export interface PublicKeyCredentialDescriptorJSON {
  type: 'public-key'
  id: string
  transports?: AuthenticatorTransport[]
}

export interface PublicKeyCredentialUserEntityJSON {
  id: string
  name: string
  displayName: string
}

export interface PublicKeyCredentialRpEntityJSON {
  name: string
  id?: string
}

export interface PublicKeyCredentialParametersJSON {
  type: 'public-key'
  alg: number
}

export interface AuthenticatorSelectionCriteriaJSON {
  authenticatorAttachment?: AuthenticatorAttachment
  residentKey?: ResidentKeyRequirement
  requireResidentKey?: boolean
  userVerification?: UserVerificationRequirement
}

export interface PublicKeyCredentialCreationOptionsJSON {
  rp: PublicKeyCredentialRpEntityJSON
  user: PublicKeyCredentialUserEntityJSON
  challenge: string
  pubKeyCredParams: PublicKeyCredentialParametersJSON[]
  timeout?: number
  excludeCredentials?: PublicKeyCredentialDescriptorJSON[]
  authenticatorSelection?: AuthenticatorSelectionCriteriaJSON
  attestation?: AttestationConveyancePreference
}

export interface PublicKeyCredentialRequestOptionsJSON {
  challenge: string
  timeout?: number
  rpId?: string
  allowCredentials?: PublicKeyCredentialDescriptorJSON[]
  userVerification?: UserVerificationRequirement
}

export interface WebAuthnCreationOptionsResponse {
  publicKey: PublicKeyCredentialCreationOptionsJSON
}

export interface WebAuthnRequestOptionsResponse {
  publicKey: PublicKeyCredentialRequestOptionsJSON
}

export interface CredentialAssertionJSON {
  id: string
  type: string
  rawId: string
  response: {
    clientDataJSON: string
    authenticatorData: string
    signature: string
    userHandle: string | null
  }
}

export interface CredentialAttestationJSON {
  id: string
  type: string
  rawId: string
  response: {
    clientDataJSON: string
    attestationObject: string
  }
}

export function base64UrlToArrayBuffer(base64url: string): ArrayBuffer {
  const base64 = base64url.replace(/-/g, '+').replace(/_/g, '/')
  const padded = base64 + '='.repeat((4 - (base64.length % 4)) % 4)
  const binary = atob(padded)
  return Uint8Array.from(binary, (char) => char.charCodeAt(0)).buffer
}

export function arrayBufferToBase64Url(buffer: ArrayBuffer): string {
  const bytes = new Uint8Array(buffer)
  const binary = Array.from(bytes, (byte) => String.fromCharCode(byte)).join('')
  return btoa(binary).replace(/\+/g, '-').replace(/\//g, '_').replace(/=/g, '')
}

export function prepareCreationOptions(
  options: WebAuthnCreationOptionsResponse
): PublicKeyCredentialCreationOptions {
  const pk = options.publicKey
  return {
    ...pk,
    challenge: base64UrlToArrayBuffer(pk.challenge),
    user: {
      ...pk.user,
      id: base64UrlToArrayBuffer(pk.user.id),
    },
    excludeCredentials: (pk.excludeCredentials ?? []).map((cred) => ({
      ...cred,
      id: base64UrlToArrayBuffer(cred.id),
    })),
  }
}

export function prepareRequestOptions(
  options: WebAuthnRequestOptionsResponse
): PublicKeyCredentialRequestOptions {
  const pk = options.publicKey
  return {
    ...pk,
    challenge: base64UrlToArrayBuffer(pk.challenge),
    allowCredentials: (pk.allowCredentials ?? []).map((cred) => ({
      ...cred,
      id: base64UrlToArrayBuffer(cred.id),
    })),
  }
}

export function serializeAttestationResponse(
  credential: PublicKeyCredential
): CredentialAttestationJSON {
  const response = credential.response as AuthenticatorAttestationResponse
  return {
    id: credential.id,
    type: credential.type,
    rawId: arrayBufferToBase64Url(credential.rawId),
    response: {
      clientDataJSON: arrayBufferToBase64Url(response.clientDataJSON),
      attestationObject: arrayBufferToBase64Url(response.attestationObject),
    },
  }
}

export function serializeAssertionResponse(
  credential: PublicKeyCredential
): CredentialAssertionJSON {
  const response = credential.response as AuthenticatorAssertionResponse
  return {
    id: credential.id,
    type: credential.type,
    rawId: arrayBufferToBase64Url(credential.rawId),
    response: {
      clientDataJSON: arrayBufferToBase64Url(response.clientDataJSON),
      authenticatorData: arrayBufferToBase64Url(response.authenticatorData),
      signature: arrayBufferToBase64Url(response.signature),
      userHandle: response.userHandle
        ? arrayBufferToBase64Url(response.userHandle)
        : null,
    },
  }
}