Use upstream slack-go/slack again (#1018)

vendor/github.com/slack-go/slack/pins.go

@@ -0,0 +1,94 @@
+package slack
+
+import (
+	"context"
+	"errors"
+	"net/url"
+)
+
+type listPinsResponseFull struct {
+	Items  []Item
+	Paging `json:"paging"`
+	SlackResponse
+}
+
+// AddPin pins an item in a channel
+func (api *Client) AddPin(channel string, item ItemRef) error {
+	return api.AddPinContext(context.Background(), channel, item)
+}
+
+// AddPinContext pins an item in a channel with a custom context
+func (api *Client) AddPinContext(ctx context.Context, channel string, item ItemRef) error {
+	values := url.Values{
+		"channel": {channel},
+		"token":   {api.token},
+	}
+	if item.Timestamp != "" {
+		values.Set("timestamp", item.Timestamp)
+	}
+	if item.File != "" {
+		values.Set("file", item.File)
+	}
+	if item.Comment != "" {
+		values.Set("file_comment", item.Comment)
+	}
+
+	response := &SlackResponse{}
+	if err := api.postMethod(ctx, "pins.add", values, response); err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// RemovePin un-pins an item from a channel
+func (api *Client) RemovePin(channel string, item ItemRef) error {
+	return api.RemovePinContext(context.Background(), channel, item)
+}
+
+// RemovePinContext un-pins an item from a channel with a custom context
+func (api *Client) RemovePinContext(ctx context.Context, channel string, item ItemRef) error {
+	values := url.Values{
+		"channel": {channel},
+		"token":   {api.token},
+	}
+	if item.Timestamp != "" {
+		values.Set("timestamp", item.Timestamp)
+	}
+	if item.File != "" {
+		values.Set("file", item.File)
+	}
+	if item.Comment != "" {
+		values.Set("file_comment", item.Comment)
+	}
+
+	response := &SlackResponse{}
+	if err := api.postMethod(ctx, "pins.remove", values, response); err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// ListPins returns information about the items a user reacted to.
+func (api *Client) ListPins(channel string) ([]Item, *Paging, error) {
+	return api.ListPinsContext(context.Background(), channel)
+}
+
+// ListPinsContext returns information about the items a user reacted to with a custom context.
+func (api *Client) ListPinsContext(ctx context.Context, channel string) ([]Item, *Paging, error) {
+	values := url.Values{
+		"channel": {channel},
+		"token":   {api.token},
+	}
+
+	response := &listPinsResponseFull{}
+	err := api.postMethod(ctx, "pins.list", values, response)
+	if err != nil {
+		return nil, nil, err
+	}
+	if !response.Ok {
+		return nil, nil, errors.New(response.Error)
+	}
+	return response.Items, &response.Paging, nil
+}