@mwcp/otel/src/lib/decorator.helper.async.ts

midway component for open telemetry

import assert from 'node:assert'

import { processDecoratorSpanData } from './decorator.helper.base.js'
import type {
  DecoratorContext,
  DecoratorExecutorParam,
  DecoratorTraceDataResp,
  TraceDecoratorOptions,
} from './trace.service/index.trace.service.js'
import { getSpan, isSpanEnded } from './util.js'

// #region processDecoratorBeforeAfterAsync

/**
 * @description options.{traceContext|span} may be modified with `traceContext` returned by `before()` or `after()`
 */
export async function processDecoratorBeforeAfterAsync(
  type: 'before' | 'after' | 'afterThrow',
  options: DecoratorExecutorParam<TraceDecoratorOptions>,
): Promise<DecoratorTraceDataResp> {

  const { mergedDecoratorParam, span, traceService } = options
  // not check traceService due to TraceInit decorator
  assert(span, 'span is required')

  const func = mergedDecoratorParam?.[type]
  if (typeof func === 'function') {
    assert(! isSpanEnded(span), 'span is ended after method call')
    const decoratorContext: DecoratorContext = {
      webApp: options.webApp,
      webContext: options.webContext,
      traceService: options.traceService,
      traceContext: options.traceContext,
      traceSpan: span,
      traceScope: options.traceScope,
      /** Caller Class name */
      instanceName: options.instanceName,
      /** Caller method name */
      methodName: options.methodName,
      instance: options.instance,
    }

    // const funcBind = isArrowFunction(func) ? func : func.bind(decoratorContext.instance) // sometimes not work detect arrow function
    const funcBind = func.bind(decoratorContext.instance)

    let data: DecoratorTraceDataResp
    if (type === 'before') {
      const func2 = funcBind
      // @ts-expect-error param type
      data = await func2(options.methodArgs, decoratorContext)
    }
    else if (type === 'after') {
      const func2 = funcBind
      // @ts-expect-error param type
      data = await func2(options.methodArgs, options.methodResult, decoratorContext)
    }
    else {
      const func2 = funcBind
      assert(options.error, 'options.error is required')
      // @ts-expect-error param type
      data = await func2(options.methodArgs, options.error, decoratorContext)
    }

    if (data && Object.keys(data).length) {
      const eventName = type
      if (data.events && ! data.events['event']) {
        data.events['event'] = eventName
      }

      if (data.traceContext) {
        options.traceContext = data.traceContext
        options.span = getSpan(options.traceContext)
      }
      assert(options.span, `processDecoratorBeforeAfterAsync(): span is required with new traceContext returned by "${type}()"`)

      processDecoratorSpanData(options.rootTraceContext, traceService, options.span, data)
      return data
    }

    return null
  }
}