/**
 * SSE Polling Example Client (SEP-1699)
 *
 * Connects (2025-era), calls `long-operation`, and asserts the result arrives
 * AFTER the server's mid-stream `closeSSE()` — i.e. the client transport
 * automatically reconnects with `Last-Event-ID` and replays the events the
 * `eventStore` buffered while disconnected. Also asserts every progress log
 * (including the one emitted while disconnected) was delivered.
 */
import { check, parseExampleArgs } from '@mcp-examples/shared';
import { Client, StreamableHTTPClientTransport } from '@modelcontextprotocol/client';

const { url } = parseExampleArgs();

// `closeSSE`/`eventStore` live on the sessionful-2025 transport, so this
// story is legacy-only by design — it was previously reaching 2025 by
// negotiation fallback; pin it.
const client = new Client({ name: 'sse-polling-client', version: '1.0.0' }, { versionNegotiation: { mode: 'legacy' } });
const logs: string[] = [];
client.setNotificationHandler('notifications/message', n => {
    logs.push(String(n.params.data));
});

const transport = new StreamableHTTPClientTransport(new URL(url));
// The mid-stream disconnect surfaces as a transport error before the
// automatic reconnect; that is the EXPECTED flow, not a failure.
transport.onerror = () => {};
await client.connect(transport);

let lastEventId: string | undefined;
const result = await client.request(
    { method: 'tools/call', params: { name: 'long-operation', arguments: {} } },
    { onresumptiontoken: token => (lastEventId = token) }
);

const text = (result as { content?: Array<{ type: string; text?: string }> }).content?.[0]?.text ?? '';
check.match(text, /completed successfully/);
check.ok(lastEventId, 'resumption tokens should have been observed');
// The 75% line is emitted WHILE the client is disconnected; receiving it
// proves the event store replayed it on reconnect. (Replay ordering relative
// to the terminal result is not asserted — the result resolving is the
// signal the disconnect was survived.)
check.ok(
    logs.some(l => l.includes('75%')),
    `events emitted while disconnected should be replayed (got: ${logs.join(' | ')})`
);

await client.close();