From 3bb3585c097714c390395935edcbdd28c60a1ed5 Mon Sep 17 00:00:00 2001
From: Richard Gregory <richardgrecoson@gmail.com>
Date: Sun, 18 Feb 2024 18:49:22 +0100
Subject: [PATCH] Implement Telegram alert client

---
 internal/client/slack.go    |   2 +-
 internal/client/telegram.go | 105 ++++++++++++++++++++++++++++++++++++
 2 files changed, 106 insertions(+), 1 deletion(-)
 create mode 100644 internal/client/telegram.go

diff --git a/internal/client/slack.go b/internal/client/slack.go
index 249ecd32..9dbe2ce2 100644
--- a/internal/client/slack.go
+++ b/internal/client/slack.go
@@ -43,7 +43,7 @@ type slackClient struct {
 // NewSlackClient ... Initializer
 func NewSlackClient(cfg *SlackConfig, name string) SlackClient {
 	if cfg.URL == "" {
-		logging.NoContext().Warn("No Slack webhook URL not provided")
+		logging.NoContext().Warn("No Slack webhook URL provided")
 	}
 
 	return &slackClient{
diff --git a/internal/client/telegram.go b/internal/client/telegram.go
new file mode 100644
index 00000000..960ba5bf
--- /dev/null
+++ b/internal/client/telegram.go
@@ -0,0 +1,105 @@
+package client
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/base-org/pessimism/internal/core"
+	"github.com/base-org/pessimism/internal/logging"
+)
+
+type TelegramClient interface {
+	AlertClient
+}
+
+type TelegramConfig struct {
+	Token  string
+	ChatID string
+}
+
+type telegramClient struct {
+	token  string
+	chatID string
+	client *http.Client
+}
+
+func NewTelegramClient(cfg *TelegramConfig) TelegramClient {
+	if cfg.Token == "" {
+		logging.NoContext().Warn("No Telegram token provided")
+	}
+
+	return &telegramClient{
+		token:  cfg.Token,
+		chatID: cfg.ChatID,
+		client: &http.Client{},
+	}
+}
+
+type TelegramPayload struct {
+	ChatID string `json:"chat_id"`
+	Text   string `json:"text"`
+}
+
+type TelegramAPIResponse struct {
+	Ok     bool            `json:"ok"`
+	Result json.RawMessage `json:"result"` // Might not be needed for basic response handling
+	Error  string          `json:"description"`
+}
+
+func (tr *TelegramAPIResponse) ToAlertResponse() *AlertAPIResponse {
+	if tr.Ok {
+		return &AlertAPIResponse{
+			Status:  core.SuccessStatus,
+			Message: "Message sent successfully",
+		}
+	}
+	return &AlertAPIResponse{
+		Status:  core.FailureStatus,
+		Message: tr.Error,
+	}
+}
+
+func (tc *telegramClient) PostEvent(ctx context.Context, data *AlertEventTrigger) (*AlertAPIResponse, error) {
+	payload := TelegramPayload{
+		ChatID: tc.chatID,
+		Text:   data.Message,
+	}
+
+	payloadBytes, err := json.Marshal(payload)
+	if err != nil {
+		return nil, err
+	}
+
+	url := fmt.Sprintf("https://api.telegram.org/bot%s/sendMessage", tc.token)
+	req, err := http.NewRequestWithContext(ctx, "POST", url, bytes.NewReader(payloadBytes))
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Content-Type", "application/json")
+
+	resp, err := tc.client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	respBytes, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	var apiResp TelegramAPIResponse
+	if err = json.Unmarshal(respBytes, &apiResp); err != nil {
+		return nil, fmt.Errorf("could not unmarshal telegram response: %w", err)
+	}
+
+	return apiResp.ToAlertResponse(), nil
+}
+
+func (tc *telegramClient) GetName() string {
+	return "TelegramClient"
+}