package notify

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
)

// Telegram delivers notifications via the Telegram Bot API sendMessage
// endpoint. Config is {"chat_id": "..."}; secret is the bot token and is
// never logged.
type Telegram struct {
	BaseURL string
	HTTP    *http.Client
}

func (t *Telegram) Send(ctx context.Context, cfg json.RawMessage, secret string, ev Event) error {
	var c struct {
		ChatID string `json:"chat_id"`
	}
	if err := json.Unmarshal(cfg, &c); err != nil {
		return err
	}
	body, _ := json.Marshal(map[string]string{
		"chat_id": c.ChatID,
		"text":    fmt.Sprintf("[%s] %s → %s\n%s", ev.Project, ev.Domain, ev.Status, ev.Summary),
	})
	url := t.BaseURL + "/bot" + secret + "/sendMessage"
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(body))
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", "application/json")
	resp, err := t.HTTP.Do(req)
	if err != nil {
		// Do NOT wrap/return err as-is: *url.Error.Error() embeds the full
		// request URL, which contains the bot token (/bot<secret>/...). A
		// caller logging this error would leak the secret.
		return errors.New("telegram: request failed")
	}
	defer resp.Body.Close()
	if resp.StatusCode >= 300 {
		return fmt.Errorf("telegram: status %d", resp.StatusCode)
	}
	return nil
}