Add Dependency Injection Framework with IDependencyManager, IDependencyProvider, Type, and NamedType Classes

src/di/DependencyManager.ts

@@ -0,0 +1,206 @@
+import type IDependencyProvider from "./IDependencyProvider";
+import type IDisposable from "../lang/IDisposable";
+import Disposable from "../lang/Disposable";
+import Type from "./Type";
+import type IDependencyManager from "./IDependencyManager";
+
+type Constructor<T = unknown> = new (...args: unknown[]) => T;
+type ModuleLoader = (modulePath: string) => Promise<Constructor | { default: Constructor }>;
+
+export default class DependencyManager implements IDependencyManager {
+  private readonly _moduleLoader: ModuleLoader;
+  private readonly _types: Type[];
+  private readonly _eagerTypes: Type[];
+  private readonly _providers: IDependencyProvider[];
+  private readonly _injections: Map<string, Type[]>;
+  private readonly _pending: Type[];
+
+  constructor(moduleLoader: ModuleLoader) {
+    if (typeof moduleLoader !== "function") {
+      throw new Error("Module loader must be a function");
+    }
+
+    this._moduleLoader = moduleLoader;
+    this._types = [];
+    this._eagerTypes = [];
+    this._providers = [];
+    this._injections = new Map();
+    this._pending = [];
+  }
+
+  public defineDependencies(type: Type, dependencies: Type[]): IDisposable {
+    if (!(type instanceof Type)) {
+      throw new Error("Type must be a Type");
+    }
+
+    if (!Array.isArray(dependencies)) {
+      throw new Error("Dependencies must be an array");
+    }
+
+    for (const dependency of dependencies) {
+      if (!(dependency instanceof Type)) {
+        throw new Error("Dependency must be a Type");
+      }
+    }
+
+    const key = type.toURN();
+
+    if (this._injections.has(key)) {
+      throw new Error(
+        `Dependencies already defined for type [${type.toString()}]`,
+      );
+    }
+
+    this._injections.set(key, dependencies);
+    this._types.push(type);
+
+    console.debug(`Dependencies for [${type}] defined as [${dependencies}]`);
+
+    return new Disposable(() => this._injections.delete(key));
+  }
+
+  public getDependencies(type: Type): Type[] | undefined {
+    if (!(type instanceof Type)) {
+      throw new Error("Type must be an instance of Type");
+    }
+
+    return this._injections.get(type.toURN());
+  }
+
+  public addProvider(provider: IDependencyProvider): IDisposable {
+    if (!this.isProvider(provider)) {
+      throw new Error("Provider must implement IDependencyProvider");
+    }
+
+    this._providers.push(provider);
+
+    return new Disposable(() => {
+      const index = this._providers.indexOf(provider);
+      if (index !== -1) {
+        this._providers.splice(index, 1);
+      }
+    });
+  }
+
+  public async resolveProvider(type: Type): Promise<IDependencyProvider> {
+    return this.resolve(type);
+  }
+
+  public async instantiateType(type: Type): Promise<unknown> {
+    if (!(type instanceof Type)) {
+      throw new Error('Type must be an instance of Type');
+    }
+
+    const key = type.toURN();
+
+    // Check for circular dependencies
+    if (this._pending.includes(type)) {
+      const pendingChain = this._pending.map((t) => t.toString()).join(' -> ');
+      throw new Error(
+        `Failed to resolve ${type} due to circular dependency: ${pendingChain}`
+      );
+    }
+
+    this._pending.push(type);
+
+    try {
+      // Get dependencies for this type
+      const dependencies = this._injections.get(key) || [];
+
+      // Resolve all dependencies
+      const resolvedDependencies = await Promise.all(
+        dependencies.map(async (dependency) => {
+          const provider = await this.resolveProvider(dependency);
+          let instance = await provider.provide(dependency);
+
+          // Handle nested providers
+          if (this.isProvider(instance)) {
+            instance = await (instance as IDependencyProvider).provide(dependency);
+          }
+
+          return instance;
+        })
+      );
+
+      // Load the module
+      const module = await this._moduleLoader(type.getType());
+      const Constructor = 'default' in module ? module.default : module;
+
+      if (!Constructor) {
+        throw new Error(`Could not load type "${type.getType()}"`);
+      }
+
+      // Instantiate with resolved dependencies
+      const instance = this.injectDependencies(Constructor, resolvedDependencies);
+
+      // Handle if the instance is itself a provider
+      if (this.isProvider(instance)) {
+        return await (instance as IDependencyProvider).provide(type);
+      }
+
+      return instance;
+    } finally {
+      // Remove from pending stack
+      const index = this._pending.indexOf(type);
+      if (index !== -1) {
+        this._pending.splice(index, 1);
+      }
+    }
+  }
+
+  public addEagerType(type: Type): void {
+    if (!(type instanceof Type)) {
+      throw new Error("Type must be an instance of Type");
+    }
+
+    this._eagerTypes.push(type);
+  }
+
+  public async getEagerTypes(): Promise<Type[]> {
+    return Promise.resolve([...this._eagerTypes]);
+  }
+
+  public async getTypes(): Promise<Type[]> {
+    return Promise.resolve([...this._types]);
+  }
+
+  private isProvider(obj: unknown): obj is IDependencyProvider {
+    return (
+      obj !== null &&
+      typeof obj === "object" &&
+      "canProvide" in obj &&
+      "provide" in obj &&
+      typeof (obj as IDependencyProvider).canProvide === "function" &&
+      typeof (obj as IDependencyProvider).provide === "function"
+    );
+  }
+
+  private resolve(type: Type): IDependencyProvider {
+    if (!(type instanceof Type)) {
+      throw new Error("Type must be an instance of Type");
+    }
+
+    const candidates = this._providers.filter((provider) =>
+      provider.canProvide(type),
+    );
+
+    if (candidates.length === 0) {
+      throw new Error(`No provider for [${type.toString()}]`);
+    }
+
+    if (candidates.length > 1) {
+      const candidateNames = candidates.map((c) => c.toString()).join(", ");
+      throw new Error(`Multiple providers for ${type}: ${candidateNames}`);
+    }
+
+    return candidates[0] as IDependencyProvider;
+  }
+
+  private injectDependencies(Constructor: Constructor, dependencies: unknown[]): unknown {
+    if (dependencies.length === 0) {
+      return new Constructor();
+    }
+
+    return new Constructor(...dependencies);
+  }
+}