import split from 'split2'

import {validateDocument} from '../documentHasErrors.js'
import type {SanityDocument} from '../types.js'
import {
  ReplacementCharError,
  validateLineForReplacementChar,
} from './validateReplacementCharacters.js'

export interface JsonStreamerOptions {
  allowReplacementCharacters?: boolean | undefined
}

export function getJsonStreamer(options: JsonStreamerOptions = {}): NodeJS.ReadWriteStream {
  let lineNumber = 0
  const {allowReplacementCharacters} = options

  const getErrorMessage = (err: Error): string => {
    const suffix =
      lineNumber === 1 ? '\n\nMake sure this is valid ndjson (one JSON-document *per line*)' : ''

    return `Failed to parse line #${lineNumber}: ${err.message}${suffix}`
  }

  return split(parseRow)

  function parseRow(this: NodeJS.ReadWriteStream, row: string) {
    lineNumber++

    if (!row) {
      return undefined
    }

    try {
      // Check for replacement characters before parsing JSON
      if (allowReplacementCharacters !== true) {
        const replacementError = validateLineForReplacementChar(row, lineNumber)
        if (replacementError) {
          throw new ReplacementCharError(replacementError)
        }
      }

      const doc = JSON.parse(row) as SanityDocument
      const error = validateDocument(doc)
      if (error) {
        throw new Error(error)
      }

      return doc
    } catch (err) {
      if (err instanceof ReplacementCharError) {
        this.emit('error', err)
      } else if (err instanceof Error) {
        this.emit('error', new Error(getErrorMessage(err)))
      } else {
        this.emit(
          'error',
          new Error(`Unknown error occurred at line #${lineNumber}: ${String(err)}`),
        )
      }
    }

    return undefined
  }
}