import {z} from 'zod'

export type CreateApiPaymentsPrepareArgs = {body: {merchant_uid: string, amount: number, currency?: string | undefined}};

export type CreateApiPaymentsPrepareOptions = {baseUrl?: string | undefined, fetch?: typeof fetch | undefined};

export const paymentPrepareAnnotation = z.object({merchant_uid: z.string().optional(), amount: z.number().optional(), currency: z.string().optional()});

export const paymentPrepareResponse = z.object({code: z.number().int().optional(), message: z.string().optional(), response: paymentPrepareAnnotation.optional()});

export const validateResponse = async <Output>(
  schema: {
    readonly '~standard': {
      readonly validate: (value: unknown) => ({ readonly value: Output; readonly issues?: undefined } | { readonly issues: ReadonlyArray<{ readonly message: string; readonly path?: ReadonlyArray<PropertyKey | { readonly key: PropertyKey }> | undefined }> }) | Promise<{ readonly value: Output; readonly issues?: undefined } | { readonly issues: ReadonlyArray<{ readonly message: string; readonly path?: ReadonlyArray<PropertyKey | { readonly key: PropertyKey }> | undefined }> }>
    }
  },
  value: unknown
): Promise<Output> => {
  const result = await schema['~standard'].validate(value)

  if (result.issues !== undefined) {
    const detail = result.issues
      .map(({ message, path }) =>
        path?.length
          ? `${path.map((segment) => String(typeof segment === 'object' ? segment.key : segment)).join('.')}: ${message}`
          : message
      )
      .join('; ')

    throw new Error(`Response does not match the schema: ${detail}`, { cause: { issues: result.issues } })
  }

  return result.value
};

/**
 * 결제금액 사전등록 API
 * 
 * POST /payments/prepare
 */
export const createApiPaymentsPrepare = async (args: CreateApiPaymentsPrepareArgs, options?: CreateApiPaymentsPrepareOptions) => {
const {baseUrl = "https://api.iamport.kr", fetch: fetchFn = fetch} = options ?? {}

const query = new URLSearchParams()
const headers = new Headers()
headers.set('content-type', "application/x-www-form-urlencoded")
headers.set('accept', "application/json")

const url = `${baseUrl.replace(/\/+$/, '')}/payments/prepare${query.size > 0 ? `?${query}` : ''}`

const res = await fetchFn(url, {method: "POST", headers, body: new URLSearchParams(Object.entries(args.body).flatMap(([key, value]) => (value == null ? [] : [[key, String(value)]])))})

if (!res.ok) throw new Error(`Request failed with status ${res.status}`, {cause: {status: res.status, body: await res.text()}})

return validateResponse(paymentPrepareResponse, await res.json())
};