feat: create merger and factory for the Caip25Permission

packages/multichain/src/caip25Permission.test.ts

@@ -37,6 +37,7 @@ describe('caip25EndowmentBuilder', () => {
         endowmentGetter: expect.any(Function),
         allowedCaveats: [Caip25CaveatType],
         validator: expect.any(Function),
+        merger: expect.any(Function),
       });
 
       expect(specification.endowmentGetter()).toBeNull();
@@ -470,6 +471,213 @@ describe('caip25EndowmentBuilder', () => {
       );
     });
   });
+
+  describe('permission merger', () => {
+    const initLeftValue: Caip25CaveatValue = {
+      optionalScopes: {
+        'eip155:1': {
+          accounts: ['eip155:1:0xdead'],
+        },
+      },
+      requiredScopes: {},
+      isMultichainOrigin: false,
+    };
+
+    // @ts-expect-error TODO: update type in caip25Permission
+    const { merger } = caip25EndowmentBuilder.specificationBuilder({
+      methodHooks: {
+        findNetworkClientIdByChainId: jest.fn(),
+        listAccounts: jest.fn(),
+      },
+    });
+
+    it.each<{
+      rightValue: Caip25CaveatValue;
+      expectedMergedValue: Caip25CaveatValue;
+      expectedDiff: Caip25CaveatValue;
+    }>([
+      {
+        rightValue: {
+          optionalScopes: {
+            'eip155:1': {
+              accounts: ['eip155:1:0xbeef'],
+            },
+          },
+          requiredScopes: {},
+          isMultichainOrigin: false,
+        },
+        expectedMergedValue: {
+          optionalScopes: {
+            'eip155:1': { accounts: ['eip155:1:0xdead', 'eip155:1:0xbeef'] },
+          },
+          requiredScopes: {},
+          isMultichainOrigin: false,
+        },
+        expectedDiff: {
+          optionalScopes: {
+            'eip155:1': {
+              accounts: ['eip155:1:0xbeef'],
+            },
+          },
+          isMultichainOrigin: false,
+          requiredScopes: {},
+        },
+      },
+      {
+        rightValue: {
+          optionalScopes: {
+            'eip155:10': {
+              accounts: [],
+            },
+          },
+          requiredScopes: {},
+          isMultichainOrigin: false,
+        },
+        expectedMergedValue: {
+          optionalScopes: {
+            'eip155:1': { accounts: ['eip155:1:0xdead'] },
+            'eip155:10': {
+              accounts: [],
+            },
+          },
+          requiredScopes: {},
+          isMultichainOrigin: false,
+        },
+        expectedDiff: {
+          optionalScopes: {
+            'eip155:10': {
+              accounts: [],
+            },
+          },
+          isMultichainOrigin: false,
+          requiredScopes: {},
+        },
+      },
+      {
+        rightValue: {
+          optionalScopes: {
+            'eip155:10': {
+              accounts: ['eip155:10:0xbeef'],
+            },
+          },
+          requiredScopes: {},
+          isMultichainOrigin: false,
+        },
+        expectedMergedValue: {
+          optionalScopes: {
+            'eip155:1': { accounts: ['eip155:1:0xdead'] },
+            'eip155:10': { accounts: ['eip155:10:0xbeef'] },
+          },
+          requiredScopes: {},
+          isMultichainOrigin: false,
+        },
+        expectedDiff: {
+          optionalScopes: {
+            'eip155:10': {
+              accounts: ['eip155:10:0xbeef'],
+            },
+          },
+          isMultichainOrigin: false,
+          requiredScopes: {},
+        },
+      },
+      {
+        rightValue: {
+          optionalScopes: {
+            'eip155:1': {
+              accounts: ['eip155:1:0xdead', 'eip155:1:0xbeef'],
+            },
+            'eip155:10': {
+              accounts: ['eip155:10:0xdead', 'eip155:10:0xbeef'],
+            },
+          },
+          requiredScopes: {},
+          isMultichainOrigin: false,
+        },
+        expectedMergedValue: {
+          optionalScopes: {
+            'eip155:1': { accounts: ['eip155:1:0xdead', 'eip155:1:0xbeef'] },
+            'eip155:10': { accounts: ['eip155:10:0xdead', 'eip155:10:0xbeef'] },
+          },
+          requiredScopes: {},
+          isMultichainOrigin: false,
+        },
+        expectedDiff: {
+          optionalScopes: {
+            'eip155:1': {
+              accounts: ['eip155:1:0xbeef'],
+            },
+            'eip155:10': {
+              accounts: ['eip155:10:0xdead', 'eip155:10:0xbeef'],
+            },
+          },
+          isMultichainOrigin: false,
+          requiredScopes: {},
+        },
+      },
+      {
+        rightValue: {
+          optionalScopes: {
+            'eip155:1': {
+              accounts: ['eip155:1:0xdead', 'eip155:1:0xbadd'],
+            },
+            'eip155:10': {
+              accounts: ['eip155:10:0xbeef', 'eip155:10:0xbadd'],
+            },
+            'eip155:426161': {
+              accounts: [
+                'eip155:426161:0xdead',
+                'eip155:426161:0xbeef',
+                'eip155:426161:0xbadd',
+              ],
+            },
+          },
+          requiredScopes: {},
+          isMultichainOrigin: false,
+        },
+        expectedMergedValue: {
+          optionalScopes: {
+            'eip155:1': { accounts: ['eip155:1:0xdead', 'eip155:1:0xbadd'] },
+            'eip155:10': { accounts: ['eip155:10:0xbeef', 'eip155:10:0xbadd'] },
+            'eip155:426161': {
+              accounts: [
+                'eip155:426161:0xdead',
+                'eip155:426161:0xbeef',
+                'eip155:426161:0xbadd',
+              ],
+            },
+          },
+          requiredScopes: {},
+          isMultichainOrigin: false,
+        },
+        expectedDiff: {
+          optionalScopes: {
+            'eip155:1': { accounts: ['eip155:1:0xbadd'] },
+            'eip155:10': { accounts: ['eip155:10:0xbeef', 'eip155:10:0xbadd'] },
+            'eip155:426161': {
+              accounts: [
+                'eip155:426161:0xdead',
+                'eip155:426161:0xbeef',
+                'eip155:426161:0xbadd',
+              ],
+            },
+          },
+          isMultichainOrigin: false,
+          requiredScopes: {},
+        },
+      },
+    ])(
+      'should return the expected merged value $expectedMergedValue and expected diff $expectedDiff',
+      async ({ rightValue, expectedMergedValue, expectedDiff }) => {
+        const [newValue, diff] = merger(initLeftValue, rightValue);
+
+        expect(newValue).toStrictEqual(
+          expect.objectContaining(expectedMergedValue),
+        );
+        expect(diff).toStrictEqual(expect.objectContaining(expectedDiff));
+      },
+    );
+  });
 });
 
 describe('caip25CaveatBuilder', () => {

packages/multichain/src/caip25Permission.ts

@@ -4,12 +4,14 @@ import type {
   EndowmentGetterParams,
   ValidPermissionSpecification,
   PermissionValidatorConstraint,
+  PermissionFactory,
   PermissionConstraint,
   EndowmentCaveatSpecificationConstraint,
 } from '@metamask/permission-controller';
 import {
   CaveatMutatorOperation,
   PermissionType,
+  constructPermission,
 } from '@metamask/permission-controller';
 import type { CaipAccountId, Json } from '@metamask/utils';
 import {
@@ -24,8 +26,10 @@ import { cloneDeep, isEqual } from 'lodash';
 import { getEthAccounts } from './adapters/caip-permission-adapter-eth-accounts';
 import { assertIsInternalScopesObject } from './scope/assert';
 import { isSupportedScopeString } from './scope/supported';
+import { getUniqueArrayItems } from './scope/transform';
 import {
   parseScopeString,
+  type InternalScopeString,
   type ExternalScopeString,
   type InternalScopeObject,
   type InternalScopesObject,
@@ -158,6 +162,7 @@ type Caip25EndowmentSpecification = ValidPermissionSpecification<{
   targetName: typeof Caip25EndowmentPermissionName;
   endowmentGetter: (_options?: EndowmentGetterParams) => null;
   validator: PermissionValidatorConstraint;
+  factory: PermissionFactory<PermissionConstraint, Record<string, unknown>>;
   allowedCaveats: Readonly<NonEmptyArray<string>> | null;
 }>;
 
@@ -187,6 +192,39 @@ const specificationBuilder: PermissionSpecificationBuilder<
         );
       }
     },
+    factory: (permissionOptions, _requestData) => {
+      return constructPermission({
+        ...permissionOptions,
+      });
+    },
+    // TODO: Update Caip25EndowmentSpecification type with proper merger type
+    merger: (leftValue: Caip25CaveatValue, rightValue: Caip25CaveatValue) => {
+      const partiallyMergedValue = mergeScopesForCaip25CaveatValue(
+        leftValue,
+        rightValue,
+        'requiredScopes',
+      );
+
+      const mergedValue = mergeScopesForCaip25CaveatValue(
+        partiallyMergedValue,
+        rightValue,
+        'optionalScopes',
+      );
+
+      const partialDiff = diffScopesForCaip25CaveatValue(
+        leftValue,
+        mergedValue,
+        'requiredScopes',
+      );
+
+      const diff = diffScopesForCaip25CaveatValue(
+        partialDiff,
+        mergedValue,
+        'optionalScopes',
+      );
+
+      return [mergedValue, diff];
+    },
   };
 };
 
@@ -347,3 +385,86 @@ function removeScope(
     operation: CaveatMutatorOperation.RevokePermission,
   };
 }
+
+/**
+ *
+ * @param leftValue - The existing CAIP-25 permission caveat value.
+ * @param rightValue - The incoming CAIP-25 permission caveat value.
+ * @param scopeToMerge - The required or optional scopes from the [CAIP-25](https://github.com/ChainAgnostic/CAIPs/blob/main/CAIPs/caip-25.md) request.
+ * @returns The combined CAIP-25 permission caveat value.
+ */
+function mergeScopesForCaip25CaveatValue(
+  leftValue: Caip25CaveatValue,
+  rightValue: Caip25CaveatValue,
+  scopeToMerge: keyof Pick<
+    Caip25CaveatValue,
+    'optionalScopes' | 'requiredScopes'
+  >,
+): Caip25CaveatValue {
+  const newValue = cloneDeep(leftValue);
+
+  Object.entries(rightValue[scopeToMerge]).forEach(
+    ([scopeString, rightScopeObject]) => {
+      const internalScopeString = scopeString as InternalScopeString;
+      const leftRequiredScopeObject =
+        newValue[scopeToMerge][internalScopeString];
+      if (!leftRequiredScopeObject) {
+        newValue[scopeToMerge][internalScopeString] = rightScopeObject;
+      } else {
+        newValue[scopeToMerge][internalScopeString] = {
+          accounts: getUniqueArrayItems([
+            ...leftRequiredScopeObject.accounts,
+            ...rightScopeObject.accounts,
+          ]),
+        };
+      }
+    },
+  );
+
+  return newValue;
+}
+
+/**
+ *
+ * @param originalValue - The existing CAIP-25 permission caveat value.
+ * @param mergedValue - The result from merging existing and incoming CAIP-25 permission caveat values.
+ * @param scopeToMerge - The required or optional scopes from the [CAIP-25](https://github.com/ChainAgnostic/CAIPs/blob/main/CAIPs/caip-25.md) request.
+ * @returns The differential between original and merged CAIP-25 permission caveat values.
+ */
+function diffScopesForCaip25CaveatValue(
+  originalValue: Caip25CaveatValue,
+  mergedValue: Caip25CaveatValue,
+  scopeToMerge: keyof Pick<
+    Caip25CaveatValue,
+    'optionalScopes' | 'requiredScopes'
+  >,
+): Caip25CaveatValue {
+  const diff = cloneDeep(originalValue);
+
+  for (const [scopeString, mergedScopeObject] of Object.entries(
+    mergedValue[scopeToMerge],
+  )) {
+    const internalScopeString = scopeString as InternalScopeString;
+    const originalScopeObject = diff[scopeToMerge][internalScopeString];
+
+    if (originalScopeObject) {
+      const newAccounts = mergedScopeObject.accounts.filter(
+        (account) =>
+          !diff[scopeToMerge][
+            scopeString as InternalScopeString
+          ]?.accounts.includes(account),
+      );
+      if (newAccounts.length > 0) {
+        diff[scopeToMerge][internalScopeString] = {
+          accounts: newAccounts,
+        };
+        continue;
+      }
+      delete diff[scopeToMerge][internalScopeString];
+    } else {
+      diff[scopeToMerge][internalScopeString] = mergedScopeObject;
+    }
+  }
+
+  return diff;
+}