import { createServer, type IncomingHttpHeaders } from 'node:http';

import { mkdir, readFile, rename, writeFile } from 'node:fs/promises';

import { dirname } from 'node:path';

import { createCipheriv, createDecipheriv, createHash, randomBytes } from 'node:crypto';

import {

  LiveSessionActivationSchema,

  type LiveSessionActivation,

} from '../../../packages/protocol/src/index.js';

import {

  createAgentRuntimeConnector,

  HttpAgentRuntimeAdapter,

  OpenClaspClient,

  type RuntimeSessionStore,

} from '../../../packages/sdk/src/index.js';

class JsonFileRuntimeSessionStore implements RuntimeSessionStore {

  private loading: Promise<void> | undefined;

  private readonly sessions = new Map<string, LiveSessionActivation>();

  private writes = Promise.resolve();

  private readonly key: Buffer;

  constructor(

    private readonly filename: string,

    encryptionSecret: string,

  ) {

    this.key = createHash('sha256')

      .update(`openclasp-runtime-sessions:${encryptionSecret}`)

      .digest();

  }

  private async load() {

    this.loading ??= (async () => {

      try {

        const envelope = JSON.parse(await readFile(this.filename, 'utf8')) as {

          version: number;

          iv: string;

          authTag: string;

          ciphertext: string;

        };

        if (envelope.version !== 1) throw new Error('Unsupported runtime session file');

        const decipher = createDecipheriv(

          'aes-256-gcm',

          this.key,

          Buffer.from(envelope.iv, 'base64url'),

        );

        decipher.setAuthTag(Buffer.from(envelope.authTag, 'base64url'));

        const plaintext = Buffer.concat([

          decipher.update(Buffer.from(envelope.ciphertext, 'base64url')),

          decipher.final(),

        ]).toString('utf8');

        const values = JSON.parse(plaintext) as unknown[];

        for (const value of values) {

          const session = LiveSessionActivationSchema.parse(value);

          this.sessions.set(session.interactionId, session);

        }

      } catch (error) {

        if ((error as NodeJS.ErrnoException).code !== 'ENOENT') throw error;

      }

    })();

    await this.loading;

  }

  async get(interactionId: string) {

    await this.load();

    return this.sessions.get(interactionId);

  }

  async put(interactionId: string, session: LiveSessionActivation) {

    await this.load();

    this.sessions.set(interactionId, LiveSessionActivationSchema.parse(session));

    this.writes = this.writes.then(async () => {

      await mkdir(dirname(this.filename), { recursive: true });

      const temporary = `${this.filename}.${process.pid}.tmp`;

      const iv = randomBytes(12);

      const cipher = createCipheriv('aes-256-gcm', this.key, iv);

      const ciphertext = Buffer.concat([

        cipher.update(JSON.stringify([...this.sessions.values()])),

        cipher.final(),

      ]);

      await writeFile(

        temporary,

        JSON.stringify({

          version: 1,

          iv: iv.toString('base64url'),

          authTag: cipher.getAuthTag().toString('base64url'),

          ciphertext: ciphertext.toString('base64url'),

        }),

        { mode: 0o600 },

      );

      await rename(temporary, this.filename);

    });

    await this.writes;

  }

}

function required(name: string) {

  const value = process.env[name]?.trim();

  if (!value) throw new Error(`${name} is required`);

  return value;

}

function sdkBaseUrl(value: string) {

  return `${value.replace(/\/$/, '').replace(/\/v0\.1$/, '')}/v0.1`;

}

function requestHeaders(headers: IncomingHttpHeaders) {

  const output = new Headers();

  for (const [name, value] of Object.entries(headers)) {

    if (Array.isArray(value)) for (const entry of value) output.append(name, entry);

    else if (value !== undefined) output.set(name, value);

  }

  return output;

}

async function readBody(request: NodeJS.ReadableStream, maximumBytes = 2_000_000) {

  const chunks: Buffer[] = [];

  let size = 0;

  for await (const chunk of request) {

    const value = Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk);

    size += value.byteLength;

    if (size > maximumBytes) throw new Error('Request body is too large');

    chunks.push(value);

  }

  return Buffer.concat(chunks).toString('utf8');

}

const accessToken = required('OPENCLASP_AGENT_TOKEN');

const runtimeUrl = new URL(required('OPENCLASP_RUNTIME_URL'));

if (runtimeUrl.protocol !== 'https:') throw new Error('OPENCLASP_RUNTIME_URL must use HTTPS');

const agentAdapterUrl = required('AGENT_ADAPTER_URL');

const openClaspUrl = process.env.OPENCLASP_URL?.trim() || 'https://openclasp.vercel.app';

const client = new OpenClaspClient(sdkBaseUrl(openClaspUrl), accessToken);

const bootstrap = await client.getRuntimeBootstrap();

const sessions = new JsonFileRuntimeSessionStore(

  process.env.OPENCLASP_SESSION_FILE?.trim() || './data/openclasp-sessions.json',

  process.env.OPENCLASP_SESSION_SECRET?.trim() || accessToken,

);

const adapter = new HttpAgentRuntimeAdapter(agentAdapterUrl, {

  ...(process.env.AGENT_ADAPTER_TOKEN?.trim()

    ? { bearerToken: process.env.AGENT_ADAPTER_TOKEN.trim() }

    : {}),

  timeoutMs: Number(process.env.AGENT_ADAPTER_TIMEOUT_MS ?? 30_000),

});

const handler = createAgentRuntimeConnector({

  agentId: bootstrap.agentId,

  a2aEndpoint: runtimeUrl.toString(),

  openClaspUrl,

  adapter,

  sessions,

});

let ready = false;

const server = createServer(async (request, response) => {

  const path = new URL(request.url ?? '/', runtimeUrl).pathname;

  if (request.method === 'GET' && (path === '/health' || path === '/ready')) {

    const status = path === '/health' || ready ? 200 : 503;

    response.writeHead(status, { 'content-type': 'application/json' });

    response.end(JSON.stringify({ status: status === 200 ? 'ready' : 'starting' }));

    return;

  }

  if (request.method !== 'POST' || path !== runtimeUrl.pathname) {

    response.writeHead(404, { 'content-type': 'application/json' });

    response.end(JSON.stringify({ error: 'not_found' }));

    return;

  }

  try {

    const body = await readBody(request);

    const result = await handler(

      new Request(runtimeUrl, {

        method: 'POST',

        headers: requestHeaders(request.headers),

        body,

      }),

    );

    const headers: Record<string, string> = {};

    result.headers.forEach((value, name) => (headers[name] = value));

    response.writeHead(result.status, headers);

    response.end(await result.text());

  } catch (error) {

    response.writeHead(500, { 'content-type': 'application/json' });

    response.end(

      JSON.stringify({ error: error instanceof Error ? error.message : 'runtime_failed' }),

    );

  }

});

const port = Number(process.env.PORT ?? 8080);

const host = process.env.HOST?.trim() || '0.0.0.0';

await new Promise<void>((resolve, reject) => {

  server.once('error', reject);

  server.listen(port, host, resolve);

});

await client.connectRuntime(runtimeUrl.toString());

ready = true;

console.log(`OpenClasp runtime connected for ${bootstrap.agentId} at ${runtimeUrl.toString()}`);

const heartbeat = setInterval(() => void client.heartbeatRuntime().catch(() => undefined), 60_000);

heartbeat.unref();

for (const signal of ['SIGINT', 'SIGTERM'] as const) {

  process.once(signal, () => {

    clearInterval(heartbeat);

    server.close(() => process.exit(0));

  });

}