From b14d7083878c961fa5918bc15976aaec4440a3a2 Mon Sep 17 00:00:00 2001
From: Ibrahim <dev.code.ibra@gmail.com>
Date: Fri, 19 Nov 2021 14:57:15 +0300
Subject: [PATCH] add slack library

Signed-off-by: Ibrahim <dev.code.ibra@gmail.com>
---
 slack/slack.go      | 77 +++++++++++++++++++++++++++++++++++++++++++++
 slack/slack_test.go | 43 +++++++++++++++++++++++++
 2 files changed, 120 insertions(+)
 create mode 100644 slack/slack.go
 create mode 100644 slack/slack_test.go

diff --git a/slack/slack.go b/slack/slack.go
new file mode 100644
index 0000000..5c431b8
--- /dev/null
+++ b/slack/slack.go
@@ -0,0 +1,77 @@
+package slack
+
+import (
+	"encoding/json"
+	"errors"
+
+	"gopkg.in/resty.v1"
+)
+
+var (
+	errorBadResponse = "API call gave an other-than-200 result"
+	errorEmptyText   = "refusing to send an empty message, consider calling slack.SetText() first"
+)
+
+// Provider provides an interface to interact with the Slack Webhook API
+type Provider struct {
+	Debug      bool
+	Payload    Payload
+	WebhookURL string
+}
+
+// Payload holds information about the message we want to send. Any of these values except Text may be left empty to
+// use the defaults for the Webhook. IconEmoji and IconURL are mutually exclusive, do not set both.
+// https://api.slack.com/incoming-webhooks#posting_with_webhooks
+type Payload struct {
+	Channel   string `json:"channel,omitempty"`
+	IconEmoji string `json:"icon_emoji,omitempty"`
+	IconURL   string `json:"icon_url,omitempty"`
+	Text      string `json:"text,omitempty"`
+	Username  string `json:"username,omitempty"`
+}
+
+// New creates a new invocation of this Provider wrapper
+func New(webhookURL string) Provider {
+	return Provider{
+		WebhookURL: webhookURL,
+	}
+}
+
+// SetText sets the message text, i.e. what will be displayed in the Slack window
+func (a *Provider) SetText(text string) {
+	a.Payload.Text = text
+}
+
+// Send sends a message to Slack
+func (a *Provider) Send() error {
+	if a.Payload.Text == "" {
+		return errors.New(errorEmptyText)
+	}
+	body, err := json.Marshal(a.Payload)
+	if err != nil {
+		return err
+	}
+
+	restyResult, err := resty.
+		SetDebug(a.Debug).
+		SetHostURL(a.WebhookURL).
+		R().
+		SetFormData(map[string]string{"payload": string(body)}).
+		Post(a.WebhookURL)
+
+	if err != nil {
+		return err
+	}
+
+	if restyResult.StatusCode() != 200 {
+		return errors.New(errorBadResponse)
+	}
+
+	return nil
+}
+
+// SendText sets message text and sends the message, a convenience wrapper for SetText and Send
+func (a *Provider) SendText(text string) error {
+	a.SetText(text)
+	return a.Send()
+}
diff --git a/slack/slack_test.go b/slack/slack_test.go
new file mode 100644
index 0000000..385ece5
--- /dev/null
+++ b/slack/slack_test.go
@@ -0,0 +1,43 @@
+package slack
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// generic helper for loading Slack API wrapper with Webhook URL
+func getAPI(t *testing.T) Provider {
+	webhookURL := os.Getenv("SLACK_WEBHOOK_URL")
+	require.NotEmpty(t, webhookURL, "ParameterNotFound: SLACK_WEBHOOK_URL")
+
+	api := New(webhookURL)
+	api.Payload.IconEmoji = ":robot_face:"
+	api.Payload.Username = "Insights Slack - Unit Test"
+
+	return api
+}
+
+func TestSendEmpty(t *testing.T) {
+	api := getAPI(t)
+
+	err := api.Send()
+	assert.EqualError(t, err, errorEmptyText)
+}
+
+func TestSendNotEmpty(t *testing.T) {
+	api := getAPI(t)
+	api.SetText("TestSendNotEmpty Test Content")
+
+	err := api.Send()
+	assert.NoError(t, err, "unexpected err from api.Send()")
+}
+
+func TestSendText(t *testing.T) {
+	api := getAPI(t)
+
+	err := api.SendText("TestSendText Test Content")
+	assert.NoError(t, err, "unexpected err from api.SendText()")
+}