Feature/issue 28 user lookup (#35)

* added the user by id lookup (standard)

* add the user by username lookup

* added user dictionary

* added tweet raw dictionary

* added the user raw dictionary

* added examples

* updated the readme

* fixed the golint suggestions

* corrected example comments

v2/README.md

@@ -22,6 +22,10 @@ Here are the current twitter `v2` API features supported:
 *  [Tweet Lookup](https://developer.twitter.com/en/docs/twitter-api/tweets/lookup/introduction)
     * [example](./_examples/tweet-lookup)
 * [Tweet Dictionary](https://developer.twitter.com/en/docs/twitter-api/data-dictionary/object-model/tweet) - the tweet and all of its references related to it
+*  [User Lookup](https://developer.twitter.com/en/docs/twitter-api/users/lookup/introduction)
+    * [example](./_examples/user-lookup)
+    * [example: by usernames](./_examples/username-lookup)
+* [User Dictionary](https://developer.twitter.com/en/docs/twitter-api/data-dictionary/object-model/user) - the user and all of its references related to it
 
 ## Examples
 Much like `v1`, there is an `_example` directory to demostrate library usage.  Refer to the [readme](./_examples) for more information.

v2/_examples/README.md

@@ -4,8 +4,22 @@ Within this directory there are basic examples for the twitter v2 APIs.
 In order to run these examples, an authorization token will need to be provided.
 
 ## Tweet Lookup
-This [example](./tweet-lookup) demostrats the tweets lookup API call. 
+This [example](./tweet-lookup) demonstrates the tweets lookup API call. 
 
 ```
 go run *.go -token=YOUR_API_TOKEN -ids=1261326399320715264,1278347468690915330
 ```
+
+## User Lookup
+This [example](./user-lookup) demonstrates the users lookup API call.
+
+```
+go run *.go -token=YOUR_API_TOKEN -ids=2244994945,18080585
+```
+
+## Username Lookup
+This [example](./username-lookup) demonstrates the usernames lookup API call.
+
+```
+go run *.go -token=YOUR_API_TOKEN -ids=TwitterDev,MongoDB
+```

v2/_examples/user-lookup/main.go

@@ -0,0 +1,56 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"flag"
+	"fmt"
+	"log"
+	"net/http"
+	"strings"
+
+	twitter "github.com/g8rswimmer/go-twitter/v2"
+)
+
+type authorize struct {
+	Token string
+}
+
+func (a authorize) Add(req *http.Request) {
+	req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", a.Token))
+}
+
+/**
+	In order to run, the user will need to provide the bearer token and the list of user ids.
+**/
+func main() {
+	token := flag.String("token", "", "twitter API token")
+	ids := flag.String("ids", "", "user ids")
+	flag.Parse()
+
+	client := &twitter.Client{
+		Authorizer: authorize{
+			Token: *token,
+		},
+		Client: http.DefaultClient,
+		Host:   "https://api.twitter.com",
+	}
+	opts := twitter.UserLookupOpts{
+		Expansions: []twitter.Expansion{twitter.ExpansionPinnedTweetID},
+	}
+
+	fmt.Println("Callout to user lookup callout")
+
+	userResponse, err := client.UserLookup(context.Background(), strings.Split(*ids, ","), opts)
+	if err != nil {
+		log.Panicf("user lookup error: %v", err)
+	}
+
+	dictionaries := userResponse.Raw.UserDictionaries()
+
+	enc, err := json.MarshalIndent(dictionaries, "", "    ")
+	if err != nil {
+		log.Panic(err)
+	}
+	fmt.Println(string(enc))
+}

v2/_examples/username-lookup/main.go

@@ -0,0 +1,56 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"flag"
+	"fmt"
+	"log"
+	"net/http"
+	"strings"
+
+	twitter "github.com/g8rswimmer/go-twitter/v2"
+)
+
+type authorize struct {
+	Token string
+}
+
+func (a authorize) Add(req *http.Request) {
+	req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", a.Token))
+}
+
+/**
+	In order to run, the user will need to provide the bearer token and the list of usernames.
+**/
+func main() {
+	token := flag.String("token", "", "twitter API token")
+	names := flag.String("names", "", "user names")
+	flag.Parse()
+
+	client := &twitter.Client{
+		Authorizer: authorize{
+			Token: *token,
+		},
+		Client: http.DefaultClient,
+		Host:   "https://api.twitter.com",
+	}
+	opts := twitter.UserLookupOpts{
+		Expansions: []twitter.Expansion{twitter.ExpansionPinnedTweetID},
+	}
+
+	fmt.Println("Callout to user lookup callout")
+
+	userResponse, err := client.UserNameLookup(context.Background(), strings.Split(*names, ","), opts)
+	if err != nil {
+		log.Panicf("user lookup error: %v", err)
+	}
+
+	dictionaries := userResponse.Raw.UserDictionaries()
+
+	enc, err := json.MarshalIndent(dictionaries, "", "    ")
+	if err != nil {
+		log.Panic(err)
+	}
+	fmt.Println(string(enc))
+}

v2/client.go

@@ -9,7 +9,9 @@ import (
 )
 
 const (
-	tweetMaxIDs = 100
+	tweetMaxIDs  = 100
+	userMaxIDs   = 100
+	userMaxNames = 100
 )
 
 // Client is used to make twitter v2 API callouts.
@@ -82,3 +84,131 @@ func (c *Client) TweetLookup(ctx context.Context, ids []string, opts TweetLookup
 		Raw: raw,
 	}, nil
 }
+
+// UserLookup returns information about an user or group of users specified by a group of user ids.
+func (c *Client) UserLookup(ctx context.Context, ids []string, opts UserLookupOpts) (*UserLookupResponse, error) {
+	ep := userLookupEndpoint.url(c.Host)
+	switch {
+	case len(ids) == 0:
+		return nil, fmt.Errorf("user lookup: an id is required: %w", ErrParameter)
+	case len(ids) > userMaxIDs:
+		return nil, fmt.Errorf("user lookup: ids %d is greater than max %d: %w", len(ids), userMaxIDs, ErrParameter)
+	case len(ids) == 1:
+		ep += fmt.Sprintf("/%s", ids[0])
+	default:
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, ep, nil)
+	if err != nil {
+		return nil, fmt.Errorf("user lookup request: %w", err)
+	}
+	req.Header.Add("Accept", "application/json")
+	c.Authorizer.Add(req)
+	opts.addQuery(req)
+	if len(ids) > 1 {
+		q := req.URL.Query()
+		q.Add("ids", strings.Join(ids, ","))
+		req.URL.RawQuery = q.Encode()
+	}
+
+	resp, err := c.Client.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("user lookup response: %w", err)
+	}
+	defer resp.Body.Close()
+
+	decoder := json.NewDecoder(resp.Body)
+
+	if resp.StatusCode != http.StatusOK {
+		e := &ErrorResponse{}
+		if err := decoder.Decode(e); err != nil {
+			return nil, fmt.Errorf("user lookup response error decode: %w", err)
+		}
+		e.StatusCode = resp.StatusCode
+		return nil, e
+	}
+
+	raw := &UserRaw{}
+	switch {
+	case len(ids) == 1:
+		single := &userraw{}
+		if err := decoder.Decode(single); err != nil {
+			return nil, fmt.Errorf("user lookup single dictionary: %w", err)
+		}
+		raw.Users = make([]*UserObj, 1)
+		raw.Users[0] = single.User
+		raw.Includes = single.Includes
+		raw.Errors = single.Errors
+	default:
+		if err := decoder.Decode(raw); err != nil {
+			return nil, fmt.Errorf("user lookup dictionary: %w", err)
+		}
+	}
+	return &UserLookupResponse{
+		Raw: raw,
+	}, nil
+}
+
+// UserNameLookup returns information about an user or group of users specified by a group of usernames.
+func (c *Client) UserNameLookup(ctx context.Context, usernames []string, opts UserLookupOpts) (*UserLookupResponse, error) {
+	ep := userNameLookupEndpoint.url(c.Host)
+	switch {
+	case len(usernames) == 0:
+		return nil, fmt.Errorf("username lookup: an username is required: %w", ErrParameter)
+	case len(usernames) > userMaxIDs:
+		return nil, fmt.Errorf("username lookup: usernames %d is greater than max %d: %w", len(usernames), userMaxNames, ErrParameter)
+	case len(usernames) == 1:
+		ep += fmt.Sprintf("/username/%s", usernames[0])
+	default:
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, ep, nil)
+	if err != nil {
+		return nil, fmt.Errorf("username lookup request: %w", err)
+	}
+	req.Header.Add("Accept", "application/json")
+	c.Authorizer.Add(req)
+	opts.addQuery(req)
+	if len(usernames) > 1 {
+		q := req.URL.Query()
+		q.Add("usernames", strings.Join(usernames, ","))
+		req.URL.RawQuery = q.Encode()
+	}
+
+	resp, err := c.Client.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("username lookup response: %w", err)
+	}
+	defer resp.Body.Close()
+
+	decoder := json.NewDecoder(resp.Body)
+
+	if resp.StatusCode != http.StatusOK {
+		e := &ErrorResponse{}
+		if err := decoder.Decode(e); err != nil {
+			return nil, fmt.Errorf("username lookup response error decode: %w", err)
+		}
+		e.StatusCode = resp.StatusCode
+		return nil, e
+	}
+
+	raw := &UserRaw{}
+	switch {
+	case len(usernames) == 1:
+		single := &userraw{}
+		if err := decoder.Decode(single); err != nil {
+			return nil, fmt.Errorf("username lookup single dictionary: %w", err)
+		}
+		raw.Users = make([]*UserObj, 1)
+		raw.Users[0] = single.User
+		raw.Includes = single.Includes
+		raw.Errors = single.Errors
+	default:
+		if err := decoder.Decode(raw); err != nil {
+			return nil, fmt.Errorf("username lookup dictionary: %w", err)
+		}
+	}
+	return &UserLookupResponse{
+		Raw: raw,
+	}, nil
+}