import { integer, pgTable, text } from "drizzle-orm/pg-core";
import type { Pool } from "pg";
import { describe, expect, it, vi } from "vitest";
import { createModuleDatabaseView } from "../src/modules/database.js";

const testTable = pgTable("core_module_database_test", {
  id: integer("id").primaryKey(),
  name: text("name").notNull(),
});

function fakePool(): Pool {
  return {
    connect: vi.fn(),
    end: vi.fn(),
    on: vi.fn(),
    query: vi.fn(),
  } as unknown as Pool;
}

describe("createModuleDatabaseView", () => {
  it("wraps an externally owned pool without constructing, connecting to, registering an error listener on, or closing one itself", () => {
    const pool = fakePool();

    const database = createModuleDatabaseView(pool);

    expect(database).toBeDefined();
    expect(vi.mocked(pool.connect)).not.toHaveBeenCalled();
    expect(vi.mocked(pool.end)).not.toHaveBeenCalled();
    expect(vi.mocked(pool.on)).not.toHaveBeenCalled();
    expect(vi.mocked(pool.query)).not.toHaveBeenCalled();
  });

  it("exposes exactly the intended query surface, frozen, with no raw pool/client/session/dialect escape hatch", () => {
    const database = createModuleDatabaseView(fakePool());

    expect(Object.keys(database).sort()).toEqual([
      "delete",
      "execute",
      "insert",
      "select",
      "selectDistinct",
      "selectDistinctOn",
      "transaction",
      "update",
    ]);
    expect(Object.isFrozen(database)).toBe(true);
    for (const forbidden of ["$client", "_", "query", "session", "dialect", "pool", "with"]) {
      expect(forbidden in database).toBe(false);
    }
  });

  it("keeps every forwarded operation correctly bound to its underlying Drizzle instance, even when destructured off the facade", async () => {
    const database = createModuleDatabaseView(fakePool());
    const {
      select,
      selectDistinct,
      selectDistinctOn,
      insert,
      update,
      delete: remove,
      execute,
      transaction,
    } = database;

    // Each of these synchronously builds a query object from `this.session`/`this.dialect` without
    // performing I/O — if the forwarded method lost its `this` binding when destructured (a real JS
    // pitfall for plain prototype methods), the very first property access inside would throw.
    expect(() => select()).not.toThrow();
    expect(() => selectDistinct()).not.toThrow();
    expect(() => selectDistinctOn([testTable.name])).not.toThrow();
    expect(() => insert(testTable)).not.toThrow();
    expect(() => update(testTable)).not.toThrow();
    expect(() => remove(testTable)).not.toThrow();
    expect(() => execute("select 1")).not.toThrow();

    let transactionResult: unknown;
    expect(() => {
      transactionResult = transaction(async () => undefined);
    }).not.toThrow();
    expect(transactionResult).toBeInstanceOf(Promise);
    // The fake pool cannot complete a real transaction; only the synchronous binding matters here.
    await Promise.resolve(transactionResult).catch(() => undefined);
  });

  it("never constructs a second pool — the given pool instance is the only one ever touched", () => {
    const pool = fakePool();

    createModuleDatabaseView(pool);
    createModuleDatabaseView(pool);

    // Two views built from the same pool never allocate a new connection — there is nothing on
    // `pool` for either call to have invoked at all (see the construction test above), so calling
    // this twice is itself the proof that no per-call pool allocation ever happens.
    expect(vi.mocked(pool.connect)).not.toHaveBeenCalled();
  });
});