From 8f41f3481901f817ed74a9966dd8cf02cd7edf60 Mon Sep 17 00:00:00 2001
From: Daisuke Maki <lestrrat+github@gmail.com>
Date: Wed, 12 Apr 2017 19:55:51 +0900
Subject: [PATCH] implement channels.invite

---
 channels.go | 63 ++++++++++++++++++++++++++++-------------------------
 client.go   | 24 ++++++++++++++++++++
 2 files changed, 57 insertions(+), 30 deletions(-)

diff --git a/channels.go b/channels.go
index 06cc652..9d83e55 100644
--- a/channels.go
+++ b/channels.go
@@ -34,13 +34,8 @@ func (c *ChannelsArchiveCall) Do(ctx context.Context) error {
 	const endpoint = "channels.archive"
 
 	var res SlackResponse
-
-	if err := c.service.client.postForm(ctx, endpoint, c.Values(), &res); err != nil {
-		return errors.Wrapf(err, `failed to post to %s`, endpoint)
-	}
-
-	if !res.OK {
-		return errors.New(res.Error.String())
+	if err := genericPost(ctx, c.service.client, endpoint, c.Values(), &res); err != nil {
+		return err
 	}
 
 	return nil
@@ -78,17 +73,10 @@ func (c *ChannelsCreateCall) Validate(b bool) *ChannelsCreateCall {
 
 func (c *ChannelsCreateCall) Do(ctx context.Context) error {
 	const endpoint = "channels.archive"
-
 	var res SlackResponse
-
-	if err := c.service.client.postForm(ctx, endpoint, c.Values(), &res); err != nil {
-		return errors.Wrapf(err, `failed to post to %s`, endpoint)
-	}
-
-	if !res.OK {
-		return errors.New(res.Error.String())
+	if err := genericPost(ctx, c.service.client, endpoint, c.Values(), &res); err != nil {
+		return err
 	}
-
 	return nil
 }
 
@@ -177,12 +165,8 @@ func (c *ChannelsHistoryCall) Do(ctx context.Context) (*ChannelsHistoryResponse,
 		*ChannelsHistoryResponse
 	}
 
-	if err := c.service.client.postForm(ctx, endpoint, c.Values(), &res); err != nil {
-		return nil, errors.Wrapf(err, `failed to post to %s`, endpoint)
-	}
-
-	if !res.OK {
-		return nil, errors.New(res.Error.String())
+	if err := genericPost(ctx, c.service.client, endpoint, c.Values(), &res); err != nil {
+		return nil, err
 	}
 
 	return res.ChannelsHistoryResponse, nil
@@ -216,7 +200,7 @@ func (c *ChannelsInfoCall) Do(ctx context.Context) (*objects.Channel, error) {
 		*objects.Channel `json:"channel"`
 	}
 
-	if err := c.service.client.postForm(ctx, endpoint, c.Values(), &res); err != nil {
+	if err := genericPost(ctx, c.service.client, endpoint, c.Values(), &res); err != nil {
 		return nil, errors.Wrapf(err, `failed to post to %s`, endpoint)
 	}
 
@@ -227,6 +211,30 @@ func (c *ChannelsInfoCall) Do(ctx context.Context) (*objects.Channel, error) {
 	return res.Channel, nil
 }
 
+// ChannelsInviteCall is created via Channels.Invite() method
+type ChannelsInviteCall struct {
+	service *ChannelsService
+	channel string
+	user    string
+}
+
+func (s *ChannelsService) Invite(channelID, userID string) *ChannelsInviteCall {
+	return &ChannelsInviteCall{
+		service: s,
+		channel: channelID,
+		user:    userID,
+	}
+}
+
+func (c *ChannelsInviteCall) Values() url.Values {
+	v := url.Values{
+		"token":   {c.service.token},
+		"channel": {c.channel},
+		"user":    {c.user},
+	}
+	return v
+}
+
 // ChannelsListCall is created via Channels.List() method
 type ChannelsListCall struct {
 	service      *ChannelsService
@@ -262,13 +270,8 @@ func (c *ChannelsListCall) Do(ctx context.Context) (objects.ChannelList, error)
 		objects.ChannelList `json:"channels"`
 	}
 
-	if err := c.service.client.postForm(ctx, endpoint, c.Values(), &res); err != nil {
-		return nil, errors.Wrapf(err, `failed to post to %s`, endpoint)
-	}
-
-	if !res.OK {
-		return nil, errors.New(res.Error.String())
+	if err := genericPost(ctx, c.service.client, endpoint, c.Values(), &res); err != nil {
+		return nil, err
 	}
-
 	return res.ChannelList, nil
 }
diff --git a/client.go b/client.go
index 604894a..a00ae0b 100644
--- a/client.go
+++ b/client.go
@@ -233,3 +233,27 @@ func (c *httpClient) get(octx context.Context, path string, f url.Values, data i
 	defer res.Body.Close()
 	return c.parseResponse(path, res.Body, data)
 }
+
+func (r SlackResponse) err() error {
+	return errors.New(r.Error.String())
+}
+
+func (r SlackResponse) ok() bool {
+	return r.OK
+}
+
+type genericResponse interface {
+	ok() bool
+	err() error
+}
+
+func genericPost(ctx context.Context, client *httpClient, endpoint string, v url.Values, res genericResponse) error {
+	if err := client.postForm(ctx, endpoint, v, res); err != nil {
+		return errors.Wrapf(err, `failed to post to %s`, endpoint)
+	}
+
+	if !res.ok() {
+		return res.err()
+	}
+	return nil
+}