package alert

import (
	"bytes"
	"encoding/json"
	"fmt"
	"net/http"
	"time"
)

const defaultTimeout = 8 * time.Second

type textMessage struct {
	MsgType string `json:"msg_type"`
	Content struct {
		Text string `json:"text"`
	} `json:"content"`
}

// SendText sends a plain text message to a Lark/Feishu webhook.
func SendText(webhookURL, message string) error {
	if webhookURL == "" {
		return fmt.Errorf("webhook URL is empty")
	}
	if message == "" {
		return fmt.Errorf("message is empty")
	}

	payload := textMessage{MsgType: "text"}
	payload.Content.Text = message
	body, err := json.Marshal(payload)
	if err != nil {
		return fmt.Errorf("failed to marshal webhook payload: %w", err)
	}

	req, err := http.NewRequest(http.MethodPost, webhookURL, bytes.NewReader(body))
	if err != nil {
		return fmt.Errorf("failed to create webhook request: %w", err)
	}
	req.Header.Set("Content-Type", "application/json")

	client := &http.Client{Timeout: defaultTimeout}
	resp, err := client.Do(req)
	if err != nil {
		return fmt.Errorf("webhook request failed: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		return fmt.Errorf("webhook returned status %d", resp.StatusCode)
	}
	return nil
}