import {z} from 'zod'

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

export const metricsErrorRateDto = z.object({component: z.string(), totalRequests: z.number(), totalErrors: z.number(), errorRate: z.number(), windowMinutes: z.number()});

export const metricsSummaryDto = z.object({errorRate: z.array(metricsErrorRateDto), reviewsProcessed: z.number(), reviewsFailed: z.number(), avgReviewDurationMs: z.number(), timestamp: z.string()});

export const metricsSummaryResponseDto = z.object({statusCode: z.number(), type: z.string(), data: metricsSummaryDto});

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
};

/**
 * Metrics summary
 * 
 * GET /internal/metrics/summary
 */
export const getApiInternalMetricsSummary = async (options?: GetApiInternalMetricsSummaryOptions) => {
const {baseUrl = "http://localhost:3001", fetch: fetchFn = fetch, jwt} = options ?? {}

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

if (jwt !== undefined) headers.set('authorization', `Bearer ${jwt}`)

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