From dfa6c4074323f1977a2a896162870830e2ea02aa Mon Sep 17 00:00:00 2001
From: Ku6epXBOCTuK <Ku6epXBOCTuK@gmail.com>
Date: Wed, 4 Feb 2026 12:50:38 +0500
Subject: [PATCH] refactor: change null to undefined

---
 plans/core-features-plan.md             | 12 +++++++----
 src/components/AppContainer.svelte      | 28 ++++++++++++-------------
 src/components/AppContent.svelte        | 26 +++++++++--------------
 src/components/BackgroundPreview.svelte |  2 +-
 src/components/ErrorMessage.svelte      |  8 +++----
 src/components/ImageCropper.svelte      |  6 +++---
 src/components/ImageManager.svelte      |  2 +-
 src/components/ImageUpload.svelte       | 16 +++++++-------
 src/components/MainSection.svelte       | 19 ++++-------------
 src/components/PanelList.svelte         | 10 ++++-----
 src/components/Sidebar.svelte           | 21 ++++---------------
 src/components/TextManager.svelte       |  6 +++---
 src/lib/services/imageService.ts        |  3 ++-
 src/lib/types/panel.ts                  |  2 +-
 src/lib/utils/panelStorage.ts           |  7 +++----
 src/routes/+page.svelte                 |  8 +++----
 src/services/exportService.ts           |  6 +++---
 src/services/imageService.ts            |  1 +
 src/stores/panelStore.ts                |  6 +++---
 src/stores/uiStore.ts                   |  8 +++----
 tsconfig.json                           |  4 +++-
 21 files changed, 89 insertions(+), 112 deletions(-)

diff --git a/plans/core-features-plan.md b/plans/core-features-plan.md
index 137a00b..555e54f 100644
--- a/plans/core-features-plan.md
+++ b/plans/core-features-plan.md
@@ -40,6 +40,7 @@ interface ImageUploadProps {
 - **Error Handling**: Invalid crop areas ✅
 
 **Implementation Details:**
+
 - Integrated cropperjs v2.1.0 with Web Components
 - Used `$toCanvas()` method to get HTMLCanvasElement
 - Implemented proper error handling with user-friendly messages
@@ -147,7 +148,7 @@ interface Panel {
 }
 
 interface PanelManagerProps {
-  currentPanel: Panel | null;
+  currentPanel: Panel | undefined;
   onPanelUpdate: (panel: Panel) => void;
 }
 
@@ -255,11 +256,11 @@ interface ImageUploadResult {
 
 ```typescript
 // Core stores
-export const panelStore = writable<Panel | null>(null);
+export const panelStore = writable<Panel | undefined>(undefined);
 export const uiStore = writable({
   isLoading: false,
-  error: null as string | null,
-  currentStep: "upload" as "upload" | "crop" | "text" | "preview",
+  error: string | undefined,
+  currentStep: "upload" | "crop" | "text" | "preview",
 });
 ```
 
@@ -359,11 +360,13 @@ _Estimated Duration: 5 weeks_
 **Challenge:** cropperjs v2.x uses Web Components API which differs significantly from v1.x
 
 **Solution:**
+
 1. Used `getCropperCanvas()` to get `<cropper-canvas>` Web Component
 2. Called `$toCanvas()` method to convert to HTMLCanvasElement
 3. Applied `toDataURL()` on the resulting canvas to get base64 image
 
 **Code Example:**
+
 ```typescript
 const cropperCanvasElement = cropper.getCropperCanvas();
 const canvas = await cropperCanvasElement.$toCanvas({
@@ -375,6 +378,7 @@ const croppedImage = canvas.toDataURL("image/png");
 ```
 
 **Key Points:**
+
 - cropperjs v2.x methods return Web Components, not standard DOM elements
 - `$toCanvas()` is an async method that returns HTMLCanvasElement
 - Proper error handling is essential for user experience
diff --git a/src/components/AppContainer.svelte b/src/components/AppContainer.svelte
index 6b8827c..ce4babc 100644
--- a/src/components/AppContainer.svelte
+++ b/src/components/AppContainer.svelte
@@ -4,10 +4,10 @@
   import AppContent from "./AppContent.svelte";
 
   interface Props {
-    errorMessage: string | null;
-    uploadedImage: string | null;
+    errorMessage: string | undefined;
+    uploadedImage: string | undefined;
     texts: Array<{ id: string; text: string }>;
-    backgroundImage: string | null;
+    backgroundImage: string | undefined;
     panels: any[];
     onUploadNewImage: () => void;
     onImageUpload: (image: string) => void;
@@ -34,12 +34,12 @@
     onTextUpdate,
     onTextDelete,
     onDownload,
-    onDownloadAll
+    onDownloadAll,
   }: Props = $props();
 </script>
 
 <div class="app-container">
-  <AppHeader onUploadNewImage={onUploadNewImage} />
+  <AppHeader {onUploadNewImage} />
 
   <ErrorMessage {errorMessage} />
 
@@ -48,15 +48,15 @@
     {texts}
     {backgroundImage}
     {panels}
-    onImageUpload={onImageUpload}
-    onCropComplete={onCropComplete}
-    onCropCancel={onCropCancel}
-    onTextAdd={onTextAdd}
-    onTextUpdate={onTextUpdate}
-    onTextDelete={onTextDelete}
-    onUploadNewImage={onUploadNewImage}
-    onDownload={onDownload}
-    onDownloadAll={onDownloadAll}
+    {onImageUpload}
+    {onCropComplete}
+    {onCropCancel}
+    {onTextAdd}
+    {onTextUpdate}
+    {onTextDelete}
+    {onUploadNewImage}
+    {onDownload}
+    {onDownloadAll}
   />
 </div>
 
diff --git a/src/components/AppContent.svelte b/src/components/AppContent.svelte
index 4aff209..826dacb 100644
--- a/src/components/AppContent.svelte
+++ b/src/components/AppContent.svelte
@@ -3,9 +3,9 @@
   import Sidebar from "./Sidebar.svelte";
 
   interface Props {
-    uploadedImage: string | null;
+    uploadedImage: string | undefined;
     texts: Array<{ id: string; text: string }>;
-    backgroundImage: string | null;
+    backgroundImage: string | undefined;
     panels: any[];
     onImageUpload: (image: string) => void;
     onCropComplete: (croppedImage: string) => void;
@@ -31,7 +31,7 @@
     onTextDelete,
     onUploadNewImage,
     onDownload,
-    onDownloadAll
+    onDownloadAll,
   }: Props = $props();
 </script>
 
@@ -39,20 +39,14 @@
   <MainSection
     {uploadedImage}
     {texts}
-    onImageUpload={onImageUpload}
-    onCropComplete={onCropComplete}
-    onCropCancel={onCropCancel}
-    onTextAdd={onTextAdd}
-    onTextUpdate={onTextUpdate}
-    onTextDelete={onTextDelete}
-  />
-  <Sidebar
-    {backgroundImage}
-    {panels}
-    onUploadNewImage={onUploadNewImage}
-    onDownload={onDownload}
-    onDownloadAll={onDownloadAll}
+    {onImageUpload}
+    {onCropComplete}
+    {onCropCancel}
+    {onTextAdd}
+    {onTextUpdate}
+    {onTextDelete}
   />
+  <Sidebar {backgroundImage} {panels} {onUploadNewImage} {onDownload} {onDownloadAll} />
 </div>
 
 <style>
diff --git a/src/components/BackgroundPreview.svelte b/src/components/BackgroundPreview.svelte
index 4976501..d38bd95 100644
--- a/src/components/BackgroundPreview.svelte
+++ b/src/components/BackgroundPreview.svelte
@@ -2,7 +2,7 @@
   import { Button } from "../lib/components/ui";
 
   interface Props {
-    backgroundImage?: string | null;
+    backgroundImage?: string | undefined;
     onUploadNewImage: () => void;
   }
 
diff --git a/src/components/ErrorMessage.svelte b/src/components/ErrorMessage.svelte
index 25b4937..035ee12 100644
--- a/src/components/ErrorMessage.svelte
+++ b/src/components/ErrorMessage.svelte
@@ -1,14 +1,14 @@
 <script lang="ts">
   interface Props {
-    message: string | null;
+    errorMessage: string | undefined;
   }
 
-  let { message }: Props = $props();
+  let { errorMessage }: Props = $props();
 </script>
 
-{#if message}
+{#if errorMessage}
   <div class="error-message">
-    {message}
+    {errorMessage}
   </div>
 {/if}
 
diff --git a/src/components/ImageCropper.svelte b/src/components/ImageCropper.svelte
index e6cf97d..4e8b793 100644
--- a/src/components/ImageCropper.svelte
+++ b/src/components/ImageCropper.svelte
@@ -15,9 +15,9 @@
   let { imageSrc, onCropComplete, onCancel }: Props = $props();
 
   let imageElement: HTMLImageElement;
-  let cropper: CropperJS | null = null;
+  let cropper: CropperJS | undefined = undefined;
   let isProcessing = $state(false);
-  let errorMessage = $state<string | null>(null);
+  let errorMessage = $state<string | undefined>(undefined);
 
   let imageService = new ImageService();
 
@@ -46,7 +46,7 @@
 
     try {
       isProcessing = true;
-      errorMessage = null;
+      errorMessage = undefined;
       setLoading(true);
 
       console.log("Calling getCropperCanvas");
diff --git a/src/components/ImageManager.svelte b/src/components/ImageManager.svelte
index 49684ad..b6cec04 100644
--- a/src/components/ImageManager.svelte
+++ b/src/components/ImageManager.svelte
@@ -4,7 +4,7 @@
 
   interface Props {
     currentStep: string;
-    uploadedImage: string | null;
+    uploadedImage: string | undefined;
     onImageUpload: (image: string) => void;
     onCropComplete: (croppedImage: string) => void;
     onCropCancel: () => void;
diff --git a/src/components/ImageUpload.svelte b/src/components/ImageUpload.svelte
index e772c5b..63ecbff 100644
--- a/src/components/ImageUpload.svelte
+++ b/src/components/ImageUpload.svelte
@@ -15,15 +15,15 @@
 
   let { onImageSelect }: Props = $props();
 
-  let dropZone = $state<HTMLElement | null>(null);
-  let fileInput = $state<HTMLInputElement | null>(null);
-  let urlInput = $state<HTMLInputElement | null>(null);
-  let urlForm = $state<HTMLFormElement | null>(null);
+  let dropZone = $state<HTMLElement | undefined>(undefined);
+  let fileInput = $state<HTMLInputElement | undefined>(undefined);
+  let urlInput = $state<HTMLInputElement | undefined>(undefined);
+  let urlForm = $state<HTMLFormElement | undefined>(undefined);
 
   let isDragOver = $state(false);
   let showUrlInput = $state(false);
-  let uploadedImage = $state<string | null>(null);
-  let errorMessage = $state<string | null>(null);
+  let uploadedImage = $state<string | undefined>(undefined);
+  let errorMessage = $state<string | undefined>(undefined);
 
   const uiError = $derived($uiStore.error?.error);
 
@@ -148,8 +148,8 @@
   }
 
   function resetUpload() {
-    uploadedImage = null;
-    errorMessage = null;
+    uploadedImage = undefined;
+    errorMessage = undefined;
     showUrlInput = false;
     setCurrentStep("upload");
   }
diff --git a/src/components/MainSection.svelte b/src/components/MainSection.svelte
index 49bab69..09fd47f 100644
--- a/src/components/MainSection.svelte
+++ b/src/components/MainSection.svelte
@@ -4,7 +4,7 @@
   import TextSection from "./TextSection.svelte";
 
   interface Props {
-    uploadedImage: string | null;
+    uploadedImage: string | undefined;
     texts: Array<{ id: string; text: string }>;
     onImageUpload: (image: string) => void;
     onCropComplete: (croppedImage: string) => void;
@@ -22,25 +22,14 @@
     onCropCancel,
     onTextAdd,
     onTextUpdate,
-    onTextDelete
+    onTextDelete,
   }: Props = $props();
 </script>
 
 <div class="main-section">
-  <ImageManager
-    currentStep={$uiStore.currentStep}
-    {uploadedImage}
-    onImageUpload={onImageUpload}
-    onCropComplete={onCropComplete}
-    onCropCancel={onCropCancel}
-  />
+  <ImageManager currentStep={$uiStore.currentStep} {uploadedImage} {onImageUpload} {onCropComplete} {onCropCancel} />
   {#if $uiStore.currentStep === "text"}
-    <TextSection
-      {texts}
-      onTextAdd={onTextAdd}
-      onTextUpdate={onTextUpdate}
-      onTextDelete={onTextDelete}
-    />
+    <TextSection {texts} {onTextAdd} {onTextUpdate} {onTextDelete} />
   {/if}
 </div>
 
diff --git a/src/components/PanelList.svelte b/src/components/PanelList.svelte
index f9a2edb..390dd0e 100644
--- a/src/components/PanelList.svelte
+++ b/src/components/PanelList.svelte
@@ -12,8 +12,8 @@
   let { onPanelSelect, onPanelDelete }: Props = $props();
 
   let panels = $state<Panel[]>([]);
-  let selectedPanelId = $state<string | null>(null);
-  let errorMessage = $state<string | null>(null);
+  let selectedPanelId = $state<string | undefined>(undefined);
+  let errorMessage = $state<string | undefined>(undefined);
 
   onMount(() => {
     loadPanels();
@@ -21,7 +21,7 @@
 
   function loadPanels() {
     try {
-      errorMessage = null;
+      errorMessage = undefined;
       panels = panelStorage.getAllPanels();
 
       // Если есть текущая панель в store, отмечаем её как выбранную
@@ -41,7 +41,7 @@
 
   function handlePanelDelete(panelId: string) {
     try {
-      errorMessage = null;
+      errorMessage = undefined;
       const result = panelStorage.deletePanel(panelId);
 
       if (result.success) {
@@ -49,7 +49,7 @@
 
         // Если удалили выбранную панель, сбрасываем выбор
         if (selectedPanelId === panelId) {
-          selectedPanelId = null;
+          selectedPanelId = undefined;
         }
 
         // Уведомляем родительский компонент
diff --git a/src/components/Sidebar.svelte b/src/components/Sidebar.svelte
index e54a22a..6a73c09 100644
--- a/src/components/Sidebar.svelte
+++ b/src/components/Sidebar.svelte
@@ -4,33 +4,20 @@
   import PanelsList from "./PanelsList.svelte";
 
   interface Props {
-    backgroundImage: string | null;
+    backgroundImage: string | undefined;
     panels: any[];
     onUploadNewImage: () => void;
     onDownload: (panel: any) => Promise<void>;
     onDownloadAll: () => Promise<void>;
   }
 
-  let {
-    backgroundImage,
-    panels,
-    onUploadNewImage,
-    onDownload,
-    onDownloadAll
-  }: Props = $props();
+  let { backgroundImage, panels, onUploadNewImage, onDownload, onDownloadAll }: Props = $props();
 </script>
 
 <div class="sidebar">
   {#if $uiStore.currentStep === "text"}
-    <BackgroundPreview
-      {backgroundImage}
-      onUploadNewImage={onUploadNewImage}
-    />
-    <PanelsList
-      {panels}
-      onDownload={onDownload}
-      onDownloadAll={onDownloadAll}
-    />
+    <BackgroundPreview {backgroundImage} {onUploadNewImage} />
+    <PanelsList {panels} {onDownload} {onDownloadAll} />
   {/if}
 </div>
 
diff --git a/src/components/TextManager.svelte b/src/components/TextManager.svelte
index c3e3276..353aa61 100644
--- a/src/components/TextManager.svelte
+++ b/src/components/TextManager.svelte
@@ -11,14 +11,14 @@
   let { onTextAdd, onTextUpdate, onTextDelete, texts }: Props = $props();
 
   let newText = $state("");
-  let errorMessage = $state<string | null>(null);
+  let errorMessage = $state<string | undefined>(undefined);
 
   // Общие настройки текста для всех панелей
   let commonTextSettings = $state({
     fontSize: 18,
     fontFamily: "Arial",
     color: "#ffffff",
-    textAlign: "center" as "left" | "center" | "right",
+    textAlign: "left" | "center" | "right",
     paddingX: 10,
     verticalOffset: 0,
   });
@@ -47,7 +47,7 @@
     }
 
     try {
-      errorMessage = null;
+      errorMessage = undefined;
       onTextAdd(newText.trim());
       newText = "";
     } catch (error) {
diff --git a/src/lib/services/imageService.ts b/src/lib/services/imageService.ts
index 21f682d..1d1338a 100644
--- a/src/lib/services/imageService.ts
+++ b/src/lib/services/imageService.ts
@@ -87,7 +87,7 @@ export class ImageService {
       }
 
       // Find image item
-      let imageItem: DataTransferItem | null = null;
+      let imageItem: DataTransferItem | undefined = undefined;
       for (let i = 0; i < items.length; i++) {
         if (items[i].type.indexOf("image") !== -1) {
           imageItem = items[i];
@@ -184,6 +184,7 @@ export class ImageService {
   private fileToBase64(file: File): Promise<string> {
     return new Promise((resolve, reject) => {
       const reader = new FileReader();
+      // TODO: look for a better way to handle errors non strings
       reader.onload = () => resolve(reader.result as string);
       reader.onerror = () => reject(new ImageError("Ошибка чтения файла"));
       reader.readAsDataURL(file);
diff --git a/src/lib/types/panel.ts b/src/lib/types/panel.ts
index 19ea067..0b18ca7 100644
--- a/src/lib/types/panel.ts
+++ b/src/lib/types/panel.ts
@@ -42,7 +42,7 @@ export interface ImageCropResult {
 
 export interface UIState {
   isLoading: boolean;
-  error: string | null;
+  error: string | undefined;
   currentStep: "upload" | "crop" | "text" | "preview";
   showCropModal: boolean;
   showTextManager: boolean;
diff --git a/src/lib/utils/panelStorage.ts b/src/lib/utils/panelStorage.ts
index cd92b70..dee0198 100644
--- a/src/lib/utils/panelStorage.ts
+++ b/src/lib/utils/panelStorage.ts
@@ -1,4 +1,3 @@
-
 import type { Panel } from "../types/panel";
 import { ImageError } from "../types/errors";
 import { handleError, logError } from "./errorHandler";
@@ -72,13 +71,13 @@ export class PanelStorage {
   /**
    * Загружает панель по ID
    */
-  getPanelById(id: string): Panel | null {
+  getPanelById(id: string): Panel | undefined {
     try {
       const panels = this.getAllPanels();
-      return panels.find((p) => p.id === id) || null;
+      return panels.find((p) => p.id === id) || undefined;
     } catch (error) {
       logError(error, "Failed to get panel by id");
-      return null;
+      return undefined;
     }
   }
 
diff --git a/src/routes/+page.svelte b/src/routes/+page.svelte
index f5ecb99..8454c64 100644
--- a/src/routes/+page.svelte
+++ b/src/routes/+page.svelte
@@ -8,10 +8,10 @@
 
   import AppContainer from "../components/AppContainer.svelte";
 
-  let uploadedImage = $state<string | null>(null);
+  let uploadedImage = $state<string | undefined>(undefined);
   let panels = $state<Panel[]>([]);
   let texts = $state<Array<{ id: string; text: string }>>([]);
-  let backgroundImage = $state<string | null>(null);
+  let backgroundImage = $state<string | undefined>(undefined);
 
   onMount(async () => {
     try {
@@ -32,14 +32,14 @@
 
   function handleCropComplete(croppedImage: string) {
     backgroundImage = croppedImage;
-    uploadedImage = null;
+    uploadedImage = undefined;
     imageService.handleCropComplete(croppedImage);
     panels = panelService.updatePanelsBackground(panels, croppedImage);
     panels = panelService.updatePanelsFromTexts(texts, panels, croppedImage);
   }
 
   function handleCropCancel() {
-    uploadedImage = null;
+    uploadedImage = undefined;
     imageService.handleCropCancel();
   }
 
diff --git a/src/services/exportService.ts b/src/services/exportService.ts
index 62f8fb8..58148b1 100644
--- a/src/services/exportService.ts
+++ b/src/services/exportService.ts
@@ -4,7 +4,7 @@ import { setLoading } from "../stores/uiStore";
 
 export class ExportService {
   private static instance: ExportService;
-  private errorMessage: string | null = null;
+  private errorMessage: string | undefined = undefined;
 
   private constructor() {}
 
@@ -15,11 +15,11 @@ export class ExportService {
     return ExportService.instance;
   }
 
-  getErrorMessage(): string | null {
+  getErrorMessage(): string | undefined {
     return this.errorMessage;
   }
 
-  setErrorMessage(message: string | null): void {
+  setErrorMessage(message: string | undefined): void {
     this.errorMessage = message;
   }
 
diff --git a/src/services/imageService.ts b/src/services/imageService.ts
index e042f0d..91faacf 100644
--- a/src/services/imageService.ts
+++ b/src/services/imageService.ts
@@ -19,6 +19,7 @@ export class ImageService {
     const blob = await response.blob();
     return new Promise((resolve, reject) => {
       const reader = new FileReader();
+      // TODO: look for a better handle non string
       reader.onload = () => resolve(reader.result as string);
       reader.onerror = reject;
       reader.readAsDataURL(blob);
diff --git a/src/stores/panelStore.ts b/src/stores/panelStore.ts
index 53f3aaf..5063ae8 100644
--- a/src/stores/panelStore.ts
+++ b/src/stores/panelStore.ts
@@ -2,7 +2,7 @@ import { writable, type Writable } from "svelte/store";
 import { type Panel } from "../lib/types/panel";
 import { v4 as uuidv4 } from "uuid";
 
-export const panelStore: Writable<Panel | null> = writable(null);
+export const panelStore: Writable<Panel | undefined> = writable(undefined);
 
 export const createEmptyPanel = (height: number = 100): Panel => {
   return {
@@ -30,7 +30,7 @@ export const addTextToPanel = (panel: Panel, text: string): Panel => {
     fontSize: 18,
     fontFamily: "Arial",
     color: "#ffffff",
-    textAlign: "center" as const,
+    textAlign: "center",
     paddingX: 10,
     verticalOffset: 0,
   };
@@ -58,7 +58,7 @@ export const createPanelFromText = (backgroundImage: string, text: string, heigh
     fontSize: 18,
     fontFamily: "Arial",
     color: "#ffffff",
-    textAlign: "center" as const,
+    textAlign: "center",
     paddingX: 10,
     verticalOffset: 0,
   };
diff --git a/src/stores/uiStore.ts b/src/stores/uiStore.ts
index e4e9c21..db48a80 100644
--- a/src/stores/uiStore.ts
+++ b/src/stores/uiStore.ts
@@ -3,7 +3,7 @@ import { type UIState } from "../lib/types/panel";
 
 export const uiStore: Writable<UIState> = writable({
   isLoading: false,
-  error: null,
+  error: undefined,
   currentStep: "text",
   showCropModal: false,
   showTextManager: false,
@@ -13,12 +13,12 @@ export const setLoading = (loading: boolean): void => {
   uiStore.update((state) => ({ ...state, isLoading: loading }));
 };
 
-export const setError = (error: string | null): void => {
+export const setError = (error: string | undefined): void => {
   uiStore.update((state) => ({ ...state, error }));
 };
 
 export const clearError = (): void => {
-  setError(null);
+  setError(undefined);
 };
 
 export const setCurrentStep = (step: UIState["currentStep"]): void => {
@@ -36,7 +36,7 @@ export const showTextManager = (show: boolean): void => {
 export const resetUI = (): void => {
   uiStore.set({
     isLoading: false,
-    error: null,
+    error: undefined,
     currentStep: "text",
     showCropModal: false,
     showTextManager: false,
diff --git a/tsconfig.json b/tsconfig.json
index 2c2ed3c..2087b7c 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -10,6 +10,8 @@
 		"skipLibCheck": true,
 		"sourceMap": true,
 		"strict": true,
+		"strictNullChecks": true,
+		"exactOptionalPropertyTypes": true,
 		"moduleResolution": "bundler"
 	}
 	// Path aliases are handled by https://svelte.dev/docs/kit/configuration#alias
@@ -17,4 +19,4 @@
 	//
 	// To make changes to top-level options such as include and exclude, we recommend extending
 	// the generated config; see https://svelte.dev/docs/kit/configuration#typescript
-}
+}
\ No newline at end of file