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import type { Context } from '../../context.ts'import { HTTPException } from '../../http-exception.ts'import type { MiddlewareHandler } from '../../types.ts'
const ERROR_MESSAGE = 'Payload Too Large'
type OnError = (c: Context) => Response | Promise<Response>type BodyLimitOptions = {  maxSize: number  onError?: OnError}
class BodyLimitError extends Error {  constructor(message: string) {    super(message)    this.name = 'BodyLimitError'  }}
/** * Body Limit Middleware * * @example * ```ts * app.post( *  '/hello', *  bodyLimit({ *    maxSize: 100 * 1024, // 100kb *    onError: (c) => { *      return c.text('overflow :(', 413) *    } *  }), *  (c) => { *    return c.text('pass :)') *  } * ) * ``` */export const bodyLimit = (options: BodyLimitOptions): MiddlewareHandler => {  const onError: OnError =    options.onError ||    (() => {      const res = new Response(ERROR_MESSAGE, {        status: 413,      })      throw new HTTPException(413, { res })    })  const maxSize = options.maxSize
  return async function bodyLimit(c, next) {    if (!c.req.raw.body) {      // maybe GET or HEAD request      return next()    }
    if (c.req.raw.headers.has('content-length')) {      // we can trust content-length header because it's already validated by server      const contentLength = parseInt(c.req.raw.headers.get('content-length') || '0', 10)      return contentLength > maxSize ? onError(c) : next()    }
    // maybe chunked transfer encoding
    let size = 0    const rawReader = c.req.raw.body.getReader()    const reader = new ReadableStream({      async start(controller) {        try {          for (;;) {            const { done, value } = await rawReader.read()            if (done) {              break            }            size += value.length            if (size > maxSize) {              controller.error(new BodyLimitError(ERROR_MESSAGE))              break            }
            controller.enqueue(value)          }        } finally {          controller.close()        }      },    })
    c.req.raw = new Request(c.req.raw, { body: reader })
    await next()
    if (c.error instanceof BodyLimitError) {      c.res = await onError(c)    }  }}