import {z} from 'zod'

export type FiFastRequest = {prompt: string, system?: (string | null) | undefined, tools?: (Array<{[key: string]: unknown}> | null) | undefined, toolConfig?: ({[key: string]: unknown} | null) | undefined, responseSchema?: ({[key: string]: unknown} | null) | undefined, responseMimeType?: (string | null) | undefined, model?: ('gemini-3.1-pro-preview' | 'gemini-3.1-flash-lite-preview' | 'gemini-3-flash-preview' | 'gemini-2.5-flash-preview-05-20' | 'gemini-2.5-flash') | undefined, thinkingBudget?: (number | null) | undefined, temperature?: number | undefined, maxOutputTokens?: number | undefined};

export type CreateApiV4FiFastArgs = {body: FiFastRequest};

export type CreateApiV4FiFastOptions = {baseUrl: string, fetch?: typeof fetch | undefined};

export const fiFastResponse = z.object({content: z.record(z.string(), z.unknown()), usage: z.record(z.string(), z.unknown()).nullable().optional(), model: z.string(), finishReason: z.string().nullable().optional()});

export const responseMeta = z.object({requestId: z.string().optional(), timestamp: z.string().optional(), durationMs: z.number().int().nullable().optional()});

export const successResponseFiFastResponse = z.object({success: z.literal(true), data: fiFastResponse, meta: responseMeta.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
};

/**
 * Thin authenticated proxy to Vertex AI generateContent
 * 
 * POST /v4/fi-fast
 */
export const createApiV4FiFast = async (args: CreateApiV4FiFastArgs, options: CreateApiV4FiFastOptions) => {
const {baseUrl, fetch: fetchFn = fetch} = options ?? {}

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

const url = `${baseUrl.replace(/\/+$/, '')}/v4/fi-fast${query.size > 0 ? `?${query}` : ''}`

const res = await fetchFn(url, {method: "POST", headers, body: JSON.stringify(args.body)})

if (!res.ok) throw new Error(`Request failed with status ${res.status}`, {cause: {status: res.status, body: await res.text()}})

return validateResponse(successResponseFiFastResponse, await res.json())
};