import { BareError } from './BareServer.js';

const MAX_HEADER_VALUE = 3072;

/**

*

* Splits headers according to spec

* @param headers

* @returns Split headers

*/

export function splitHeaders(headers: Headers): Headers {

const output = new Headers(headers);

if (headers.has('x-bare-headers')) {

const value = headers.get('x-bare-headers')!;

if (value.length > MAX_HEADER_VALUE) {

output.delete('x-bare-headers');

let split = 0;

for (let i = 0; i < value.length; i += MAX_HEADER_VALUE) {

const part = value.slice(i, i + MAX_HEADER_VALUE);

const id = split++;

output.set(`x-bare-headers-${id}`, `;${part}`);

}

}

}

return output;

}

/**

* Joins headers according to spec

* @param headers

* @returns Joined headers

*/

export function joinHeaders(headers: Headers): Headers {

const output = new Headers(headers);

const prefix = 'x-bare-headers';

if (headers.has(`${prefix}-0`)) {

const join: string[] = [];

for (const [header, value] of headers) {

if (!header.startsWith(prefix)) {

continue;

}

if (!value.startsWith(';')) {

throw new BareError(400, {

code: 'INVALID_BARE_HEADER',

id: `request.headers.${header}`,

message: `Value didn't begin with semi-colon.`,

});

}

const id = parseInt(header.slice(prefix.length + 1));

join[id] = value.slice(1);

output.delete(header);

}

output.set(prefix, join.join(''));

}

return output;

}