import {z} from 'zod'

export type GetApiUsageArgs = {start_date: string, end_date: string, timezone?: string | undefined};

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

export const webUsage = z.object({messages: z.number(), web_pages_scraped: z.number(), files_uploaded: z.number()});

export const wordUsage = z.object({messages: z.number(), redlines_applied: z.number(), drafts_applied: z.number()});

export const apiUsage = z.object({requests: z.number(), by_operation: z.record(z.string(), z.number())});

export const usageSummaryResponse = z.object({start_date: z.string(), end_date: z.string(), timezone: z.string(), web: webUsage, word: wordUsage, api: apiUsage});

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 usage summary
 * 
 * GET /usage
 */
export const getApiUsage = async (args: GetApiUsageArgs, options?: GetApiUsageOptions) => {
const {baseUrl = "https://app.gc.ai/api/external/v1", fetch: fetchFn = fetch, ApiKeyAuth} = options ?? {}

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

if (args.start_date != null) query.append("start_date", String(args.start_date))
if (args.end_date != null) query.append("end_date", String(args.end_date))
if (args.timezone != null) query.append("timezone", String(args.timezone))
if (ApiKeyAuth !== undefined) headers.set("Authorization", ApiKeyAuth)

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