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import { bytes } from '../deps.ts'import { FormDataBody, FormFile } from '../types.ts'
const encoder = new TextEncoder()const decoder = new TextDecoder()
const encode = {  contentType: encoder.encode('Content-Type'),  filename: encoder.encode('filename'),  name: encoder.encode('name'),  dashdash: encoder.encode('--'),  boundaryEqual: encoder.encode('boundary='),  returnNewline2: encoder.encode('\r\n\r\n'),  carriageReturn: encoder.encode('\r'),}
export async function multiParser(  body: Deno.Reader,  contentType: string): Promise<FormDataBody> {  let buf = await Deno.readAll(body)  let boundaryByte = getBoundary(contentType)
  if (!boundaryByte) {    throw new Error('No boundary data information')  }
  // Generate an array of Uint8Array  const pieces = getFieldPieces(buf, boundaryByte!)
  // Set all the pieces into one single object  const form = getForm(pieces)
  return form}
function createFormData(): FormDataBody {  return {    fields: {},    files: [],    getFile(key: string) {      return this.files.find((i) => i.name === key)    },    get(key: string) {      return this.fields[key]    },  }}
function getForm(pieces: Uint8Array[]) {  let form: FormDataBody = createFormData()
  for (let piece of pieces) {    const { headerByte, contentByte } = splitPiece(piece)    const headers = getHeaders(headerByte)
    // it's a string field    if (typeof headers === 'string') {      // empty content, discard it      if (contentByte.byteLength === 1 && contentByte[0] === 13) {        continue      }
      // headers = "field1"      else {        form.fields[headers] = decoder.decode(contentByte)      }    }
    // it's a file field    else {      let file: FormFile = {        name: headers.name,        filename: headers.filename,        contentType: headers.contentType,        size: contentByte.byteLength,        content: contentByte,      }
      form.files.push(file)    }  }  return form}
function getHeaders(headerByte: Uint8Array) {  let contentTypeIndex = bytes.indexOf(headerByte, encode.contentType)
  // no contentType, it may be a string field, return name only  if (contentTypeIndex < 0) {    return getNameOnly(headerByte)  }
  // file field, return with name, filename and contentType  else {    return getHeaderNContentType(headerByte, contentTypeIndex)  }}
function getHeaderNContentType(  headerByte: Uint8Array,  contentTypeIndex: number,) {  let headers: Record<string, string> = {}
  let contentDispositionByte = headerByte.slice(0, contentTypeIndex - 2)  headers = getHeaderOnly(contentDispositionByte)
  // jump over <Content-Type: >  let contentTypeByte = headerByte.slice(    contentTypeIndex + encode.contentType.byteLength + 2,  )
  headers.contentType = decoder.decode(contentTypeByte)  return headers}
function getHeaderOnly(headerLineByte: Uint8Array) {  let headers: Record<string, string> = {}
  let filenameIndex = bytes.indexOf(headerLineByte, encode.filename)  if (filenameIndex < 0) {    headers.name = getNameOnly(headerLineByte)  } else {    headers = getNameNFilename(headerLineByte, filenameIndex)  }  return headers}
function getNameNFilename(headerLineByte: Uint8Array, filenameIndex: number) {  // fetch filename first  let nameByte = headerLineByte.slice(0, filenameIndex - 2)  let filenameByte = headerLineByte.slice(    filenameIndex + encode.filename.byteLength + 2,    headerLineByte.byteLength - 1,  )
  let name = getNameOnly(nameByte)  let filename = decoder.decode(filenameByte)  return { name, filename }}
function getNameOnly(headerLineByte: Uint8Array) {  let nameIndex = bytes.indexOf(headerLineByte, encode.name)
  // jump <name="> and get string inside double quote => "string"  let nameByte = headerLineByte.slice(    nameIndex + encode.name.byteLength + 2,    headerLineByte.byteLength - 1,  )
  return decoder.decode(nameByte)}
function splitPiece(piece: Uint8Array) {  const contentIndex = bytes.indexOf(piece, encode.returnNewline2)  const headerByte = piece.slice(0, contentIndex)  const contentByte = piece.slice(contentIndex + 4)
  return { headerByte, contentByte }}
function getFieldPieces(  buf: Uint8Array,  boundaryByte: Uint8Array,): Uint8Array[] {  const startBoundaryByte = bytes.concat(encode.dashdash, boundaryByte)  const endBoundaryByte = bytes.concat(startBoundaryByte, encode.dashdash)
  const pieces = []
  while (!bytes.startsWith(buf, endBoundaryByte)) {    // jump over boundary + '\r\n'    buf = buf.slice(startBoundaryByte.byteLength + 2)    let boundaryIndex = bytes.indexOf(buf, startBoundaryByte)
    // get field content piece    pieces.push(buf.slice(0, boundaryIndex - 1))    buf = buf.slice(boundaryIndex)  }
  return pieces}
function getBoundary(contentType: string): Uint8Array | undefined {  let contentTypeByte = encoder.encode(contentType)  let boundaryIndex = bytes.indexOf(contentTypeByte, encode.boundaryEqual)
  if (boundaryIndex >= 0) {    // jump over 'boundary=' to get the real boundary    let boundary = contentTypeByte.slice(      boundaryIndex + encode.boundaryEqual.byteLength,    )    return boundary  } else {    return undefined  }}