http://challenge.shopcurbside.com

curbside-challenge.go

package main

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"net/http"
	"strings"

	"github.com/pkg/errors"
)

const curbsideURL = "http://challenge.shopcurbside.com"

func main() {
	sessionToken, err := getSession()
	if err != nil {
		log.Fatal(err)
	}
	if err := start(sessionToken); err != nil {
		log.Fatal(err)
	}
}

func start(sessionToken string) error {
	req, err := http.NewRequest(http.MethodGet, curbsideURL+"/start", nil)
	req.Header.Add("Session", sessionToken)
	if err != nil {
		return err
	}
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return err
	}
	response := Response{}
	if err := json.NewDecoder(resp.Body).Decode(&response); err != nil {
		return errors.Wrap(err, "decoding response in start")
	}
	for _, id := range response.Next {
		if err := getNext(sessionToken, id); err != nil {
			return err
		}
	}
	return nil
}

func getSession() (string, error) {
	resp, err := http.Get(curbsideURL + "/get-session")
	if err != nil {
		return "", err
	}
	sessionBytes, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return "", err
	}
	if err := resp.Body.Close(); err != nil {
		return "", err
	}
	return strings.TrimSpace(string(sessionBytes)), nil
}

func getNext(sessionToken, cur string) error {
	req, err := http.NewRequest(http.MethodGet, curbsideURL+"/"+cur, nil)
	req.Header.Add("Session", sessionToken)
	if err != nil {
		return err
	}
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return err
	}
	if resp.StatusCode == http.StatusBadRequest {
		body, err := ioutil.ReadAll(resp.Body)
		if err != nil {
			return err
		}
		if strings.HasPrefix(string(body), "Invalid session id") {
			newToken, err := getSession()
			if err != nil {
				return err
			}
			if err := getNext(newToken, cur); err != nil {
				return err
			}
		}
	}
	if resp.StatusCode >= 300 {
		return errors.Wrapf(err, "code=%d", resp.StatusCode)
	}
	var (
		buf      = &bytes.Buffer{}
		r        = io.TeeReader(resp.Body, buf)
		response = Response{}
	)
	if err := json.NewDecoder(r).Decode(&response); err != nil {
		// Try decoding "next" as a single string.
		rs := ResponseSingle{}
		if err := json.NewDecoder(buf).Decode(&rs); err != nil {
			return errors.Wrap(err, "decoding response in getNext")
		}
		if err := getNext(sessionToken, rs.Next); err != nil {
			return err
		}
	}
	if len(response.Secret) > 0 {
		fmt.Printf("%s", response.Secret)
		return nil
	}
	for _, id := range response.Next {
		if err := getNext(sessionToken, id); err != nil {
			return err
		}
	}
	return nil
}

type Response struct {
	Next   []string `json:"next"`
	Secret string   `json:"secret"`
}

type ResponseSingle struct {
	Next   string `json:"next"`
	Secret string `json:"secret"`
}