WIP: CLI, relates to #46

client/client.go

@@ -0,0 +1,135 @@
+package client
+
+import (
+	"bufio"
+	"context"
+	"encoding/json"
+	"fmt"
+	"log"
+	"net/http"
+	"strings"
+	"sync"
+	"time"
+)
+
+const (
+	DefaultBaseURL = "https://ntfy.sh"
+)
+
+const (
+	MessageEvent   = "message"
+	KeepaliveEvent = "keepalive"
+	OpenEvent      = "open"
+)
+
+type Client struct {
+	BaseURL       string
+	Messages      chan *Message
+	subscriptions map[string]*subscription
+	mu            sync.Mutex
+}
+
+type Message struct {
+	ID       string
+	Event    string
+	Time     int64
+	Topic    string
+	Message  string
+	Title    string
+	Priority int
+	Tags     []string
+	BaseURL  string
+	TopicURL string
+	Raw      string
+}
+
+type subscription struct {
+	cancel context.CancelFunc
+}
+
+var DefaultClient = New()
+
+func New() *Client {
+	return &Client{
+		Messages:      make(chan *Message),
+		subscriptions: make(map[string]*subscription),
+	}
+}
+
+func (c *Client) Publish(topicURL, message string, options ...PublishOption) error {
+	req, _ := http.NewRequest("POST", topicURL, strings.NewReader(message))
+	for _, option := range options {
+		if err := option(req); err != nil {
+			return err
+		}
+	}
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return err
+	}
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("unexpected response %d from server", resp.StatusCode)
+	}
+	return err
+}
+
+func (c *Client) Subscribe(topicURL string) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if _, ok := c.subscriptions[topicURL]; ok {
+		return
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	c.subscriptions[topicURL] = &subscription{cancel}
+	go handleConnectionLoop(ctx, c.Messages, topicURL)
+}
+
+func (c *Client) Unsubscribe(topicURL string) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	sub, ok := c.subscriptions[topicURL]
+	if !ok {
+		return
+	}
+	sub.cancel()
+	return
+}
+
+func handleConnectionLoop(ctx context.Context, msgChan chan *Message, topicURL string) {
+	for {
+		if err := handleConnection(ctx, msgChan, topicURL); err != nil {
+			log.Printf("connection to %s failed: %s", topicURL, err.Error())
+		}
+		select {
+		case <-ctx.Done():
+			log.Printf("connection to %s exited", topicURL)
+			return
+		case <-time.After(5 * time.Second):
+		}
+	}
+}
+
+func handleConnection(ctx context.Context, msgChan chan *Message, topicURL string) error {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, fmt.Sprintf("%s/json", topicURL), nil)
+	if err != nil {
+		return err
+	}
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+	scanner := bufio.NewScanner(resp.Body)
+	for scanner.Scan() {
+		var m *Message
+		line := scanner.Text()
+		if err := json.NewDecoder(strings.NewReader(line)).Decode(&m); err != nil {
+			return err
+		}
+		m.BaseURL = strings.TrimSuffix(topicURL, "/"+m.Topic) // FIXME hack!
+		m.TopicURL = topicURL
+		m.Raw = line
+		msgChan <- m
+	}
+	return nil
+}