Fix: edge case causing extreme height in Architecture Diagrams

.changeset/angry-bags-brake.md

@@ -0,0 +1,5 @@
+---
+'mermaid': patch
+---
+
+fix: architecture diagrams no longer grow to extreme heights due to conflicting alignments

cypress/integration/rendering/architecture.spec.ts

@@ -171,6 +171,58 @@ describe.skip('architecture diagram', () => {
             `
     );
   });
+
+  it('should render an architecture diagram with a resonable height', () => {
+    imgSnapshotTest(
+      `architecture-beta
+              group federated(cloud)[Federated Environment]
+                  service server1(server)[System] in federated
+                  service edge(server)[Edge Device] in federated
+                  server1:R -- L:edge
+
+              group on_prem(cloud)[Hub]
+                  service firewall(server)[Firewall Device] in on_prem
+                  service server(server)[Server] in on_prem
+                  firewall:R -- L:server
+
+                  service db1(database)[db1] in on_prem
+                  service db2(database)[db2] in on_prem
+                  service db3(database)[db3] in on_prem
+                  service db4(database)[db4] in on_prem
+                  service db5(database)[db5] in on_prem
+                  service db6(database)[db6] in on_prem
+
+                  junction mid in on_prem
+                  server:B -- T:mid
+
+                  junction 1Leftofmid in on_prem
+                  1Leftofmid:R -- L:mid
+                  1Leftofmid:B -- T:db1
+
+                  junction 2Leftofmid in on_prem
+                  2Leftofmid:R -- L:1Leftofmid
+                  2Leftofmid:B -- T:db2
+
+                  junction 3Leftofmid in on_prem
+                  3Leftofmid:R -- L:2Leftofmid
+                  3Leftofmid:B -- T:db3
+
+                  junction 1RightOfMid in on_prem
+                  mid:R -- L:1RightOfMid
+                  1RightOfMid:B -- T:db4
+
+                  junction 2RightOfMid in on_prem
+                  1RightOfMid:R -- L:2RightOfMid
+                  2RightOfMid:B -- T:db5        
+
+                  junction 3RightOfMid in on_prem
+                  2RightOfMid:R -- L:3RightOfMid
+                  3RightOfMid:B -- T:db6         
+
+                  edge:R -- L:firewall
+      `
+    );
+  });
 });
 
 // Skipped as the layout is not deterministic, and causes issues in E2E tests.

packages/mermaid/src/diagrams/architecture/architectureDb.ts

@@ -13,6 +13,7 @@ import {
   setDiagramTitle,
 } from '../common/commonDb.js';
 import type {
+  ArchitectureAlignment,
   ArchitectureDB,
   ArchitectureDirectionPair,
   ArchitectureDirectionPairMap,
@@ -25,6 +26,7 @@ import type {
   ArchitectureState,
 } from './architectureTypes.js';
 import {
+  getArchitectureDirectionAlignment,
   getArchitectureDirectionPair,
   isArchitectureDirection,
   isArchitectureJunction,
@@ -211,19 +213,38 @@ const addEdge = function ({
 const getEdges = (): ArchitectureEdge[] => state.records.edges;
 
 /**
- * Returns the current diagram's adjacency list & spatial map.
+ * Returns the current diagram's adjacency list, spatial map, & group alignments.
  * If they have not been created, run the algorithms to generate them.
  * @returns
  */
 const getDataStructures = () => {
   if (state.records.dataStructures === undefined) {
+    // Tracks how groups are aligned with one another. Generated while creating the adj list
+    const groupAlignments: Record<
+      string,
+      Record<string, Exclude<ArchitectureAlignment, 'bend'>>
+    > = {};
+
     // Create an adjacency list of the diagram to perform BFS on
     // Outer reduce applied on all services
     // Inner reduce applied on the edges for a service
     const adjList = Object.entries(state.records.nodes).reduce<
       Record<string, ArchitectureDirectionPairMap>
     >((prevOuter, [id, service]) => {
       prevOuter[id] = service.edges.reduce<ArchitectureDirectionPairMap>((prevInner, edge) => {
+        // track the direction groups connect to one another
+        const lhsGroupId = getNode(edge.lhsId)?.in;
+        const rhsGroupId = getNode(edge.rhsId)?.in;
+        if (lhsGroupId && rhsGroupId && lhsGroupId !== rhsGroupId) {
+          const alignment = getArchitectureDirectionAlignment(edge.lhsDir, edge.rhsDir);
+          if (alignment !== 'bend') {
+            groupAlignments[lhsGroupId] ??= {};
+            groupAlignments[lhsGroupId][rhsGroupId] = alignment;
+            groupAlignments[rhsGroupId] ??= {};
+            groupAlignments[rhsGroupId][lhsGroupId] = alignment;
+          }
+        }
+
         if (edge.lhsId === id) {
           // source is LHS
           const pair = getArchitectureDirectionPair(edge.lhsDir, edge.rhsDir);
@@ -245,6 +266,7 @@ const getDataStructures = () => {
     // Configuration for the initial pass of BFS
     const firstId = Object.keys(adjList)[0];
     const visited = { [firstId]: 1 };
+    // If a key is present in this object, it has not been visited
     const notVisited = Object.keys(adjList).reduce(
       (prev, id) => (id === firstId ? prev : { ...prev, [id]: 1 }),
       {} as Record<string, number>
@@ -283,6 +305,7 @@ const getDataStructures = () => {
     state.records.dataStructures = {
       adjList,
       spatialMaps,
+      groupAlignments,
     };
   }
   return state.records.dataStructures;

packages/mermaid/src/diagrams/architecture/architectureRenderer.ts

@@ -12,7 +12,9 @@ import { setupGraphViewbox } from '../../setupGraphViewbox.js';
 import { getConfigField } from './architectureDb.js';
 import { architectureIcons } from './architectureIcons.js';
 import type {
+  ArchitectureAlignment,
   ArchitectureDataStructures,
+  ArchitectureGroupAlignments,
   ArchitectureJunction,
   ArchitectureSpatialMap,
   EdgeSingular,
@@ -149,25 +151,91 @@ function addEdges(edges: ArchitectureEdge[], cy: cytoscape.Core) {
   });
 }
 
-function getAlignments(spatialMaps: ArchitectureSpatialMap[]): fcose.FcoseAlignmentConstraint {
+function getAlignments(
+  db: ArchitectureDB,
+  spatialMaps: ArchitectureSpatialMap[],
+  groupAlignments: ArchitectureGroupAlignments
+): fcose.FcoseAlignmentConstraint {
+  /**
+   * Flattens the alignment object so nodes in different groups will be in the same alignment array IFF their groups don't connect in a conflicting alignment
+   *
+   * i.e., two groups which connect horizontally should not have nodes with vertical alignments to one another
+   *
+   * See: #5952
+   *
+   * @param alignmentObj - alignment object with the outer key being the row/col # and the inner key being the group name mapped to the nodes on that axis in the group
+   * @param alignmentDir - alignment direction
+   * @returns flattened alignment object with an arbitrary key mapping to nodes in the same row/col
+   */
+  const flattenAlignments = (
+    alignmentObj: Record<number, Record<string, string[]>>,
+    alignmentDir: ArchitectureAlignment
+  ): Record<string, string[]> => {
+    return Object.entries(alignmentObj).reduce(
+      (prev, [dir, alignments]) => {
+        // prev is the mapping of x/y coordinate to an array of the nodes in that row/column
+        let cnt = 0;
+        const arr = Object.entries(alignments); // [group name, array of nodes within the group on axis dir]
+        if (arr.length === 1) {
+          // If only one group exists in the row/column, we don't need to do anything else
+          prev[dir] = arr[0][1];
+          return prev;
+        }
+        for (let i = 0; i < arr.length - 1; i++) {
+          for (let j = i + 1; j < arr.length; j++) {
+            const [aGroupId, aNodeIds] = arr[i];
+            const [bGroupId, bNodeIds] = arr[j];
+            const alignment = groupAlignments[aGroupId]?.[bGroupId]; // Get how the two groups are intended to align (undefined if they aren't)
+
+            if (alignment === alignmentDir) {
+              // If the intended alignment between the two groups is the same as the alignment we are parsing
+              prev[dir] ??= [];
+              prev[dir] = [...prev[dir], ...aNodeIds, ...bNodeIds]; // add the node ids of both groups to the axis array in prev
+            } else if (aGroupId === 'default' || bGroupId === 'default') {
+              // If either of the groups are in the default space (not in a group), use the same behavior as above
+              prev[dir] ??= [];
+              prev[dir] = [...prev[dir], ...aNodeIds, ...bNodeIds];
+            } else {
+              // Otherwise, the nodes in the two groups are not intended to align
+              const keyA = `${dir}-${cnt++}`;
+              prev[keyA] = aNodeIds;
+              const keyB = `${dir}-${cnt++}`;
+              prev[keyB] = bNodeIds;
+            }
+          }
+        }
+
+        return prev;
+      },
+      {} as Record<string, string[]>
+    );
+  };
+
   const alignments = spatialMaps.map((spatialMap) => {
-    const horizontalAlignments: Record<number, string[]> = {};
-    const verticalAlignments: Record<number, string[]> = {};
+    const horizontalAlignments: Record<number, Record<string, string[]>> = {};
+    const verticalAlignments: Record<number, Record<string, string[]>> = {};
+
     // Group service ids in an object with their x and y coordinate as the key
     Object.entries(spatialMap).forEach(([id, [x, y]]) => {
-      if (!horizontalAlignments[y]) {
-        horizontalAlignments[y] = [];
-      }
-      if (!verticalAlignments[x]) {
-        verticalAlignments[x] = [];
-      }
-      horizontalAlignments[y].push(id);
-      verticalAlignments[x].push(id);
+      const nodeGroup = db.getNode(id)?.in ?? 'default';
+
+      horizontalAlignments[y] ??= {};
+      horizontalAlignments[y][nodeGroup] ??= [];
+      horizontalAlignments[y][nodeGroup].push(id);
+
+      verticalAlignments[x] ??= {};
+      verticalAlignments[x][nodeGroup] ??= [];
+      verticalAlignments[x][nodeGroup].push(id);
     });
+
     // Merge the values of each object into a list if the inner list has at least 2 elements
     return {
-      horiz: Object.values(horizontalAlignments).filter((arr) => arr.length > 1),
-      vert: Object.values(verticalAlignments).filter((arr) => arr.length > 1),
+      horiz: Object.values(flattenAlignments(horizontalAlignments, 'horizontal')).filter(
+        (arr) => arr.length > 1
+      ),
+      vert: Object.values(flattenAlignments(verticalAlignments, 'vertical')).filter(
+        (arr) => arr.length > 1
+      ),
     };
   });
 
@@ -244,7 +312,8 @@ function layoutArchitecture(
   junctions: ArchitectureJunction[],
   groups: ArchitectureGroup[],
   edges: ArchitectureEdge[],
-  { spatialMaps }: ArchitectureDataStructures
+  db: ArchitectureDB,
+  { spatialMaps, groupAlignments }: ArchitectureDataStructures
 ): Promise<cytoscape.Core> {
   return new Promise((resolve) => {
     const renderEl = select('body').append('div').attr('id', 'cy').attr('style', 'display:none');
@@ -318,9 +387,8 @@ function layoutArchitecture(
     addServices(services, cy);
     addJunctions(junctions, cy);
     addEdges(edges, cy);
-
     // Use the spatial map to create alignment arrays for fcose
-    const alignmentConstraint = getAlignments(spatialMaps);
+    const alignmentConstraint = getAlignments(db, spatialMaps, groupAlignments);
 
     // Create the relative constraints for fcose by using an inverse of the spatial map and performing BFS on it
     const relativePlacementConstraint = getRelativeConstraints(spatialMaps);
@@ -454,7 +522,7 @@ export const draw: DrawDefinition = async (text, id, _version, diagObj: Diagram)
   await drawServices(db, servicesElem, services);
   drawJunctions(db, servicesElem, junctions);
 
-  const cy = await layoutArchitecture(services, junctions, groups, edges, ds);
+  const cy = await layoutArchitecture(services, junctions, groups, edges, db, ds);
 
   await drawEdges(edgesElem, cy);
   await drawGroups(groupElem, cy);

packages/mermaid/src/diagrams/architecture/architectureTypes.ts

@@ -7,6 +7,8 @@ import type cytoscape from 'cytoscape';
 |       Architecture Diagram Types        |
 \*=======================================*/
 
+export type ArchitectureAlignment = 'vertical' | 'horizontal' | 'bend';
+
 export type ArchitectureDirection = 'L' | 'R' | 'T' | 'B';
 export type ArchitectureDirectionX = Extract<ArchitectureDirection, 'L' | 'R'>;
 export type ArchitectureDirectionY = Extract<ArchitectureDirection, 'T' | 'B'>;
@@ -170,6 +172,18 @@ export const getArchitectureDirectionXYFactors = function (
   }
 };
 
+export const getArchitectureDirectionAlignment = function (
+  a: ArchitectureDirection,
+  b: ArchitectureDirection
+): ArchitectureAlignment {
+  if (isArchitectureDirectionXY(a, b)) {
+    return 'bend';
+  } else if (isArchitectureDirectionX(a)) {
+    return 'horizontal';
+  }
+  return 'vertical';
+};
+
 export interface ArchitectureStyleOptions {
   archEdgeColor: string;
   archEdgeArrowColor: string;
@@ -249,9 +263,27 @@ export interface ArchitectureDB extends DiagramDB {
 
 export type ArchitectureAdjacencyList = Record<string, ArchitectureDirectionPairMap>;
 export type ArchitectureSpatialMap = Record<string, number[]>;
+
+/**
+ * Maps the direction that groups connect from.
+ *
+ * **Outer key**: ID of group A
+ *
+ * **Inner key**: ID of group B
+ *
+ * **Value**: 'vertical' or 'horizontal'
+ *
+ * Note: tmp[groupA][groupB] == tmp[groupB][groupA]
+ */
+export type ArchitectureGroupAlignments = Record<
+  string,
+  Record<string, Exclude<ArchitectureAlignment, 'bend'>>
+>;
+
 export interface ArchitectureDataStructures {
   adjList: ArchitectureAdjacencyList;
   spatialMaps: ArchitectureSpatialMap[];
+  groupAlignments: ArchitectureGroupAlignments;
 }
 
 export interface ArchitectureState extends Record<string, unknown> {