j].Value }
func (p PairList) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }