Implement Telegram alert client

Author: richardgreg

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{

internal/client/telegram.go

@@ -0,0 +1,112 @@
+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"
+)
+
+// TelegramConfig stores configuration for the Telegram bot
+type TelegramConfig struct {
+	Token  string // Bot token received from BotFather
+	ChatID string // Chat ID where messages will be sent
+}
+
+// TelegramClient interface for sending alerts
+type TelegramClient interface {
+	AlertClient
+}
+
+// telegramClient implementation of TelegramClient
+type telegramClient struct {
+	token  string
+	chatID string
+	client *http.Client
+}
+
+// NewTelegramClient initializes a new Telegram client with given config
+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{},
+	}
+}
+
+// TelegramPayload structure for the message payload
+type TelegramPayload struct {
+	ChatID string `json:"chat_id"`
+	Text   string `json:"text"`
+}
+
+// PostEvent sends an alert message to the specified Telegram chat
+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
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("telegram API returned bad status code %d: %s", resp.StatusCode, string(respBytes))
+	}
+
+	// Simplified handling
+	var apiResp struct {
+		Ok     bool            `json:"ok"`
+		Result json.RawMessage `json:"result"`
+		Error  string          `json:"description"`
+	}
+	if err = json.Unmarshal(respBytes, &apiResp); err != nil {
+		return nil, fmt.Errorf("could not unmarshal telegram response: %w", err)
+	}
+
+	if !apiResp.Ok {
+		return &AlertAPIResponse{
+			Status:  core.FailureStatus,
+			Message: apiResp.Error,
+		}, nil
+	}
+
+	return &AlertAPIResponse{
+		Status:  core.SuccessStatus,
+		Message: "Message sent successfully",
+	}, nil
+}
+
+// GetName returns the name of the Telegram client
+func (tc telegramClient) GetName() string {
+	return "TelegramClient"
+}