import { propagation, context } from '@opentelemetry/api';
import { VERSION } from '@opentelemetry/core';
import { InstrumentationBase, InstrumentationNodeModuleDefinition } from '@opentelemetry/instrumentation';
import { getIsolationScope, httpRequestToRequestData, stripUrlQueryAndFragment, withIsolationScope, generateSpanId, getCurrentScope, logger, getClient, getBreadcrumbLogLevelFromHttpStatusCode, addBreadcrumb, parseUrl, getSanitizedUrlString } from '@sentry/core';
import { DEBUG_BUILD } from '../../debug-build.js';
import { getRequestUrl } from '../../utils/getRequestUrl.js';
import { stealthWrap } from './utils.js';
import { getRequestInfo } from './vendor/getRequestInfo.js';

const INSTRUMENTATION_NAME = '@sentry/instrumentation-http';

// We only want to capture request bodies up to 1mb.
const MAX_BODY_BYTE_LENGTH = 1024 * 1024;

/**
 * This custom HTTP instrumentation is used to isolate incoming requests and annotate them with additional information.
 * It does not emit any spans.
 *
 * The reason this is isolated from the OpenTelemetry instrumentation is that users may overwrite this,
 * which would lead to Sentry not working as expected.
 *
 * Important note: Contrary to other OTEL instrumentation, this one cannot be unwrapped.
 * It only does minimal things though and does not emit any spans.
 *
 * This is heavily inspired & adapted from:
 * https://github.com/open-telemetry/opentelemetry-js/blob/f8ab5592ddea5cba0a3b33bf8d74f27872c0367f/experimental/packages/opentelemetry-instrumentation-http/src/http.ts
 */
class SentryHttpInstrumentation extends InstrumentationBase {
   constructor(config = {}) {
    super(INSTRUMENTATION_NAME, VERSION, config);
  }

  /** @inheritdoc */
   init() {
    return [this._getHttpsInstrumentation(), this._getHttpInstrumentation()];
  }

  /** Get the instrumentation for the http module. */
   _getHttpInstrumentation() {
    return new InstrumentationNodeModuleDefinition(
      'http',
      ['*'],
      (moduleExports) => {
        // Patch incoming requests for request isolation
        stealthWrap(moduleExports.Server.prototype, 'emit', this._getPatchIncomingRequestFunction());

        // Patch outgoing requests for breadcrumbs
        const patchedRequest = stealthWrap(moduleExports, 'request', this._getPatchOutgoingRequestFunction());
        stealthWrap(moduleExports, 'get', this._getPatchOutgoingGetFunction(patchedRequest));

        return moduleExports;
      },
      () => {
        // no unwrap here
      },
    );
  }

  /** Get the instrumentation for the https module. */
   _getHttpsInstrumentation() {
    return new InstrumentationNodeModuleDefinition(
      'https',
      ['*'],
      (moduleExports) => {
        // Patch incoming requests for request isolation
        stealthWrap(moduleExports.Server.prototype, 'emit', this._getPatchIncomingRequestFunction());

        // Patch outgoing requests for breadcrumbs
        const patchedRequest = stealthWrap(moduleExports, 'request', this._getPatchOutgoingRequestFunction());
        stealthWrap(moduleExports, 'get', this._getPatchOutgoingGetFunction(patchedRequest));

        return moduleExports;
      },
      () => {
        // no unwrap here
      },
    );
  }

  /**
   * Patch the incoming request function for request isolation.
   */
   _getPatchIncomingRequestFunction()

 {
    // eslint-disable-next-line @typescript-eslint/no-this-alias
    const instrumentation = this;
    const { ignoreIncomingRequestBody } = instrumentation.getConfig();

    return (
      original,
    ) => {
      return function incomingRequest( ...args) {
        // Only traces request events
        if (args[0] !== 'request') {
          return original.apply(this, args);
        }

        instrumentation._diag.debug('http instrumentation for incoming request');

        const isolationScope = getIsolationScope().clone();
        const request = args[1] ;
        const response = args[2] ;

        const normalizedRequest = httpRequestToRequestData(request);

        // request.ip is non-standard but some frameworks set this
        const ipAddress = (request ).ip || request.socket?.remoteAddress;

        const url = request.url || '/';
        if (!ignoreIncomingRequestBody?.(url, request)) {
          patchRequestToCaptureBody(request, isolationScope);
        }

        // Update the isolation scope, isolate this request
        isolationScope.setSDKProcessingMetadata({ normalizedRequest, ipAddress });

        // attempt to update the scope's `transactionName` based on the request URL
        // Ideally, framework instrumentations coming after the HttpInstrumentation
        // update the transactionName once we get a parameterized route.
        const httpMethod = (request.method || 'GET').toUpperCase();
        const httpTarget = stripUrlQueryAndFragment(url);

        const bestEffortTransactionName = `${httpMethod} ${httpTarget}`;

        isolationScope.setTransactionName(bestEffortTransactionName);

        if (instrumentation.getConfig().trackIncomingRequestsAsSessions !== false) {
          recordRequestSession({
            requestIsolationScope: isolationScope,
            response,
            sessionFlushingDelayMS: instrumentation.getConfig().sessionFlushingDelayMS ?? 60000,
          });
        }

        return withIsolationScope(isolationScope, () => {
          // Set a new propagationSpanId for this request
          // We rely on the fact that `withIsolationScope()` will implicitly also fork the current scope
          // This way we can save an "unnecessary" `withScope()` invocation
          getCurrentScope().getPropagationContext().propagationSpanId = generateSpanId();

          // If we don't want to extract the trace from the header, we can skip this
          if (!instrumentation.getConfig().extractIncomingTraceFromHeader) {
            return original.apply(this, args);
          }

          const ctx = propagation.extract(context.active(), normalizedRequest.headers);
          return context.with(ctx, () => {
            return original.apply(this, args);
          });
        });
      };
    };
  }

  /**
   * Patch the outgoing request function for breadcrumbs.
   */
   _getPatchOutgoingRequestFunction()

 {
    // eslint-disable-next-line @typescript-eslint/no-this-alias
    const instrumentation = this;

    return (original) => {
      return function outgoingRequest( ...args) {
        instrumentation._diag.debug('http instrumentation for outgoing requests');

        // Making a copy to avoid mutating the original args array
        // We need to access and reconstruct the request options object passed to `ignoreOutgoingRequests`
        // so that it matches what Otel instrumentation passes to `ignoreOutgoingRequestHook`.
        // @see https://github.com/open-telemetry/opentelemetry-js/blob/7293e69c1e55ca62e15d0724d22605e61bd58952/experimental/packages/opentelemetry-instrumentation-http/src/http.ts#L756-L789
        const argsCopy = [...args];

        const options = argsCopy.shift() ;

        const extraOptions =
          typeof argsCopy[0] === 'object' && (typeof options === 'string' || options instanceof URL)
            ? (argsCopy.shift() )
            : undefined;

        const { optionsParsed } = getRequestInfo(instrumentation._diag, options, extraOptions);

        const request = original.apply(this, args) ;

        request.prependListener('response', (response) => {
          const _breadcrumbs = instrumentation.getConfig().breadcrumbs;
          const breadCrumbsEnabled = typeof _breadcrumbs === 'undefined' ? true : _breadcrumbs;

          const _ignoreOutgoingRequests = instrumentation.getConfig().ignoreOutgoingRequests;
          const shouldCreateBreadcrumb =
            typeof _ignoreOutgoingRequests === 'function'
              ? !_ignoreOutgoingRequests(getRequestUrl(request), optionsParsed)
              : true;

          if (breadCrumbsEnabled && shouldCreateBreadcrumb) {
            addRequestBreadcrumb(request, response);
          }
        });

        return request;
      };
    };
  }

  /** Path the outgoing get function for breadcrumbs. */
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
   _getPatchOutgoingGetFunction(clientRequest) {
    return (_original) => {
      // Re-implement http.get. This needs to be done (instead of using
      // getPatchOutgoingRequestFunction to patch it) because we need to
      // set the trace context header before the returned http.ClientRequest is
      // ended. The Node.js docs state that the only differences between
      // request and get are that (1) get defaults to the HTTP GET method and
      // (2) the returned request object is ended immediately. The former is
      // already true (at least in supported Node versions up to v10), so we
      // simply follow the latter. Ref:
      // https://nodejs.org/dist/latest/docs/api/http.html#http_http_get_options_callback
      // https://github.com/googleapis/cloud-trace-nodejs/blob/master/src/instrumentations/instrumentation-http.ts#L198
      return function outgoingGetRequest(...args) {
        const req = clientRequest(...args);
        req.end();
        return req;
      };
    };
  }
}

/** Add a breadcrumb for outgoing requests. */
function addRequestBreadcrumb(request, response) {
  const data = getBreadcrumbData(request);

  const statusCode = response.statusCode;
  const level = getBreadcrumbLogLevelFromHttpStatusCode(statusCode);

  addBreadcrumb(
    {
      category: 'http',
      data: {
        status_code: statusCode,
        ...data,
      },
      type: 'http',
      level,
    },
    {
      event: 'response',
      request,
      response,
    },
  );
}

function getBreadcrumbData(request) {
  try {
    // `request.host` does not contain the port, but the host header does
    const host = request.getHeader('host') || request.host;
    const url = new URL(request.path, `${request.protocol}//${host}`);
    const parsedUrl = parseUrl(url.toString());

    const data = {
      url: getSanitizedUrlString(parsedUrl),
      'http.method': request.method || 'GET',
    };

    if (parsedUrl.search) {
      data['http.query'] = parsedUrl.search;
    }
    if (parsedUrl.hash) {
      data['http.fragment'] = parsedUrl.hash;
    }

    return data;
  } catch {
    return {};
  }
}

/**
 * This method patches the request object to capture the body.
 * Instead of actually consuming the streamed body ourselves, which has potential side effects,
 * we monkey patch `req.on('data')` to intercept the body chunks.
 * This way, we only read the body if the user also consumes the body, ensuring we do not change any behavior in unexpected ways.
 */
function patchRequestToCaptureBody(req, isolationScope) {
  let bodyByteLength = 0;
  const chunks = [];

  /**
   * We need to keep track of the original callbacks, in order to be able to remove listeners again.
   * Since `off` depends on having the exact same function reference passed in, we need to be able to map
   * original listeners to our wrapped ones.
   */
  const callbackMap = new WeakMap();

  try {
    // eslint-disable-next-line @typescript-eslint/unbound-method
    req.on = new Proxy(req.on, {
      apply: (target, thisArg, args) => {
        const [event, listener, ...restArgs] = args;

        if (DEBUG_BUILD) {
          logger.log(INSTRUMENTATION_NAME, 'Patching request.on', event);
        }

        if (event === 'data') {
          const callback = new Proxy(listener, {
            apply: (target, thisArg, args) => {
              try {
                const chunk = args[0] ;
                const bufferifiedChunk = Buffer.from(chunk);

                if (bodyByteLength < MAX_BODY_BYTE_LENGTH) {
                  chunks.push(bufferifiedChunk);
                  bodyByteLength += bufferifiedChunk.byteLength;
                } else if (DEBUG_BUILD) {
                  logger.log(
                    INSTRUMENTATION_NAME,
                    `Dropping request body chunk because maximum body length of ${MAX_BODY_BYTE_LENGTH}b is exceeded.`,
                  );
                }
              } catch (err) {
                DEBUG_BUILD && logger.error(INSTRUMENTATION_NAME, 'Encountered error while storing body chunk.');
              }

              return Reflect.apply(target, thisArg, args);
            },
          });

          callbackMap.set(listener, callback);

          return Reflect.apply(target, thisArg, [event, callback, ...restArgs]);
        }

        return Reflect.apply(target, thisArg, args);
      },
    });

    // Ensure we also remove callbacks correctly
    // eslint-disable-next-line @typescript-eslint/unbound-method
    req.off = new Proxy(req.off, {
      apply: (target, thisArg, args) => {
        const [, listener] = args;

        const callback = callbackMap.get(listener);
        if (callback) {
          callbackMap.delete(listener);

          const modifiedArgs = args.slice();
          modifiedArgs[1] = callback;
          return Reflect.apply(target, thisArg, modifiedArgs);
        }

        return Reflect.apply(target, thisArg, args);
      },
    });

    req.on('end', () => {
      try {
        const body = Buffer.concat(chunks).toString('utf-8');
        if (body) {
          isolationScope.setSDKProcessingMetadata({ normalizedRequest: { data: body } });
        }
      } catch (error) {
        if (DEBUG_BUILD) {
          logger.error(INSTRUMENTATION_NAME, 'Error building captured request body', error);
        }
      }
    });
  } catch (error) {
    if (DEBUG_BUILD) {
      logger.error(INSTRUMENTATION_NAME, 'Error patching request to capture body', error);
    }
  }
}

/**
 * Starts a session and tracks it in the context of a given isolation scope.
 * When the passed response is finished, the session is put into a task and is
 * aggregated with other sessions that may happen in a certain time window
 * (sessionFlushingDelayMs).
 *
 * The sessions are always aggregated by the client that is on the current scope
 * at the time of ending the response (if there is one).
 */
// Exported for unit tests
function recordRequestSession({
  requestIsolationScope,
  response,
  sessionFlushingDelayMS,
}

) {
  requestIsolationScope.setSDKProcessingMetadata({
    requestSession: { status: 'ok' },
  });
  response.once('close', () => {
    // We need to grab the client off the current scope instead of the isolation scope because the isolation scope doesn't hold any client out of the box.
    const client = getClient();
    const requestSession = requestIsolationScope.getScopeData().sdkProcessingMetadata.requestSession;

    if (client && requestSession) {
      DEBUG_BUILD && logger.debug(`Recorded request session with status: ${requestSession.status}`);

      const roundedDate = new Date();
      roundedDate.setSeconds(0, 0);
      const dateBucketKey = roundedDate.toISOString();

      const existingClientAggregate = clientToRequestSessionAggregatesMap.get(client);
      const bucket = existingClientAggregate?.[dateBucketKey] || { exited: 0, crashed: 0, errored: 0 };
      bucket[({ ok: 'exited', crashed: 'crashed', errored: 'errored' } )[requestSession.status]]++;

      if (existingClientAggregate) {
        existingClientAggregate[dateBucketKey] = bucket;
      } else {
        DEBUG_BUILD && logger.debug('Opened new request session aggregate.');
        const newClientAggregate = { [dateBucketKey]: bucket };
        clientToRequestSessionAggregatesMap.set(client, newClientAggregate);

        const flushPendingClientAggregates = () => {
          clearTimeout(timeout);
          unregisterClientFlushHook();
          clientToRequestSessionAggregatesMap.delete(client);

          const aggregatePayload = Object.entries(newClientAggregate).map(
            ([timestamp, value]) => ({
              started: timestamp,
              exited: value.exited,
              errored: value.errored,
              crashed: value.crashed,
            }),
          );
          client.sendSession({ aggregates: aggregatePayload });
        };

        const unregisterClientFlushHook = client.on('flush', () => {
          DEBUG_BUILD && logger.debug('Sending request session aggregate due to client flush');
          flushPendingClientAggregates();
        });
        const timeout = setTimeout(() => {
          DEBUG_BUILD && logger.debug('Sending request session aggregate due to flushing schedule');
          flushPendingClientAggregates();
        }, sessionFlushingDelayMS).unref();
      }
    }
  });
}

const clientToRequestSessionAggregatesMap = new Map

();

export { SentryHttpInstrumentation, recordRequestSession };
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