package mock

import (
	"fmt"
	"sync"
	"testing"
	"time"
)

func TestFileSystem_CreateFile(t *testing.T) {
	fs := NewFileSystem()
	content := []byte("hello world")

	err := fs.CreateFile("/test/hello.txt", content)
	if err != nil {
		t.Fatalf("CreateFile failed: %v", err)
	}

	f := fs.GetFile("/test/hello.txt")
	if f == nil {
		t.Fatal("File not found after creation")
	}
	if string(f.Content) != "hello world" {
		t.Errorf("Content = %q, want %q", string(f.Content), "hello world")
	}
	if f.Name != "hello.txt" {
		t.Errorf("Name = %q, want %q", f.Name, "hello.txt")
	}
	if f.Size != int64(len(content)) {
		t.Errorf("Size = %d, want %d", f.Size, len(content))
	}
	if f.IsDir {
		t.Error("IsDir should be false for a file")
	}
}

func TestFileSystem_ReadFile(t *testing.T) {
	fs := NewFileSystem()
	fs.CreateFile("/test/data.txt", []byte("data"))

	content, err := fs.ReadFile("/test/data.txt")
	if err != nil {
		t.Fatalf("ReadFile failed: %v", err)
	}
	if string(content) != "data" {
		t.Errorf("ReadFile returned %q, want %q", string(content), "data")
	}
}

func TestFileSystem_ReadFile_NotFound(t *testing.T) {
	fs := NewFileSystem()

	_, err := fs.ReadFile("/nonexistent.txt")
	if err == nil {
		t.Fatal("Expected error for nonexistent file, got nil")
	}
}

func TestFileSystem_WriteFile(t *testing.T) {
	fs := NewFileSystem()
	fs.CreateFile("/test/update.txt", []byte("original"))

	err := fs.WriteFile("/test/update.txt", []byte("updated"))
	if err != nil {
		t.Fatalf("WriteFile failed: %v", err)
	}

	content, _ := fs.ReadFile("/test/update.txt")
	if string(content) != "updated" {
		t.Errorf("Content = %q, want %q", string(content), "updated")
	}
}

func TestFileSystem_WriteFile_CreatesFile(t *testing.T) {
	fs := NewFileSystem()

	err := fs.WriteFile("/newfile.txt", []byte("data"))
	if err != nil {
		t.Fatalf("WriteFile should create file, got error: %v", err)
	}

	content, err := fs.ReadFile("/newfile.txt")
	if err != nil {
		t.Fatalf("File should exist after write: %v", err)
	}
	if string(content) != "data" {
		t.Errorf("Content = %q, want %q", string(content), "data")
	}
}

func TestFileSystem_DeleteFile(t *testing.T) {
	fs := NewFileSystem()
	fs.CreateFile("/test/delete.txt", []byte("to delete"))

	err := fs.DeleteFile("/test/delete.txt")
	if err != nil {
		t.Fatalf("DeleteFile failed: %v", err)
	}

	if fs.FileExists("/test/delete.txt") {
		t.Error("File should not exist after deletion")
	}
}

func TestFileSystem_DeleteFile_NotFound(t *testing.T) {
	fs := NewFileSystem()

	err := fs.DeleteFile("/nonexistent.txt")
	if err == nil {
		t.Fatal("Expected error for nonexistent file, got nil")
	}
}

func TestFileSystem_CreateDir(t *testing.T) {
	fs := NewFileSystem()

	err := fs.CreateDir("/test/dir")
	if err != nil {
		t.Fatalf("CreateDir failed: %v", err)
	}

	if !fs.DirExists("/test/dir") {
		t.Error("Dir should exist after creation")
	}

	f := fs.GetFile("/test/dir")
	if f == nil {
		t.Fatal("Directory file not found")
	}
	if !f.IsDir {
		t.Error("IsDir should be true for a directory")
	}
	if f.Name != "dir" {
		t.Errorf("Name = %q, want %q", f.Name, "dir")
	}
}

func TestFileSystem_ReadDir(t *testing.T) {
	fs := NewFileSystem()
	fs.CreateDir("/test/dir")
	fs.CreateFile("/test/dir/a.txt", []byte("a"))
	fs.CreateFile("/test/dir/b.txt", []byte("b"))
	fs.CreateFile("/test/dir/c.txt", []byte("c"))

	entries, err := fs.ReadDir("/test/dir")
	if err != nil {
		t.Fatalf("ReadDir failed: %v", err)
	}

	if len(entries) != 3 {
		t.Fatalf("Expected 3 entries, got %d", len(entries))
	}

	// Check alphabetical order
	if entries[0].Name() != "a.txt" {
		t.Errorf("First entry = %q, want %q", entries[0].Name(), "a.txt")
	}
	if entries[1].Name() != "b.txt" {
		t.Errorf("Second entry = %q, want %q", entries[1].Name(), "b.txt")
	}
	if entries[2].Name() != "c.txt" {
		t.Errorf("Third entry = %q, want %q", entries[2].Name(), "c.txt")
	}
}

func TestFileSystem_ReadDir_Empty(t *testing.T) {
	fs := NewFileSystem()
	fs.CreateDir("/test/empty")

	entries, err := fs.ReadDir("/test/empty")
	if err != nil {
		t.Fatalf("ReadDir failed: %v", err)
	}

	if len(entries) != 0 {
		t.Errorf("Expected 0 entries, got %d", len(entries))
	}
}

func TestFileSystem_FileExists(t *testing.T) {
	fs := NewFileSystem()
	fs.CreateFile("/test/exist.txt", []byte("data"))

	if !fs.FileExists("/test/exist.txt") {
		t.Error("File should exist")
	}
	if fs.FileExists("/test/noexist.txt") {
		t.Error("Nonexistent file should not exist")
	}
}

func TestFileSystem_DirExists(t *testing.T) {
	fs := NewFileSystem()
	fs.CreateDir("/test/dir")

	if !fs.DirExists("/test/dir") {
		t.Error("Directory should exist")
	}
	if fs.DirExists("/test/noexist") {
		t.Error("Nonexistent directory should not exist")
	}
}

func TestFileSystem_Count(t *testing.T) {
	fs := NewFileSystem()
	fs.CreateFile("/test/a.txt", []byte("a"))
	fs.CreateFile("/test/b.txt", []byte("b"))
	fs.CreateDir("/test/dir")

	files, dirs := fs.Count()
	if files != 2 {
		t.Errorf("Files = %d, want 2", files)
	}
	if dirs != 1 {
		t.Errorf("Dirs = %d, want 1", dirs)
	}
}

func TestFileSystem_SetDelay(t *testing.T) {
	fs := NewFileSystem()
	fs.SetDelay(50 * time.Millisecond)

	start := time.Now()
	fs.ReadFile("/nonexistent.txt") // Will fail but delay should still apply
	elapsed := time.Since(start)

	if elapsed < 40*time.Millisecond {
		t.Errorf("Expected delay ~50ms, got %v", elapsed)
	}
}

func TestFileSystem_SetChangeEvents(t *testing.T) {
	fs := NewFileSystem()
	ch := make(chan FileChangeEvent, 10)
	fs.SetChangeEvents(ch)

	fs.CreateFile("/test/notify.txt", []byte("data"))

	select {
	case event := <-ch:
		if event.Path != "/test/notify.txt" {
			t.Errorf("Event path = %q, want %q", event.Path, "/test/notify.txt")
		}
		if event.EventType != "Created" {
			t.Errorf("Event type = %q, want %q", event.EventType, "Created")
		}
	case <-time.After(100 * time.Millisecond):
		t.Fatal("Expected change event, got none")
	}
}

func TestFileSystem_SetChangeEvents_NilChannel(t *testing.T) {
	fs := NewFileSystem()
	fs.SetChangeEvents(nil) // Disable notifications

	// Should not panic
	fs.CreateFile("/test/silent.txt", []byte("data"))
}

func TestFileSystem_AddFile(t *testing.T) {
	fs := NewFileSystem()
	modTime := time.Date(2024, 1, 1, 0, 0, 0, 0, time.UTC)

	fs.AddFile("/test/pre.txt", []byte("pre"), modTime)

	f := fs.GetFile("/test/pre.txt")
	if f == nil {
		t.Fatal("File not found after AddFile")
	}
	if !f.ModTime.Equal(modTime) {
		t.Errorf("ModTime = %v, want %v", f.ModTime, modTime)
	}
}

func TestFileSystem_RemoveFile(t *testing.T) {
	fs := NewFileSystem()
	fs.AddFile("/test/remove.txt", []byte("data"), time.Now())

	fs.RemoveFile("/test/remove.txt")

	if fs.FileExists("/test/remove.txt") {
		t.Error("File should not exist after RemoveFile")
	}
}

func TestFileSystem_ListPaths(t *testing.T) {
	fs := NewFileSystem()
	fs.CreateFile("/test/a.txt", []byte("a"))
	fs.CreateFile("/test/b.txt", []byte("b"))
	fs.CreateFile("/other/c.txt", []byte("c"))

	paths := fs.ListPaths("/test/")
	if len(paths) != 2 {
		t.Errorf("ListPaths returned %d paths, want 2", len(paths))
	}

	pathsAll := fs.ListPaths("")
	if len(pathsAll) != 3 {
		t.Errorf("ListPaths with empty prefix returned %d paths, want 3", len(pathsAll))
	}
}

func TestFileSystem_ConcurrentAccess(t *testing.T) {
	fs := NewFileSystem()

	var wg sync.WaitGroup
	for i := 0; i < 100; i++ {
		wg.Add(1)
		go func(n int) {
			defer wg.Done()
			path := fmt.Sprintf("/test/concurrent_%d.txt", n)
			fs.CreateFile(path, []byte(fmt.Sprintf("content %d", n)))
			fs.ReadFile(path)
			fs.DeleteFile(path)
		}(i)
	}

	wg.Wait()
}