import {
Controller,
Get,
Post,
Body,
Param,
Res,
HttpStatus,
} from '@nestjs/common';
import { Response } from 'express';
import { CalculatorService } from '../services/calculator.service';
import { SessionService } from '../services/session.service';
import {
CalculationRequest,
CalculationResponse,
SessionEvent,
} from '../interfaces/calculator.interfaces';
@Controller('calculator')
export class CalculatorController {
constructor(
private readonly calculatorService: CalculatorService,
private readonly sessionService: SessionService,
) {}
@Get('stream')
async streamCalculations(@Res() response: Response): Promise<void> {
// Set headers for SSE
response.setHeader('Content-Type', 'text/event-stream');
response.setHeader('Cache-Control', 'no-cache');
response.setHeader('Connection', 'keep-alive');
response.setHeader('X-Accel-Buffering', 'no'); // For NGINX proxy buffering
// Create a new session
const { sessionId, events } = this.sessionService.createSession();
// Send session ID as first event
response.write(
`data: ${JSON.stringify({ type: 'connected', sessionId })}\n\n`,
);
// Subscribe to session events
const subscription = events.subscribe(
(event: SessionEvent) => {
response.write(`data: ${JSON.stringify(event)}\n\n`);
},
(error) => {
console.error('SSE error:', error);
response.end();
},
() => {
response.end();
},
);
// Handle client disconnect
response.on('close', () => {
subscription.unsubscribe();
this.sessionService.closeSession(sessionId);
console.log(`Client disconnected, session ${sessionId} closed`);
});
}
@Post('calculate/:sessionId')
calculate(
@Param('sessionId') sessionId: string,
@Body() request: CalculationRequest,
): CalculationResponse {
try {
return this.calculatorService.calculate(sessionId, request);
} catch (error) {
// Emit error event to the client
try {
const events = this.sessionService.getSessionEvents(sessionId);
events.next({
type: 'error',
data: {
message: error.message,
status: error.status || HttpStatus.INTERNAL_SERVER_ERROR,
},
});
} catch {
// Session might not exist
}
// Re-throw the error for HTTP response
throw error;
}
}
@Get('history/:sessionId')
getHistory(@Param('sessionId') sessionId: string) {
return this.calculatorService.getHistory(sessionId);
}
@Get('sessions')
getAllSessions() {
return this.sessionService.getAllSessions();
}
}
