From cb2aee37f7ae56736f453aa794d75953bca6f9bb Mon Sep 17 00:00:00 2001
From: Emmanuel Ogbizi-Ugbe <iamogbz+github@gmail.com>
Date: Sat, 12 Sep 2020 12:53:57 -0400
Subject: [PATCH] chore: add duck selector namespacing

---
 src/components/Provider.tsx   |  2 +-
 src/createRootDuck.ts         |  6 +++++-
 src/utils/combineSelectors.ts | 19 +++++++++++++++++++
 3 files changed, 25 insertions(+), 2 deletions(-)
 create mode 100644 src/utils/combineSelectors.ts

diff --git a/src/components/Provider.tsx b/src/components/Provider.tsx
index cdce9342..1c4ead5a 100644
--- a/src/components/Provider.tsx
+++ b/src/components/Provider.tsx
@@ -1,7 +1,7 @@
 import * as React from "react";
-import { useGetter } from "src/hooks/useGetter";
 import { ActionTypes } from "src/utils/actionTypes";
 import { createAction } from "src/createAction";
+import { useGetter } from "src/hooks/useGetter";
 
 export function Provider<S, T extends string, P>({
     children,
diff --git a/src/createRootDuck.ts b/src/createRootDuck.ts
index 59c97ca1..41fac2ec 100644
--- a/src/createRootDuck.ts
+++ b/src/createRootDuck.ts
@@ -1,4 +1,5 @@
 import { combineReducers } from "./utils/combineReducers";
+import { combineSelectors } from "./utils/combineSelectors";
 
 export function createRootDuck<
     D extends Duck<S, N, T, P, R, Q, U>[],
@@ -22,7 +23,10 @@ export function createRootDuck<
         const duckName = duck.name;
         rootDuck.actions[duckName] = duck.actions;
         rootDuck.initialState[duckName] = duck.initialState;
-        rootDuck.selectors[duckName] = duck.selectors;
+        rootDuck.selectors[duckName] = combineSelectors(
+            duckName,
+            duck.selectors,
+        );
         reducerMapping[duckName] = duck.reducer;
     }
     rootDuck.reducer = combineReducers(rootDuck.initialState, reducerMapping);
diff --git a/src/utils/combineSelectors.ts b/src/utils/combineSelectors.ts
new file mode 100644
index 00000000..69d22c5f
--- /dev/null
+++ b/src/utils/combineSelectors.ts
@@ -0,0 +1,19 @@
+export function combineSelectors<
+    S,
+    T extends string,
+    P,
+    R,
+    N extends string,
+    Q extends string
+>(
+    duckName: N,
+    selectors?: SelectorMapping<S, R, T, P, Q>,
+): SelectorMapping<S, R, T, P, Q> | undefined {
+    if (!selectors) return;
+    const duckSelectors = {} as SelectorMapping<S, R, T, P, Q>;
+    for (const s of Object.keys(selectors) as Q[]) {
+        duckSelectors[s] = (state: S): R =>
+            selectors[s](((state as unknown) as Record<string, S>)[duckName]);
+    }
+    return duckSelectors;
+}