import { SourceMapConsumer, RawSourceMap } from 'source-map'
import { ModuleGraph } from '../server/moduleGraph'

let offset: number
try {
  new Function('throw new Error(1)')()
} catch (e) {
  // in Node 12, stack traces account for the function wrapper.
  // in Node 13 and later, the function wrapper adds two lines,
  // which must be subtracted to generate a valid mapping
  const match = /:(\d+):\d+\)$/.exec(e.stack.split('\n')[1])
  offset = match ? +match[1] - 1 : 0
}

export function ssrRewriteStacktrace(
  stack: string,
  moduleGraph: ModuleGraph
): string {
  return stack
    .split('\n')
    .map((line) => {
      return line.replace(
        /^ {4}at (?:(.+?)\s+\()?(?:(.+?):(\d+)(?::(\d+))?)\)?/,
        (input, varName, url, line, column) => {
          if (!url) return input

          const mod = moduleGraph.urlToModuleMap.get(url)
          const rawSourceMap = mod?.ssrTransformResult?.map

          if (!rawSourceMap) {
            return input
          }

          const consumer = new SourceMapConsumer(
            rawSourceMap as any as RawSourceMap
          )

          const pos = consumer.originalPositionFor({
            line: Number(line) - offset,
            column: Number(column),
            bias: SourceMapConsumer.LEAST_UPPER_BOUND
          })

          if (!pos.source) {
            return input
          }

          const source = `${pos.source}:${pos.line || 0}:${pos.column || 0}`
          if (!varName || varName === 'eval') {
            return `    at ${source}`
          } else {
            return `    at ${varName} (${source})`
          }
        }
      )
    })
    .join('\n')
}