From d296658f649f96de4c560b126f4954ba49394869 Mon Sep 17 00:00:00 2001
From: Madeorsk <m@deor.sk>
Date: Sun, 29 Jun 2025 15:59:52 +0200
Subject: [PATCH] Add model builder.

---
 src/model/builder.ts  | 77 +++++++++++++++++++++++++++++++++++++++++++
 src/model/index.ts    |  4 +--
 tests/builder.test.ts | 35 ++++++++++++++++++++
 3 files changed, 114 insertions(+), 2 deletions(-)
 create mode 100644 src/model/builder.ts
 create mode 100644 tests/builder.test.ts

diff --git a/src/model/builder.ts b/src/model/builder.ts
new file mode 100644
index 0000000..6dd5447
--- /dev/null
+++ b/src/model/builder.ts
@@ -0,0 +1,77 @@
+import {
+	defineModel,
+	IdentifierDefinition,
+	ModelDefinition,
+	ModelShape,
+} from "./model";
+import {ConstructorOf} from "../utils";
+import {Definition} from "./property-definition";
+
+/**
+ * Model definition builder.
+ */
+export class ModelBuilder<
+	T extends object,
+	Shape extends ModelShape<T>,
+	Identifier extends IdentifierDefinition<T, Shape>,
+> {
+	/**
+	 * The built model definition.
+	 */
+	definition: ModelDefinition<T, Shape, Identifier>;
+
+	/**
+	 * Define a new property.
+	 * @param name The new property name.
+	 * @param definition The new property definition.
+	 */
+	property<
+		SerializedType,
+		PropertyName extends Exclude<keyof T, keyof Shape>,
+		PropertyDefinition extends Definition<SerializedType, T[PropertyName]>,
+	>(name: PropertyName, definition: PropertyDefinition) {
+		(this.definition.properties[name] as Definition<unknown, T[typeof name]>) =
+			definition;
+
+		return this as unknown as ModelBuilder<
+			T,
+			Shape & {[k in PropertyName]: PropertyDefinition},
+			Identifier
+		>;
+	}
+
+	/**
+	 * Set the model identifier.
+	 * @param identifier The new model identifier.
+	 */
+	identifier<NewIdentifier extends IdentifierDefinition<T, Shape>>(
+		identifier: NewIdentifier,
+	) {
+		(this.definition.identifier as unknown) = identifier;
+		return this as unknown as ModelBuilder<T, Shape, NewIdentifier>;
+	}
+
+	/**
+	 * Define a model using the current model definition.
+	 */
+	define() {
+		return defineModel(this.definition);
+	}
+}
+
+/**
+ * Initialize a model builder for the provided class.
+ * @param Class The class for which to build a model.
+ */
+export function newModel<
+	T extends object,
+	Shape extends ModelShape<T> = object,
+	Identifier extends IdentifierDefinition<T, Shape> = never,
+>(Class: ConstructorOf<T>): ModelBuilder<T, Shape, Identifier> {
+	const builder = new ModelBuilder<T, Shape, Identifier>();
+	builder.definition = {
+		Class,
+		properties: {} as Shape,
+	};
+	return builder;
+}
diff --git a/src/model/index.ts b/src/model/index.ts
index a91c018..986894f 100644
--- a/src/model/index.ts
+++ b/src/model/index.ts
@@ -1,8 +1,8 @@
-import * as property from "./properties";
-export {property};
+export * as property from "./properties";
 
 export * from "./model";
 export {Definition} from "./property-definition";
+export {newModel, ModelBuilder} from "./builder";
 
 export {ArrayType} from "./types/array";
 export {BooleanType} from "./types/boolean";
diff --git a/tests/builder.test.ts b/tests/builder.test.ts
new file mode 100644
index 0000000..b3df0d3
--- /dev/null
+++ b/tests/builder.test.ts
@@ -0,0 +1,35 @@
+import {describe, expect, test} from "vitest";
+
+import {defineModel, newModel, s} from "../src/library";
+
+class Testest {
+	foo: string;
+	bar: number;
+	baz: boolean;
+}
+
+describe("model builder", () => {
+	const modelBuilder = newModel(Testest)
+		.property("foo", s.property.string())
+		.property("bar", s.property.decimal())
+		.property("baz", s.property.boolean())
+		.identifier("foo");
+
+	test("build model definition", () => {
+		expect(modelBuilder.definition).toStrictEqual({
+			Class: Testest,
+			identifier: "foo",
+			properties: {
+				foo: s.property.string(),
+				bar: s.property.decimal(),
+				baz: s.property.boolean(),
+			},
+		});
+	});
+
+	test("build a model", () => {
+		expect(modelBuilder.define()).toStrictEqual(
+			defineModel(modelBuilder.definition),
+		);
+	});
+});