Fix for head tail regex match logic, when both regexp produce matching groups

- unit tests

src/custom-sort/custom-sort.spec.ts

@@ -347,6 +347,38 @@ describe('determineSortingGroup', () => {
 				path: 'Some parent folder/Part:123-icle.md'
 			});
 		});
+		it('should match head and tail, when advanced regexp in both, head and tail', () => {
+			// given
+			const file: TFile = mockTFile('Part 555-6 123-icle', 'md', 444, MOCK_TIMESTAMP + 555, MOCK_TIMESTAMP + 666);
+			const sortSpec: CustomSortSpec = {
+				targetFoldersPaths: ['Some parent folder'],
+				groups: [{
+					type: CustomSortGroupType.ExactHeadAndTail,
+					regexPrefix: {
+						regex: /^Part *(\d+(?:-\d+)*)/i,
+						normalizerFn: CompoundDashNumberNormalizerFn
+					},
+					regexSuffix: {
+						regex: / *(\d+(?:-\d+)*)-icle$/i,
+						normalizerFn: CompoundDashNumberNormalizerFn
+					}
+				}]
+			}
+
+			// when
+			const result = determineSortingGroup(file, sortSpec)
+
+			// then
+			expect(result).toEqual({
+				groupIdx: 0, // Matched!
+				isFolder: false,
+				sortString: "00000555|00000006//00000123////Part 555-6 123-icle.md",
+				matchGroup: '00000555|00000006//00000123//',
+				ctime: MOCK_TIMESTAMP + 555,
+				mtime: MOCK_TIMESTAMP + 666,
+				path: 'Some parent folder/Part 555-6 123-icle.md'
+			});
+		});
 	})
 	describe('CustomSortGroupType.ExactPrefix', () => {
 		it('should correctly recognize exact prefix', () => {

src/custom-sort/custom-sort.ts

@@ -191,6 +191,16 @@ export const getSorterFnFor = (sorting: CustomSortOrder, currentUIselectedSortin
 	}
 }
 
+// logic of primary and secondary sorting:
+// 0th - compare groupIdx
+// 1st - apply primary, if 0 then
+// 2nd - apply secondary if present, if 0 or not present then
+// 3rd - apply folder-level order (which also will probably return 0)
+// 4th - apply the UI-selected
+// 5th - if not known, use CustomSortOrder.default
+
+
+
 function getComparator(sortSpec: CustomSortSpec, currentUIselectedSorting?: string): SorterFn {
 	const compareTwoItems = (itA: FolderItemForSorting, itB: FolderItemForSorting) => {
 		if (itA.groupIdx != undefined && itB.groupIdx != undefined) {
@@ -208,7 +218,9 @@ function getComparator(sortSpec: CustomSortSpec, currentUIselectedSorting?: stri
 		} else {
 			// should never happen - groupIdx is not known for at least one of items to compare.
 			// The logic of determining the index always sets some idx
-			// Yet for sanity and to satisfy TS code analyzer a fallback to default behavior below
+			// Yet for sanity and to satisfy TS code analyzer some valid behavior below
+			if (itA.groupIdx !== undefined) return -1
+			if (itB.groupIdx !== undefined) return 1
 			return getSorterFnFor(CustomSortOrder.default, currentUIselectedSorting)(itA, itB)
 		}
 	}
@@ -313,7 +325,10 @@ export const determineSortingGroup = function (entry: TFile | TFolder, spec: Cus
 						// check for overlapping of prefix and suffix match (not allowed)
 						if ((fullMatchLeft!.length + fullMatchRight!.length) <= nameForMatching.length) {
 							determined = true
-							matchedGroup = matchedGroupLeft ?? matchedGroupRight
+
+							if (matchedGroupLeft || matchedGroupRight) {
+								matchedGroup = (matchedGroupLeft && matchedGroupRight) ? (matchedGroupLeft + matchedGroupRight) : (matchedGroupLeft ?? matchedGroupRight)
+							}
 						}
 					}
 			}