import { Injectable } from '@nestjs/common';
import { ModelClass } from 'objection';
import { BaseModel } from './base.model';
import { DynamicModelFactory, ObjectMetadata } from './dynamic-model.factory';

/**
 * Registry to store and retrieve dynamic models
 * One registry per tenant
 */
@Injectable()
export class ModelRegistry {
  private registry = new Map<string, ModelClass<BaseModel>>();

  /**
   * Register a model in the registry
   */
  registerModel(apiName: string, modelClass: ModelClass<BaseModel>): void {
    this.registry.set(apiName, modelClass);
  }

  /**
   * Get a model from the registry
   */
  getModel(apiName: string): ModelClass<BaseModel> {
    const model = this.registry.get(apiName);
    if (!model) {
      throw new Error(`Model for ${apiName} not found in registry`);
    }
    return model;
  }

  /**
   * Check if a model exists in the registry
   */
  hasModel(apiName: string): boolean {
    return this.registry.has(apiName);
  }

  /**
   * Create and register a model from metadata
   */
  createAndRegisterModel(
    metadata: ObjectMetadata,
  ): ModelClass<BaseModel> {
    // Create model with a getModel function that resolves from this registry
    // Returns undefined if model not found (for models not yet registered)
    const model = DynamicModelFactory.createModel(
      metadata,
      (apiName: string) => this.registry.get(apiName),
    );
    this.registerModel(metadata.apiName, model);
    return model;
  }

  /**
   * Get all registered model names
   */
  getAllModelNames(): string[] {
    return Array.from(this.registry.keys());
  }

  /**
   * Clear the registry (useful for testing)
   */
  clear(): void {
    this.registry.clear();
  }
}