Find out who retweeted your tweet, sorted by how many followers they have.

retweeted_by.go

package main

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

type User struct {
	ScreenName string `json:"screen_name"`
	Followers  int    `json:"followers_count"`
}

type Users []User

func (u Users) Len() int           { return len(u) }
func (u Users) Swap(i, j int)      { u[i], u[j] = u[j], u[i] }
func (u Users) Less(i, j int) bool { return u[i].Followers > u[j].Followers }

func getRetweeters(id uint64, page int) (Users, error) {
	resp, err := http.Get("http://api.twitter.com/1/statuses/" + strconv.FormatUint(id, 10) + "/retweeted_by.json?count=100&page=" + strconv.Itoa(page))
	if err != nil {
		return Users{}, err
	}
	respBytes, err := ioutil.ReadAll(resp.Body)
	resp.Body.Close()
	if err != nil {
		return Users{}, err
	}
	var users Users
	err = json.Unmarshal(respBytes, &users)
	if err != nil {
		return Users{}, err
	}
	return users, nil
}

func main() {
	var id uint64
	flag.Uint64Var(&id, "id", 0, "id of the tweet")
	flag.Parse()

	if id == 0 {
		panic("ID must be set.")
	}
	responses := 1
	page := 1
	users := Users{}
	for responses > 0 {
		retweeters, err := getRetweeters(id, page)
		if err != nil {
			panic(err)
		}
		users = append(users, retweeters...)
		responses = len(retweeters)
		page = page + 1
	}
	sort.Sort(users)
	followers := 0
	for _, rt := range users {
		fmt.Printf("@%s\t%d followers\thttps://twitter.com/%s\n", rt.ScreenName, rt.Followers, rt.ScreenName)
		followers = followers + rt.Followers
	}
	fmt.Printf("Retweeted by %d people with a total of %d followers.\n", len(users), followers)
}