// tera-seriald owns validated CH01-CH48 line configuration for TERA boards.
package main

import (
	"context"
	"errors"
	"fmt"
	"log"
	"net"
	"os"
	"os/signal"
	"path/filepath"
	"strconv"
	"strings"
	"syscall"
	"time"

	"tera-clone/services/tera-api/internal/domain"
	"tera-clone/services/tera-api/internal/logservice"
	"tera-clone/services/tera-api/internal/logstorage"
	"tera-clone/services/tera-api/internal/serial"
)

func main() {
	controlSocketPath := getenv("TERA_SERIALD_SOCKET", serial.DefaultSocketPath)
	streamSocketPath := getenv("TERA_SERIALD_STREAM_SOCKET", serial.DefaultStreamSocketPath)
	mappingPath := getenv("TERA_SERIALD_MAPPING", "/etc/tera/serial-map.json")
	hardwareProfile := getenv("TERA_SERIALD_HARDWARE_PROFILE", "fet3568j-c")
	controller, err := serial.LoadMappingController(mappingPath, hardwareProfile)
	if err != nil {
		log.Printf("tera-seriald is fail-closed: %v", err)
		controller = nil
	}
	if controller != nil {
		defer func() {
			if err := controller.Close(); err != nil {
				log.Printf("tera-seriald serial hold close failed: %v", err)
			}
		}()
	}
	controlListener, err := listen(controlSocketPath)
	if err != nil {
		log.Fatalf("tera-seriald control socket setup failed: %v", err)
	}
	streamListener, err := listen(streamSocketPath)
	if err != nil {
		_ = controlListener.Close()
		_ = os.Remove(controlSocketPath)
		log.Fatalf("tera-seriald stream socket setup failed: %v", err)
	}
	defer func() {
		_ = controlListener.Close()
		_ = streamListener.Close()
		_ = os.Remove(controlSocketPath)
		_ = os.Remove(streamSocketPath)
	}()

	unavailable := serial.UnavailableController{Reason: "validated serial mapping is not installed"}
	var hardware serial.Controller = unavailable
	var streamResolver serial.StreamResolver = unavailable
	if controller != nil {
		hardware = controller
		streamResolver = controller
	}
	eventSink := serial.NewBoundedStreamEventSink(getenvInt("TERA_SERIALD_EVENT_QUEUE", 1024))
	streamManager, err := serial.NewStreamLeaseManager(streamResolver, serial.StreamLeaseOptions{Events: eventSink})
	if err != nil {
		log.Fatalf("tera-seriald stream manager setup failed: %v", err)
	}
	reporterContext, stopReporter := context.WithCancel(context.Background())
	defer stopReporter()
	var linkMonitor serial.LinkStateController = serial.DisabledLinkStateController{
		Reason: "CTS/DSR/DCD are excluded from unified RX/CR connection status",
	}
	if controller != nil && getenvBool("TERA_SERIALD_LINK_SCAN_ENABLED", false) {
		controller.SetLinkWorkerCount(getenvInt("TERA_SERIALD_LINK_WORKERS", 8))
		monitor, monitorErr := serial.NewLinkMonitor(controller, serial.LinkMonitorOptions{
			Interval: time.Duration(getenvInt("TERA_SERIALD_LINK_SCAN_INTERVAL_MS", 1000)) * time.Millisecond,
		})
		if monitorErr != nil {
			log.Fatalf("tera-seriald link monitor setup failed: %v", monitorErr)
		}
		linkMonitor = monitor
		go monitor.Run(reporterContext)
	}
	crProbeEnabled := controller != nil && getenvBool("TERA_SERIALD_CR_PROBE_ENABLED", true)
	var crProbeGroups []serial.CRProbeGroup
	if controller != nil {
		crProbeGroups = controller.CRProbeGroups()
	}
	crProbeManager, err := serial.NewCRProbeManager(streamManager, serial.CRProbeOptions{
		Enabled:          crProbeEnabled,
		ResponseTimeout:  time.Duration(getenvInt("TERA_SERIALD_CR_PROBE_TIMEOUT_MS", 100)) * time.Millisecond,
		SweepInterval:    time.Duration(getenvInt("TERA_SERIALD_CR_PROBE_SWEEP_SECONDS", 4)) * time.Second,
		BetweenChannels:  time.Duration(getenvInt("TERA_SERIALD_CR_PROBE_SPACING_MS", 20)) * time.Millisecond,
		QuietPeriod:      time.Duration(getenvInt("TERA_SERIALD_CR_PROBE_QUIET_SECONDS", 5)) * time.Second,
		StartupDelay:     time.Duration(getenvInt("TERA_SERIALD_CR_PROBE_STARTUP_DELAY_SECONDS", 30)) * time.Second,
		Workers:          getenvInt("TERA_SERIALD_CR_PROBE_WORKERS", 2),
		Groups:           crProbeGroups,
		ConfirmResponses: getenvInt("TERA_SERIALD_CR_PROBE_CONFIRM_RESPONSES", 1),
		DownMisses:       getenvInt("TERA_SERIALD_CR_PROBE_DOWN_MISSES", 2),
	})
	if err != nil {
		log.Fatalf("tera-seriald CR probe setup failed: %v", err)
	}
	if crProbeEnabled {
		for _, group := range crProbeGroups {
			log.Printf("tera-seriald CR probe group pci_bdf=%s channels=%d", group.ID, len(group.Channels))
		}
	}
	go crProbeManager.Run(reporterContext)
	logJournal := logservice.Journal(logservice.NewClient(getenv("TERA_SERIALD_LOG_SOCKET", logservice.DefaultSocketPath)))
	go reportStreamEvents(reporterContext, streamManager, eventSink.Events(), logJournal, time.Duration(getenvInt("TERA_SERIALD_REPORT_INTERVAL_SECONDS", 10))*time.Second)
	controlServer := serial.SocketServer{Controller: hardware, Capture: streamManager, CRProbe: crProbeManager, Links: linkMonitor}
	streamServer := serial.StreamSocketServer{Manager: streamManager}
	done := make(chan error, 2)
	go func() { done <- controlServer.Serve(controlListener) }()
	go func() { done <- streamServer.Serve(streamListener) }()
	log.Printf("tera-seriald serving validated serial configuration on %s", controlSocketPath)
	log.Printf("tera-seriald serving exclusive serial streams on %s", streamSocketPath)

	signals := make(chan os.Signal, 1)
	signal.Notify(signals, syscall.SIGINT, syscall.SIGTERM)
	select {
	case signal := <-signals:
		log.Printf("tera-seriald stopping after %s", signal)
		stopReporter()
		_ = controlListener.Close()
		_ = streamListener.Close()
		_ = streamManager.Close()
		for range 2 {
			if err := <-done; err != nil {
				log.Printf("tera-seriald stop error: %v", err)
			}
		}
	case err := <-done:
		stopReporter()
		_ = controlListener.Close()
		_ = streamListener.Close()
		_ = streamManager.Close()
		if err != nil {
			log.Fatalf("tera-seriald failed: %v", err)
		}
	}
}

func listen(socketPath string) (net.Listener, error) {
	if socketPath == "" || !filepath.IsAbs(socketPath) {
		return nil, errors.New("TERA_SERIALD_SOCKET must be an absolute path")
	}
	if err := os.MkdirAll(filepath.Dir(socketPath), 0o750); err != nil {
		return nil, err
	}
	if info, err := os.Lstat(socketPath); err == nil {
		if info.Mode()&os.ModeSocket == 0 {
			return nil, errors.New("refusing to replace non-socket serial control path")
		}
		if err := os.Remove(socketPath); err != nil {
			return nil, err
		}
	} else if !os.IsNotExist(err) {
		return nil, err
	}
	listener, err := net.Listen("unix", socketPath)
	if err != nil {
		return nil, err
	}
	if err := os.Chmod(socketPath, 0o660); err != nil {
		_ = listener.Close()
		return nil, err
	}
	return listener, nil
}

func getenv(key, fallback string) string {
	if value := os.Getenv(key); value != "" {
		return value
	}
	return fallback
}

func getenvInt(key string, fallback int) int {
	value := os.Getenv(key)
	if value == "" {
		return fallback
	}
	parsed, err := strconv.Atoi(value)
	if err != nil || parsed <= 0 {
		return fallback
	}
	return parsed
}

func getenvBool(key string, fallback bool) bool {
	value := os.Getenv(key)
	if value == "" {
		return fallback
	}
	parsed, err := strconv.ParseBool(value)
	if err != nil {
		return fallback
	}
	return parsed
}

type streamIntervalTotal struct {
	rx uint64
	tx uint64
}

func reportStreamEvents(ctx context.Context, manager *serial.StreamLeaseManager, events <-chan serial.StreamEvent, journal logservice.Journal, interval time.Duration) {
	if interval <= 0 {
		interval = 10 * time.Second
	}
	ticker := time.NewTicker(interval)
	defer ticker.Stop()
	totals := make(map[string]streamIntervalTotal)
	var storageFailures uint64
	var lastStorageError error
	flush := func() {
		for key, total := range totals {
			if total.rx != 0 || total.tx != 0 {
				log.Printf("tera-seriald stream interval lease=%s rx_bytes=%d tx_bytes=%d", key, total.rx, total.tx)
			}
			delete(totals, key)
		}
		snapshot := manager.Snapshot()
		log.Printf("tera-seriald stream status active_leases=%d rx_bytes=%d tx_bytes=%d dropped_events=%d storage_failures=%d", snapshot.ActiveLeases, snapshot.RXBytes, snapshot.TXBytes, snapshot.DroppedEvents, storageFailures)
		if lastStorageError != nil {
			log.Printf("tera-seriald payload logging degraded: %v", lastStorageError)
			lastStorageError = nil
		}
	}
	defer flush()
	for {
		select {
		case event := <-events:
			key := event.Channel + "/" + event.LeaseID
			switch event.Direction {
			case "open", "close":
				log.Printf("tera-seriald stream lifecycle channel=%s lease=%s client=%s action=%s", event.Channel, event.LeaseID, event.ClientID, event.Direction)
			case "rx":
				total := totals[key]
				total.rx += event.Bytes
				totals[key] = total
				if err := recordPayload(journal, event); err != nil {
					storageFailures++
					lastStorageError = err
				}
			case "tx":
				total := totals[key]
				total.tx += event.Bytes
				totals[key] = total
				if err := recordPayload(journal, event); err != nil {
					storageFailures++
					lastStorageError = err
				}
			}
		case <-ticker.C:
			flush()
		case <-ctx.Done():
			return
		}
	}
}

func recordPayload(journal logservice.Journal, event serial.StreamEvent) error {
	if journal == nil || len(event.Payload) == 0 {
		return nil
	}
	record := domain.PortLogEvent{
		Timestamp: event.Timestamp, Channel: event.Channel, EventType: "traffic",
		Direction: strings.ToUpper(event.Direction), Actor: event.ClientID,
		Message: fmt.Sprintf("%s %d serial payload byte(s)", strings.ToUpper(event.Direction), len(event.Payload)),
		Payload: append([]byte(nil), event.Payload...), PayloadBytes: len(event.Payload), PayloadEncoding: "base64",
		DisplayFormat: event.LogFormat, ShowTimestamp: event.ShowTimestamp, ShowDirection: event.ShowDirection,
		ShowUsername: event.ShowUsername, ShowIPAddress: event.ShowIPAddress, ShowPort: event.ShowPort,
	}
	return journal.Append(logstorage.ClassPort, event.Timestamp, record)
}