Fix: Restrict block insert, move, and replace attending to allowedBlo…

…cks, locking, and child blocks (#14003)

Supersedes: https://github.com/WordPress/gutenberg/pull/7301/files
Uses the select control implemented in #13924.
This PR changes the action creators to be a generator and have all the required validations before yielding the action.

Fixes: #14568;
Fixes: #10186;
Fixes: #13099;

Missing the update to the unit tests.

## How has this been tested?
Test block: [gist.github.com/jorgefilipecosta/b7194daac3ce26827522694fb4252c1c#file-testallowedblocksmiddleware-js](https://gist.github.com/jorgefilipecosta/b7194daac3ce26827522694fb4252c1c#file-testallowedblocksmiddleware-js)

I pasted the test block referred in the browser console.
I added the Product block.
I verified I cannot move using drag & drop the Buy button out of the Product block. (child block restriction.
I verified I cannot move using drag & drop a paragraph created outside of the Product block inside the product block. (allowed blocks restriction).
I verified that if I press enter in the buy button or image inside the product block, a paragraph is not created (allowed blocks restriction).
I added two galleries outside the product block, multi-selected them, and copied them ( ctrl + c ), I pasted them inside the list block inside the Product block and I verified they were not added (allowed blocks restriction).

I verified that when we have a template lock and we press enter on the title we now do not insert unallowed blocks.
Template lock code:

```
add_filter( 'allowed_block_types', function( $allowed_block_types, $post ) {
	if ( $post->post_type === 'post' ) {
	    return $allowed_block_types;
	}
	return [ 'core/image', 'core/button' ];
}, 10, 2 );
```
I verified that if we disable the paragraph, e.g., with a filter or inside the test block, pressing enter on the title or in placeholders does not add paragraph blocks. Pressing the sibling inserter also does not insert the paragraph (PR #7226).
Code to disable paragraph:

```
function myplugin_register_book_lock_post_type() {
    $args = array(
        'public' => true,
	  	'template_lock' => 'all',
        'label'  => 'Books Lock',
        'show_in_rest' => true,
        'template' => array(
            array( 'core/image', array(
            ) ),
            array( 'core/heading', array(
                'placeholder' => 'Add Author...',
            ) ),
            array( 'core/paragraph', array(
                'placeholder' => 'Add Description...',
            ) ),
        ),
    );
    register_post_type( 'book_lock', $args );
}
add_action( 'init', 'myplugin_register_book_lock_post_type' );
```
I added two image blocks, multi-selected them, copied them and tried to paste them on the list inside the test block. I checked the image blocks were not added inside the test block.

All these actions are possible in master.

Todo: If we accept this approach, end 2 end tests will be created before the merge that replicate this manual tests.

packages/block-editor/src/store/actions.js

@@ -1,7 +1,7 @@
 /**
  * External dependencies
  */
-import { castArray } from 'lodash';
+import { castArray, first } from 'lodash';
 
 /**
  * WordPress dependencies
@@ -13,6 +13,25 @@ import { getDefaultBlockName, createBlock } from '@wordpress/blocks';
  */
 import { select } from './controls';
 
+/**
+ * Generator which will yield a default block insert action if there
+ * are no other blocks at the root of the editor. This generator should be used
+ * in actions which may result in no blocks remaining in the editor (removal,
+ * replacement, etc).
+ */
+function* ensureDefaultBlock() {
+	const count = yield select(
+		'core/block-editor',
+		'getBlockCount',
+	);
+
+	// To avoid a focus loss when removing the last block, assure there is
+	// always a default block if the last of the blocks have been removed.
+	if ( count === 0 ) {
+		yield insertDefaultBlock();
+	}
+}
+
 /**
  * Returns an action object used in signalling that blocks state should be
  * reset to the specified array of blocks, taking precedence over any other
@@ -202,15 +221,36 @@ export function toggleSelection( isSelectionEnabled = true ) {
  * @param {(string|string[])} clientIds Block client ID(s) to replace.
  * @param {(Object|Object[])} blocks    Replacement block(s).
  *
- * @return {Object} Action object.
+ * @yields {Object} Action object.
  */
-export function replaceBlocks( clientIds, blocks ) {
-	return {
+export function* replaceBlocks( clientIds, blocks ) {
+	clientIds = castArray( clientIds );
+	blocks = castArray( blocks );
+	const rootClientId = yield select(
+		'core/block-editor',
+		'getBlockRootClientId',
+		first( clientIds )
+	);
+	// Replace is valid if the new blocks can be inserted in the root block.
+	for ( let index = 0; index < blocks.length; index++ ) {
+		const block = blocks[ index ];
+		const canInsertBlock = yield select(
+			'core/block-editor',
+			'canInsertBlockType',
+			block.name,
+			rootClientId
+		);
+		if ( ! canInsertBlock ) {
+			return;
+		}
+	}
+	yield {
 		type: 'REPLACE_BLOCKS',
-		clientIds: castArray( clientIds ),
-		blocks: castArray( blocks ),
+		clientIds,
+		blocks,
 		time: Date.now(),
 	};
+	yield* ensureDefaultBlock();
 }
 
 /**
@@ -256,16 +296,51 @@ export const moveBlocksUp = createOnMove( 'MOVE_BLOCKS_UP' );
  * @param  {?string} toRootClientId   Root client ID destination.
  * @param  {number}  index            The index to move the block into.
  *
- * @return {Object} Action object.
+ * @yields {Object} Action object.
  */
-export function moveBlockToPosition( clientId, fromRootClientId, toRootClientId, index ) {
-	return {
+export function* moveBlockToPosition( clientId, fromRootClientId, toRootClientId, index ) {
+	const templateLock = yield select(
+		'core/block-editor',
+		'getTemplateLock',
+		fromRootClientId
+	);
+
+	// If locking is equal to all on the original clientId (fromRootClientId),
+	// it is not possible to move the block to any other position.
+	if ( templateLock === 'all' ) {
+		return;
+	}
+
+	const action = {
 		type: 'MOVE_BLOCK_TO_POSITION',
 		fromRootClientId,
 		toRootClientId,
 		clientId,
 		index,
 	};
+	// If moving inside the same root block the move is always possible.
+	if ( fromRootClientId === toRootClientId ) {
+		yield action;
+		return;
+	}
+
+	const blockName = yield select(
+		'core/block-editor',
+		'getBlockName',
+		clientId
+	);
+
+	const canInsertBlock = yield select(
+		'core/block-editor',
+		'canInsertBlockType',
+		blockName,
+		toRootClientId
+	);
+
+	// If moving to other parent block, the move is possible if we can insert a block of the same type inside the new parent block.
+	if ( canInsertBlock ) {
+		yield action;
+	}
 }
 
 /**
@@ -279,8 +354,18 @@ export function moveBlockToPosition( clientId, fromRootClientId, toRootClientId,
  *
  * @return {Object} Action object.
  */
-export function insertBlock( block, index, rootClientId, updateSelection = true ) {
-	return insertBlocks( [ block ], index, rootClientId, updateSelection );
+export function insertBlock(
+	block,
+	index,
+	rootClientId,
+	updateSelection = true,
+) {
+	return insertBlocks(
+		[ block ],
+		index,
+		rootClientId,
+		updateSelection
+	);
 }
 
 /**
@@ -292,17 +377,37 @@ export function insertBlock( block, index, rootClientId, updateSelection = true
  * @param {?string}  rootClientId    Optional root client ID of block list on which to insert.
  * @param {?boolean} updateSelection If true block selection will be updated.  If false, block selection will not change. Defaults to true.
  *
- * @return {Object} Action object.
- */
-export function insertBlocks( blocks, index, rootClientId, updateSelection = true ) {
-	return {
-		type: 'INSERT_BLOCKS',
-		blocks: castArray( blocks ),
-		index,
-		rootClientId,
-		time: Date.now(),
-		updateSelection,
-	};
+ *  @return {Object} Action object.
+ */
+export function* insertBlocks(
+	blocks,
+	index,
+	rootClientId,
+	updateSelection = true
+) {
+	blocks = castArray( blocks );
+	const allowedBlocks = [];
+	for ( const block of blocks ) {
+		const isValid = yield select(
+			'core/block-editor',
+			'canInsertBlockType',
+			block.name,
+			rootClientId
+		);
+		if ( isValid ) {
+			allowedBlocks.push( block );
+		}
+	}
+	if ( allowedBlocks.length ) {
+		return {
+			type: 'INSERT_BLOCKS',
+			blocks: allowedBlocks,
+			index,
+			rootClientId,
+			time: Date.now(),
+			updateSelection,
+		};
+	}
 }
 
 /**
@@ -394,16 +499,9 @@ export function* removeBlocks( clientIds, selectPrevious = true ) {
 		clientIds,
 	};
 
-	const count = yield select(
-		'core/block-editor',
-		'getBlockCount',
-	);
-
 	// To avoid a focus loss when removing the last block, assure there is
 	// always a default block if the last of the blocks have been removed.
-	if ( count === 0 ) {
-		yield insertDefaultBlock();
-	}
+	yield* ensureDefaultBlock();
 }
 
 /**

packages/block-editor/src/store/effects.js

@@ -17,14 +17,12 @@ import {
 	replaceBlocks,
 	selectBlock,
 	setTemplateValidity,
-	insertDefaultBlock,
 	resetBlocks,
 } from './actions';
 import {
 	getBlock,
 	getBlocks,
 	getSelectedBlockCount,
-	getBlockCount,
 	getTemplateLock,
 	getTemplate,
 	isValidTemplate,
@@ -60,23 +58,6 @@ export function validateBlocksToTemplate( action, store ) {
 	}
 }
 
-/**
- * Effect handler which will return a default block insertion action if there
- * are no other blocks at the root of the editor. This is expected to be used
- * in actions which may result in no blocks remaining in the editor (removal,
- * replacement, etc).
- *
- * @param {Object} action Action which had initiated the effect handler.
- * @param {Object} store  Store instance.
- *
- * @return {?Object} Default block insert action, if no other blocks exist.
- */
-export function ensureDefaultBlock( action, store ) {
-	if ( ! getBlockCount( store.getState() ) ) {
-		return insertDefaultBlock();
-	}
-}
-
 export default {
 	MERGE_BLOCKS( action, store ) {
 		const { dispatch } = store;
@@ -127,9 +108,6 @@ export default {
 	RESET_BLOCKS: [
 		validateBlocksToTemplate,
 	],
-	REPLACE_BLOCKS: [
-		ensureDefaultBlock,
-	],
 	MULTI_SELECT: ( action, { getState } ) => {
 		const blockCount = getSelectedBlockCount( getState() );