import { readFile } from "node:fs/promises";

import { afterEach, describe, expect, it, vi } from "vitest";
import { createRequire } from "node:module";

import { getAuthRuntimeConfig } from "@/lib/auth/config";
import type { AuthSession } from "@/lib/auth/session";

const { getOptionalAuthSession } = vi.hoisted(() => ({
  getOptionalAuthSession: vi.fn<() => Promise<AuthSession | null>>()
}));

vi.mock("@/lib/server/auth/current-user", () => ({ getOptionalAuthSession }));

import * as currentSessionRoute from "@/app/api/auth/me/route";

type ExpectedConfig = {
  required: boolean;
  configured: boolean;
  sessionSecret: string | null;
};

type CurrentSessionFixture = {
  version: 1;
  path: string;
  methods: {
    GET: MethodContract;
    HEAD: MethodContract & { executesGet: true };
    OPTIONS: MethodContract;
    unsupported: MethodContract & { methods: string[] };
  };
  authConfigurationCases: Array<{
    name: string;
    environment: Record<string, string>;
    expected: ExpectedConfig;
  }>;
  responses: {
    anonymous: CurrentSessionResponse;
    authenticatedUser: CurrentSessionResponse;
    unboundSuperAdministrator: CurrentSessionResponse;
  };
  forbiddenSessionKeys: string[];
  infrastructureError: {
    directGet: "rejects";
    transportStatus: number;
    mustNotReturnAnonymous: boolean;
  };
};

type MethodContract = {
  status: number;
  body: "json" | "empty";
  contentType: string | null;
  allow: string | null;
};

type CurrentSessionResponse = {
  authenticated: boolean;
  authRequired: boolean;
  authConfigured: boolean;
  authMode: "user" | "admin" | null;
  user: Record<string, unknown> | null;
};

const fixtureUrl = new URL("../contracts/auth/current-session-v1.json", import.meta.url);
const require = createRequire(import.meta.url);
const authEnvironmentKeys = [
  "NODE_ENV",
  "ZHINIAN_AUTH_REQUIRED",
  "ZHINIAN_AUTH_DISABLED",
  "ZHINIAN_AUTH_SESSION_SECRET",
  "AUTH_SESSION_SECRET",
  "NEXTAUTH_SECRET"
] as const;
const originalEnvironment = new Map(authEnvironmentKeys.map((key) => [key, process.env[key]]));

afterEach(() => {
  getOptionalAuthSession.mockReset();
  restoreAuthEnvironment();
});

async function loadFixture(): Promise<CurrentSessionFixture> {
  return JSON.parse(await readFile(fixtureUrl, "utf8")) as CurrentSessionFixture;
}

function restoreAuthEnvironment() {
  for (const key of authEnvironmentKeys) {
    const original = originalEnvironment.get(key);
    if (original === undefined) Reflect.deleteProperty(process.env, key);
    else Reflect.set(process.env, key, original);
  }
}

function configureAuthEnvironment(environment: Record<string, string>) {
  for (const key of authEnvironmentKeys) Reflect.deleteProperty(process.env, key);
  for (const [key, value] of Object.entries(environment)) Reflect.set(process.env, key, value);
}

function sessionFor(response: CurrentSessionResponse): AuthSession {
  if (!response.user || !response.authMode) throw new Error("authenticated fixture response required");
  return {
    version: 1,
    authMode: response.authMode,
    issuedAt: 100,
    expiresAt: 200,
    sessionVersion: 7,
    accessToken: "must-not-leak",
    tokenType: "bearer",
    user: response.user as AuthSession["user"]
  };
}

async function expectJsonResponse(expected: CurrentSessionResponse) {
  const fixture = await loadFixture();
  const response = await currentSessionRoute.GET();

  expect(response.status).toBe(fixture.methods.GET.status);
  expect(response.headers.get("content-type")).toBe(fixture.methods.GET.contentType);
  expect(response.headers.get("allow")).toBe(fixture.methods.GET.allow);
  expect(await response.json()).toEqual(expected);
}

describe("current session HTTP v1 cross-language contract", () => {
  it("freezes the path and Next.js automatic method semantics", async () => {
    const fixture = await loadFixture();

    expect(fixture.version).toBe(1);
    expect(fixture.path).toBe("/api/auth/me");
    expect(Object.keys(currentSessionRoute).sort()).toEqual(["GET", "runtime"]);
    expect(currentSessionRoute.runtime).toBe("nodejs");
    expect(fixture.methods).toEqual({
      GET: { status: 200, body: "json", contentType: "application/json", allow: null },
      HEAD: {
        status: 200,
        body: "empty",
        contentType: "application/json",
        allow: null,
        executesGet: true
      },
      OPTIONS: { status: 204, body: "empty", contentType: null, allow: "GET, HEAD, OPTIONS" },
      unsupported: {
        methods: ["POST", "PUT", "PATCH", "DELETE"],
        status: 405,
        body: "empty",
        contentType: null,
        allow: null
      }
    });

    const { autoImplementMethods } = require(
      "next/dist/server/route-modules/app-route/helpers/auto-implement-methods.js"
    ) as {
      autoImplementMethods: (handlers: Record<string, unknown>) => Record<string, () => Promise<Response>>;
    };
    const handlers = autoImplementMethods({ GET: currentSessionRoute.GET });
    getOptionalAuthSession.mockResolvedValue(null);
    configureAuthEnvironment({ NODE_ENV: "development" });

    for (const method of ["HEAD", "OPTIONS", ...fixture.methods.unsupported.methods]) {
      const response = await handlers[method]();
      const expected = method === "HEAD"
        ? fixture.methods.HEAD
        : method === "OPTIONS"
          ? fixture.methods.OPTIONS
          : fixture.methods.unsupported;
      expect(response.status, method).toBe(expected.status);
      expect(response.headers.get("content-type"), method).toBe(expected.contentType);
      expect(response.headers.get("allow"), method).toBe(expected.allow);
      if (method !== "HEAD") expect(await response.text(), method).toBe("");
    }
  });

  it("consumes every auth configuration case through the real runtime resolver", async () => {
    const fixture = await loadFixture();

    expect(fixture.authConfigurationCases.length).toBeGreaterThanOrEqual(4);
    for (const testCase of fixture.authConfigurationCases) {
      configureAuthEnvironment(testCase.environment);
      const config = getAuthRuntimeConfig();
      expect(
        {
          required: config.required,
          configured: config.configured,
          sessionSecret: config.sessionSecret ?? null
        },
        testCase.name
      ).toEqual(testCase.expected);
    }
  });

  it("returns the exact five-key anonymous response", async () => {
    const fixture = await loadFixture();
    configureAuthEnvironment({ NODE_ENV: "development" });
    getOptionalAuthSession.mockResolvedValue(null);

    expect(Object.keys(fixture.responses.anonymous).sort()).toEqual(
      ["authenticated", "authRequired", "authConfigured", "authMode", "user"].sort()
    );
    await expectJsonResponse(fixture.responses.anonymous);
  });

  it.each(["authenticatedUser", "unboundSuperAdministrator"] as const)(
    "returns the exact public projection for %s and omits optional fields",
    async (caseName) => {
      const fixture = await loadFixture();
      const expected = fixture.responses[caseName];
      configureAuthEnvironment({
        NODE_ENV: "production",
        ZHINIAN_AUTH_SESSION_SECRET: "route-test-secret"
      });
      getOptionalAuthSession.mockResolvedValue(sessionFor(expected));

      await expectJsonResponse(expected);
      const serialized = JSON.stringify(expected);
      for (const key of fixture.forbiddenSessionKeys) {
        expect(serialized, `${caseName} leaked ${key}`).not.toContain(`"${key}"`);
      }
      if (caseName === "unboundSuperAdministrator") {
        expect(expected.user).not.toHaveProperty("tenantId");
        expect(expected.user).not.toHaveProperty("organizationId");
        expect(expected.user).not.toHaveProperty("organizationName");
      }
    }
  );

  it("propagates infrastructure errors for transport mapping instead of returning anonymous", async () => {
    const fixture = await loadFixture();
    const failure = new Error("authorization snapshot unavailable");
    configureAuthEnvironment({
      NODE_ENV: "production",
      ZHINIAN_AUTH_SESSION_SECRET: "route-test-secret"
    });
    getOptionalAuthSession.mockRejectedValue(failure);

    expect(fixture.infrastructureError).toEqual({
      directGet: "rejects",
      transportStatus: 500,
      mustNotReturnAnonymous: true
    });
    await expect(currentSessionRoute.GET()).rejects.toBe(failure);
  });
});