import {z} from 'zod'

export type GetApiAccountLimitsOptions = {baseUrl?: string | undefined, kalshiAccessKey?: string | undefined, kalshiAccessSignature?: string | undefined, kalshiAccessTimestamp?: string | undefined, fetch?: typeof fetch | undefined};

export const bucketLimit = z.object({refill_rate: z.number().int(), bucket_capacity: z.number().int()});

export const exchangeInstance = z.enum(["event_contract", "margined"]);

export const apiUsageLevelGrant = z.object({exchange_instance: exchangeInstance, level: z.string(), expires_ts: z.number().int().nullable().optional(), source: z.string()});

export const getAccountApiLimitsResponse = z.object({usage_tier: z.string(), read: bucketLimit, write: bucketLimit, grants: z.array(apiUsageLevelGrant)});

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
};

/**
 * Get Account API Limits
 * 
 * GET /account/limits
 */
export const getApiAccountLimits = async (options?: GetApiAccountLimitsOptions) => {
const {baseUrl = "https://external-api.kalshi.com/trade-api/v2", fetch: fetchFn = fetch, kalshiAccessKey, kalshiAccessSignature, kalshiAccessTimestamp} = options ?? {}

const query = new URLSearchParams()
const headers = new Headers()
headers.set('accept', "application/json")

if (kalshiAccessKey !== undefined) headers.set("KALSHI-ACCESS-KEY", kalshiAccessKey)
if (kalshiAccessSignature !== undefined) headers.set("KALSHI-ACCESS-SIGNATURE", kalshiAccessSignature)
if (kalshiAccessTimestamp !== undefined) headers.set("KALSHI-ACCESS-TIMESTAMP", kalshiAccessTimestamp)

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

const res = await fetchFn(url, {method: "GET", headers})

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

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