instrumentation.ts

import * as Sentry from '@sentry/nextjs'
import { runStartupValidation } from './lib/rate-limit-validation'
import { logger } from './lib/logger'

export async function register() {
  // Set E2E_TEST flag globally for client-side detection
  if (process.env.E2E_TEST === 'true') {
    if (typeof window !== 'undefined') {
      (window as any).__E2E_TEST = true
    }
    if (typeof globalThis !== 'undefined') {
      (globalThis as any).__E2E_TEST = true
    }
  }

  // Initialize Sentry for both Node.js and Edge server runtimes
  if (process.env.NEXT_RUNTIME === 'nodejs' || process.env.NEXT_RUNTIME === 'edge') {
    Sentry.init({
      dsn: process.env.SENTRY_DSN,
      tracesSampleRate: 1.0,
      environment: process.env.NODE_ENV,
    })
  }

  // Validate rate limiter configuration on startup
  // Skip during build phase to prevent Redis initialization crashes
  // NEXT_PHASE is set by Next.js build process
  const isBuildPhase = process.env.NEXT_PHASE === 'phase-production-build';
  
  if (process.env.NEXT_RUNTIME === 'nodejs' && !isBuildPhase) {
    try {
      await runStartupValidation()
    } catch (error) {
      logger.error('Startup: Rate limiter validation failed', error as Error, {
        action: 'startup_validation',
        component: 'instrumentation'
      })

      // In production runtime (not build), only fail if Redis is explicitly required
      const redisRequired = process.env.ENABLE_RATE_LIMITING !== 'false';
      if (process.env.NODE_ENV === 'production' && redisRequired) {
        logger.warn('Rate limiter validation failed but continuing with fallback', {
          action: 'startup_validation_fallback'
        })
        // Don't throw - allow fallback to in-memory rate limiting
      }
    }
  }
}


// Hook to capture request errors from nested React Server Components
// https://docs.sentry.io/platforms/javascript/guides/nextjs/manual-setup/#errors-from-nested-react-server-components
export function onRequestError(err: unknown) {
  try {
    // Attempt to capture request error with Sentry
    // Wrap in extra try-catch because Sentry's captureRequestError can fail 
    // if it tries to access headers in a context where they are unavailable (Next.js 15 edge case)
    try {
      if (typeof Sentry.captureRequestError === 'function') {
        // @ts-ignore
        Sentry.captureRequestError(err)
      } else {
        Sentry.captureException(err instanceof Error ? err : new Error(String(err)))
      }
    } catch (sentryError) {
      // Fallback to simple exception capture if request error capture fails
      Sentry.captureException(err instanceof Error ? err : new Error(String(err)))
    }
  } catch (error) {
    logger.error('Failed to capture request error in Sentry', error as Error, {
      action: 'sentry_capture_error'
    })
  }
}