package host

import (
	"os"
	"path/filepath"
	"sync/atomic"
	"testing"
	"time"
)

func TestWatcher_DetectsNewFiles(t *testing.T) {
	dir := t.TempDir()

	// Create initial file
	initialFile := filepath.Join(dir, "initial.go")
	if err := os.WriteFile(initialFile, []byte("package main"), 0644); err != nil {
		t.Fatal(err)
	}

	var changeCount int32
	w := NewWatcher(dir, func() {
		atomic.AddInt32(&changeCount, 1)
	}, WithInterval(50*time.Millisecond))

	if err := w.Start(); err != nil {
		t.Fatal(err)
	}
	defer w.Stop()

	// Create new file
	newFile := filepath.Join(dir, "new.go")
	if err := os.WriteFile(newFile, []byte("package main"), 0644); err != nil {
		t.Fatal(err)
	}

	// Wait for detection
	time.Sleep(200 * time.Millisecond)

	if count := atomic.LoadInt32(&changeCount); count == 0 {
		t.Error("Expected change to be detected for new file")
	}
}

func TestWatcher_DetectsModifiedFiles(t *testing.T) {
	dir := t.TempDir()

	// Create initial file
	file := filepath.Join(dir, "test.go")
	if err := os.WriteFile(file, []byte("package main"), 0644); err != nil {
		t.Fatal(err)
	}

	var changeCount int32
	w := NewWatcher(dir, func() {
		atomic.AddInt32(&changeCount, 1)
	}, WithInterval(50*time.Millisecond))

	if err := w.Start(); err != nil {
		t.Fatal(err)
	}
	defer w.Stop()

	// Ensure mod time will be different
	time.Sleep(100 * time.Millisecond)

	// Modify file
	if err := os.WriteFile(file, []byte("package main\n// updated"), 0644); err != nil {
		t.Fatal(err)
	}

	// Wait for detection
	time.Sleep(200 * time.Millisecond)

	if count := atomic.LoadInt32(&changeCount); count == 0 {
		t.Error("Expected change to be detected for modified file")
	}
}

func TestWatcher_DetectsDeletedFiles(t *testing.T) {
	dir := t.TempDir()

	// Create initial file
	file := filepath.Join(dir, "test.go")
	if err := os.WriteFile(file, []byte("package main"), 0644); err != nil {
		t.Fatal(err)
	}

	var changeCount int32
	w := NewWatcher(dir, func() {
		atomic.AddInt32(&changeCount, 1)
	}, WithInterval(50*time.Millisecond))

	if err := w.Start(); err != nil {
		t.Fatal(err)
	}
	defer w.Stop()

	// Delete file
	if err := os.Remove(file); err != nil {
		t.Fatal(err)
	}

	// Wait for detection
	time.Sleep(200 * time.Millisecond)

	if count := atomic.LoadInt32(&changeCount); count == 0 {
		t.Error("Expected change to be detected for deleted file")
	}
}

func TestWatcher_IgnoresNonMatchingExtensions(t *testing.T) {
	dir := t.TempDir()

	// Create initial go file
	goFile := filepath.Join(dir, "main.go")
	if err := os.WriteFile(goFile, []byte("package main"), 0644); err != nil {
		t.Fatal(err)
	}

	var changeCount int32
	w := NewWatcher(dir, func() {
		atomic.AddInt32(&changeCount, 1)
	}, WithInterval(50*time.Millisecond), WithExtensions(".go"))

	if err := w.Start(); err != nil {
		t.Fatal(err)
	}
	defer w.Stop()

	// Create non-matching file
	txtFile := filepath.Join(dir, "readme.txt")
	if err := os.WriteFile(txtFile, []byte("readme"), 0644); err != nil {
		t.Fatal(err)
	}

	// Wait
	time.Sleep(200 * time.Millisecond)

	if count := atomic.LoadInt32(&changeCount); count != 0 {
		t.Error("Expected no change detected for non-matching extension")
	}
}

func TestWatcher_CustomExtensions(t *testing.T) {
	dir := t.TempDir()

	// Create initial file
	file := filepath.Join(dir, "style.css")
	if err := os.WriteFile(file, []byte("body {}"), 0644); err != nil {
		t.Fatal(err)
	}

	var changeCount int32
	w := NewWatcher(dir, func() {
		atomic.AddInt32(&changeCount, 1)
	}, WithInterval(50*time.Millisecond), WithExtensions(".css", ".html"))

	if err := w.Start(); err != nil {
		t.Fatal(err)
	}
	defer w.Stop()

	// Ensure mod time will be different
	time.Sleep(100 * time.Millisecond)

	// Modify css file
	if err := os.WriteFile(file, []byte("body { color: red; }"), 0644); err != nil {
		t.Fatal(err)
	}

	// Wait for detection
	time.Sleep(200 * time.Millisecond)

	if count := atomic.LoadInt32(&changeCount); count == 0 {
		t.Error("Expected change to be detected for custom extension")
	}
}

func TestWatcher_SkipsHiddenDirs(t *testing.T) {
	dir := t.TempDir()

	// Create hidden directory with go file
	hiddenDir := filepath.Join(dir, ".hidden")
	if err := os.MkdirAll(hiddenDir, 0755); err != nil {
		t.Fatal(err)
	}

	// Create a visible go file first
	visibleFile := filepath.Join(dir, "visible.go")
	if err := os.WriteFile(visibleFile, []byte("package main"), 0644); err != nil {
		t.Fatal(err)
	}

	var changeCount int32
	w := NewWatcher(dir, func() {
		atomic.AddInt32(&changeCount, 1)
	}, WithInterval(50*time.Millisecond))

	if err := w.Start(); err != nil {
		t.Fatal(err)
	}
	defer w.Stop()

	// Create file in hidden directory
	hiddenFile := filepath.Join(hiddenDir, "hidden.go")
	if err := os.WriteFile(hiddenFile, []byte("package main"), 0644); err != nil {
		t.Fatal(err)
	}

	// Wait
	time.Sleep(200 * time.Millisecond)

	if count := atomic.LoadInt32(&changeCount); count != 0 {
		t.Error("Expected no change detected for hidden directory")
	}
}