@datadog/browser-logs/src/domain/assembly.ts

import type { Context, EventRateLimiter, RawError } from '@datadog/browser-core'
import {
  DISCARDED,
  ErrorSource,
  HookNames,
  buildTags,
  combine,
  createEventRateLimiter,
  getRelativeTime,
} from '@datadog/browser-core'
import type { CommonContext } from '../rawLogsEvent.types'
import type { LogsEvent } from '../logsEvent.types'
import type { LogsConfiguration } from './configuration'
import type { LifeCycle } from './lifeCycle'
import { LifeCycleEventType } from './lifeCycle'
import { STATUSES } from './logger'
import type { Hooks } from './hooks'

export function startLogsAssembly(
  configuration: LogsConfiguration,
  lifeCycle: LifeCycle,
  hooks: Hooks,
  getCommonContext: () => CommonContext,
  reportError: (error: RawError) => void,
  eventRateLimit?: number
) {
  const statusWithCustom = (STATUSES as string[]).concat(['custom'])
  const logRateLimiters: { [key: string]: EventRateLimiter } = {}
  statusWithCustom.forEach((status) => {
    logRateLimiters[status] = createEventRateLimiter(status, reportError, eventRateLimit)
  })

  lifeCycle.subscribe(
    LifeCycleEventType.RAW_LOG_COLLECTED,
    ({ rawLogsEvent, messageContext = undefined, savedCommonContext = undefined, domainContext, ddtags = [] }) => {
      const startTime = getRelativeTime(rawLogsEvent.date)
      const commonContext = savedCommonContext || getCommonContext()
      const defaultLogsEventAttributes = hooks.triggerHook(HookNames.Assemble, {
        startTime,
      })

      if (defaultLogsEventAttributes === DISCARDED) {
        return
      }

      const defaultDdtags = buildTags(configuration)

      const log = combine(
        {
          view: commonContext.view,
        },
        defaultLogsEventAttributes,
        rawLogsEvent,
        messageContext,
        {
          ddtags: defaultDdtags.concat(ddtags).join(','),
        }
      ) as LogsEvent & Context

      if (
        configuration.beforeSend?.(log, domainContext) === false ||
        (log.origin !== ErrorSource.AGENT &&
          (logRateLimiters[log.status] ?? logRateLimiters['custom']).isLimitReached())
      ) {
        return
      }

      lifeCycle.notify(LifeCycleEventType.LOG_COLLECTED, log)
    }
  )
}