tuner/backend/process/mediamtx.go

package process

import (
	"bufio"
	"fmt"
	"io"
	"log"
	"os"
	"os/exec"
	"sync"
	"time"

	"tuner/models"
)

// MediaMTXManager manages the MediaMTX child process.
type MediaMTXManager struct {
	mu         sync.Mutex
	cmd        *exec.Cmd
	binaryPath string
	configPath string
	extraEnv   []string
	startTime  time.Time
	lastError  string
	stopCh     chan struct{}
	stopped    bool
}

// NewMediaMTXManager creates a new manager for the MediaMTX process.
func NewMediaMTXManager(binaryPath, configPath string) *MediaMTXManager {
	return &MediaMTXManager{
		binaryPath: binaryPath,
		configPath: configPath,
	}
}

// SetEnv sets additional environment variables (e.g. MTX_HLSVARIANT) that are
// passed to MediaMTX. Must be called before Start.
func (m *MediaMTXManager) SetEnv(env []string) {
	m.mu.Lock()
	defer m.mu.Unlock()
	m.extraEnv = env
}

// Start launches the MediaMTX process. It auto-restarts on unexpected exit.
func (m *MediaMTXManager) Start() error {
	m.mu.Lock()
	defer m.mu.Unlock()

	if m.cmd != nil && m.cmd.Process != nil {
		return fmt.Errorf("mediamtx already running (pid %d)", m.cmd.Process.Pid)
	}

	return m.startLocked()
}

func (m *MediaMTXManager) startLocked() error {
	_, err := exec.LookPath(m.binaryPath)
	if err != nil {
		m.lastError = fmt.Sprintf("binary not found: %s", m.binaryPath)
		return fmt.Errorf("mediamtx binary not found: %s", m.binaryPath)
	}

	m.cmd = exec.Command(m.binaryPath, m.configPath)
	if len(m.extraEnv) > 0 {
		m.cmd.Env = append(os.Environ(), m.extraEnv...)
	}
	m.lastError = ""
	m.stopped = false
	m.stopCh = make(chan struct{})

	// Capture stdout/stderr for logging
	stdout, _ := m.cmd.StdoutPipe()
	stderr, _ := m.cmd.StderrPipe()

	if err := m.cmd.Start(); err != nil {
		m.lastError = err.Error()
		return fmt.Errorf("start mediamtx: %w", err)
	}

	m.startTime = time.Now()
	log.Printf("[mediamtx] started with pid %d", m.cmd.Process.Pid)

	go m.logOutput("stdout", stdout)
	go m.logOutput("stderr", stderr)

	// Monitor in background and auto-restart on unexpected exit
	go m.monitor()

	return nil
}

func (m *MediaMTXManager) logOutput(name string, r io.Reader) {
	scanner := bufio.NewScanner(r)
	for scanner.Scan() {
		log.Printf("[mediamtx:%s] %s", name, scanner.Text())
	}
}

func (m *MediaMTXManager) monitor() {
	err := m.cmd.Wait()

	m.mu.Lock()
	defer m.mu.Unlock()

	// Check if this was a deliberate stop
	select {
	case <-m.stopCh:
		log.Println("[mediamtx] stopped")
		return
	default:
	}

	if err != nil {
		m.lastError = err.Error()
		log.Printf("[mediamtx] exited unexpectedly: %v — restarting in 2s", err)
	} else {
		log.Println("[mediamtx] exited unexpectedly (status 0) — restarting in 2s")
	}

	m.cmd = nil

	// Auto-restart after a brief delay (without lock held)
	go func() {
		time.Sleep(2 * time.Second)
		m.mu.Lock()
		defer m.mu.Unlock()
		if m.stopped {
			return
		}
		if m.cmd != nil {
			return // already restarted
		}
		if err := m.startLocked(); err != nil {
			log.Printf("[mediamtx] auto-restart failed: %v", err)
		}
	}()
}

// Stop kills the MediaMTX process.
func (m *MediaMTXManager) Stop() error {
	m.mu.Lock()
	defer m.mu.Unlock()

	m.stopped = true

	if m.cmd == nil || m.cmd.Process == nil {
		return nil
	}

	if m.stopCh != nil {
		close(m.stopCh)
	}

	if err := m.cmd.Process.Kill(); err != nil {
		return fmt.Errorf("kill mediamtx: %w", err)
	}

	m.cmd = nil
	log.Println("[mediamtx] killed")
	return nil
}

// Restart stops and restarts the MediaMTX process.
func (m *MediaMTXManager) Restart() error {
	if err := m.Stop(); err != nil {
		return err
	}
	time.Sleep(500 * time.Millisecond)
	return m.Start()
}

// Status returns the current process status.
func (m *MediaMTXManager) Status() models.ProcessInfo {
	m.mu.Lock()
	defer m.mu.Unlock()

	info := models.ProcessInfo{
		Error: m.lastError,
	}

	if m.cmd != nil && m.cmd.Process != nil {
		info.Running = true
		info.PID = m.cmd.Process.Pid
		info.Uptime = time.Since(m.startTime).Truncate(time.Second).String()
	}

	return info
}