Add Adjust Page Scale tool to V2 (#4429)

# Description of Changes
Add Adjust Page Scale tool to V2

frontend/public/locales/en-GB/translation.json

@@ -1468,7 +1468,6 @@
     "submit": "Submit"
   },
   "scalePages": {
-    "tags": "resize,modify,dimension,adapt",
     "title": "Adjust page-scale",
     "header": "Adjust page-scale",
     "pageSize": "Size of a page of the document.",
@@ -1476,6 +1475,44 @@
     "scaleFactor": "Zoom level (crop) of a page.",
     "submit": "Submit"
   },
+  "adjustPageScale": {
+    "tags": "resize,modify,dimension,adapt",
+    "title": "Adjust Page Scale",
+    "header": "Adjust Page Scale",
+    "scaleFactor": {
+      "label": "Scale Factor"
+    },
+    "pageSize": {
+      "label": "Target Page Size",
+      "keep": "Keep Original Size",
+      "letter": "Letter",
+      "legal": "Legal"
+    },
+    "submit": "Adjust Page Scale",
+    "error": {
+      "failed": "An error occurred while adjusting the page scale."
+    },
+    "tooltip": {
+      "header": {
+        "title": "Page Scale Settings Overview"
+      },
+      "description": {
+        "title": "Description",
+        "text": "Adjust the size of PDF content and change the page dimensions."
+      },
+      "scaleFactor": {
+        "title": "Scale Factor",
+        "text": "Controls how large or small the content appears on the page. Content is scaled and centred - if scaled content is larger than the page size, it may be cropped.",
+        "bullet1": "1.0 = Original size",
+        "bullet2": "0.5 = Half size (50% smaller)",
+        "bullet3": "2.0 = Double size (200% larger, may crop)"
+      },
+      "pageSize": {
+        "title": "Target Page Size",
+        "text": "Sets the dimensions of the output PDF pages. 'Keep Original Size' maintains current dimensions, whilst other options resize to standard paper sizes."
+      }
+    }
+  },
   "add-page-numbers": {
     "tags": "paginate,label,organize,index"
   },

frontend/src/components/tools/adjustPageScale/AdjustPageScaleSettings.test.tsx

@@ -0,0 +1,64 @@
+import { describe, expect, test, vi, beforeEach } from 'vitest';
+import { render, screen } from '@testing-library/react';
+import { MantineProvider } from '@mantine/core';
+import AdjustPageScaleSettings from './AdjustPageScaleSettings';
+import { AdjustPageScaleParameters, PageSize } from '../../../hooks/tools/adjustPageScale/useAdjustPageScaleParameters';
+
+// Mock useTranslation with predictable return values
+const mockT = vi.fn((key: string, fallback?: string) => fallback || `mock-${key}`);
+vi.mock('react-i18next', () => ({
+  useTranslation: () => ({ t: mockT })
+}));
+
+// Wrapper component to provide Mantine context
+const TestWrapper = ({ children }: { children: React.ReactNode }) => (
+  <MantineProvider>{children}</MantineProvider>
+);
+
+describe('AdjustPageScaleSettings', () => {
+  const defaultParameters: AdjustPageScaleParameters = {
+    scaleFactor: 1.0,
+    pageSize: PageSize.KEEP,
+  };
+
+  const mockOnParameterChange = vi.fn();
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  test('should render without crashing', () => {
+    render(
+      <TestWrapper>
+        <AdjustPageScaleSettings
+          parameters={defaultParameters}
+          onParameterChange={mockOnParameterChange}
+        />
+      </TestWrapper>
+    );
+
+    // Basic render test - component renders without throwing
+    expect(screen.getByText('Scale Factor')).toBeInTheDocument();
+    expect(screen.getByText('Target Page Size')).toBeInTheDocument();
+  });
+
+  test('should render with custom parameters', () => {
+    const customParameters: AdjustPageScaleParameters = {
+      scaleFactor: 2.5,
+      pageSize: PageSize.A4,
+    };
+
+    render(
+      <TestWrapper>
+        <AdjustPageScaleSettings
+          parameters={customParameters}
+          onParameterChange={mockOnParameterChange}
+        />
+      </TestWrapper>
+    );
+
+    // Component renders successfully with custom parameters
+    expect(screen.getByText('Scale Factor')).toBeInTheDocument();
+    expect(screen.getByText('Target Page Size')).toBeInTheDocument();
+  });
+});

frontend/src/components/tools/adjustPageScale/AdjustPageScaleSettings.tsx

@@ -0,0 +1,55 @@
+import { Stack, NumberInput, Select } from "@mantine/core";
+import { useTranslation } from "react-i18next";
+import { AdjustPageScaleParameters, PageSize } from "../../../hooks/tools/adjustPageScale/useAdjustPageScaleParameters";
+
+interface AdjustPageScaleSettingsProps {
+  parameters: AdjustPageScaleParameters;
+  onParameterChange: <K extends keyof AdjustPageScaleParameters>(key: K, value: AdjustPageScaleParameters[K]) => void;
+  disabled?: boolean;
+}
+
+const AdjustPageScaleSettings = ({ parameters, onParameterChange, disabled = false }: AdjustPageScaleSettingsProps) => {
+  const { t } = useTranslation();
+
+  const pageSizeOptions = [
+    { value: PageSize.KEEP, label: t('adjustPageScale.pageSize.keep', 'Keep Original Size') },
+    { value: PageSize.A0, label: 'A0' },
+    { value: PageSize.A1, label: 'A1' },
+    { value: PageSize.A2, label: 'A2' },
+    { value: PageSize.A3, label: 'A3' },
+    { value: PageSize.A4, label: 'A4' },
+    { value: PageSize.A5, label: 'A5' },
+    { value: PageSize.A6, label: 'A6' },
+    { value: PageSize.LETTER, label: t('adjustPageScale.pageSize.letter', 'Letter') },
+    { value: PageSize.LEGAL, label: t('adjustPageScale.pageSize.legal', 'Legal') },
+  ];
+
+  return (
+    <Stack gap="md">
+      <NumberInput
+        label={t('adjustPageScale.scaleFactor.label', 'Scale Factor')}
+        value={parameters.scaleFactor}
+        onChange={(value) => onParameterChange('scaleFactor', typeof value === 'number' ? value : 1.0)}
+        min={0.1}
+        max={10.0}
+        step={0.1}
+        decimalScale={2}
+        disabled={disabled}
+      />
+
+      <Select
+        label={t('adjustPageScale.pageSize.label', 'Target Page Size')}
+        value={parameters.pageSize}
+        onChange={(value) => {
+          if (value && Object.values(PageSize).includes(value as PageSize)) {
+            onParameterChange('pageSize', value as PageSize);
+          }
+        }}
+        data={pageSizeOptions}
+        disabled={disabled}
+      />
+    </Stack>
+  );
+};
+
+export default AdjustPageScaleSettings;

frontend/src/components/tooltips/useAdjustPageScaleTips.ts

@@ -0,0 +1,31 @@
+import { useTranslation } from 'react-i18next';
+import { TooltipContent } from '../../types/tips';
+
+export const useAdjustPageScaleTips = (): TooltipContent => {
+  const { t } = useTranslation();
+
+  return {
+    header: {
+      title: t("adjustPageScale.tooltip.header.title", "Page Scale Settings Overview")
+    },
+    tips: [
+      {
+        title: t("adjustPageScale.tooltip.description.title", "Description"),
+        description: t("adjustPageScale.tooltip.description.text", "Adjust the size of PDF content and change the page dimensions.")
+      },
+      {
+        title: t("adjustPageScale.tooltip.scaleFactor.title", "Scale Factor"),
+        description: t("adjustPageScale.tooltip.scaleFactor.text", "Controls how large or small the content appears on the page. Content is scaled and centered - if scaled content is larger than the page size, it may be cropped."),
+        bullets: [
+          t("adjustPageScale.tooltip.scaleFactor.bullet1", "1.0 = Original size"),
+          t("adjustPageScale.tooltip.scaleFactor.bullet2", "0.5 = Half size (50% smaller)"),
+          t("adjustPageScale.tooltip.scaleFactor.bullet3", "2.0 = Double size (200% larger, may crop)")
+        ]
+      },
+      {
+        title: t("adjustPageScale.tooltip.pageSize.title", "Target Page Size"),
+        description: t("adjustPageScale.tooltip.pageSize.text", "Sets the dimensions of the output PDF pages. 'Keep Original Size' maintains current dimensions, while other options resize to standard paper sizes.")
+      }
+    ]
+  };
+};

frontend/src/data/useTranslatedToolRegistry.tsx

@@ -49,8 +49,11 @@ import ChangePermissionsSettings from "../components/tools/changePermissions/Cha
 import FlattenSettings from "../components/tools/flatten/FlattenSettings";
 import RedactSingleStepSettings from "../components/tools/redact/RedactSingleStepSettings";
 import Redact from "../tools/Redact";
+import AdjustPageScale from "../tools/AdjustPageScale";
 import { ToolId } from "../types/toolId";
 import MergeSettings from '../components/tools/merge/MergeSettings';
+import { adjustPageScaleOperationConfig } from "../hooks/tools/adjustPageScale/useAdjustPageScaleOperation";
+import AdjustPageScaleSettings from "../components/tools/adjustPageScale/AdjustPageScaleSettings";
 
 const showPlaceholderTools = true; // Show all tools; grey out unavailable ones in UI
 
@@ -337,11 +340,14 @@ export function useFlatToolRegistry(): ToolRegistry {
       "adjust-page-size-scale": {
         icon: <LocalIcon icon="crop-free-rounded" width="1.5rem" height="1.5rem" />,
         name: t("home.scalePages.title", "Adjust page size/scale"),
-        component: null,
-
+        component: AdjustPageScale,
         description: t("home.scalePages.desc", "Change the size/scale of a page and/or its contents."),
         categoryId: ToolCategoryId.STANDARD_TOOLS,
         subcategoryId: SubcategoryId.PAGE_FORMATTING,
+        maxFiles: -1,
+        endpoints: ["scale-pages"],
+        operationConfig: adjustPageScaleOperationConfig,
+        settingsComponent: AdjustPageScaleSettings,
       },
       addPageNumbers: {
         icon: <LocalIcon icon="123-rounded" width="1.5rem" height="1.5rem" />,

frontend/src/hooks/tools/adjustPageScale/useAdjustPageScaleOperation.ts

@@ -0,0 +1,30 @@
+import { useTranslation } from 'react-i18next';
+import { useToolOperation, ToolType } from '../shared/useToolOperation';
+import { createStandardErrorHandler } from '../../../utils/toolErrorHandler';
+import { AdjustPageScaleParameters, defaultParameters } from './useAdjustPageScaleParameters';
+
+export const buildAdjustPageScaleFormData = (parameters: AdjustPageScaleParameters, file: File): FormData => {
+  const formData = new FormData();
+  formData.append("fileInput", file);
+  formData.append("scaleFactor", parameters.scaleFactor.toString());
+  formData.append("pageSize", parameters.pageSize);
+  return formData;
+};
+
+export const adjustPageScaleOperationConfig = {
+  toolType: ToolType.singleFile,
+  buildFormData: buildAdjustPageScaleFormData,
+  operationType: 'adjustPageScale',
+  endpoint: '/api/v1/general/scale-pages',
+  filePrefix: 'scaled_',
+  defaultParameters,
+} as const;
+
+export const useAdjustPageScaleOperation = () => {
+  const { t } = useTranslation();
+
+  return useToolOperation<AdjustPageScaleParameters>({
+    ...adjustPageScaleOperationConfig,
+    getErrorMessage: createStandardErrorHandler(t('adjustPageScale.error.failed', 'An error occurred while adjusting the page scale.'))
+  });
+};

frontend/src/hooks/tools/adjustPageScale/useAdjustPageScaleParameters.test.ts

@@ -0,0 +1,142 @@
+import { describe, expect, test } from 'vitest';
+import { renderHook, act } from '@testing-library/react';
+import { useAdjustPageScaleParameters, defaultParameters, PageSize, AdjustPageScaleParametersHook } from './useAdjustPageScaleParameters';
+
+describe('useAdjustPageScaleParameters', () => {
+  test('should initialize with default parameters', () => {
+    const { result } = renderHook(() => useAdjustPageScaleParameters());
+
+    expect(result.current.parameters).toStrictEqual(defaultParameters);
+    expect(result.current.parameters.scaleFactor).toBe(1.0);
+    expect(result.current.parameters.pageSize).toBe(PageSize.KEEP);
+  });
+
+  test.each([
+    { paramName: 'scaleFactor' as const, value: 0.5 },
+    { paramName: 'scaleFactor' as const, value: 2.0 },
+    { paramName: 'scaleFactor' as const, value: 10.0 },
+    { paramName: 'pageSize' as const, value: PageSize.A4 },
+    { paramName: 'pageSize' as const, value: PageSize.LETTER },
+    { paramName: 'pageSize' as const, value: PageSize.LEGAL },
+  ])('should update parameter $paramName to $value', ({ paramName, value }) => {
+    const { result } = renderHook(() => useAdjustPageScaleParameters());
+
+    act(() => {
+      result.current.updateParameter(paramName, value);
+    });
+
+    expect(result.current.parameters[paramName]).toBe(value);
+  });
+
+  test('should reset parameters to defaults', () => {
+    const { result } = renderHook(() => useAdjustPageScaleParameters());
+
+    // First, change some parameters
+    act(() => {
+      result.current.updateParameter('scaleFactor', 2.5);
+      result.current.updateParameter('pageSize', PageSize.A3);
+    });
+
+    expect(result.current.parameters.scaleFactor).toBe(2.5);
+    expect(result.current.parameters.pageSize).toBe(PageSize.A3);
+
+    // Then reset
+    act(() => {
+      result.current.resetParameters();
+    });
+
+    expect(result.current.parameters).toStrictEqual(defaultParameters);
+  });
+
+  test('should return correct endpoint name', () => {
+    const { result } = renderHook(() => useAdjustPageScaleParameters());
+
+    expect(result.current.getEndpointName()).toBe('scale-pages');
+  });
+
+  test.each([
+    {
+      description: 'with default parameters',
+      setup: () => {},
+      expected: true
+    },
+    {
+      description: 'with valid scale factor 0.1',
+      setup: (hook: AdjustPageScaleParametersHook) => {
+        hook.updateParameter('scaleFactor', 0.1);
+      },
+      expected: true
+    },
+    {
+      description: 'with valid scale factor 10.0',
+      setup: (hook: AdjustPageScaleParametersHook) => {
+        hook.updateParameter('scaleFactor', 10.0);
+      },
+      expected: true
+    },
+    {
+      description: 'with A4 page size',
+      setup: (hook: AdjustPageScaleParametersHook) => {
+        hook.updateParameter('pageSize', PageSize.A4);
+      },
+      expected: true
+    },
+    {
+      description: 'with invalid scale factor 0',
+      setup: (hook: AdjustPageScaleParametersHook) => {
+        hook.updateParameter('scaleFactor', 0);
+      },
+      expected: false
+    },
+    {
+      description: 'with negative scale factor',
+      setup: (hook: AdjustPageScaleParametersHook) => {
+        hook.updateParameter('scaleFactor', -0.5);
+      },
+      expected: false
+    }
+  ])('should validate parameters correctly $description', ({ setup, expected }) => {
+    const { result } = renderHook(() => useAdjustPageScaleParameters());
+
+    act(() => {
+      setup(result.current);
+    });
+
+    expect(result.current.validateParameters()).toBe(expected);
+  });
+
+  test('should handle all PageSize enum values', () => {
+    const { result } = renderHook(() => useAdjustPageScaleParameters());
+
+    Object.values(PageSize).forEach(pageSize => {
+      act(() => {
+        result.current.updateParameter('pageSize', pageSize);
+      });
+
+      expect(result.current.parameters.pageSize).toBe(pageSize);
+      expect(result.current.validateParameters()).toBe(true);
+    });
+  });
+
+  test('should handle scale factor edge cases', () => {
+    const { result } = renderHook(() => useAdjustPageScaleParameters());
+
+    // Test very small valid scale factor
+    act(() => {
+      result.current.updateParameter('scaleFactor', 0.01);
+    });
+    expect(result.current.validateParameters()).toBe(true);
+
+    // Test scale factor just above zero
+    act(() => {
+      result.current.updateParameter('scaleFactor', 0.001);
+    });
+    expect(result.current.validateParameters()).toBe(true);
+
+    // Test exactly zero (invalid)
+    act(() => {
+      result.current.updateParameter('scaleFactor', 0);
+    });
+    expect(result.current.validateParameters()).toBe(false);
+  });
+});

frontend/src/hooks/tools/adjustPageScale/useAdjustPageScaleParameters.ts

@@ -0,0 +1,37 @@
+import { BaseParameters } from '../../../types/parameters';
+import { useBaseParameters, BaseParametersHook } from '../shared/useBaseParameters';
+
+export enum PageSize {
+  KEEP = 'KEEP',
+  A0 = 'A0',
+  A1 = 'A1',
+  A2 = 'A2',
+  A3 = 'A3',
+  A4 = 'A4',
+  A5 = 'A5',
+  A6 = 'A6',
+  LETTER = 'LETTER',
+  LEGAL = 'LEGAL'
+}
+
+export interface AdjustPageScaleParameters extends BaseParameters {
+  scaleFactor: number;
+  pageSize: PageSize;
+}
+
+export const defaultParameters: AdjustPageScaleParameters = {
+  scaleFactor: 1.0,
+  pageSize: PageSize.KEEP,
+};
+
+export type AdjustPageScaleParametersHook = BaseParametersHook<AdjustPageScaleParameters>;
+
+export const useAdjustPageScaleParameters = (): AdjustPageScaleParametersHook => {
+  return useBaseParameters({
+    defaultParameters,
+    endpointName: 'scale-pages',
+    validateFn: (params) => {
+      return params.scaleFactor > 0;
+    },
+  });
+};

frontend/src/tools/AdjustPageScale.tsx

@@ -0,0 +1,58 @@
+import { useTranslation } from "react-i18next";
+import { createToolFlow } from "../components/tools/shared/createToolFlow";
+import AdjustPageScaleSettings from "../components/tools/adjustPageScale/AdjustPageScaleSettings";
+import { useAdjustPageScaleParameters } from "../hooks/tools/adjustPageScale/useAdjustPageScaleParameters";
+import { useAdjustPageScaleOperation } from "../hooks/tools/adjustPageScale/useAdjustPageScaleOperation";
+import { useBaseTool } from "../hooks/tools/shared/useBaseTool";
+import { BaseToolProps, ToolComponent } from "../types/tool";
+import { useAdjustPageScaleTips } from "../components/tooltips/useAdjustPageScaleTips";
+
+const AdjustPageScale = (props: BaseToolProps) => {
+  const { t } = useTranslation();
+  const adjustPageScaleTips = useAdjustPageScaleTips();
+
+  const base = useBaseTool(
+    'adjustPageScale',
+    useAdjustPageScaleParameters,
+    useAdjustPageScaleOperation,
+    props
+  );
+
+  return createToolFlow({
+    files: {
+      selectedFiles: base.selectedFiles,
+      isCollapsed: base.hasResults,
+    },
+    steps: [
+      {
+        title: "Settings",
+        isCollapsed: base.settingsCollapsed,
+        onCollapsedClick: base.settingsCollapsed ? base.handleSettingsReset : undefined,
+        tooltip: adjustPageScaleTips,
+        content: (
+          <AdjustPageScaleSettings
+            parameters={base.params.parameters}
+            onParameterChange={base.params.updateParameter}
+            disabled={base.endpointLoading}
+          />
+        ),
+      },
+    ],
+    executeButton: {
+      text: t("adjustPageScale.submit", "Adjust Page Scale"),
+      isVisible: !base.hasResults,
+      loadingText: t("loading"),
+      onClick: base.handleExecute,
+      disabled: !base.params.validateParameters() || !base.hasFiles || !base.endpointEnabled,
+    },
+    review: {
+      isVisible: base.hasResults,
+      operation: base.operation,
+      title: t("adjustPageScale.title", "Page Scale Results"),
+      onFileClick: base.handleThumbnailClick,
+      onUndo: base.handleUndo,
+    },
+  });
+};
+
+export default AdjustPageScale as ToolComponent;