Create PostAndCommentService, holds common methods

Some functionality such as saving, voting, deleting, etc. is common to
both posts and comments, so this service will hold such methods.

Tweaked the separate post/comment services accordingly. Fixed tests.

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

post-and-comment.go

@@ -0,0 +1,162 @@
+package reddit
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"net/url"
+)
+
+// PostAndCommentService handles communication with the post and comment
+// related methods of the Reddit API.
+// This service holds functionality common to both posts and comments.
+//
+// Reddit API docs: https://www.reddit.com/dev/api/#section_links_and_comments
+type PostAndCommentService service
+
+type vote int
+
+// Reddit interprets -1, 0, 1 as downvote, no vote, and upvote, respectively.
+const (
+	downvote vote = iota - 1
+	novote
+	upvote
+)
+
+// Delete deletes a post or comment via its full ID.
+func (s *PostAndCommentService) Delete(ctx context.Context, id string) (*Response, error) {
+	path := "api/del"
+
+	form := url.Values{}
+	form.Set("id", id)
+
+	req, err := s.client.NewRequestWithForm(http.MethodPost, path, form)
+	if err != nil {
+		return nil, err
+	}
+
+	return s.client.Do(ctx, req, nil)
+}
+
+// Save saves a post or comment.
+func (s *PostAndCommentService) Save(ctx context.Context, id string) (*Response, error) {
+	path := "api/save"
+
+	form := url.Values{}
+	form.Set("id", id)
+
+	req, err := s.client.NewRequestWithForm(http.MethodPost, path, form)
+	if err != nil {
+		return nil, err
+	}
+
+	return s.client.Do(ctx, req, nil)
+}
+
+// Unsave unsaves a post or comment.
+func (s *PostAndCommentService) Unsave(ctx context.Context, id string) (*Response, error) {
+	path := "api/unsave"
+
+	form := url.Values{}
+	form.Set("id", id)
+
+	req, err := s.client.NewRequestWithForm(http.MethodPost, path, form)
+	if err != nil {
+		return nil, err
+	}
+
+	return s.client.Do(ctx, req, nil)
+}
+
+// EnableReplies enables inbox replies for one of your posts or comments.
+func (s *PostAndCommentService) EnableReplies(ctx context.Context, id string) (*Response, error) {
+	path := "api/sendreplies"
+
+	form := url.Values{}
+	form.Set("id", id)
+	form.Set("state", "true")
+
+	req, err := s.client.NewRequestWithForm(http.MethodPost, path, form)
+	if err != nil {
+		return nil, err
+	}
+
+	return s.client.Do(ctx, req, nil)
+}
+
+// DisableReplies dsables inbox replies for one of your posts or comments.
+func (s *PostAndCommentService) DisableReplies(ctx context.Context, id string) (*Response, error) {
+	path := "api/sendreplies"
+
+	form := url.Values{}
+	form.Set("id", id)
+	form.Set("state", "false")
+
+	req, err := s.client.NewRequestWithForm(http.MethodPost, path, form)
+	if err != nil {
+		return nil, err
+	}
+
+	return s.client.Do(ctx, req, nil)
+}
+
+// Lock locks a post or comment, preventing it from receiving new comments.
+func (s *PostAndCommentService) Lock(ctx context.Context, id string) (*Response, error) {
+	path := "api/lock"
+
+	form := url.Values{}
+	form.Set("id", id)
+
+	req, err := s.client.NewRequestWithForm(http.MethodPost, path, form)
+	if err != nil {
+		return nil, err
+	}
+
+	return s.client.Do(ctx, req, nil)
+}
+
+// Unlock unlocks a post or comment, allowing it to receive new comments.
+func (s *PostAndCommentService) Unlock(ctx context.Context, id string) (*Response, error) {
+	path := "api/unlock"
+
+	form := url.Values{}
+	form.Set("id", id)
+
+	req, err := s.client.NewRequestWithForm(http.MethodPost, path, form)
+	if err != nil {
+		return nil, err
+	}
+
+	return s.client.Do(ctx, req, nil)
+}
+
+func (s *PostAndCommentService) vote(ctx context.Context, id string, vote vote) (*Response, error) {
+	path := "api/vote"
+
+	form := url.Values{}
+	form.Set("id", id)
+	form.Set("dir", fmt.Sprint(vote))
+	form.Set("rank", "10")
+
+	req, err := s.client.NewRequestWithForm(http.MethodPost, path, form)
+	if err != nil {
+		return nil, err
+	}
+
+	return s.client.Do(ctx, req, nil)
+}
+
+// Upvote upvotes a post or a comment.
+func (s *PostAndCommentService) Upvote(ctx context.Context, id string) (*Response, error) {
+	return s.vote(ctx, id, upvote)
+}
+
+// Downvote downvotes a post or a comment.
+func (s *PostAndCommentService) Downvote(ctx context.Context, id string) (*Response, error) {
+	return s.vote(ctx, id, downvote)
+}
+
+// RemoveVote removes your vote on a post or a comment.
+func (s *PostAndCommentService) RemoveVote(ctx context.Context, id string) (*Response, error) {
+	return s.vote(ctx, id, novote)
+}