fix list indentation

packages/rich-text/src/indent-list-items.js

@@ -6,6 +6,36 @@ import { LINE_SEPARATOR } from './special-characters';
 import { normaliseFormats } from './normalise-formats';
 import { getLineIndex } from './get-line-index';
 
+/**
+ * Gets the line index of the first previous list item with higher indentation.
+ *
+ * @param {Object} value      Value to search.
+ * @param {number} lineIndex  Line index of the list item to compare with.
+ *
+ * @return {boolean} The line index.
+ */
+function getTargetLevelLineIndex( { text, formats }, lineIndex ) {
+	const startFormats = formats[ lineIndex ] || [];
+
+	let index = lineIndex;
+
+	while ( index-- ) {
+		if ( text[ index ] !== LINE_SEPARATOR ) {
+			continue;
+		}
+
+		const formatsAtIndex = formats[ index ] || [];
+
+		// Return the first line index that is one level higher. If the level is
+		// lower or equal, there is no result.
+		if ( formatsAtIndex.length === startFormats.length + 1 ) {
+			return index;
+		} else if ( formatsAtIndex.length <= startFormats.length ) {
+			return;
+		}
+	}
+}
+
 /**
  * Indents any selected list items if possible.
  *
@@ -23,62 +53,39 @@ export function indentListItems( value, rootFormat ) {
 	}
 
 	const { text, formats, start, end } = value;
+	const previousLineIndex = getLineIndex( value, lineIndex );
 	const formatsAtLineIndex = formats[ lineIndex ] || [];
-	const targetFormats = formats[ getLineIndex( value, lineIndex ) ] || [];
+	const formatsAtPreviousLineIndex = formats[ previousLineIndex ] || [];
 
 	// The the indentation of the current line is greater than previous line,
 	// then the line cannot be furter indented.
-	if ( formatsAtLineIndex.length > targetFormats.length ) {
+	if ( formatsAtLineIndex.length > formatsAtPreviousLineIndex.length ) {
 		return value;
 	}
 
 	const newFormats = formats.slice();
+	const targetLevelLineIndex = getTargetLevelLineIndex( value, lineIndex );
 
 	for ( let index = lineIndex; index < end; index++ ) {
 		if ( text[ index ] !== LINE_SEPARATOR ) {
 			continue;
 		}
 
-		// If the indentation of the previous line is the same as the current
-		// line, then duplicate the type and append all current types. E.g.
-		//
-		// 1. one
-		// 2. two <= Selected
-		//   * three <= Selected
-		//
-		// should become:
-		//
-		// 1. one
-		//   1. two <= Selected
-		//     * three <= Selected
-		//
-		//   ^ Inserted list
-		//
-		// Otherwise take the target formats and append traling lists. E.g.
-		//
-		// 1. one
-		//   * target
-		// 2. two <= Selected
-		//   * three <= Selected
-		//
-		// should become:
-		//
-		// 1. one
-		//   * target
-		//   * two <= Selected
-		//     * three <= Selected
-		//
-		if ( targetFormats.length === formatsAtLineIndex.length ) {
+		// Get the previous list, and if there's a child list, take over the
+		// formats. If not, duplicate the last level and create a new level.
+		if ( targetLevelLineIndex ) {
+			const targetFormats = formats[ targetLevelLineIndex ] || [];
+			newFormats[ index ] = targetFormats.concat(
+				( newFormats[ index ] || [] ).slice( targetFormats.length - 1 )
+			);
+		} else {
+			const targetFormats = formats[ previousLineIndex ] || [];
 			const lastformat = targetFormats[ targetFormats.length - 1 ] || rootFormat;
 
 			newFormats[ index ] = targetFormats.concat(
 				[ lastformat ],
 				( newFormats[ index ] || [] ).slice( targetFormats.length )
 			);
-		} else {
-			newFormats[ index ] = targetFormats.concat(
-				( newFormats[ index ] || [] ).slice( targetFormats.length - 1 )
-			);
 		}
 	}
 

packages/rich-text/src/test/indent-list-items.js

@@ -130,4 +130,26 @@ describe( 'indentListItems', () => {
 		expect( result ).not.toBe( record );
 		expect( getSparseArrayLength( result.formats ) ).toBe( 2 );
 	} );
+
+	it( 'should indent one level at a time', () => {
+		// As we're testing list formats, the text should remain the same.
+		const text = `1${ LINE_SEPARATOR }2${ LINE_SEPARATOR }3${ LINE_SEPARATOR }4`;
+		const record = {
+			formats: [ , [ ul ], , [ ul, ul ], , , , ],
+			text,
+			start: 6,
+			end: 6,
+		};
+		const expected = {
+			formats: [ , [ ul ], , [ ul, ul ], , [ ul ], , ],
+			text,
+			start: 6,
+			end: 6,
+		};
+		const result = indentListItems( deepFreeze( record ), ul );
+
+		expect( result ).toEqual( expected );
+		expect( result ).not.toBe( record );
+		expect( getSparseArrayLength( result.formats ) ).toBe( 3 );
+	} );
 } );