feat(generation): add support for TypeScript types generation

.github/CODEOWNERS

@@ -19,6 +19,7 @@
 /packages/discovery/                                 @brendt @aidan-casey
 /packages/event-bus/                                 @brendt @aidan-casey
 /packages/generation/                                @brendt
+/packages/generation/src/TypeScript                  @innocenzi
 /packages/http/                                      @brendt @aidan-casey
 /packages/http-client/                               @aidan-casey
 /packages/icon/                                      @innocenzi

docs/2-features/18-typescript.md

@@ -0,0 +1,107 @@
+---
+title: TypeScript
+description: "Tempest provides the ability to generate TypeScript interfaces from PHP classes to ease integration with TypeScript-based front-ends."
+keywords: ["Experimental", "Generation"]
+experimental: true
+---
+
+## Overview
+
+When building applications with TypeScript-based front-ends like [Inertia](https://inertiajs.com), keeping your client-side types synchronized with your PHP backend can be tedious and error-prone.
+
+Tempest solves this by automatically generating TypeScript definitions from your PHP value objects, data transfer objects, and enums.
+
+You can choose to output a single `.d.ts` declaration file or a directory tree of individual `.ts` modules, depending on your project's needs.
+
+## Generating types
+
+Mark any PHP class with the {b`#[Tempest\Generation\TypeScript\AsType]`} attribute to instruct Tempest that a matching TypeScript interface must be generated based on its public properties.
+
+By default, all application enums are also included automatically without needing an attribute. Generate your TypeScript definitions by running `generate:typescript-types`:
+
+```sh ">_ generate:typescript-types"
+✓ // Generated 14 type definitions across 2 namespaces.
+```
+
+This command scans your marked classes, generates the corresponding TypeScript definitions, and writes them to your configured output location.
+
+## Customizing type resolution
+
+Tempest provides several built-in type resolvers for common types: strings, numbers, dates, enums and class references.
+
+You can add your own resolver by providing implementations of {b`Tempest\Generation\TypeScript\TypeResolvers\TypeResolver`}. This interface requires a `canResolve()` method to determine if the resolver can handle a given type, and a `resolve()` method to perform the actual resolution.
+
+The following is the actual implementation of the built-in resolver that handles scalar types:
+
+```php ScalarTypeResolver.php
+#[Priority(Priority::LOW)]
+final class ScalarTypeResolver implements TypeResolver
+{
+    public function canResolve(TypeReflector $type): bool
+    {
+        return $type->isBuiltIn()
+            && in_array($type->getName(), ['string', 'int', 'float', 'bool'], strict: true);
+    }
+
+    public function resolve(TypeReflector $type, TypeScriptGenerator $generator): ResolvedType
+    {
+        return new ResolvedType(match ($type->getName()) {
+            'string' => 'string',
+            'int', 'float' => 'number',
+            'bool' => 'boolean',
+        });
+    }
+}
+```
+
+:::info
+Type resolvers are automatically [discovered](../1-essentials/05-discovery.md) and do not need to be registered manually.
+:::
+
+## Configuring output location
+
+By default, Tempest generates a `types.d.ts` definition file at the root of the project, in which the generated types are organized by namespace.
+
+This may be configured by creating a `typescript.config.php` [configuration file](../1-essentials/06-configuration.md#configuration-files) and returning one of the available configuration objects.
+
+### Single file output
+
+To keep all of the TypeScript definitions in a single `.d.ts` declaration file, which is the default, return a {b`Tempest\Generation\TypeScript\Writers\NamespacedTypeScriptGenerationConfig`} object and specify the desired output filename.
+
+```php
+use Tempest\Generation\TypeScript\Writers\NamespacedTypeScriptGenerationConfig;
+
+return new NamespacedTypeScriptGenerationConfig(
+    filename: 'types.d.ts',
+);
+```
+
+The declaration file should be automatically picked up by TypeScript—if not, ensure that it's included in the `include` property of your `tsconfig.json`:
+
+```json
+{
+	"include": ["types.d.ts"]
+}
+```
+
+You may then reference the generated types globally by using their namespaces:
+
+```ts
+defineProps<{
+	entry: Module.Changelog.ChangelogEntry
+}>()
+```
+
+### Directory structure output
+
+If you prefer to mirror your PHP namespace structure in separate files, you may return a {b`Tempest\Generation\TypeScript\Writers\DirectoryTypeScriptGenerationConfig`} configuration object:
+
+```php
+use Tempest\Generation\TypeScript\Writers\DirectoryTypeScriptGenerationConfig;
+
+return new DirectoryTypeScriptGenerationConfig(
+    directory: 'src/Web/types',
+);
+```
+
+This creates a directory tree of individual `.ts` files, making it easier to navigate your types. Each namespace gets its own file, and imports between files are handled automatically.

packages/generation/src/TypeScript/AsType.php

@@ -0,0 +1,13 @@
+<?php
+
+namespace Tempest\Generation\TypeScript;
+
+use Attribute;
+
+/**
+ * Marks this class as a source for TypeScript type generation.
+ */
+#[Attribute(Attribute::TARGET_CLASS)]
+final class AsType
+{
+}

packages/generation/src/TypeScript/GenerateTypesCommand.php

@@ -0,0 +1,45 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tempest\Generation\TypeScript;
+
+use Tempest\Console\ConsoleCommand;
+use Tempest\Console\HasConsole;
+use Tempest\Container\Container;
+
+final class GenerateTypesCommand
+{
+    use HasConsole;
+
+    public function __construct(
+        private readonly TypeScriptGenerationConfig $config,
+        private readonly TypeScriptGenerator $generator,
+        private readonly Container $container,
+    ) {}
+
+    #[ConsoleCommand(
+        name: 'generate:typescript-types',
+        description: 'Generate TypeScript types from PHP classes.',
+    )]
+    public function __invoke(): void
+    {
+        $this->console->writeln();
+
+        $output = $this->generator->generate();
+
+        if ($output->isEmpty()) {
+            $this->console->warning('No types found to generate.');
+            return;
+        }
+
+        $writer = $this->container->get($this->config->writer);
+        $writer->write($output);
+
+        $this->console->success(sprintf(
+            'Generated %d type definitions across %d namespaces.',
+            count($output->getAllDefinitions()),
+            count($output->getNamespaces()),
+        ));
+    }
+}

packages/generation/src/TypeScript/GenericTypeScriptGenerator.php

@@ -0,0 +1,62 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tempest\Generation\TypeScript;
+
+use Tempest\Generation\TypeScript\StructureResolvers\ClassStructureResolver;
+use Tempest\Generation\TypeScript\StructureResolvers\EnumStructureResolver;
+use Tempest\Reflection\TypeReflector;
+
+final class GenericTypeScriptGenerator implements TypeScriptGenerator
+{
+    private ?TypesRepository $repository = null;
+
+    public function __construct(
+        private readonly TypeScriptGenerationConfig $config,
+        private readonly ClassStructureResolver $classResolver,
+        private readonly EnumStructureResolver $enumResolver,
+    ) {}
+
+    public function generate(): TypeScriptOutput
+    {
+        $this->repository = new TypesRepository();
+
+        foreach ($this->config->sources as $className) {
+            $this->include($className);
+        }
+
+        $grouped = [];
+
+        foreach ($this->repository->getAll() as $definition) {
+            $namespace = $definition->namespace;
+            $grouped[$namespace] ??= [];
+            $grouped[$namespace][] = $definition;
+        }
+
+        ksort($grouped);
+
+        return new TypeScriptOutput(
+            namespaces: $grouped,
+        );
+    }
+
+    public function include(string $className): void
+    {
+        if ($this->repository->has($className)) {
+            return;
+        }
+
+        $type = new TypeReflector($className);
+
+        if ($type->isEnum()) {
+            $this->repository->add($this->enumResolver->resolve($type, $this));
+            return;
+        }
+
+        if ($type->isClass() || $type->isInterface()) {
+            $this->repository->add($this->classResolver->resolve($type, $this));
+            return;
+        }
+    }
+}

packages/generation/src/TypeScript/InterfaceDefinition.php

@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tempest\Generation\TypeScript;
+
+use Tempest\Reflection\TypeReflector;
+use Tempest\Support\Str;
+
+/**
+ * Represents a TypeScript interface definition generated from a PHP class.
+ */
+final class InterfaceDefinition
+{
+    public string $namespace {
+        get {
+            if (! Str\contains($this->class, '\\')) {
+                return '';
+            }
+
+            return Str\before_last($this->class, '\\');
+        }
+    }
+
+    /**
+     * @param PropertyDefinition[] $properties
+     */
+    public function __construct(
+        public string $class,
+        public TypeReflector $originalType,
+        public array $properties,
+    ) {}
+}

packages/generation/src/TypeScript/PropertyDefinition.php

@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tempest\Generation\TypeScript;
+
+/**
+ * Represents a property in a TypeScript interface.
+ */
+final readonly class PropertyDefinition
+{
+    /**
+     * @param string $name The name of the property.
+     * @param string $definition The TypeScript definition of the property.
+     * @param null|string $fqcn The PHP FQCN of the original type.
+     */
+    public function __construct(
+        public string $name,
+        public string $definition,
+        public bool $isNullable,
+        public ?string $fqcn = null,
+    ) {}
+}

packages/generation/src/TypeScript/ResolvedType.php

@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tempest\Generation\TypeScript;
+
+/**
+ * Represents a PHP type resolved to a TypeScript one as a string.
+ */
+final readonly class ResolvedType
+{
+    /**
+     * @param string $type A resolved TypeScript type.
+     * @param null|string $fqcn The PHP FQCN of the original type.
+     */
+    public function __construct(
+        public string $type,
+        public ?string $fqcn = null,
+    ) {}
+}

packages/generation/src/TypeScript/StructureResolver.php

@@ -0,0 +1,15 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tempest\Generation\TypeScript;
+
+use Tempest\Reflection\TypeReflector;
+
+interface StructureResolver
+{
+    /**
+     * Resolves a PHP type into a TypeScript definition.
+     */
+    public function resolve(TypeReflector $type, TypeScriptGenerator $generator): TypeDefinition|InterfaceDefinition;
+}