// /sw.js — tee streaming response and persist to localforage exactly like index (no stream id)
try {
  importScripts('https://cdn.jsdelivr.net/npm/localforage@1.10.0/dist/localforage.min.js');
} catch (e) {
  // importScripts may be blocked by CSP; we'll report via PING_STATUS
}

const TARGET_SUBSTRING = 'openrouter.ai/api/v1/chat/completions';
const THREADS_KEY = 'threads_v1';
const gid = () => Math.random().toString(36).slice(2,9) + '-' + Date.now().toString(36);
const now = () => Date.now();

let lfAvailable = (typeof localforage !== 'undefined');
let lfLoadError = lfAvailable ? null : 'localforage not present in SW';

async function broadcast(msg) {
  try {
    const clients = await self.clients.matchAll({ includeUncontrolled: true, type: 'window' });
    for (const c of clients) {
      try { c.postMessage(msg); } catch (e) { /* ignore per-client errors */ }
    }
  } catch (e) { /* ignore */ }
}

/* read/write exactly like index */
async function readThreads() {
  if (!lfAvailable) throw new Error('localforage unavailable: ' + lfLoadError);
  const v = await localforage.getItem(THREADS_KEY);
  return Array.isArray(v) ? v : (v ? v : []);
}
async function writeThreads(threads) {
  if (!lfAvailable) throw new Error('localforage unavailable: ' + lfLoadError);
  return localforage.setItem(THREADS_KEY, threads);
}

/* choose last thread by updatedAt, fallback to threads[0] or null */
function pickLastThread(threads) {
  if (!Array.isArray(threads) || threads.length === 0) return null;
  return threads.slice().sort((a,b)=> (b.updatedAt||0) - (a.updatedAt||0))[0];
}

/* upsert: if last message is assistant -> update it, else append one.
   message shape matches index: { role:'assistant', content, contentParts:[{type:'text',text}] } */
function upsertAssistantInThread(thread, text) {
  thread.updatedAt = now();
  thread.messages = thread.messages || [];
  const last = thread.messages.length ? thread.messages[thread.messages.length - 1] : null;
  if (last && last.role === 'assistant') {
    last.content = text;
    last.contentParts = [{ type: 'text', text }];
    last.updatedAt = now();
    return { threadId: thread.id, messageId: last.id || null, action: 'updated' };
  } else {
    const msg = {
      // intentionally do not add extra custom ids/flags beyond minimal fields
      role: 'assistant',
      content: text,
      contentParts: [{ type: 'text', text }]
    };
    thread.messages.push(msg);
    return { threadId: thread.id, messageId: msg.id || null, action: 'appended' };
  }
}

/* lifecycle */
self.addEventListener('install', ev => self.skipWaiting());
self.addEventListener('activate', ev => ev.waitUntil(self.clients.claim()));

/* fetch handler: tee and persist chunks */
self.addEventListener('fetch', event => {
  try {
    const url = String(event.request.url || '');
    if (!url.includes(TARGET_SUBSTRING)) return; // ignore unrelated fetches

    event.respondWith((async () => {
      const resUp = await fetch(event.request);
      if (!resUp || !resUp.body) return resUp;

      // minimal meta for broadcasts
      const meta = { url, startedAt: now(), bytes: 0 };
      broadcast({ type: 'INTERCEPT_START', meta });

      const [clientStream, swStream] = resUp.body.tee();
      const saveTask = (async () => {
        const reader = swStream.getReader();
        const decoder = new TextDecoder('utf-8');
        let acc = '';
        let lastSavedText = null;

        try {
          while (true) {
            const { value, done } = await reader.read();
            if (done) break;
            const chunk = decoder.decode(value, { stream: true });
            acc += chunk;
            meta.bytes += (value ? (value.byteLength || 0) : chunk.length);

            // only attempt save if text actually changed since last save
            if (lastSavedText !== acc) {
              const p = (async () => {
                try {
                  const threads = await readThreads();
                  let thread = pickLastThread(threads);
                  if (!thread) {
                    // create thread if none — keep shape index uses
                    thread = { id: 'sw-thread-' + gid(), title: 'Missed while backgrounded', pinned:false, updatedAt: now(), messages: [] };
                    threads.unshift(thread);
                  }
                  const res = upsertAssistantInThread(thread, acc);
                  await writeThreads(threads); // exact index call
                  lastSavedText = acc;
                  broadcast({ type: 'INTERCEPT_SAVE', meta: { threadId: res.threadId, action: res.action, bytes: meta.bytes, textLen: acc.length } });
                } catch (err) {
                  broadcast({ type: 'INTERCEPT_ERROR', meta: { error: String(err && err.message ? err.message : err) } });
                }
              })();

              // attach save promise to SW lifecycle
              try { event.waitUntil(p); } catch (e) { /* ignore in some runtimes */ }
            }
          }

          // final flush if needed (if lastSavedText changed)
          if (lastSavedText !== acc) {
            try {
              const threads = await readThreads();
              let thread = pickLastThread(threads);
              if (!thread) {
                thread = { id: 'sw-thread-' + gid(), title: 'Missed while backgrounded', pinned:false, updatedAt: now(), messages: [] };
                threads.unshift(thread);
              }
              const res = upsertAssistantInThread(thread, acc);
              await writeThreads(threads);
              broadcast({ type: 'INTERCEPT_SAVE', meta: { threadId: res.threadId, action: res.action, bytes: meta.bytes, textLen: acc.length } });
            } catch (err) {
              broadcast({ type: 'INTERCEPT_ERROR', meta: { error: String(err && err.message ? err.message : err) } });
            }
          }

          broadcast({ type: 'INTERCEPT_END', meta: { bytes: meta.bytes, endedAt: now() } });
        } catch (err) {
          broadcast({ type: 'INTERCEPT_ERROR', meta: { error: String(err && err.message ? err.message : err) } });
        }
      })();

      // keep SW alive while saves run
      try { event.waitUntil(saveTask); } catch (e) { /* ignore */ }

      return new Response(clientStream, {
        status: resUp.status,
        statusText: resUp.statusText,
        headers: resUp.headers
      });
    })());
  } catch (err) {
    broadcast({ type: 'INTERCEPT_ERROR', meta: { error: String(err && err.message ? err.message : err) } });
  }
});

/* message handler: concise debug commands */
self.addEventListener('message', event => {
  const data = event.data || {};
  (async () => {
    try {
      if (data.type === 'PING') {
        if (event.ports && event.ports[0]) event.ports[0].postMessage({ type: 'PONG', ts: now() });
        else broadcast({ type: 'PONG', ts: now() });
        return;
      }

      if (data.type === 'PING_STATUS') {
        const reply = { type: 'PONG_STATUS', ts: now(), lfAvailable, lfLoadError };
        if (event.ports && event.ports[0]) event.ports[0].postMessage(reply);
        else broadcast(reply);
        return;
      }

      if (data.type === 'TEST_WRITE') {
        if (!lfAvailable) {
          const out = { type: 'TEST_WRITE_RESULT', ok: false, error: 'localforage unavailable: ' + lfLoadError };
          if (event.ports && event.ports[0]) event.ports[0].postMessage(out); else broadcast(out);
          return;
        }
        try {
          const threads = await readThreads();
          const tid = 'sw-test-' + gid();
          const nowMs = now();
          const t = { id: tid, title: 'SW test ' + new Date(nowMs).toISOString(), pinned:false, updatedAt: nowMs, messages: [ { role:'assistant', content:'sw test write @ ' + new Date(nowMs).toISOString(), contentParts:[{type:'text',text:'sw test write'}] } ] };
          threads.unshift(t);
          await writeThreads(threads);
          const out = { type: 'TEST_WRITE_RESULT', ok:true, tid };
          if (event.ports && event.ports[0]) event.ports[0].postMessage(out); else broadcast(out);
        } catch (err) {
          const out = { type: 'TEST_WRITE_RESULT', ok:false, error: String(err && err.message ? err.message : err) };
          if (event.ports && event.ports[0]) event.ports[0].postMessage(out); else broadcast(out);
        }
        return;
      }

      if (data.type === 'READ_KEY') {
        const key = data.key || THREADS_KEY;
        if (!lfAvailable) {
          const res = { type: 'READ_KEY_RESULT', ok:false, key, error: 'localforage unavailable: ' + lfLoadError };
          if (event.ports && event.ports[0]) event.ports[0].postMessage(res); else broadcast(res);
          return;
        }
        try {
          const value = await localforage.getItem(key);
          const out = { type: 'READ_KEY_RESULT', ok:true, key, value };
          if (event.ports && event.ports[0]) event.ports[0].postMessage(out); else broadcast(out);
        } catch (err) {
          const out = { type: 'READ_KEY_RESULT', ok:false, key, error: String(err && err.message ? err.message : err) };
          if (event.ports && event.ports[0]) event.ports[0].postMessage(out); else broadcast(out);
        }
        return;
      }

      if (data.type === 'LIST_SW_SAVED') {
        if (!lfAvailable) {
          const res = { type:'LIST_SW_SAVED_RESULT', ok:false, error: 'localforage unavailable: ' + lfLoadError };
          if (event.ports && event.ports[0]) event.ports[0].postMessage(res); else broadcast(res);
          return;
        }
        try {
          const threads = await readThreads();
          const found = [];
          for (const t of (threads || [])) {
            for (const m of (t.messages || [])) {
              if (m && m.role === 'assistant') {
                // we can't know whether assistant messages were created by SW or page; include short snippet
                found.push({ threadId: t.id, snippet: (m.content||'').slice(0,200) });
              }
            }
          }
          const out = { type: 'LIST_SW_SAVED_RESULT', ok: true, found };
          if (event.ports && event.ports[0]) event.ports[0].postMessage(out); else broadcast(out);
        } catch (err) {
          const out = { type: 'LIST_SW_SAVED_RESULT', ok:false, error: String(err && err.message ? err.message : err) };
          if (event.ports && event.ports[0]) event.ports[0].postMessage(out); else broadcast(out);
        }
        return;
      }

      if (data.type === 'CLEAR_TESTS') {
        if (!lfAvailable) {
          const res = { type:'CLEAR_TESTS_RESULT', ok:false, error: 'localforage unavailable: ' + lfLoadError };
          if (event.ports && event.ports[0]) event.ports[0].postMessage(res); else broadcast(res);
          return;
        }
        try {
          const threads = await readThreads();
          const before = threads.length;
          const cleaned = threads.filter(t => !(t.id && String(t.id).startsWith('sw-test-')));
          await writeThreads(cleaned);
          const removed = before - cleaned.length;
          const out = { type:'CLEAR_TESTS_RESULT', ok:true, removed };
          if (event.ports && event.ports[0]) event.ports[0].postMessage(out); else broadcast(out);
        } catch (err) {
          const out = { type:'CLEAR_TESTS_RESULT', ok:false, error: String(err && err.message ? err.message : err) };
          if (event.ports && event.ports[0]) event.ports[0].postMessage(out); else broadcast(out);
        }
        return;
      }

    } catch (err) {
      const r = { type: 'SW_ERROR', error: String(err && err.message ? err.message : err) };
      if (event.ports && event.ports[0]) event.ports[0].postMessage(r); else broadcast(r);
    }
  })();
});