import { beforeEach, describe, expect, it, vi } from "vitest";

const poolConstructor = vi.hoisted(() => vi.fn());
const betterAuthMock = vi.hoisted(() => vi.fn());
const drizzleAdapterMock = vi.hoisted(() => vi.fn());
const serveMock = vi.hoisted(() => vi.fn());
const processOnSpy = vi.hoisted(() => vi.fn());

vi.mock("pg", () => ({ Pool: poolConstructor }));
vi.mock("better-auth", () => ({ betterAuth: betterAuthMock }));
vi.mock("better-auth/adapters/drizzle", () => ({ drizzleAdapter: drizzleAdapterMock }));
vi.mock("@hono/node-server", () => ({ serve: serveMock }));

import { createApiRuntimeConfig } from "../src/config.js";
import { installShutdownSignalHandlers, startApi } from "../src/server.js";

function validConfig() {
  return createApiRuntimeConfig(
    {
      databaseUrl: "postgresql://ekklesia:ekklesia@127.0.0.1:5432/ekklesia",
      host: "127.0.0.1",
      identity: {
        baseUrl: "https://identity.example.test",
        secret: "correct-horse-battery-staple-0123456789",
        trustedOrigins: ["https://identity.example.test"],
      },
      port: 0,
    },
    { environment: "production" },
  );
}

/** A minimal fake `ServerType`: enough of Node's `http.Server` shape for `bindServer`/`shutdown`
 * to drive without a real socket. `close` and `once` are spies so tests can assert call counts;
 * `triggerError` simulates the server's own `'error'` event (e.g. a bind failure). */
function fakeServer() {
  let errorHandler: ((error: Error) => void) | undefined;
  const server = {
    address: () => ({ address: "127.0.0.1", family: "IPv4", port: 4_000 }),
    close: vi.fn((callback?: () => void) => {
      callback?.();
      return server;
    }),
    listening: true,
    once: vi.fn((event: string, handler: (error: Error) => void) => {
      if (event === "error") {
        errorHandler = handler;
      }
      return server;
    }),
  };
  return {
    server,
    triggerError: (error: Error) => errorHandler?.(error),
  };
}

/** Resolves the listening callback asynchronously, matching real `@hono/node-server` behavior
 * (the callback fires on the `listening` event, after `serve()` itself has already returned) —
 * resolving synchronously would reference `bindServer`'s own `server` const before it is
 * initialized. */
function mockSuccessfulServe() {
  const { server, triggerError } = fakeServer();
  serveMock.mockImplementation((_options: unknown, listeningListener?: () => void) => {
    queueMicrotask(() => listeningListener?.());
    return server;
  });
  return { server, triggerError };
}

function mockFailingServe(error: Error) {
  const { server, triggerError } = fakeServer();
  serveMock.mockImplementation(() => {
    queueMicrotask(() => triggerError(error));
    return server;
  });
  return server;
}

/** Captures signal handlers registered via `process.on` without ever installing a real one, so a
 * test can trigger "SIGINT"/"SIGTERM" by calling the captured function directly. */
function mockProcessOn(): { handlers: Record<string, () => void>; restore: () => void } {
  const handlers: Record<string, () => void> = {};
  const fake = vi.fn((event: string, handler: () => void) => {
    handlers[event] = handler;
    return process;
  });
  const onSpy = vi.spyOn(process, "on").mockImplementation(fake as unknown as typeof process.on);
  return { handlers, restore: () => onSpy.mockRestore() };
}

describe("Ekklesia API import safety", () => {
  const originalEnv = { ...process.env };
  const originalProcessOn = process.on.bind(process);

  beforeEach(() => {
    poolConstructor.mockClear();
    betterAuthMock.mockClear();
    drizzleAdapterMock.mockClear();
    serveMock.mockClear();
    processOnSpy.mockClear();
    for (const key of Object.keys(process.env)) {
      if (!(key in originalEnv)) {
        delete process.env[key];
      }
    }
    process.env = { ...originalEnv };
    process.on = originalProcessOn;
  });

  it("does not construct a database pool, Better Auth, or an HTTP server merely by importing the app factory", async () => {
    await import("../src/app.js");

    expect(poolConstructor).not.toHaveBeenCalled();
    expect(betterAuthMock).not.toHaveBeenCalled();
    expect(serveMock).not.toHaveBeenCalled();
  });

  it("does not construct a database pool, Better Auth, or an HTTP server merely by importing configuration", async () => {
    await import("../src/config.js");

    expect(poolConstructor).not.toHaveBeenCalled();
    expect(betterAuthMock).not.toHaveBeenCalled();
    expect(serveMock).not.toHaveBeenCalled();
  });

  it("does not read environment variables, connect to PostgreSQL, construct Better Auth, start a server, or install signal handlers merely by importing the executable server module", async () => {
    // Deliberately leave every runtime-required environment variable unset. If importing this
    // module performed any runtime composition, missing configuration would throw here.
    delete process.env.DATABASE_URL;
    delete process.env.EKKLESIA_IDENTITY_SECRET;
    delete process.env.EKKLESIA_IDENTITY_BASE_URL;
    delete process.env.EKKLESIA_IDENTITY_TRUSTED_ORIGINS;
    const onSpy = vi.spyOn(process, "on").mockImplementation(processOnSpy);

    await expect(import("../src/server.js")).resolves.toBeDefined();

    expect(poolConstructor).not.toHaveBeenCalled();
    expect(betterAuthMock).not.toHaveBeenCalled();
    expect(drizzleAdapterMock).not.toHaveBeenCalled();
    expect(serveMock).not.toHaveBeenCalled();
    expect(processOnSpy).not.toHaveBeenCalled();
    onSpy.mockRestore();
  });

  it("exposes startApi and main as explicit functions without invoking them at import time", async () => {
    const module = await import("../src/server.js");

    expect(typeof module.startApi).toBe("function");
    expect(typeof module.main).toBe("function");
    expect(serveMock).not.toHaveBeenCalled();
  });
});

describe("Ekklesia API shutdown lifecycle", () => {
  beforeEach(() => {
    poolConstructor.mockReset();
    betterAuthMock.mockReset();
    drizzleAdapterMock.mockClear();
    serveMock.mockReset();
  });

  it("makes every concurrent shutdown caller await the exact same server-close and pool-close, each exactly once", async () => {
    const poolEnd = vi.fn().mockResolvedValue(undefined);
    poolConstructor.mockImplementation(function fakePool() {
      return { end: poolEnd, on: vi.fn() };
    });
    betterAuthMock.mockReturnValue({ api: { getSession: vi.fn() }, handler: vi.fn() });
    const { server } = mockSuccessfulServe();

    const running = await startApi(validConfig());

    await Promise.all([running.shutdown(), running.shutdown(), running.shutdown()]);

    expect(server.close).toHaveBeenCalledTimes(1);
    expect(poolEnd).toHaveBeenCalledTimes(1);
  });

  it("keeps shutdown idempotent for calls made after the first has already resolved", async () => {
    const poolEnd = vi.fn().mockResolvedValue(undefined);
    poolConstructor.mockImplementation(function fakePool() {
      return { end: poolEnd, on: vi.fn() };
    });
    betterAuthMock.mockReturnValue({ api: { getSession: vi.fn() }, handler: vi.fn() });
    const { server } = mockSuccessfulServe();

    const running = await startApi(validConfig());
    await running.shutdown();
    await running.shutdown();

    expect(server.close).toHaveBeenCalledTimes(1);
    expect(poolEnd).toHaveBeenCalledTimes(1);
  });

  it("closes an already-created database pool when identity construction fails during startup", async () => {
    const poolEnd = vi.fn().mockResolvedValue(undefined);
    poolConstructor.mockImplementation(function fakePool() {
      return { end: poolEnd, on: vi.fn() };
    });
    betterAuthMock.mockImplementation(() => {
      throw new Error("postgresql://admin:secret@db.internal.example/x");
    });

    await expect(startApi(validConfig())).rejects.toMatchObject({
      code: "IDENTITY_CONSTRUCTION_FAILED",
    });

    expect(poolEnd).toHaveBeenCalledTimes(1);
    expect(serveMock).not.toHaveBeenCalled();
  });

  it("closes an already-created database pool when the server fails to bind its listen address", async () => {
    const poolEnd = vi.fn().mockResolvedValue(undefined);
    poolConstructor.mockImplementation(function fakePool() {
      return { end: poolEnd, on: vi.fn() };
    });
    betterAuthMock.mockReturnValue({ api: { getSession: vi.fn() }, handler: vi.fn() });
    mockFailingServe(new Error("EADDRINUSE"));

    await expect(startApi(validConfig())).rejects.toThrow();

    expect(poolEnd).toHaveBeenCalledTimes(1);
  });

  it("wires SIGINT/SIGTERM to the same shutdown lifecycle and only calls the injected exit, never the real process.exit", async () => {
    const { handlers, restore } = mockProcessOn();
    const shutdown = vi.fn().mockResolvedValue(undefined);
    const exit = vi.fn();

    installShutdownSignalHandlers({ shutdown }, exit);

    expect(handlers.SIGINT).toEqual(expect.any(Function));
    expect(handlers.SIGTERM).toEqual(expect.any(Function));

    handlers.SIGINT?.();
    await Promise.resolve();
    await Promise.resolve();

    expect(shutdown).toHaveBeenCalledTimes(1);
    expect(exit).toHaveBeenCalledWith(0);

    // A second signal after the first must not trigger a second shutdown.
    handlers.SIGTERM?.();
    await Promise.resolve();
    expect(shutdown).toHaveBeenCalledTimes(1);
    expect(exit).toHaveBeenCalledTimes(1);

    restore();
  });

  it("exits with a failure code, without throwing, when signal-triggered shutdown itself fails", async () => {
    const { handlers, restore } = mockProcessOn();
    const shutdown = vi.fn().mockRejectedValue(new Error("pool close failed"));
    const exit = vi.fn();

    installShutdownSignalHandlers({ shutdown }, exit);
    handlers.SIGTERM?.();
    await Promise.resolve();
    await Promise.resolve();

    expect(exit).toHaveBeenCalledWith(1);

    restore();
  });
});