Introduce usage of nested RUIProvider (#541)

src/docs/customize/global-props.md

@@ -83,3 +83,53 @@ React.createElement(() => {
   );
 });
 ```
+
+## Nesting
+
+Global props can be nested. This is useful e.g. when you want to configure
+props across whole application and then override some of them in a specific
+part of the application.
+
+When nested `RUIProvider` is used, the props are merged deeply together. This
+means that you can extend specific object with new props or override existing
+ones. If you need to remove some prop, you can set it to `undefined`.
+
+```docoff-react-preview
+React.createElement(() => {
+  const [variant, setVariant] = React.useState('filled');
+  return (
+    <RUIProvider globalProps={{
+      Grid: {
+        columns: {
+          xs: '1fr',
+          md: '1fr 1fr',
+        },
+        justifyItems: 'center',
+        rows: {
+          xs: '50px',
+          md: '100px',
+        },
+      },
+    }}>
+      <RUIProvider globalProps={{
+        Grid: {
+          columns: {
+            sm: '1fr 1fr 1fr',
+          },
+          justifyItems: 'undefined',
+          rows: undefined,
+        },
+      }}>
+        <Grid>
+          <docoff-placeholder bordered>Grid item</docoff-placeholder>
+          <docoff-placeholder bordered>Grid item</docoff-placeholder>
+          <docoff-placeholder bordered>Grid item</docoff-placeholder>
+          <docoff-placeholder bordered>Grid item</docoff-placeholder>
+          <docoff-placeholder bordered>Grid item</docoff-placeholder>
+          <docoff-placeholder bordered>Grid item</docoff-placeholder>
+        </Grid>
+      </RUIProvider>
+    </RUIProvider>
+  );
+});
+```

src/provider/RUIProvider.jsx

@@ -1,19 +1,22 @@
 import PropTypes from 'prop-types';
 import React, {
+  useContext,
   useMemo,
 } from 'react';
 import defaultTranslations from '../translations/en';
+import { mergeDeep } from '../utils/mergeDeep';
 import RUIContext from './RUIContext';
 
 const RUIProvider = ({
   children,
   globalProps,
   translations,
 }) => {
+  const context = useContext(RUIContext);
   const childProps = useMemo(() => ({
-    globalProps,
-    translations,
-  }), [globalProps, translations]);
+    globalProps: mergeDeep(context?.globalProps || {}, globalProps),
+    translations: mergeDeep(context?.translations || {}, translations),
+  }), [context, globalProps, translations]);
 
   return (
     <RUIContext.Provider

src/provider/__tests__/RUIProvider.test.jsx

@@ -3,8 +3,9 @@ import {
   render,
   within,
 } from '@testing-library/react';
-import { Badge } from '../../components/Badge';
 import { Alert } from '../../components/Alert';
+import { Badge } from '../../components/Badge';
+import { Grid } from '../../components/Grid';
 import RUIProvider from '../RUIProvider';
 
 describe('rendering', () => {
@@ -36,4 +37,77 @@ describe('rendering', () => {
 
     assert(dom.container.firstChild);
   });
+
+  it('renders with nested providers', () => {
+    const dom = render((
+      <RUIProvider
+        globalProps={{
+          Grid: {
+            alignContent: {
+              sm: 'column',
+              xs: 'row dense',
+            },
+            autoFlow: {
+              sm: 'column',
+              xs: 'row dense',
+            },
+            justifyItems: 'center',
+            tag: 'main',
+          },
+        }}
+      >
+        <RUIProvider
+          globalProps={{
+            Grid: {
+              alignContent: undefined,
+              autoFlow: {
+                lg: 'column',
+                sm: undefined,
+                xs: 'row dense',
+              },
+              justifyContent: undefined,
+              justifyItems: undefined,
+              tag: 'section',
+            },
+          }}
+        >
+          <RUIProvider
+            globalProps={{
+              Grid: {
+                autoFlow: {
+                  md: 'column',
+                },
+                justifyContent: 'center',
+              },
+            }}
+          >
+            <Grid>
+              <div>
+                Content text
+              </div>
+            </Grid>
+          </RUIProvider>
+        </RUIProvider>
+      </RUIProvider>
+    ));
+
+    // Assert alignContent
+    expect(dom.container.firstChild.style.cssText.includes('--rui-local-align-content')).toBeFalsy();
+
+    // Assert autoFlow
+    expect(dom.container.firstChild.style.cssText.includes('--rui-local-auto-flow-lg: column')).toBeTruthy();
+    expect(dom.container.firstChild.style.cssText.includes('--rui-local-auto-flow-md: column')).toBeTruthy();
+    expect(dom.container.firstChild.style.cssText.includes('--rui-local-auto-flow-sm')).toBeFalsy();
+    expect(dom.container.firstChild.style.cssText.includes('--rui-local-auto-flow-xs: row dense')).toBeTruthy();
+
+    // Assert justifyContent
+    expect(dom.container.firstChild.style.cssText.includes('--rui-local-justify-content-xs: center;')).toBeTruthy();
+
+    // Assert justifyItems
+    expect(dom.container.firstChild.style.cssText.includes('--rui-local-justify-items')).toBeFalsy();
+
+    // Assert tag
+    expect(dom.container.firstChild.tagName).toEqual('SECTION');
+  });
 });
+

src/utils/__tests__/mergeDeep.js

@@ -0,0 +1,80 @@
+import { mergeDeep } from '../mergeDeep';
+
+describe('mergeDeep', () => {
+  it('adds new attributes', () => {
+    const obj1 = {};
+    const obj2 = {
+      props: {
+        className: 'class',
+        style: {
+          color: 'white',
+        },
+      },
+      state: {
+        items: [1, 2],
+        itemsSize: 2,
+      },
+    };
+    const expectedObj = {
+      props: {
+        className: 'class',
+        style: {
+          color: 'white',
+        },
+      },
+      state: {
+        items: [1, 2],
+        itemsSize: 2,
+      },
+    };
+
+    expect(mergeDeep(obj1, obj2)).toEqual(expectedObj);
+  });
+
+  it('merges with existing attributes', () => {
+    const obj1 = {
+      props: {
+        children: ['child1', 'child2'],
+        className: 'class',
+        parent: 'parent',
+        style: {
+          color: 'white',
+        },
+      },
+      state: {
+        items: [1, 2],
+        itemsSize: 2,
+      },
+    };
+    const obj2 = {
+      props: {
+        children: null,
+        className: 'class1 class2',
+        style: {
+          backgroundColor: 'black',
+        },
+      },
+      state: {
+        items: [3, 4, 5],
+        itemsSize: 3,
+      },
+    };
+    const expectedObj = {
+      props: {
+        children: null,
+        className: 'class1 class2',
+        parent: 'parent',
+        style: {
+          backgroundColor: 'black',
+          color: 'white',
+        },
+      },
+      state: {
+        items: [3, 4, 5],
+        itemsSize: 3,
+      },
+    };
+
+    expect(mergeDeep(obj1, obj2)).toEqual(expectedObj);
+  });
+});

src/utils/mergeDeep.js

@@ -0,0 +1,28 @@
+const isObject = (obj) => obj && typeof obj === 'object' && !Array.isArray(obj);
+
+/**
+ * Performs a deep merge of objects and returns new object.
+ *
+ * @param {...object} objects
+ * @returns {object}
+ */
+export const mergeDeep = (...objects) => objects.reduce((prev, obj) => {
+  if (obj == null) {
+    return prev;
+  }
+
+  const newObject = { ...prev };
+
+  Object.keys(obj).forEach((key) => {
+    const previousVal = prev[key];
+    const currentVal = obj[key];
+
+    if (isObject(previousVal) && isObject(currentVal)) {
+      newObject[key] = mergeDeep(previousVal, currentVal);
+    } else {
+      newObject[key] = currentVal;
+    }
+  });
+
+  return newObject;
+}, {});