import { mongodbClient } from "../mongodb-client";
import { MongoClient } from "mongodb";

describe("MongoDBClient Validation", () => {
  const originalEnv = process.env;

  beforeEach(() => {
    process.env = { ...originalEnv };
    delete process.env.MONGO_URI;
    delete process.env.MONGODB_URI;
    delete process.env.MONGODB_DB_NAME;

    // Force reset singleton state
    (mongodbClient as any).client = null;
    (mongodbClient as any).db = null;
  });

  afterAll(async () => {
    process.env = originalEnv;
    // Ensure we are disconnected
    await mongodbClient.disconnect();
  });

  it("should throw error if no URI is provided", async () => {
    await expect(mongodbClient.connect()).rejects.toThrow(
      "[core-db] Configuration Error: 'MONGO_URI' is missing",
    );
  });

  it("should throw error if an invalid URI format is provided", async () => {
    await expect(mongodbClient.connect("not-a-mongo-uri")).rejects.toThrow(
      "[core-db] Connection Error: The provided MongoDB URI is invalid",
    );
  });

  it("should throw error if URI is valid but database name is missing", async () => {
    // We mock the actual MongoClient connection so it doesn't try to hit a real network
    const connectSpy = jest
      .spyOn(MongoClient.prototype, "connect")
      .mockResolvedValue({} as any);

    const uriWithoutDb = "mongodb://127.0.0.1:27017";
    await expect(mongodbClient.connect(uriWithoutDb)).rejects.toThrow(
      "[core-db] Database name not specified",
    );

    connectSpy.mockRestore();
  });

  it("should succeed when valid URI and DB name are provided", async () => {
    const mockDb = { databaseName: "my-db" };
    const connectSpy = jest
      .spyOn(MongoClient.prototype, "connect")
      .mockResolvedValue({} as any);
    const dbSpy = jest
      .spyOn(MongoClient.prototype, "db")
      .mockReturnValue(mockDb as any);

    const validUri = "mongodb://127.0.0.1:27017/my-db";
    await mongodbClient.connect(validUri);

    expect(mongodbClient.getDb()).toBeDefined();
    expect(mongodbClient.getDb().databaseName).toBe("my-db");

    connectSpy.mockRestore();
    dbSpy.mockRestore();
  });
});