web/packages/common/logger/createLogger.ts

import * as Sentry from "@sentry/nextjs"
import { flatten } from "flat"

const logLevels = ["debug", "info", "warn", "error"] as const
const minimumLogLevel = (() => {
  const configuredMinimumLogLevel = (
    (process.env.MINIMUM_LOG_LEVEL ||
      process.env.NEXT_PUBLIC_MINIMUM_LOG_LEVEL) ??
    "info"
  ).toLowerCase() as (typeof logLevels)[number]

  if (!logLevels.includes(configuredMinimumLogLevel)) {
    console.warn(
      `Invalid log level configured: ${configuredMinimumLogLevel}, defaulting to 'info'`
    )

    return "info"
  }

  return configuredMinimumLogLevel
})()

function shouldLog(level: (typeof logLevels)[number]) {
  return logLevels.indexOf(level) >= logLevels.indexOf(minimumLogLevel)
}

function getLogValue(args: unknown[]): Record<string, unknown> | undefined {
  if (!args || args.length === 0) {
    return undefined
  }
  if (args.length === 1 && typeof args[0] === "object") {
    return (args[0] as Record<string, unknown>) ?? undefined
  }
  if (args.length === 1) {
    return { value: args[0] }
  }
  return flatten(args)
}

export function createLogger(loggerPrefix: string | (() => Promise<string>)) {
  const asyncWrapper: () => Promise<string> =
    typeof loggerPrefix === "string" ? async () => loggerPrefix : loggerPrefix

  const getLoggerPrefix = async () => {
    const prefix = await asyncWrapper()
    if (!prefix) {
      return ""
    }

    return `[${prefix}]`
  }

  async function log(
    level: (typeof logLevels)[number],
    message: string,
    ...args: unknown[]
  ) {
    if (!shouldLog(level)) {
      return
    }

    const logValue = getLogValue(args)

    Sentry.logger[level](
      `${await getLoggerPrefix()} ${message}`.trim(),
      logValue
    )
    console[level](`${await getLoggerPrefix()} ${message}`.trim(), ...args)
  }

  return {
    async debug(message: string, ...args: unknown[]): Promise<void> {
      await log("debug", message, ...args)
    },
    async info(message: string, ...args: unknown[]): Promise<void> {
      await log("info", message, ...args)
    },
    async warn(message: string, ...args: unknown[]): Promise<void> {
      await log("warn", message, ...args)
    },
    async error(message: string, ...args: unknown[]): Promise<void> {
      await log("error", message, ...args)
    },
  }
}