package main

import (
	"encoding/base64"
	"fmt"
	"log"
	"net/http"
	"os"
	"strings"
	"time"
)

// ntfyNotifier pushes user reports to an ntfy server. It is nil when the
// required environment variables are not set, in which case notify is a no-op.
type ntfyNotifier struct {
	url        string // full topic URL, e.g. https://ntfy.example.com/dmrmap
	user       string
	token      string
	clickBase  string
	httpClient *http.Client
}

// newNtfyNotifierFromEnv builds a notifier from NTFY_URL / NTFY_TOPIC /
// NTFY_USER / NTFY_TOKEN. Returns nil when notifications are not configured.
func newNtfyNotifierFromEnv() *ntfyNotifier {
	base := strings.TrimSpace(os.Getenv("NTFY_URL"))
	topic := strings.TrimSpace(os.Getenv("NTFY_TOPIC"))
	if base == "" || topic == "" {
		log.Println("ntfy notifications disabled (set NTFY_URL and NTFY_TOPIC to enable)")
		return nil
	}

	return &ntfyNotifier{
		url:        strings.TrimRight(base, "/") + "/" + strings.TrimLeft(topic, "/"),
		user:       strings.TrimSpace(os.Getenv("NTFY_USER")),
		token:      strings.TrimSpace(os.Getenv("NTFY_TOKEN")),
		clickBase:  strings.TrimRight(strings.TrimSpace(os.Getenv("PUBLIC_BASE_URL")), "/"),
		httpClient: &http.Client{Timeout: 10 * time.Second},
	}
}

// notifyReport sends a push notification for a new user report. It never
// blocks the caller and never fails the request that triggered it.
func (n *ntfyNotifier) notifyReport(rep UserReport) {
	if n == nil {
		return
	}
	go func() {
		if err := n.send(rep); err != nil {
			log.Printf("ntfy: failed to publish report %d: %v", rep.ID, err)
		}
	}()
}

func (n *ntfyNotifier) send(rep UserReport) error {
	body := reportTypeLabel(rep.ReportType)
	if rep.Message != "" {
		body += "\n\n" + rep.Message
	}
	body += fmt.Sprintf("\n\nRepeater ID: %d", rep.RepeaterID)

	req, err := http.NewRequest(http.MethodPost, n.url, strings.NewReader(body))
	if err != nil {
		return err
	}

	title := fmt.Sprintf("Report: %s", rep.Callsign)
	if rep.Callsign == "" {
		title = fmt.Sprintf("Report: #%d", rep.RepeaterID)
	}
	req.Header.Set("Title", title)
	req.Header.Set("Tags", "warning,radio")
	req.Header.Set("Priority", "default")
	if n.clickBase != "" {
		req.Header.Set("Click", fmt.Sprintf("%s/admin/#%d", n.clickBase, rep.RepeaterID))
	}
	n.setAuth(req)

	resp, err := n.httpClient.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode < 200 || resp.StatusCode > 299 {
		return fmt.Errorf("ntfy returned HTTP %d", resp.StatusCode)
	}
	return nil
}

// setAuth uses basic auth when a username is configured (ntfy accepts an
// access token as the password), and bearer auth for a token on its own.
func (n *ntfyNotifier) setAuth(req *http.Request) {
	switch {
	case n.user != "" && n.token != "":
		creds := base64.StdEncoding.EncodeToString([]byte(n.user + ":" + n.token))
		req.Header.Set("Authorization", "Basic "+creds)
	case n.token != "":
		req.Header.Set("Authorization", "Bearer "+n.token)
	}
}