import {z} from 'zod'

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

export const incidentHref = z.string();

export const eventSeverity = z.enum(["info", "severe", "warning"]);

export const timestamp = z.string();

export const incident = z.object({href: incidentHref.optional(), state: z.enum(["identified", "monitoring", "resolved"]).optional(), severity: eventSeverity.optional(), summary: z.string().optional(), type: z.string().optional(), created: timestamp.optional(), resolved: timestamp.optional(), updated: timestamp.optional(), subject: z.string().optional()});

export const statusIncident = z.object({type: z.literal("incident").optional(), element: incident.optional()});

export const statusTimelineEntry = z.object({time: timestamp.optional(), entry: z.lazy(() => statusElement.optional())});

export const statusTimeline = z.object({type: z.literal("timeline").optional(), element: z.array(statusTimelineEntry).optional()});

export const statusVersions = z.object({type: z.literal("versions").optional(), element: z.object({components: z.array(z.object({name: z.string().optional(), version: z.string().optional()})).optional()}).optional()});

export const statusElement: z.ZodType<StatusElement> = z.union([statusIncident, statusTimeline, statusVersions]);

export const getApiStatusResponse = z.array(statusElement);

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
};

/**
 * Status of the system
 * 
 * GET /status
 */
export const getApiStatus = async (options?: GetApiStatusOptions) => {
const {baseUrl = "https://api.webscale.com/v2", fetch: fetchFn = fetch} = options ?? {}

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

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