feat: lots more improvements

Signed-off-by: Sebastian Krupinski <krupinski01@gmail.com>

src/models/mutation-proxy.ts

@@ -0,0 +1,61 @@
+import { clonePlain } from './clone-plain';
+
+export class MutationProxy<T extends object> {
+
+    private readonly getOriginal: () => T;
+    private readonly getMutated: () => Partial<T>;
+
+    constructor(
+        getOriginal: () => T,
+        getMutated: () => Partial<T>,
+    ) {
+        this.getOriginal = getOriginal;
+        this.getMutated = getMutated;
+    }
+
+    create(): T {
+        return new Proxy({} as T, {
+            get: (_target, prop: string | symbol) => {
+                if (typeof prop !== 'string') {
+                    return undefined;
+                }
+
+                const key = prop as keyof T;
+                const mutated = this.getMutated();
+                const original = this.getOriginal();
+                return key in mutated ? mutated[key] : original[key];
+            },
+            set: (_target, prop: string | symbol, value: unknown) => {
+                if (typeof prop === 'string') {
+                    const key = prop as keyof T;
+                    (this.getMutated() as Record<keyof T, unknown>)[key] = clonePlain(value);
+                }
+
+                return true;
+            },
+            has: (_target, prop: string | symbol) => {
+                if (typeof prop !== 'string') {
+                    return false;
+                }
+
+                const mutated = this.getMutated();
+                const original = this.getOriginal();
+                return prop in mutated || prop in original;
+            },
+            ownKeys: () => {
+                const mutated = this.getMutated();
+                const original = this.getOriginal();
+
+                return Array.from(new Set([
+                    ...Reflect.ownKeys(original),
+                    ...Reflect.ownKeys(mutated),
+                ]));
+            },
+            getOwnPropertyDescriptor: () => ({
+                enumerable: true,
+                configurable: true,
+            }),
+        });
+    }
+
+}