@httpland/range-request-middleware/esm/middleware.js

HTTP range request middleware

// Copyright 2023-latest the httpland authors. All rights reserved. MIT license.
// This module is browser compatible.
import { ConditionalHeader, isNotEmpty, isNull, Method, RangeHeader, } from "./deps.js";
import { withAcceptRanges, withContentRange } from "./transform.js";
import { BytesRange } from "./ranges/bytes.js";
import { RangeUnit } from "./utils.js";
/** Create range request middleware.
 *
 * @example
 * ```ts
 * import { rangeRequest } from "https://deno.land/x/range_request_middleware@$VERSION/middleware.ts";
 * import {
 *   assert,
 *   assertEquals,
 *   assertThrows,
 * } from "https://deno.land/std/testing/asserts.ts";
 *
 * const middleware = rangeRequest();
 * const request = new Request("test:", {
 *   headers: { range: "bytes=5-9" },
 * });
 * const response = await middleware(
 *   request,
 *   () => new Response("abcdefghijklmnopqrstuvwxyz"),
 * );
 *
 * assertEquals(response.status, 206);
 * assertEquals(response.headers.get("content-range"), "bytes 5-9/26");
 * assertEquals(response.headers.get("accept-ranges"), "bytes");
 * assertEquals(await response.text(), "fghij");
 * ```
 */
export function rangeRequest(ranges) {
    const $ranges = ranges ?? [new BytesRange()];
    const units = Array.from($ranges).map((range) => range.rangeUnit);
    const unitLike = isNotEmpty(units) ? units : RangeUnit.None;
    const contentRangeMiddleware = contentRange($ranges);
    const acceptRangesMiddleware = acceptRanges(unitLike);
    return (request, next) => {
        return contentRangeMiddleware(request, (request) => acceptRangesMiddleware(request, next));
    };
}
export function contentRange(ranges) {
    const $ranges = ranges ?? [new BytesRange()];
    return async (request, next) => {
        const rangeValue = request.headers.get(RangeHeader.Range);
        // A server MUST ignore a Range header field received with a request method that is unrecognized or for which range handling is not defined. For this specification, GET is the only method for which range handling is defined.
        // @see https://www.rfc-editor.org/rfc/rfc9110#section-14.2-4
        if (request.method !== Method.Get ||
            isNull(rangeValue) ||
            request.headers.has(ConditionalHeader.IfRange))
            return next(request);
        const response = await next(request);
        return withContentRange(response, { ranges: $ranges, rangeValue });
    };
}
export function acceptRanges(unitLike) {
    const rangeUnit = unitLike ?? RangeUnit.Bytes;
    return async (request, next) => {
        const response = await next(request);
        return withAcceptRanges(response, rangeUnit);
    };
}