Add by_id endpoint, tweak UserService methods

Signed-off-by: Vartan Benohanian <vartanbeno@gmail.com>

listings.go

@@ -2,13 +2,17 @@ package geddit
 
 import (
 	"context"
+	"errors"
+	"fmt"
 	"net/http"
+	"strings"
 )
 
 // ListingsService handles communication with the link (post)
 // related methods of the Reddit API
 type ListingsService interface {
-	Get(ctx context.Context, ids ...string) (*CommentsLinksSubreddits, *Response, error)
+	Get(ctx context.Context, ids ...string) ([]Comment, []Link, []Subreddit, *Response, error)
+	GetLinks(ctx context.Context, ids ...string) ([]Link, *Response, error)
 }
 
 // ListingsServiceOp implements the Vote interface
@@ -18,9 +22,8 @@ type ListingsServiceOp struct {
 
 var _ ListingsService = &ListingsServiceOp{}
 
-// Get gets a list of things based on their IDs
-// Only links, comments, and subreddits are allowed
-func (s *ListingsServiceOp) Get(ctx context.Context, ids ...string) (*CommentsLinksSubreddits, *Response, error) {
+// Get returns comments, link, and subreddits from their IDs
+func (s *ListingsServiceOp) Get(ctx context.Context, ids ...string) ([]Comment, []Link, []Subreddit, *Response, error) {
 	type query struct {
 		IDs []string `url:"id,comma"`
 	}
@@ -28,9 +31,34 @@ func (s *ListingsServiceOp) Get(ctx context.Context, ids ...string) (*CommentsLi
 	path := "api/info"
 	path, err := addOptions(path, query{ids})
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, nil, nil, err
 	}
 
+	req, err := s.client.NewRequest(http.MethodGet, path, nil)
+	if err != nil {
+		return nil, nil, nil, nil, err
+	}
+
+	root := new(rootListing)
+	resp, err := s.client.Do(ctx, req, root)
+	if err != nil {
+		return nil, nil, nil, resp, err
+	}
+
+	comments := root.getComments().Comments
+	links := root.getLinks().Links
+	subreddits := root.getSubreddits().Subreddits
+
+	return comments, links, subreddits, resp, nil
+}
+
+// GetLinks returns links from their IDs
+func (s *ListingsServiceOp) GetLinks(ctx context.Context, ids ...string) ([]Link, *Response, error) {
+	if len(ids) == 0 {
+		return nil, nil, errors.New("must provide at least 1 id")
+	}
+
+	path := fmt.Sprintf("by_id/%s", strings.Join(ids, ","))
 	req, err := s.client.NewRequest(http.MethodGet, path, nil)
 	if err != nil {
 		return nil, nil, err
@@ -42,12 +70,5 @@ func (s *ListingsServiceOp) Get(ctx context.Context, ids ...string) (*CommentsLi
 		return nil, resp, err
 	}
 
-	v := new(CommentsLinksSubreddits)
-	v.Comments = root.getComments().Comments
-	v.Links = root.getLinks().Links
-	v.Subreddits = root.getSubreddits().Subreddits
-
-	return v, resp, nil
+	return root.getLinks().Links, resp, nil
 }
-
-// todo: do by_id next