import OpenAI from 'openai';

const TTL_MS = 20 * 60 * 1000;
const BATCH_MS = 800;
const BATCH_BYTES = 3400;
// SNAPSHOT_MIN_MS is no longer needed as we removed throttled saving.

// Heartbeat configuration: run every 4s while streaming to prevent eviction.
const HB_INTERVAL_MS = 3000;
const MAX_RUN_MS = 15 * 60 * 1000;

const CORS_HEADERS = {
  'Access-Control-Allow-Origin': '*',
  'Access-Control-Allow-Methods': 'GET, OPTIONS',
  'Access-Control-Allow-Headers': 'Content-Type, Authorization',
  'Access-Control-Max-Age': '86400',
};

const withCORS = (resp) => {
  const headers = new Headers(resp.headers);
  Object.entries(CORS_HEADERS).forEach(([k, v]) => headers.set(k, v));
  return new Response(resp.body, { ...resp, headers });
};

export default {
  async fetch(req, env) {
    const url = new URL(req.url);
    const method = req.method.toUpperCase();

    if (method === 'OPTIONS') return new Response(null, { status: 204, headers: CORS_HEADERS });

    if ((h => h !== 'sune.planetrenox.com' && !h.endsWith('.github.io'))(new URL(req.headers.get('Origin') || 'null').hostname)) return withCORS(new Response('Forbidden', { status: 403 }));

    if (url.pathname === '/ws') {
      const isGet = method === 'GET';
      const isWs = req.headers.get('Upgrade') === 'websocket';
      if (!isGet && !isWs) return withCORS(new Response('method not allowed', { status: 405 }));

      const rawUid = url.searchParams.get('uid') || 'anon';
      const uid = String(rawUid).slice(0, 64).replace(/[^a-zA-Z0-9_-]/g, '') || 'anon';
      const id = env.MY_DURABLE_OBJECT.idFromName(uid);
      const stub = env.MY_DURABLE_OBJECT.get(id);
      
      const resp = await stub.fetch(req);
      return isWs ? resp : withCORS(resp);
    }

    return withCORS(new Response('not found', { status: 404 }));
  }
}

export class MyDurableObject {
  constructor(state, env) {
    this.state = state;
    this.env = env;
    this.sockets = new Set();
    this.reset();
  }

  reset() {
    this.rid = null;
    this.buffer = [];
    this.seq = -1;
    this.phase = 'idle';
    this.error = null;
    this.controller = null;
    this.oaStream = null;
    this.pending = '';
    this.flushTimer = null;
    this.lastSavedAt = 0;
    this.lastFlushedAt = 0;
    this.hbActive = false;
    this.age = 0;
  }

  corsJSON(obj, status = 200) {
    return new Response(JSON.stringify(obj), { status, headers: { 'Content-Type': 'application/json', 'Cache-Control': 'no-store', ...CORS_HEADERS } });
  }

  send(ws, obj) { try { ws.send(JSON.stringify(obj)); } catch {} }

  bcast(obj) { this.sockets.forEach(ws => this.send(ws, obj)); }

  async autopsy() {
    if (this.rid) return;
    
    const snap = await this.state.storage.get('run').catch(() => null);
    if (!snap || (Date.now() - (snap.savedAt || 0) >= TTL_MS)) {
      if (snap) await this.state.storage.delete('run').catch(() => {});
      return;
    }

    this.rid = snap.rid || null;
    this.buffer = Array.isArray(snap.buffer) ? snap.buffer : [];
    this.seq = Number.isFinite(+snap.seq) ? +snap.seq : -1;
    this.age = snap.age || 0;
    this.phase = snap.phase || 'done';
    this.error = snap.error || null;
    this.pending = '';

    if (this.phase === 'running') {
      this.phase = 'evicted';
      this.error = 'The run was interrupted due to system eviction.';
      this.saveSnapshot(); // Persist the final 'evicted' state.
      this.stopHeartbeat().catch(() => {});
    }
  }

  saveSnapshot() {
    this.lastSavedAt = Date.now();
    return this.state.storage.put('run', { rid: this.rid, buffer: this.buffer, seq: this.seq, age: this.age, phase: this.phase, error: this.error, savedAt: this.lastSavedAt }).catch(() => {});
  }

  replay(ws, after) {
    this.buffer.forEach(it => { if (it.seq > after) this.send(ws, { type: 'delta', seq: it.seq, text: it.text }); });
    if (this.phase === 'done') this.send(ws, { type: 'done' });
    else if (['error', 'evicted'].includes(this.phase)) this.send(ws, { type: 'err', message: this.error || 'The run was terminated unexpectedly.' });
  }

  flush(force = false) {
    if (this.flushTimer) { clearTimeout(this.flushTimer); this.flushTimer = null; }
    if (this.pending) {
      this.buffer.push({ seq: ++this.seq, text: this.pending });
      this.bcast({ type: 'delta', seq: this.seq, text: this.pending });
      this.pending = '';
      this.lastFlushedAt = Date.now();
    }
    if (force) this.saveSnapshot();
  }

  queueDelta(text) {
    if (!text) return;
    this.pending += text;
    if (this.pending.length >= BATCH_BYTES) this.flush(false);
    else if (!this.flushTimer) this.flushTimer = setTimeout(() => this.flush(false), BATCH_MS);
  }

  async fetch(req) {
    if (req.method === 'OPTIONS') return new Response(null, { status: 204, headers: CORS_HEADERS });
    if (req.headers.get('Upgrade') === 'websocket') {
      const [client, server] = Object.values(new WebSocketPair());
      server.accept();
      this.sockets.add(server);
      server.addEventListener('close', () => this.sockets.delete(server));
      server.addEventListener('message', e => this.state.waitUntil(this.onMessage(server, e)));
      return new Response(null, { status: 101, webSocket: client });
    }
    if (req.method === 'GET') {
      await this.autopsy();
      const text = this.buffer.map(it => it.text).join('') + this.pending;
      const isTerminal = ['done', 'error', 'evicted'].includes(this.phase);
      const isError = ['error', 'evicted'].includes(this.phase);

      return this.corsJSON({ rid: this.rid, seq: this.seq, phase: this.phase, done: isTerminal, error: isError ? (this.error || 'The run was terminated unexpectedly.') : null, text });
    }
    return this.corsJSON({ error: 'not allowed' }, 405);
  }

  async onMessage(ws, evt) {
    await this.autopsy();
    let msg;
    try { msg = JSON.parse(String(evt.data || '')); }
    catch { return this.send(ws, { type: 'err', message: 'bad_json' }); }

    if (msg.type === 'stop') { if (msg.rid && msg.rid === this.rid) this.stop(); return; }
    if (msg.type !== 'begin') return this.send(ws, { type: 'err', message: 'bad_type' });

    const { rid, apiKey, or_body, model, messages, after, provider } = msg;
    const body = or_body || (model && Array.isArray(messages) ? { model, messages, stream: true, ...msg } : null);

    if (!rid || !apiKey || !body || !Array.isArray(body.messages) || body.messages.length === 0) return this.send(ws, { type: 'err', message: 'missing_fields' });
    if (this.phase === 'running' && rid !== this.rid) return this.send(ws, { type: 'err', message: 'busy' });
    if (rid === this.rid && this.phase !== 'idle') return this.replay(ws, Number.isFinite(+after) ? +after : -1);

    this.reset();
    this.rid = rid;
    this.phase = 'running';
    this.controller = new AbortController();
    await this.saveSnapshot();

    this.state.waitUntil(this.startHeartbeat());
    this.state.waitUntil(this.stream({ apiKey, body, provider: provider || 'openrouter' }));
  }

  async stream({ apiKey, body, provider }) {
    try {
      if (provider === 'openai') await this.streamOpenAI({ apiKey, body });
      else if (provider === 'google') await this.streamGoogle({ apiKey, body });
      else await this.streamOpenRouter({ apiKey, body });
      if (this.phase === 'running') this.stop();
    } catch (e) {
      if (this.phase === 'running') {
        const msg = String(e?.message || 'stream_failed');
        if (!((e && e.name === 'AbortError') || /abort/i.test(msg))) this.fail(msg);
      }
    }
  }

  isMultimodalMessage(m) { return m && Array.isArray(m.content) && m.content.some(p => p?.type && p.type !== 'text' && p.type !== 'input_text'); }

  extractTextFromMessage(m) {
    if (!m) return '';
    if (typeof m.content === 'string') return String(m.content);
    if (!Array.isArray(m.content)) return '';
    return m.content.filter(p => p && ['text', 'input_text'].includes(p.type)).map(p => String(p.type === 'text' ? (p.text ?? p.content ?? '') : (p.text ?? ''))).join('');
  }

  mapContentPartToResponses(part) {
    const type = part?.type || 'text';
    if (['image_url', 'input_image'].includes(type)) return (part?.image_url?.url || part?.image_url) ? { type: 'input_image', image_url: String(part?.image_url?.url || part?.image_url) } : null;
    if (['text', 'input_text'].includes(type)) return { type: 'input_text', text: String(type === 'text' ? (part.text ?? part.content ?? '') : (part.text ?? '')) };
    return { type: 'input_text', text: `[${type}:${part?.file?.filename || 'file'}]` };
  }

  buildInputForResponses(messages) {
    if (!Array.isArray(messages) || messages.length === 0) return '';
    if (!messages.some(m => this.isMultimodalMessage(m))) {
      if (messages.length === 1) return this.extractTextFromMessage(messages[0]);
      return messages.map(m => ({ role: m.role, content: this.extractTextFromMessage(m) }));
    }
    return messages.map(m => ({ role: m.role, content: Array.isArray(m.content) ? m.content.map(p => this.mapContentPartToResponses(p)).filter(Boolean) : [{ type: 'input_text', text: String(m.content || '') }] }));
  }

  mapToGoogleContents(messages) {
    const contents = messages.reduce((acc, m) => {
      const role = m.role === 'assistant' ? 'model' : 'user', text = this.extractTextFromMessage(m);
      if (!text) return acc;
      if (acc.length > 0 && acc.at(-1).role === role) acc.at(-1).parts.push({ text });
      else acc.push({ role, parts: [{ text }] });
      return acc;
    }, []);
    if (contents.at(-1)?.role !== 'user') contents.pop();
    return contents;
  }

  async streamOpenAI({ apiKey, body }) {
    const client = new OpenAI({ apiKey });
    const params = { model: body.model, input: this.buildInputForResponses(body.messages || []), temperature: body.temperature, stream: true };
    if (Number.isFinite(+body.max_tokens) && +body.max_tokens > 0) params.max_output_tokens = +body.max_tokens;
    if (Number.isFinite(+body.top_p)) params.top_p = +body.top_p;
    if (body.reasoning?.effort) params.reasoning = { effort: body.reasoning.effort };
    if (body.verbosity) params.text = { verbosity: body.verbosity };

    this.oaStream = await client.responses.stream(params);
    try {
      for await (const event of this.oaStream) {
        if (this.phase !== 'running') break;
        if (event.type.endsWith('.delta') && event.delta) this.queueDelta(event.delta);
      }
    } finally {
      try { this.oaStream?.controller?.abort(); } catch {}
      this.oaStream = null;
    }
  }

  async streamGoogle({ apiKey, body }) {
    const generationConfig = Object.entries({ temperature: body.temperature, topP: body.top_p, maxOutputTokens: body.max_tokens }).reduce((acc, [k, v]) => (Number.isFinite(+v) && +v >= 0 ? { ...acc, [k]: +v } : acc), {});
    const payload = { contents: this.mapToGoogleContents(body.messages), ...(Object.keys(generationConfig).length && { generationConfig }) };
    const resp = await fetch(`https://generativelanguage.googleapis.com/v1beta/models/${body.model}:streamGenerateContent?alt=sse`, { method: 'POST', headers: { 'Content-Type': 'application/json', 'x-goog-api-key': apiKey }, body: JSON.stringify(payload), signal: this.controller.signal });
    if (!resp.ok) throw new Error(`Google API error: ${resp.status} ${await resp.text()}`);
    const reader = resp.body.getReader();
    const decoder = new TextDecoder();
    let buffer = '';
    while (this.phase === 'running') {
      const { done, value } = await reader.read();
      if (done) break;
      buffer += decoder.decode(value, { stream: true });
      const lines = buffer.split('\n');
      buffer = lines.pop();
      lines.forEach(line => {
        if (!line.startsWith('data: ')) return;
        try { this.queueDelta(JSON.parse(line.substring(6)).candidates?.[0]?.content?.parts?.[0]?.text ?? ''); } catch {}
      });
    }
  }

  async streamOpenRouter({ apiKey, body }) {
    const client = new OpenAI({ apiKey, baseURL: 'https://openrouter.ai/api/v1' });
    const stream = await client.chat.completions.create({ ...body, stream: true }, { signal: this.controller.signal });
    for await (const chunk of stream) {
      if (this.phase !== 'running') break;
      const delta = chunk?.choices?.[0]?.delta?.content ?? '';
      if (delta) this.queueDelta(delta);
    }
  }

  stop() {
    if (this.phase !== 'running') return;
    this.flush(true);
    this.phase = 'done';
    this.error = null;
    try { this.controller?.abort(); } catch {}
    try { this.oaStream?.controller?.abort(); } catch {}
    this.saveSnapshot();
    this.bcast({ type: 'done' });
    this.state.waitUntil(this.stopHeartbeat());
  }

  fail(message) {
    if (this.phase === 'error') return;
    this.flush(true);
    this.phase = 'error';
    this.error = String(message || 'stream_failed');
    try { this.controller?.abort(); } catch {}
    try { this.oaStream?.controller?.abort(); } catch {}
    this.saveSnapshot();
    this.bcast({ type: 'err', message: this.error });
    this.state.waitUntil(this.stopHeartbeat());
  }

  async startHeartbeat() {
    if (this.hbActive || this.phase !== 'running') return;
    this.hbActive = true;
    try { await this.state.storage.setAlarm(Date.now() + HB_INTERVAL_MS); } catch {}
  }

  async stopHeartbeat() {
    this.hbActive = false;
    try { await this.state.storage.setAlarm(null); } catch {}
  }

  async Heart() {
    if (this.phase !== 'running' || !this.hbActive) return await this.stopHeartbeat();
    if (++this.age * HB_INTERVAL_MS >= MAX_RUN_MS) return this.fail('Run timed out after 15 minutes.');
    try { await this.state.storage.setAlarm(Date.now() + HB_INTERVAL_MS); } catch {}
  }

  async alarm() {
    await this.autopsy();
    await this.Heart();
  }
}