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import { Context } from './context.ts'import type { Env, NotFoundHandler, ErrorHandler } from './types.ts'
interface ComposeContext {  finalized: boolean  res: unknown}
// Based on the code in the MIT licensed `koa-compose` package.export const compose = <C extends ComposeContext, E extends Env = Env>(  middleware: Function[],  onError?: ErrorHandler<E>,  onNotFound?: NotFoundHandler<E>) => {  const middlewareLength = middleware.length  return (context: C, next?: Function) => {    let index = -1    return dispatch(0)
    function dispatch(i: number): C | Promise<C> {      if (i <= index) {        throw new Error('next() called multiple times')      }      let handler = middleware[i]      index = i      if (i === middlewareLength && next) handler = next
      let res      let isError = false
      if (!handler) {        if (context instanceof Context && context.finalized === false && onNotFound) {          res = onNotFound(context)        }      } else {        try {          res = handler(context, () => {            const dispatchRes = dispatch(i + 1)            return dispatchRes instanceof Promise ? dispatchRes : Promise.resolve(dispatchRes)          })        } catch (err) {          if (err instanceof Error && context instanceof Context && onError) {            context.error = err            res = onError(err, context)            isError = true          } else {            throw err          }        }      }
      if (!(res instanceof Promise)) {        if (res !== undefined && 'response' in res) {          res = res['response']        }        if (res && (context.finalized === false || isError)) {          context.res = res        }        return context      } else {        return res          .then((res) => {            if (res !== undefined && 'response' in res) {              res = res['response']            }            if (res && context.finalized === false) {              context.res = res            }            return context          })          .catch((err) => {            if (err instanceof Error && context instanceof Context && onError) {              context.error = err              context.res = onError(err, context)              return context            }            throw err          })      }    }  }}