Twitter Application Only Authentication

main.go

package main

import (
	"encoding/base64"
	"encoding/json"
	"net/http"
	"net/url"
	"strconv"
	"strings"
)

const Endpoint = "https://api.twitter.com"

type Token struct {
	TokenType string `json:"token_type"`
	AccessToken string `json:"access_token"`
}

func (t *Token) String() string {
	return base64.StdEncoding.EncodeToString([]byte(t.TokenType + " " + t.AccessToken))
}

type UserTimelineOptions struct {
	UserId int
	ScreenName string
	SinceId int
	Count int
	MaxId int
	TrimUser bool
	ExcludeReplies bool
	ContributorDetails bool
	IncludeRts bool
}

func (o UserTimelineOptions) Values() url.Values {
	values := url.Values{}
	if options.UserId != 0 {
		values.Add("user_id", strconv.Itoa(options.UserId))
	}
	if options.ScreenName != 0 {
		values.Add("screen_name", strconv.Itoa(options.ScreenName))
	}
	if options.SinceId != 0 {
		values.Add("since_id", strconv.Itoa(options.SinceId))
	}
	if options.Count != 0 {
		values.Add("count", strconv.Itoa(options.Count))
	}
	if options.MaxId != 0 {
		values.Add("max_id", strconv.Itoa(options.MaxId))
	}
	if options.TrimUser != true {
		values.Add("trim_user", strconv.FormatBool(options.TrimUser))
	}
	if options.ExcludeReplies != true {
		values.Add("exclude_replies", strconv.FormatBool(options.ExcludeReplies))
	}
	if options.ContributorDetails != true {
		values.Add("contributor_details", strconv.FormatBool(options.ContributorDetails))
	}
	if options.IncludeRts != false {
		values.Add("include_rts", strconv.FormatBool(options.IncludeRts))
	}
	return values
}

type Tweet struct {
}

func GetToken(consumerKey, consumerSecret string) (*Token, error) {
	basicToken := "Basic " + base64.StdEncoding.EncodeToString([]byte(consumerKey + ":" consumerSecret))

	values := url.Values{}
	values.Add("grant_type", "client_credentials")

	req, err := http.NewRequest("POST", Endpoint+"/oauth2/token", strings.NewReader(values.Encode()))
	if err != nil {
		return nil, err
	}

	req.Header.Add("Authorization", basicToken)
	req.Header.Add("Content-Type", "application/x-www-form-urlencoded;charset=UTF-8")

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

	defer res.Body.Close()

	var token Token
	if err = json.NewDecoder(res.Body).Decode(&token); err != nil {
		return nil, err
	}

	return &token, nil
}

func GetUserTimeline(token Token, options UserTimelineOptions) ([]Tweet, error) {
	values := options.Values()

	req, err := http.NewRequest("GET", Endpoint+"/1.1/statuses/user_timeline.json", nil)
	if err != nil {
		return nil, err
	}

	req,Header.Add("Authorization", token.String())
	req.Header.Add("Content-Type", "application/json; charset=utf-8")
	req.URL.RawQuery = values.Encode()

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

	defer res.Body.Close()

	var timeline []Tweet
	if err = json.NewDecoder(res.Body).Decode(timeline); err != nil {
		return nil, err
	}
	return timeline, nil
}

func main() {
	var consumerKey, consumerSecret string
	token := GetToken(consumerKey, consumerSecret)
	timeline := GetUserTimeline(token, UserTimelineOptions{})
}