//go:build windows

package main

import (
	"context"
	"flag"
	"fmt"
	"net"
	"os"
	"os/signal"
	"path/filepath"
	"sync"
	"syscall"
	"time"

	"github.com/fsnotify/fsnotify"
)

var (
	sourceDir  = flag.String("dir", "", "Source directory to watch (required)")
	connect    = flag.String("connect", "localhost:5151", "TCP address of the container to connect to")
	bufSizeKB  = flag.Int("bufsize", 256, "ReadDirectoryChangesW buffer size in KB per directory (default 256)")
)

func run() {
	flag.Parse()

	if *sourceDir == "" {
		fmt.Fprintln(os.Stderr, "Usage: sourcewatch.exe -dir <source> [-connect host:port] [-bufsize KB]")
		os.Exit(1)
	}

	level, err := ParseLogLevel(*logLevel)
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
	SetLogLevel(level)

	logInfo("watcher: scanning %s ...", *sourceDir)

	stack := NewGitignoreStack(*sourceDir)
	manifest := scanDirectory(*sourceDir, stack)

	logInfo("watcher: found %d files", len(manifest.Files))

	watcher, err := fsnotify.NewWatcher()
	if err != nil {
		logErrorf("watcher: %v", err)
		os.Exit(1)
	}
	defer watcher.Close()

	if err := addWatchersRecursively(watcher, *sourceDir, stack); err != nil {
		logErrorf("watcher: %v", err)
		os.Exit(1)
	}

	ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer cancel()

	for {
		if ctx.Err() != nil {
			return
		}

		logInfo("watcher: connecting to %s ...", *connect)

		var conn net.Conn
		for {
			if ctx.Err() != nil {
				return
			}
			conn, err = net.DialTimeout("tcp", *connect, 5*time.Second)
			if err == nil {
				break
			}
			logDebug("connect failed: %v, retrying...", err)
			select {
			case <-ctx.Done():
				return
			case <-time.After(2 * time.Second):
			}
		}

		logInfo("watcher: connected, sending manifest ...")

		if err := sendManifest(conn, manifest); err != nil {
			logErrorf("send manifest: %v", err)
			conn.Close()
			continue
		}

		logInfo("watcher: monitoring for changes ...")

		// Heartbeat goroutine to detect disconnects
		go func() {
			ticker := time.NewTicker(10 * time.Second)
			defer ticker.Stop()
			for {
				select {
				case <-ctx.Done():
					return
				case <-ticker.C:
					msg := &ProtocolMessage{Type: "ping"}
					data, _ := EncodeMessage(msg)
					data = append(data, '\n')
					if _, err := conn.Write(data); err != nil {
						logErrorf("heartbeat failed: %v", err)
						conn.Close()
						return
					}
				}
			}
		}()

		if !watchLoop(ctx, conn, watcher, manifest, stack) {
			conn.Close()
			continue
		}
		conn.Close()
		return
	}
}

func watchLoop(ctx context.Context, conn net.Conn, watcher *fsnotify.Watcher, manifest *Manifest, stack *GitignoreStack) bool {
	var mu sync.Mutex
	debounceTimers := make(map[string]*time.Timer)
	debounceOps := make(map[string]fsnotify.Op)

	for {
		select {
		case <-ctx.Done():
			return true

		case event, ok := <-watcher.Events:
			if !ok {
				return true
			}

			relPath, err := filepath.Rel(*sourceDir, event.Name)
			if err != nil {
				continue
			}

			if isGitDir(relPath) {
				continue
			}

			if stack.IsIgnored(relPath) {
				continue
			}

			logDebug("event: %s %s", event.Op, relPath)

			if event.Op&fsnotify.Create != 0 {
				srcPath := filepath.Join(*sourceDir, relPath)
				info, err := os.Lstat(srcPath)
				if err == nil && info.IsDir() {
					bufBytes := *bufSizeKB * 1024
					if hasGitignore(srcPath) {
						stack.Push(srcPath)
					}
					if err := watcher.AddWith(srcPath, fsnotify.WithBufferSize(bufBytes)); err != nil {
						logErrorf("watch %s: %v", relPath, err)
					}
					var added int
					filepath.Walk(srcPath, func(path string, info os.FileInfo, err error) error {
						if err != nil || !info.IsDir() || path == srcPath {
							return nil
						}
						if err := watcher.AddWith(path, fsnotify.WithBufferSize(bufBytes)); err != nil {
							logDebug("watch sub %s: %v", path, err)
						} else {
							added++
						}
						return nil
					})
					if added > 0 {
						logDebug("added %d sub-watchers for %s", added, relPath)
					}
				}
			}

			mu.Lock()
			if existing, exists := debounceOps[relPath]; exists {
				debounceTimers[relPath].Stop()
				debounceOps[relPath] = existing | event.Op
			} else {
				debounceOps[relPath] = event.Op
			}
			path := relPath
			debounceTimers[relPath] = time.AfterFunc(200*time.Millisecond, func() {
				mu.Lock()
				op := debounceOps[path]
				delete(debounceOps, path)
				delete(debounceTimers, path)
				mu.Unlock()

				evt := FileEvent{Path: path}
				switch {
				case op&fsnotify.Create != 0:
					evt.Op = "create"
				case op&fsnotify.Write != 0:
					evt.Op = "write"
				case op&fsnotify.Remove != 0:
					evt.Op = "remove"
				case op&fsnotify.Rename != 0:
					evt.Op = "remove"
				default:
					return
				}

				srcPath := filepath.Join(*sourceDir, path)
				switch evt.Op {
				case "create":
					if info, err := os.Lstat(srcPath); err == nil {
						linkTarget := ""
						if info.Mode()&os.ModeSymlink != 0 {
							linkTarget, _ = os.Readlink(srcPath)
						}
						manifest.Files[path] = FileMeta{
							Size:    info.Size(),
							Mode:    info.Mode(),
							ModTime: info.ModTime(),
							Symlink: linkTarget,
						}
					}
				case "write":
					if info, err := os.Lstat(srcPath); err == nil {
						linkTarget := ""
						if info.Mode()&os.ModeSymlink != 0 {
							linkTarget, _ = os.Readlink(srcPath)
						}
						manifest.Files[path] = FileMeta{
							Size:    info.Size(),
							Mode:    info.Mode(),
							ModTime: info.ModTime(),
							Symlink: linkTarget,
						}
					}
				case "remove":
					delete(manifest.Files, path)
				}

				if err := sendEvent(conn, evt); err != nil {
					logErrorf("send event: %v", err)
				}
			})
			mu.Unlock()

		case err, ok := <-watcher.Errors:
			if !ok {
				return true
			}
			logErrorf("watcher: %v", err)
			return false
		}
	}
}

func scanDirectory(root string, stack *GitignoreStack) *Manifest {
	manifest := &Manifest{Files: make(map[string]FileMeta)}

	filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return nil
		}

		relPath, err := filepath.Rel(root, path)
		if err != nil {
			return nil
		}

		if relPath == "." {
			return nil
		}

		if isGitDir(relPath) {
			if info.IsDir() {
				return filepath.SkipDir
			}
			return nil
		}

		if info.IsDir() && hasGitignore(path) {
			stack.Push(path)
		}

		if stack.IsIgnored(relPath) {
			return nil
		}

		linkTarget := ""
		if info.Mode()&os.ModeSymlink != 0 {
			linkTarget, _ = os.Readlink(path)
		}

		manifest.Files[relPath] = FileMeta{
			Size:    info.Size(),
			Mode:    info.Mode(),
			ModTime: info.ModTime(),
			Symlink: linkTarget,
		}

		return nil
	})

	return manifest
}

func sendManifest(conn net.Conn, manifest *Manifest) error {
	const batchSize = 1000
	files := make([]FileMetaJSON, 0, batchSize)
	paths := make([]string, 0, batchSize)

	for path, meta := range manifest.ToJSON() {
		paths = append(paths, path)
		files = append(files, meta)

		if len(files) >= batchSize {
			msg := &ProtocolMessage{
				Type:  "manifest_batch",
				Files: make(map[string]FileMetaJSON),
			}
			for i, p := range paths {
				msg.Files[p] = files[i]
			}
			data, err := EncodeMessage(msg)
			if err != nil {
				return err
			}
			data = append(data, '\n')
			if _, err := conn.Write(data); err != nil {
				return err
			}
			files = files[:0]
			paths = paths[:0]
		}
	}

	if len(files) > 0 {
		msg := &ProtocolMessage{
			Type:  "manifest_batch",
			Files: make(map[string]FileMetaJSON),
		}
		for i, p := range paths {
			msg.Files[p] = files[i]
		}
		data, err := EncodeMessage(msg)
		if err != nil {
			return err
		}
		data = append(data, '\n')
		if _, err := conn.Write(data); err != nil {
			return err
		}
	}

	done := &ProtocolMessage{Type: "manifest_done"}
	doneData, err := EncodeMessage(done)
	if err != nil {
		return err
	}
	doneData = append(doneData, '\n')
	_, err = conn.Write(doneData)
	return err
}

func sendEvent(conn net.Conn, evt FileEvent) error {
	msg := &ProtocolMessage{Path: evt.Path}
	switch evt.Op {
	case "create":
		msg.Type = "event_create"
	case "write":
		msg.Type = "event_write"
	case "remove":
		msg.Type = "event_remove"
	}
	data, err := EncodeMessage(msg)
	if err != nil {
		return err
	}
	data = append(data, '\n')
	_, err = conn.Write(data)
	return err
}

func addWatchersRecursively(watcher *fsnotify.Watcher, root string, stack *GitignoreStack) error {
	var count, failCount, skippedCount int
	bufBytes := *bufSizeKB * 1024
	err := filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			logDebug("walk error: %v", err)
			return nil // continue walking even if we can't stat a path
		}

		relPath, err := filepath.Rel(root, path)
		if err != nil {
			logDebug("rel error: %v", err)
			return nil
		}

		if isGitDir(relPath) {
			if info.IsDir() {
				return filepath.SkipDir
			}
			return nil
		}

		if info.IsDir() {
			if hasGitignore(path) {
				stack.Push(path)
			}
			if !stack.IsIgnored(relPath) {
				if err := watcher.AddWith(path, fsnotify.WithBufferSize(bufBytes)); err != nil {
					failCount++
					if failCount <= 10 {
						logErrorf("watch %s: %v", relPath, err)
					}
				} else {
					count++
				}
			} else {
				skippedCount++
			}
		}

		return nil
	})
	if failCount > 10 {
		logErrorf("watcher: %d additional watch failures (suppressed)", failCount-10)
	}
	logInfo("watcher: watching %d directories, skipped %d ignored, %d failed (buffer=%dKB)", count, skippedCount, failCount, *bufSizeKB)
	return err
}