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import { bytes } from "./std.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.findIndex(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.findIndex(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.findIndex(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.findIndex(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.hasPrefix(buf, endBoundaryByte)) {        // jump over boundary + '\r\n'        buf = buf.slice(startBoundaryByte.byteLength + 2);        let boundaryIndex = bytes.findIndex(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.findIndex(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;    }}