package main

import (
	"context"
	"fmt"
	"os"
	"os/signal"
	"path/filepath"
	"runtime"
	"strings"
	"syscall"
	"time"

	"github.com/spf13/cobra"
	"github.com/steveyegge/beads/cmd/bd/doctor"
	"github.com/steveyegge/beads/internal/beads"
	"github.com/steveyegge/beads/internal/daemon"
	"github.com/steveyegge/beads/internal/rpc"
	"github.com/steveyegge/beads/internal/storage/sqlite"
)

var daemonCmd = &cobra.Command{
	Use:   "daemon",
	Short: "Manage background sync daemon",
	Long: `Manage the background daemon that automatically syncs issues with git remote.

The daemon will:
- Poll for changes at configurable intervals (default: 5 seconds)
- Export pending database changes to JSONL
- Auto-commit changes if --auto-commit flag set
- Auto-push commits if --auto-push flag set
- Pull remote changes periodically
- Auto-import when remote changes detected

Common operations:
  bd daemon --start              Start the daemon (background)
  bd daemon --start --foreground Start in foreground (for systemd/supervisord)
  bd daemon --stop               Stop a running daemon
  bd daemon --status             Check if daemon is running
  bd daemon --health             Check daemon health and metrics

Run 'bd daemon' with no flags to see available options.`,
	Run: func(cmd *cobra.Command, args []string) {
		start, _ := cmd.Flags().GetBool("start")
		stop, _ := cmd.Flags().GetBool("stop")
		status, _ := cmd.Flags().GetBool("status")
		health, _ := cmd.Flags().GetBool("health")
		metrics, _ := cmd.Flags().GetBool("metrics")
		interval, _ := cmd.Flags().GetDuration("interval")
		autoCommit, _ := cmd.Flags().GetBool("auto-commit")
		autoPush, _ := cmd.Flags().GetBool("auto-push")
		localMode, _ := cmd.Flags().GetBool("local")
		logFile, _ := cmd.Flags().GetString("log")
		foreground, _ := cmd.Flags().GetBool("foreground")

		// If no operation flags provided, show help
		if !start && !stop && !status && !health && !metrics {
			_ = cmd.Help()
			return
		}

		// If auto-commit/auto-push flags weren't explicitly provided, read from config
		// (skip if --stop, --status, --health, --metrics)
		if start && !stop && !status && !health && !metrics {
			if !cmd.Flags().Changed("auto-commit") {
				if dbPath := beads.FindDatabasePath(); dbPath != "" {
					ctx := context.Background()
					store, err := sqlite.New(ctx, dbPath)
					if err == nil {
						if configVal, err := store.GetConfig(ctx, "daemon.auto_commit"); err == nil && configVal == "true" {
							autoCommit = true
						}
						_ = store.Close()
					}
				}
			}
			if !cmd.Flags().Changed("auto-push") {
				if dbPath := beads.FindDatabasePath(); dbPath != "" {
					ctx := context.Background()
					store, err := sqlite.New(ctx, dbPath)
					if err == nil {
						if configVal, err := store.GetConfig(ctx, "daemon.auto_push"); err == nil && configVal == "true" {
							autoPush = true
						}
						_ = store.Close()
					}
				}
			}
		}

		if interval <= 0 {
			fmt.Fprintf(os.Stderr, "Error: interval must be positive (got %v)\n", interval)
			os.Exit(1)
		}

		pidFile, err := getPIDFilePath()
		if err != nil {
			fmt.Fprintf(os.Stderr, "Error: %v\n", err)
			os.Exit(1)
		}

		if status {
			showDaemonStatus(pidFile)
			return
		}

		if health {
			showDaemonHealth()
			return
		}

		if metrics {
			showDaemonMetrics()
			return
		}

		if stop {
			stopDaemon(pidFile)
			return
		}

		// If we get here and --start wasn't provided, something is wrong
		// (should have been caught by help check above)
		if !start {
			fmt.Fprintf(os.Stderr, "Error: --start flag is required to start the daemon\n")
			fmt.Fprintf(os.Stderr, "Run 'bd daemon --help' to see available options\n")
			os.Exit(1)
		}

		// Skip daemon-running check if we're the forked child (BD_DAEMON_FOREGROUND=1)
		// because the check happens in the parent process before forking
		if os.Getenv("BD_DAEMON_FOREGROUND") != "1" {
			// Check if daemon is already running
			if isRunning, pid := isDaemonRunning(pidFile); isRunning {
				// Check if running daemon has compatible version
				socketPath := getSocketPathForPID(pidFile)
				if client, err := rpc.TryConnectWithTimeout(socketPath, 1*time.Second); err == nil && client != nil {
					health, healthErr := client.Health()
					_ = client.Close()

					// If we can check version and it's compatible, exit
					if healthErr == nil && health.Compatible {
						fmt.Fprintf(os.Stderr, "Error: daemon already running (PID %d, version %s)\n", pid, health.Version)
						fmt.Fprintf(os.Stderr, "Use 'bd daemon --stop' to stop it first\n")
						os.Exit(1)
					}

					// Version mismatch - auto-stop old daemon
					if healthErr == nil && !health.Compatible {
						fmt.Fprintf(os.Stderr, "Warning: daemon version mismatch (daemon: %s, client: %s)\n", health.Version, Version)
						fmt.Fprintf(os.Stderr, "Stopping old daemon and starting new one...\n")
						stopDaemon(pidFile)
						// Continue with daemon startup
					}
				} else {
					// Can't check version - assume incompatible
					fmt.Fprintf(os.Stderr, "Error: daemon already running (PID %d)\n", pid)
					fmt.Fprintf(os.Stderr, "Use 'bd daemon --stop' to stop it first\n")
					os.Exit(1)
				}
			}
		}

		// Validate --local mode constraints
		if localMode {
			if autoCommit {
				fmt.Fprintf(os.Stderr, "Error: --auto-commit cannot be used with --local mode\n")
				fmt.Fprintf(os.Stderr, "Hint: --local mode runs without git, so commits are not possible\n")
				os.Exit(1)
			}
			if autoPush {
				fmt.Fprintf(os.Stderr, "Error: --auto-push cannot be used with --local mode\n")
				fmt.Fprintf(os.Stderr, "Hint: --local mode runs without git, so pushes are not possible\n")
				os.Exit(1)
			}
		}

		// Validate we're in a git repo (skip in local mode)
		if !localMode && !isGitRepo() {
			fmt.Fprintf(os.Stderr, "Error: not in a git repository\n")
			fmt.Fprintf(os.Stderr, "Hint: run 'git init' to initialize a repository, or use --local for local-only mode\n")
			os.Exit(1)
		}

		// Check for upstream if auto-push enabled
		if autoPush && !gitHasUpstream() {
			fmt.Fprintf(os.Stderr, "Error: no upstream configured (required for --auto-push)\n")
			fmt.Fprintf(os.Stderr, "Hint: git push -u origin <branch-name>\n")
			os.Exit(1)
		}

		// Warn if starting daemon in a git worktree
		// Ensure dbPath is set for warning
		if dbPath == "" {
			if foundDB := beads.FindDatabasePath(); foundDB != "" {
				dbPath = foundDB
			}
		}
		if dbPath != "" {
			warnWorktreeDaemon(dbPath)
		}

		// Start daemon
		if localMode {
			fmt.Printf("Starting bd daemon in LOCAL mode (interval: %v, no git sync)\n", interval)
		} else {
			fmt.Printf("Starting bd daemon (interval: %v, auto-commit: %v, auto-push: %v)\n",
				interval, autoCommit, autoPush)
		}
		if logFile != "" {
			fmt.Printf("Logging to: %s\n", logFile)
		}

		startDaemon(interval, autoCommit, autoPush, localMode, foreground, logFile, pidFile)
	},
}

func init() {
	daemonCmd.Flags().Bool("start", false, "Start the daemon")
	daemonCmd.Flags().Duration("interval", 5*time.Second, "Sync check interval")
	daemonCmd.Flags().Bool("auto-commit", false, "Automatically commit changes")
	daemonCmd.Flags().Bool("auto-push", false, "Automatically push commits")
	daemonCmd.Flags().Bool("local", false, "Run in local-only mode (no git required, no sync)")
	daemonCmd.Flags().Bool("stop", false, "Stop running daemon")
	daemonCmd.Flags().Bool("status", false, "Show daemon status")
	daemonCmd.Flags().Bool("health", false, "Check daemon health and metrics")
	daemonCmd.Flags().Bool("metrics", false, "Show detailed daemon metrics")
	daemonCmd.Flags().String("log", "", "Log file path (default: .beads/daemon.log)")
	daemonCmd.Flags().Bool("foreground", false, "Run in foreground (don't daemonize)")
	daemonCmd.Flags().BoolVar(&jsonOutput, "json", false, "Output JSON format")
	rootCmd.AddCommand(daemonCmd)
}

// computeDaemonParentPID determines which parent PID the daemon should track.
// When BD_DAEMON_FOREGROUND=1 (used by startDaemon for background CLI launches),
// we return 0 to disable parent tracking, since the short-lived launcher
// process is expected to exit immediately after spawning the daemon.
// In all other cases we track the current OS parent PID.
func computeDaemonParentPID() int {
	if os.Getenv("BD_DAEMON_FOREGROUND") == "1" {
		// 0 means "not tracked" in checkParentProcessAlive
		return 0
	}
	return os.Getppid()
}
func runDaemonLoop(interval time.Duration, autoCommit, autoPush, localMode bool, logPath, pidFile string) {
	logF, log := setupDaemonLogger(logPath)
	defer func() { _ = logF.Close() }()

	// Set up signal-aware context for graceful shutdown
	ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer cancel()

	// Top-level panic recovery to ensure clean shutdown and diagnostics
	defer func() {
		if r := recover(); r != nil {
			log.log("PANIC: daemon crashed: %v", r)

			// Capture stack trace
			stackBuf := make([]byte, 4096)
			stackSize := runtime.Stack(stackBuf, false)
			stackTrace := string(stackBuf[:stackSize])
			log.log("Stack trace:\n%s", stackTrace)

			// Write crash report to daemon-error file for user visibility
			var beadsDir string
			if dbPath != "" {
				beadsDir = filepath.Dir(dbPath)
			} else if foundDB := beads.FindDatabasePath(); foundDB != "" {
				beadsDir = filepath.Dir(foundDB)
			}
			
			if beadsDir != "" {
				errFile := filepath.Join(beadsDir, "daemon-error")
				crashReport := fmt.Sprintf("Daemon crashed at %s\n\nPanic: %v\n\nStack trace:\n%s\n",
					time.Now().Format(time.RFC3339), r, stackTrace)
				// nolint:gosec // G306: Error file needs to be readable for debugging
				if err := os.WriteFile(errFile, []byte(crashReport), 0644); err != nil {
					log.log("Warning: could not write crash report: %v", err)
				}
			}
			
			// Clean up PID file
			_ = os.Remove(pidFile)
			
			log.log("Daemon terminated after panic")
		}
	}()

	// Determine database path first (needed for lock file metadata)
	daemonDBPath := dbPath
	if daemonDBPath == "" {
		if foundDB := beads.FindDatabasePath(); foundDB != "" {
			daemonDBPath = foundDB
		} else {
			log.log("Error: no beads database found")
			log.log("Hint: run 'bd init' to create a database or set BEADS_DB environment variable")
			return // Use return instead of os.Exit to allow defers to run
		}
	}

	lock, err := setupDaemonLock(pidFile, daemonDBPath, log)
	if err != nil {
		return // Use return instead of os.Exit to allow defers to run
	}
	defer func() { _ = lock.Close() }()
	defer func() { _ = os.Remove(pidFile) }()

	if localMode {
		log.log("Daemon started in LOCAL mode (interval: %v, no git sync)", interval)
	} else {
		log.log("Daemon started (interval: %v, auto-commit: %v, auto-push: %v)", interval, autoCommit, autoPush)
	}

	// Check for multiple .db files (ambiguity error)
	beadsDir := filepath.Dir(daemonDBPath)
	matches, err := filepath.Glob(filepath.Join(beadsDir, "*.db"))
	if err == nil && len(matches) > 1 {
		// Filter out backup files (*.backup-*.db, *.backup.db)
		var validDBs []string
		for _, match := range matches {
			baseName := filepath.Base(match)
			// Skip if it's a backup file (contains ".backup" in name)
			if !strings.Contains(baseName, ".backup") && baseName != "vc.db" {
				validDBs = append(validDBs, match)
			}
		}
		if len(validDBs) > 1 {
			errMsg := fmt.Sprintf("Error: Multiple database files found in %s:\n", beadsDir)
			for _, db := range validDBs {
				errMsg += fmt.Sprintf("  - %s\n", filepath.Base(db))
			}
			errMsg += fmt.Sprintf("\nBeads requires a single canonical database: %s\n", beads.CanonicalDatabaseName)
			errMsg += "Run 'bd init' to migrate legacy databases or manually remove old databases\n"
			errMsg += "Or run 'bd doctor' for more diagnostics"

			log.log(errMsg)

			// Write error to file so user can see it without checking logs
			errFile := filepath.Join(beadsDir, "daemon-error")
			// nolint:gosec // G306: Error file needs to be readable for debugging
			if err := os.WriteFile(errFile, []byte(errMsg), 0644); err != nil {
				log.log("Warning: could not write daemon-error file: %v", err)
			}

			return // Use return instead of os.Exit to allow defers to run
		}
	}

	// Validate using canonical name
	dbBaseName := filepath.Base(daemonDBPath)
	if dbBaseName != beads.CanonicalDatabaseName {
		log.log("Error: Non-canonical database name: %s", dbBaseName)
		log.log("Expected: %s", beads.CanonicalDatabaseName)
		log.log("")
		log.log("Run 'bd init' to migrate to canonical name")
		return // Use return instead of os.Exit to allow defers to run
	}

	log.log("Using database: %s", daemonDBPath)

	// Clear any previous daemon-error file on successful startup
	errFile := filepath.Join(beadsDir, "daemon-error")
	if err := os.Remove(errFile); err != nil && !os.IsNotExist(err) {
		log.log("Warning: could not remove daemon-error file: %v", err)
	}

	store, err := sqlite.New(ctx, daemonDBPath)
	if err != nil {
		log.log("Error: cannot open database: %v", err)
		return // Use return instead of os.Exit to allow defers to run
	}
	defer func() { _ = store.Close() }()
	log.log("Database opened: %s", daemonDBPath)

	// Auto-upgrade .beads/.gitignore if outdated
	gitignoreCheck := doctor.CheckGitignore()
	if gitignoreCheck.Status == "warning" || gitignoreCheck.Status == "error" {
		log.log("Upgrading .beads/.gitignore...")
		if err := doctor.FixGitignore(); err != nil {
			log.log("Warning: failed to upgrade .gitignore: %v", err)
		} else {
			log.log("Successfully upgraded .beads/.gitignore")
		}
	}

	// Hydrate from multi-repo if configured
	if results, err := store.HydrateFromMultiRepo(ctx); err != nil {
		log.log("Error: multi-repo hydration failed: %v", err)
		return // Use return instead of os.Exit to allow defers to run
	} else if results != nil {
		log.log("Multi-repo hydration complete:")
		for repo, count := range results {
			log.log("  %s: %d issues", repo, count)
		}
	}

	// Validate database fingerprint (skip in local mode - no git available)
	if localMode {
		log.log("Skipping fingerprint validation (local mode)")
	} else if err := validateDatabaseFingerprint(ctx, store, &log); err != nil {
		if os.Getenv("BEADS_IGNORE_REPO_MISMATCH") != "1" {
			log.log("Error: %v", err)
			return // Use return instead of os.Exit to allow defers to run
		}
		log.log("Warning: repository mismatch ignored (BEADS_IGNORE_REPO_MISMATCH=1)")
	}

	// Validate schema version matches daemon version
	versionCtx := context.Background()
	dbVersion, err := store.GetMetadata(versionCtx, "bd_version")
	if err != nil && err.Error() != "metadata key not found: bd_version" {
		log.log("Error: failed to read database version: %v", err)
		return // Use return instead of os.Exit to allow defers to run
	}

	if dbVersion != "" && dbVersion != Version {
		log.log("Warning: Database schema version mismatch")
		log.log("  Database version: %s", dbVersion)
		log.log("  Daemon version: %s", Version)
		log.log("  Auto-upgrading database to daemon version...")

		// Auto-upgrade database to daemon version
		// The daemon operates on its own database, so it should always use its own version
		if err := store.SetMetadata(versionCtx, "bd_version", Version); err != nil {
			log.log("Error: failed to update database version: %v", err)

			// Allow override via environment variable for emergencies
			if os.Getenv("BEADS_IGNORE_VERSION_MISMATCH") != "1" {
				return // Use return instead of os.Exit to allow defers to run
			}
			log.log("Warning: Proceeding despite version update failure (BEADS_IGNORE_VERSION_MISMATCH=1)")
		} else {
			log.log("  Database version updated to %s", Version)
		}
	} else if dbVersion == "" {
		// Old database without version metadata - set it now
		log.log("Warning: Database missing version metadata, setting to %s", Version)
		if err := store.SetMetadata(versionCtx, "bd_version", Version); err != nil {
			log.log("Error: failed to set database version: %v", err)
			return // Use return instead of os.Exit to allow defers to run
		}
	}

	// Get workspace path (.beads directory) - beadsDir already defined above
	// Get actual workspace root (parent of .beads)
	workspacePath := filepath.Dir(beadsDir)
	socketPath := filepath.Join(beadsDir, "bd.sock")
	serverCtx, serverCancel := context.WithCancel(ctx)
	defer serverCancel()

	server, serverErrChan, err := startRPCServer(serverCtx, socketPath, store, workspacePath, daemonDBPath, log)
	if err != nil {
		return
	}

	// Register daemon in global registry
	registry, err := daemon.NewRegistry()
	if err != nil {
		log.log("Warning: failed to create registry: %v", err)
	} else {
		entry := daemon.RegistryEntry{
			WorkspacePath: workspacePath,
			SocketPath:    socketPath,
			DatabasePath:  daemonDBPath,
			PID:           os.Getpid(),
			Version:       Version,
			StartedAt:     time.Now(),
		}
		if err := registry.Register(entry); err != nil {
			log.log("Warning: failed to register daemon: %v", err)
		} else {
			log.log("Registered in global registry")
		}
		// Ensure we unregister on exit
		defer func() {
			if err := registry.Unregister(workspacePath, os.Getpid()); err != nil {
				log.log("Warning: failed to unregister daemon: %v", err)
			}
		}()
	}

	ticker := time.NewTicker(interval)
	defer ticker.Stop()

	// Create sync function based on mode
	var doSync func()
	if localMode {
		doSync = createLocalSyncFunc(ctx, store, log)
	} else {
		doSync = createSyncFunc(ctx, store, autoCommit, autoPush, log)
	}
	doSync()

	// Get parent PID for monitoring (exit if parent dies)
	parentPID := computeDaemonParentPID()
	log.log("Monitoring parent process (PID %d)", parentPID)

	// Choose event loop based on BEADS_DAEMON_MODE
	daemonMode := os.Getenv("BEADS_DAEMON_MODE")
	if daemonMode == "" {
		daemonMode = "events" // Default to event-driven mode (production-ready as of v0.21.0)
	}

	switch daemonMode {
	case "events":
		log.log("Using event-driven mode")
		jsonlPath := findJSONLPath()
		if jsonlPath == "" {
			log.log("Error: JSONL path not found, cannot use event-driven mode")
			log.log("Falling back to polling mode")
			runEventLoop(ctx, cancel, ticker, doSync, server, serverErrChan, parentPID, log)
		} else {
			// Event-driven mode uses separate export-only and import-only functions
			var doExport, doAutoImport func()
			if localMode {
				doExport = createLocalExportFunc(ctx, store, log)
				doAutoImport = createLocalAutoImportFunc(ctx, store, log)
			} else {
				doExport = createExportFunc(ctx, store, autoCommit, autoPush, log)
				doAutoImport = createAutoImportFunc(ctx, store, log)
			}
			runEventDrivenLoop(ctx, cancel, server, serverErrChan, store, jsonlPath, doExport, doAutoImport, parentPID, log)
		}
	case "poll":
		log.log("Using polling mode (interval: %v)", interval)
		runEventLoop(ctx, cancel, ticker, doSync, server, serverErrChan, parentPID, log)
	default:
		log.log("Unknown BEADS_DAEMON_MODE: %s (valid: poll, events), defaulting to poll", daemonMode)
		runEventLoop(ctx, cancel, ticker, doSync, server, serverErrChan, parentPID, log)
	}
}