From 9c212669bc3dededd5433822737c1fbfb76f2adc Mon Sep 17 00:00:00 2001
From: L0RD-ZER0 <68327382+L0RD-ZER0@users.noreply.github.com>
Date: Mon, 18 Mar 2024 18:51:30 +0530
Subject: [PATCH] Add ability to send files over slack using an app token.

---
 entrypoint.sh | 11 ++++++++
 main.go       | 71 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 82 insertions(+)

diff --git a/entrypoint.sh b/entrypoint.sh
index db190bc..b55ffd1 100755
--- a/entrypoint.sh
+++ b/entrypoint.sh
@@ -27,6 +27,17 @@ fi
 
 export MSG_MODE="$mode"
 
+if [[ -n "$SLACK_FILE_UPLOAD" ]]; then
+  if [[ -z "$SLACK_TOKEN" ]]; then
+    echo -e "[\e[0;31mERROR\e[0m] Secret \`SLACK_TOKEN\` is missing and a file upload is specified. File Uploads require an application token to be present.\n"
+    exit 1
+  fi
+  if [[ -z "$SLACK_CHANNEL" ]]; then
+    echo -e "[\e[0;31mERROR\e[0m] Secret \`SLACK_CHANNEL\` is missing and a file upload is specified. File Uploads require a channel to be specified.\n"
+    exit 1
+  fi
+fi
+
 # custom path for files to override default files
 custom_path="$GITHUB_WORKSPACE/.github/slack"
 main_script="/main.sh"
diff --git a/main.go b/main.go
index f3b37d6..36e25d7 100644
--- a/main.go
+++ b/main.go
@@ -4,6 +4,8 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
+	"io"
+	"mime/multipart"
 	"net/http"
 	"os"
 	"strings"
@@ -30,6 +32,7 @@ const (
 	EnvMinimal        = "MSG_MINIMAL"
 	EnvSlackLinkNames = "SLACK_LINK_NAMES"
 	EnvThreadTs       = "SLACK_THREAD_TS"
+	EnvSlackUpload    = "SLACK_FILE_UPLOAD"
 	EnvMessageMode    = "MSG_MODE"
 )
 
@@ -300,6 +303,74 @@ func send_raw(endpoint string, payload []byte) error {
 		return err
 	}
 
+	if res.StatusCode >= 299 {
+		return fmt.Errorf("Error on message: %s\n", res.Status)
+	}
+
+	if os.Getenv(EnvSlackUpload) != "" {
+		err = sendFile(os.Getenv(EnvSlackUpload), "", os.Getenv(EnvSlackChannel), os.Getenv(EnvThreadTs))
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func sendFile(filename string, message string, channel string, thread_ts string) error {
+	file, err := os.Open(filename)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	fileData := &bytes.Buffer{}
+	writer := multipart.NewWriter(fileData)
+
+	part, err := writer.CreateFormFile("file", filename)
+	if err != nil {
+		return err
+	}
+
+	_, err = io.Copy(part, file)
+
+	err = writer.WriteField("initial_comment", message)
+	if err != nil {
+		return err
+	}
+
+	err = writer.WriteField("channels", channel)
+	if err != nil {
+		return err
+	}
+
+	if thread_ts != "" {
+		err = writer.WriteField("thread_ts", thread_ts)
+		if err != nil {
+			return err
+		}
+	}
+
+	err = writer.Close()
+	if err != nil {
+		return err
+	}
+
+	req, err := http.NewRequest("POST", "https://slack.com/api/files.upload", fileData)
+
+	if err != nil {
+		return err
+	}
+
+	req.Header.Set("Content-Type", writer.FormDataContentType())
+	req.Header.Set("Authorization", "Bearer "+os.Getenv("SLACK_TOKEN"))
+
+	client := &http.Client{}
+	res, err := client.Do(req)
+	if err != nil {
+		return err
+	}
+
 	if res.StatusCode >= 299 {
 		return fmt.Errorf("Error on message: %s\n", res.Status)
 	}