apps/worker/src/routes/simulate.ts

/**
 * POST /api/workflows/simulate
 * Dry-run simulation - offloaded entirely to external compute service
 * CF Worker just proxies the request and stores results in KV
 */
import { Hono } from 'hono';
import { z } from 'zod';
import type { Env } from '../types/env';
import type { WorkflowJob } from '../types/workflow';
import { createAuditEvent } from '../utils/audit';

export const simulateWorkflowRoute = new Hono<{ Bindings: Env }>();

const SimulateRequestSchema = z.object({
  jobId: z.string().min(1),
  mockData: z.record(z.unknown()).optional(),
});

simulateWorkflowRoute.post('/simulate', async (c) => {
  const body = await c.req.json().catch(() => null);
  if (!body) return c.json({ success: false, error: 'Invalid JSON body' }, 400);

  const parsed = SimulateRequestSchema.safeParse(body);
  if (!parsed.success) {
    return c.json({ success: false, error: 'Validation failed', details: parsed.error.flatten() }, 400);
  }

  const { jobId, mockData } = parsed.data;
  const raw = await c.env.WFO_CACHE.get(`job:${jobId}`, 'text');
  if (!raw) return c.json({ success: false, error: `Job ${jobId} not found` }, 404);

  const job = JSON.parse(raw) as WorkflowJob;

  if (!job.compiledWorkflow || !job.graph) {
    return c.json({
      success: false,
      error: 'Workflow not compiled or validated. Run /generate and /validate first.',
    }, 409);
  }

  if (job.validationReport && !job.validationReport.valid) {
    return c.json({
      success: false,
      error: 'Cannot simulate an invalid workflow. Fix validation issues first.',
      validationReport: job.validationReport,
    }, 409);
  }

  // Offload simulation to external compute (CPU-intensive)
  const resp = await fetch(`${c.env.SIMULATOR_URL}/process/simulate`, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      'X-Internal-Secret': c.env.INTERNAL_API_SECRET,
    },
    body: JSON.stringify({
      jobId,
      workflow: job.compiledWorkflow,
      graph: job.graph,
      architecturePlan: job.architecturePlan,
      mockData: mockData ?? {},
    }),
    signal: AbortSignal.timeout(25000),
  }).catch((e) => { throw new Error(`Simulator error: ${e instanceof Error ? e.message : 'unknown'}`); });

  if (!resp.ok) {
    return c.json({ success: false, error: `Simulator returned ${resp.status}` }, 502);
  }

  const result = await resp.json() as { simulationReport: WorkflowJob['simulationReport'] };

  const updated: WorkflowJob = {
    ...job,
    state: result.simulationReport?.passed ? 'simulated' : 'validated',
    simulationReport: result.simulationReport,
    updatedAt: new Date().toISOString(),
    auditLog: [
      ...job.auditLog,
      createAuditEvent(jobId, 'simulation.completed', 'system', {
        passed: result.simulationReport?.passed,
        readinessScore: result.simulationReport?.readinessScore,
      }),
    ],
  };

  await c.env.WFO_CACHE.put(`job:${jobId}`, JSON.stringify(updated), { expirationTtl: 86400 * 7 });

  return c.json({ success: true, jobId, simulationReport: result.simulationReport });
});