import {z} from 'zod'

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

export const dataset = z.object({as_of: z.string().nullable().optional(), coverage: z.array(z.string()).nullable().optional(), date_field: z.string(), date_meaning: z.string().optional(), docs: z.string(), endpoint: z.string(), filters: z.array(z.string()), item_endpoint: z.string().nullable().optional(), items_key: z.string(), name: z.string(), other_endpoints: z.array(z.string()).optional(), paging: z.string(), sorts: z.array(z.string()), status: z.enum(["ok", "delayed", "unknown"]), tag: z.string(), title: z.string()});

export const datasetsResponse = z.object({auth: z.string(), base_url: z.string(), common_fields: z.record(z.string(), z.string()), common_fields_apply_to: z.array(z.string()).optional(), datasets: z.array(dataset), openapi: z.string(), statuses: z.record(z.string(), z.string()).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
};

/**
 * List every dataset the API serves
 * 
 * GET /api/datasets
 */
export const getApiApiDatasets = async (options?: GetApiApiDatasetsOptions) => {
const {baseUrl = "https://noozra.com", fetch: fetchFn = fetch} = options ?? {}

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

const url = `${baseUrl.replace(/\/+$/, '')}/api/datasets${query.size > 0 ? `?${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(datasetsResponse, await res.json())
};