WIP: CLI, relates to #46

2021-12-16 20:33:01 -05:00 · 2021-12-16 20:33:01 -05:00 · 1e8421e8ce
commit 1e8421e8ce
parent 4346f55b29
10 changed files with 571 additions and 102 deletions
--- a/cmd/subscribe.go
+++ b/cmd/subscribe.go
@ -0,0 +1,132 @@
+package cmd
+
+import (
+	"errors"
+	"fmt"
+	"github.com/urfave/cli/v2"
+	"heckel.io/ntfy/client"
+	"heckel.io/ntfy/util"
+	"log"
+	"os"
+	"os/exec"
+	"strings"
+)
+
+var cmdSubscribe = &cli.Command{
+	Name:      "subscribe",
+	Aliases:   []string{"sub"},
+	Usage:     "Subscribe to one or more topics on a ntfy server",
+	UsageText: "ntfy subscribe [OPTIONS..] TOPIC",
+	Action:    execSubscribe,
+	Flags: []cli.Flag{
+		&cli.StringFlag{Name: "exec", Aliases: []string{"e"}, Usage: "execute command for each message event"},
+		&cli.StringFlag{Name: "since", Aliases: []string{"s"}, Usage: "return events since (Unix timestamp, or all)"},
+	},
+	Description: `(THIS COMMAND IS INCUBATING. IT MAY CHANGE WITHOUT NOTICE.)
+
+Subscribe to one or more topics on a ntfy server, and either print 
+or execute commands for every arriving message. 
+
+By default, the subscribe command just prints the JSON representation of a message. 
+When --exec is passed, each incoming message will execute a command. The message fields 
+are passed to the command as environment variables:
+
+    Variable        Aliases         Description
+    --------------- --------------- -----------------------------------
+    $NTFY_MESSAGE   $message, $m    Message body
+    $NTFY_TITLE     $title, $t      Message title
+    $NTFY_PRIORITY  $priority, $p   Message priority (1=min, 5=max)
+    $NTFY_TAGS      $tags, $ta      Message tags (comma separated list)
+    $NTFY_ID        $id             Unique message ID
+    $NTFY_TIME      $time           Unix timestamp of the message delivery
+    $NTFY_TOPIC     $topic          Topic name
+    $NTFY_EVENT     $event, $ev     Event identifier (always "message")
+
+Examples:
+  ntfy subscribe mytopic                       # Prints JSON for incoming messages to stdout
+  ntfy sub home.lan/backups alerts             # Subscribe to two different topics
+  ntfy sub --exec='notify-send "$m"' mytopic   # Execute command for incoming messages'  
+`,
+}
+
+func execSubscribe(c *cli.Context) error {
+	if c.NArg() < 1 {
+		return errors.New("topic missing")
+	}
+	log.Printf("\x1b[1;33mThis command is incubating. The interface may change without notice.\x1b[0m")
+	cl := client.DefaultClient
+	command := c.String("exec")
+	for _, topic := range c.Args().Slice() {
+		cl.Subscribe(expandTopicURL(topic))
+	}
+	for m := range cl.Messages {
+		_ = dispatchMessage(c, command, m)
+	}
+	return nil
+}
+
+func dispatchMessage(c *cli.Context, command string, m *client.Message) error {
+	if command != "" {
+		return execCommand(c, command, m)
+	}
+	fmt.Println(m.Raw)
+	return nil
+}
+
+func execCommand(c *cli.Context, command string, m *client.Message) error {
+	if m.Event == client.OpenEvent {
+		log.Printf("[%s] Connection opened, subscribed to topic", collapseTopicURL(m.TopicURL))
+	} else if m.Event == client.MessageEvent {
+		go func() {
+			if err := runCommandInternal(c, command, m); err != nil {
+				log.Printf("[%s] Command failed: %s", collapseTopicURL(m.TopicURL), err.Error())
+			}
+		}()
+	}
+	return nil
+}
+
+func runCommandInternal(c *cli.Context, command string, m *client.Message) error {
+	scriptFile, err := createTmpScript(command)
+	if err != nil {
+		return err
+	}
+	defer os.Remove(scriptFile)
+	log.Printf("[%s] Executing: %s (for message: %s)", collapseTopicURL(m.TopicURL), command, m.Raw)
+	cmd := exec.Command("sh", "-c", scriptFile)
+	cmd.Stdin = c.App.Reader
+	cmd.Stdout = c.App.Writer
+	cmd.Stderr = c.App.ErrWriter
+	cmd.Env = envVars(m)
+	return cmd.Run()
+}
+
+func createTmpScript(command string) (string, error) {
+	scriptFile := fmt.Sprintf("%s/ntfy-subscribe-%s.sh.tmp", os.TempDir(), util.RandomString(10))
+	script := fmt.Sprintf("#!/bin/sh\n%s", command)
+	if err := os.WriteFile(scriptFile, []byte(script), 0700); err != nil {
+		return "", err
+	}
+	return scriptFile, nil
+}
+
+func envVars(m *client.Message) []string {
+	env := os.Environ()
+	env = append(env, envVar(m.ID, "NTFY_ID", "id")...)
+	env = append(env, envVar(m.Event, "NTFY_EVENT", "event", "ev")...)
+	env = append(env, envVar(m.Topic, "NTFY_TOPIC", "topic")...)
+	env = append(env, envVar(fmt.Sprintf("%d", m.Time), "NTFY_TIME", "time")...)
+	env = append(env, envVar(m.Message, "NTFY_MESSAGE", "message", "m")...)
+	env = append(env, envVar(m.Title, "NTFY_TITLE", "title", "t")...)
+	env = append(env, envVar(fmt.Sprintf("%d", m.Priority), "NTFY_PRIORITY", "priority", "prio", "p")...)
+	env = append(env, envVar(strings.Join(m.Tags, ","), "NTFY_TAGS", "tags", "ta")...)
+	return env
+}
+
+func envVar(value string, vars ...string) []string {
+	env := make([]string, 0)
+	for _, v := range vars {
+		env = append(env, fmt.Sprintf("%s=%s", v, value))
+	}
+	return env
+}