import { bases } from 'multiformats/basics'
import type { MultibaseCodec } from 'multiformats'
import { allocUnsafe } from '#alloc'

function createCodec (name: string, prefix: string, encode: (buf: Uint8Array) => string, decode: (str: string) => Uint8Array): MultibaseCodec<any> {
  return {
    name,
    prefix,
    encoder: {
      name,
      prefix,
      encode
    },
    decoder: {
      decode
    }
  }
}

const string = createCodec('utf8', 'u', (buf) => {
  const decoder = new TextDecoder('utf8')
  return 'u' + decoder.decode(buf)
}, (str) => {
  const encoder = new TextEncoder()
  return encoder.encode(str.substring(1))
})

const ascii = createCodec('ascii', 'a', (buf) => {
  let string = 'a'

  for (let i = 0; i < buf.length; i++) {
    string += String.fromCharCode(buf[i])
  }
  return string
}, (str) => {
  str = str.substring(1)
  const buf = allocUnsafe(str.length)

  for (let i = 0; i < str.length; i++) {
    buf[i] = str.charCodeAt(i)
  }

  return buf
})

export type SupportedEncodings = 'utf8' | 'utf-8' | 'hex' | 'latin1' | 'ascii' | 'binary' | keyof typeof bases

const BASES: Record<SupportedEncodings, MultibaseCodec<any>> = {
  utf8: string,
  'utf-8': string,
  hex: bases.base16,
  latin1: ascii,
  ascii,
  binary: ascii,

  ...bases
}

export default BASES