Advanced typings for a strongly typed stores spec

src/public/types/strongly-typed-schema.d.ts

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+import { Dexie, TableProp } from './dexie';
+import { IndexableType, IndexableTypeArray } from './indexable-type';
+import { Table } from './table';
+
+// Indexable arrays on root level only
+type ArrayProps<T> = {
+  [K in keyof T]: K extends string
+    ? T[K] extends IndexableTypeArray
+      ? K
+      : never
+    : never;
+}[keyof T];
+
+type NumberProps<T> = {
+  [K in keyof T]: K extends string ? (T[K] extends number ? K : never) : never;
+}[keyof T];
+
+type StringProps<T> = {
+  [K in keyof T]: K extends string ? (T[K] extends string ? K : never) : never;
+}[keyof T];
+
+// Nested indexable arrays (configurable max depth)
+type ArrayKeyPaths<
+  T,
+  MAXDEPTH = 'III',
+  CURRDEPTH extends string = ''
+> = CURRDEPTH extends MAXDEPTH
+  ? ArrayProps<T>
+  :
+      | ArrayKeyPaths<T, MAXDEPTH, `${CURRDEPTH}I`>
+      | {
+          [K in keyof T]: K extends string
+            ? T[K] extends object
+              ? `${K}.${keyof T[K] extends string
+                  ? ArrayKeyPaths<T[K], MAXDEPTH, `${CURRDEPTH}I`>
+                  : never}`
+              : never
+            : never;
+        }[keyof T];
+
+// Indexable root properties
+type IndexableProps<T> = {
+  [K in keyof T]: K extends string
+    ? T[K] extends IndexableType
+      ? K
+      : never
+    : never;
+}[keyof T];
+
+// Keypaths of indexable properties and nested properteis (configurable MAXDEPTH)
+type IndexableKeyPaths<
+  T,
+  MAXDEPTH = 'III',
+  CURRDEPTH extends string = ''
+> = CURRDEPTH extends MAXDEPTH
+  ? IndexableProps<T>
+  :
+      | IndexableKeyPaths<T, MAXDEPTH, `${CURRDEPTH}I`>
+      | {
+          [K in keyof T]: K extends string
+            ? T[K] extends object
+              ? `${K}.${keyof T[K] extends string
+                  ? IndexableKeyPaths<T[K], MAXDEPTH, `${CURRDEPTH}I`>
+                  : never}`
+              : never
+            : never;
+        }[keyof T];
+
+// Compound index syntax
+type Combo<
+  T,
+  MAXDEPTH = 'III',
+  CURRDEPTH extends string = ''
+> = CURRDEPTH extends MAXDEPTH
+  ? never
+  : {
+      [P in keyof T]: P extends string
+        ? keyof Omit<T, P> extends never
+          ? P
+          : P | `${P}+${Combo<Omit<T, P>, MAXDEPTH, `${CURRDEPTH}I`>}`
+        : never;
+    }[keyof T];
+
+type IndexablePathObj<T> = {
+  [P in IndexableKeyPaths<T>]: true;
+};
+
+type SingleCombound<T> = {
+  [P in IndexableKeyPaths<T>]: `[${P}]`;
+}[IndexableKeyPaths<T>];
+
+// -------
+
+// Main generic type for Dexie index syntax
+type DexieIndexSyntax<T> =
+  | `&${IndexableKeyPaths<T>}`
+  | IndexableKeyPaths<T>
+  | `*${ArrayKeyPaths<T>}` // Wildcard for array keys
+  | Exclude<`[${Combo<IndexablePathObj<T>>}]`, SingleCombound<T>> // Combined non-array keys
+  | `&${Exclude<`[${Combo<Pick<T, IndexableProps<T>>>}]`, SingleCombound<T>>}`; // Combined non-array keys
+
+type DexiePrimaryKeySyntax<T> =
+  | ''
+  | `++${NumberProps<T>}`
+  | `@${StringProps<T>}`
+  | `&${IndexableKeyPaths<T>}`
+  | IndexableKeyPaths<T>
+  | Exclude<`[${Combo<IndexablePathObj<T>>}]`, SingleCombound<T>> // Combined non-array keys
+  | `&${Exclude<`[${Combo<IndexablePathObj<T>>}]`, SingleCombound<T>>}`;
+
+type LooseStoresSpec = { [tableName: string]: string | null | string[] };
+
+type StoresSpec<DX extends Dexie> = TableProp<DX> extends never
+  ? LooseStoresSpec
+  : {
+      [TN in TableProp<DX>]?: DX[TN] extends Table<infer T, any, any>
+        ? string | null | [DexiePrimaryKeySyntax<T>, ...DexieIndexSyntax<T>[]]
+        : never;
+    } & LooseStoresSpec;
+
+// -------
+
+/*
+type ClazzDecorator<T> = (target: new () => T) => new () => T;
+declare function index<T>(
+  ...indexSpec: DexieIndexSyntax<T>[]
+): ClazzDecorator<T>;
+
+@index(
+  "[name+id+tags]",
+  "[allanlarson+apansson+name]",
+  "ydoc.meta",
+  "fredriksod",
+  "&[name+bosse+allanlarson]",
+  "[allanlarson+apansson+blob.size]",
+)
+
+// Test example with the Friend interface
+interface Friend {
+  name: string;
+  age: number;
+  tags: string[];
+}
+
+// Example usage
+const index1: DexieIndexSyntax<Friend> = "name"; // valid
+const index2: DexieIndexSyntax<Friend> = "age"; // valid
+const index3: DexieIndexSyntax<Friend> = "*tags"; // valid (array field)
+const index4: DexieIndexSyntax<Friend> = "&[name+age]"; // valid (combined index)
+const index5: DexieIndexSyntax<Friend> = "[age+name]"; // valid (combined index)
+
+// Invalid cases
+// const invalidIndex1: DexieIndexSyntax<Friend> = '*name';        // error (* not allowed for non-array fields)
+// const invalidIndex2: DexieIndexSyntax<Friend> = '[name+*tags]'; // error (composite index cannot include *tags)
+// const invalidIndex3: DexieIndexSyntax<Friend> = '[*tags+age]';  // error (composite index cannot include *tags)
+
+// -------
+
+function stores<DX extends Dexie>(storesSpec: StoresSpec<DX>): void {
+  console.log(storesSpec);
+}
+
+const db = new Dexie("MyDatabase") as Dexie & {
+  friends: EntityTable<Friend, "name">;
+  todoItems: EntityTable<TodoItem, "id">;
+};
+
+stores<typeof db>({
+  //friends: ["&age"],
+  todoItems: [
+    "&[allanlarson+apansson+blob.size]",
+    "[allanlarson+apansson+bosse]",
+    "[allanlarson+bosse+name]",
+  ],
+});
+*/