import {z} from 'zod'

export type GetApiV2Options = {baseUrl: string, fetch?: typeof fetch | undefined};

export const parameterDescriptorV2 = z.object({name: z.string(), type: z.string(), required: z.boolean(), default: z.string().nullable().optional(), allowed_values: z.array(z.string()).nullable().optional(), description: z.string().nullable().optional()});

export const catalogEntryV2 = z.object({path: z.string(), method: z.string(), summary: z.string().nullable().optional(), description: z.string().nullable().optional(), tag: z.string().nullable().optional(), parameters: z.array(parameterDescriptorV2)});

export const catalogResponseV2 = z.object({schema_version: z.string(), title: z.string(), description: z.string(), openapi_url: z.string(), response_envelope: z.string(), endpoints: z.array(catalogEntryV2)});

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
};

/**
 * Machine-readable catalog of all v2 endpoints
 * 
 * GET /v2
 */
export const getApiV2 = async (options: GetApiV2Options) => {
const {baseUrl, fetch: fetchFn = fetch} = options ?? {}

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

const url = `${baseUrl.replace(/\/+$/, '')}/v2${query.size > 0 ? `?${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(catalogResponseV2, await res.json())
};