import { test, describe } from 'node:test';
import assert from 'node:assert/strict';
import vm from 'node:vm';
import http from 'node:http';
import { readFileSync } from 'node:fs';
import { fileURLToPath } from 'node:url';
import { dirname, join } from 'node:path';
import axios from 'axios';
import xmlbuilder2 from 'xmlbuilder2';

const __filename = fileURLToPath(import.meta.url);
const __dirname = dirname(__filename);

const proxyPath = join(__dirname, '../../src/proxyScripts/kmeContentSourceAdapter.js');
const proxyCode = readFileSync(proxyPath, 'utf-8');
const proxyScript = new vm.Script(proxyCode, { filename: 'kmeContentSourceAdapter.js' });

const helpersPath = join(__dirname, '../../src/globalVariables/kmeContentSourceAdapterHelpers.js');
const helpersCode = readFileSync(helpersPath, 'utf-8');
const helpersWrapped = `(function() {\n${helpersCode}\n})()`;
const helpersScript = new vm.Script(helpersWrapped, { filename: 'kmeContentSourceAdapterHelpers.js' });

/** Evaluate the helpers file with the provided deps (mirrors server.js loadGlobalVariables). */
function makeHelpers(deps) {
  return helpersScript.runInContext(vm.createContext(deps));
}

/**
 * Start a minimal HTTP server that handles all requests with a fixed JSON body.
 * @param {number} statusCode
 * @param {object} responseBody
 * @returns {Promise<{ server: http.Server, url: string, close: () => Promise<void> }>}
 */
function startMockServer(statusCode, responseBody) {
  return new Promise((resolve, reject) => {
    const server = http.createServer((req, res) => {
      res.writeHead(statusCode, { 'Content-Type': 'application/json' });
      res.end(JSON.stringify(responseBody));
    });
    server.listen(0, '127.0.0.1', () => {
      const { port } = server.address();
      const url = `http://127.0.0.1:${port}`;
      const close = () => new Promise((res, rej) => server.close(err => err ? rej(err) : res()));
      resolve({ server, url, close });
    });
    server.once('error', reject);
  });
}

/**
 * Start a mock token server (alias for backwards compatibility).
 */

/** Build an in-memory Redis fake. */
function makeRedisFake() {
  const _store = {};
  return {
    hSet: async (key, field, value) => { _store[`${key}:${field}`] = value; return 1; },
    hGet: async (key, field) => _store[`${key}:${field}`] ?? null,
  };
}

/** Build a capturable res object. */
function makeRes() {
  let statusCode = null;
  let body = '';
  const headers = {};
  return {
    writeHead: (code, hdrs = {}) => { statusCode = code; Object.assign(headers, hdrs); },
    end: (b = '') => { body += String(b); },
    get statusCode() { return statusCode; },
    get body() { return body; },
    get headers() { return headers; },
  };
}

// ---------------------------------------------------------------------------
// Contract: 200 OK — successful OIDC token fetch
// ---------------------------------------------------------------------------

// ---------------------------------------------------------------------------
// Contract: sitemap endpoint (T005, T012)
// ---------------------------------------------------------------------------

describe('sitemap endpoint', () => {
  /**
   * Build a VM context wired to a real token server and a real search server.
   * The token cache is pre-seeded so no real token exchange is needed.
   */
  function makeSitemapCtx({ searchUrl, tokenUrl }) {
    const redis = makeRedisFake();
    // Pre-seed a valid token so no token fetch is needed
    redis.hSet('authorization', 'token', 'sitemap-contract-token');
    redis.hSet('authorization', 'expiry', '9999999999');

    const res = makeRes();
    const kme_CSA_settings = {
      tokenUrl: tokenUrl ?? 'http://127.0.0.1:1', // not used (cache hit)
      username: 'user',
      password: 'pass',
      clientId: 'client',
      scope: 'openid',
      searchApiBaseUrl: searchUrl,
      tenant: 'test',
      proxyBaseUrl: 'https://proxy.example.com',
    };
    const deps = { URLSearchParams, URL, console, axios, xmlbuilder2, redis, kme_CSA_settings };
    const ctx = vm.createContext({
      ...deps,
      kmeContentSourceAdapterHelpers: makeHelpers(deps),
      req: { url: '/sitemap.xml', method: 'GET', headers: {} },
      res,
    });
    ctx._res = res;
    return ctx;
  }

  test('full round-trip GET /sitemap.xml → 200 application/xml with loc elements', async () => {
    const searchMock = await startMockServer(200, {
      'hydra:member': [
        { 'hydra:member': [{ 'vkm:url': 'https://kme.example.com/doc-1' }] },
      ],
    });

    try {
      const ctx = makeSitemapCtx({ searchUrl: searchMock.url });
      await proxyScript.runInContext(ctx);

      assert.strictEqual(ctx._res.statusCode, 200);
      assert.ok(ctx._res.headers['Content-Type'].includes('application/xml'),
        `Content-Type was: ${ctx._res.headers['Content-Type']}`);
      assert.ok(ctx._res.body.startsWith('<?xml'), 'body should start with XML declaration');
      assert.ok(ctx._res.body.includes('<loc>'), 'body should contain a loc element');
    } finally {
      await searchMock.close();
    }
  });

  test('empty results round-trip → 200 application/xml with urlset and no url element', async () => {
    const searchMock = await startMockServer(200, { 'hydra:member': [] });

    try {
      const ctx = makeSitemapCtx({ searchUrl: searchMock.url });
      await proxyScript.runInContext(ctx);

      assert.strictEqual(ctx._res.statusCode, 200);
      assert.ok(ctx._res.headers['Content-Type'].includes('application/xml'),
        `Content-Type was: ${ctx._res.headers['Content-Type']}`);
      assert.ok(ctx._res.body.includes('<urlset'), 'body should contain urlset');
      assert.ok(!ctx._res.body.includes('<url>'), 'body should not contain url elements for empty results');
    } finally {
      await searchMock.close();
    }
  });

  test('search server returns 503 → adapter returns 502', async () => {
    const searchMock = await startMockServer(503, { error: 'Service Unavailable' });

    try {
      const ctx = makeSitemapCtx({ searchUrl: searchMock.url });
      await proxyScript.runInContext(ctx);

      assert.strictEqual(ctx._res.statusCode, 502, `body was: ${ctx._res.body}`);
    } finally {
      await searchMock.close();
    }
  });

  test('search server hangs > 10s → adapter returns 504 within 12s', async () => {
    // Server that accepts connections but never responds
    const server = await new Promise((resolve, reject) => {
      const s = http.createServer(() => { /* intentionally hang */ });
      s.listen(0, '127.0.0.1', () => {
        const { port } = s.address();
        const close = () => new Promise((res, rej) => s.close(err => err ? rej(err) : res()));
        resolve({ server: s, url: `http://127.0.0.1:${port}`, close });
      });
      s.once('error', reject);
    });

    try {
      const ctx = makeSitemapCtx({ searchUrl: server.url });
      const start = Date.now();
      await proxyScript.runInContext(ctx);
      const elapsed = Date.now() - start;

      assert.strictEqual(ctx._res.statusCode, 504, `body was: ${ctx._res.body}`);
      assert.ok(elapsed < 12000, `Should respond within 12s, took ${elapsed}ms`);
    } finally {
      await server.close();
    }
  });
});


// ---------------------------------------------------------------------------
// Content fetch: happy path contract test — T008
// ---------------------------------------------------------------------------

describe('content fetch: happy path', () => {
  test('GET /?kmeURL=<mock-server> → 200 text/html with article body (SC-001 < 11s)', async () => {
    // Mock content server returning a valid article JSON-LD response
    const contentMock = await startMockServer(200, { 'vkm:name': 'Contract Article', 'vkm:articleBody': '<p>Contract test article</p>' });

    try {
      const redis = makeRedisFake();
      // Pre-seed token — no real token exchange needed
      await redis.hSet('authorization', 'token', 'content-contract-token');
      await redis.hSet('authorization', 'expiry', '9999999999');

      const res = makeRes();
      const kme_CSA_settings = {
        tokenUrl: 'http://127.0.0.1:1', // unreachable — not used (cache hit)
        username: 'user',
        password: 'pass',
        clientId: 'client',
        scope: 'openid',
      };
      const deps = { URLSearchParams, URL, console, axios, xmlbuilder2, redis, kme_CSA_settings };
      const ctx = vm.createContext({
        ...deps,
        kmeContentSourceAdapterHelpers: makeHelpers(deps),
        req: { url: `/?kmeURL=${encodeURIComponent(contentMock.url)}`, method: 'GET', headers: {} },
        res,
      });

      const start = Date.now();
      await proxyScript.runInContext(ctx);
      const elapsed = Date.now() - start;

      assert.strictEqual(res.statusCode, 200);
      assert.ok(
        res.headers['Content-Type'].startsWith('text/html'),
        `Content-Type was: ${res.headers['Content-Type']}`,
      );
      assert.ok(res.body.includes('<!DOCTYPE html>'), 'body should contain DOCTYPE');
      assert.ok(res.body.includes('<title>Contract Article</title>'), 'body should contain title');
      assert.ok(res.body.includes('<p>Contract test article</p>'), 'body should contain article content verbatim');
      assert.ok(elapsed < 11000, `Round-trip should be under 11 s, took ${elapsed}ms`);
    } finally {
      await contentMock.close();
    }
  });
});

// ---------------------------------------------------------------------------
// Content fetch: error handling contract tests — T012
// ---------------------------------------------------------------------------

describe('content fetch: error handling', () => {
  /** Build a content-fetch VM context wired to the given upstream URL. */
  function makeContentFetchCtx(contentUrl) {
    const redis = makeRedisFake();
    // Pre-seed token so no real auth server is needed
    redis.hSet('authorization', 'token', 'content-contract-token');
    redis.hSet('authorization', 'expiry', '9999999999');

    const res = makeRes();
    const kme_CSA_settings = {
      tokenUrl: 'http://127.0.0.1:1', // not used (cache hit)
      username: 'user',
      password: 'pass',
      clientId: 'client',
      scope: 'openid',
    };
    const deps = { URLSearchParams, URL, console, axios, xmlbuilder2, redis, kme_CSA_settings };
    const ctx = vm.createContext({
      ...deps,
      kmeContentSourceAdapterHelpers: makeHelpers(deps),
      req: { url: `/?kmeURL=${encodeURIComponent(contentUrl)}`, method: 'GET', headers: {} },
      res,
    });
    ctx._res = res;
    return ctx;
  }

  test('mock upstream returns 404 → proxy returns 404', async () => {
    const mock = await startMockServer(404, { error: 'Not Found' });

    try {
      const ctx = makeContentFetchCtx(mock.url);
      await proxyScript.runInContext(ctx);
      assert.strictEqual(ctx._res.statusCode, 404, `body was: ${ctx._res.body}`);
    } finally {
      await mock.close();
    }
  });

  test('mock upstream returns 503 → proxy returns 502', async () => {
    const mock = await startMockServer(503, { error: 'Service Unavailable' });

    try {
      const ctx = makeContentFetchCtx(mock.url);
      await proxyScript.runInContext(ctx);
      assert.strictEqual(ctx._res.statusCode, 502, `body was: ${ctx._res.body}`);
    } finally {
      await mock.close();
    }
  });

  test('server accepts connection but never responds → proxy returns 502 within 12s', async () => {
    const hangServer = await new Promise((resolve, reject) => {
      const s = http.createServer(() => { /* intentionally hang — never respond */ });
      s.listen(0, '127.0.0.1', () => {
        const { port } = s.address();
        const close = () => new Promise((res, rej) => s.close(err => err ? rej(err) : res()));
        resolve({ server: s, url: `http://127.0.0.1:${port}`, close });
      });
      s.once('error', reject);
    });

    try {
      const ctx = makeContentFetchCtx(hangServer.url);
      const start = Date.now();
      await proxyScript.runInContext(ctx);
      const elapsed = Date.now() - start;

      assert.strictEqual(ctx._res.statusCode, 502, `body was: ${ctx._res.body}`);
      assert.ok(elapsed < 12000, `Should respond within 12s, took ${elapsed}ms`);
    } finally {
      await hangServer.close();
    }
  });
});