import {z} from 'zod'

export type Entity = {text?: string | undefined, type?: string | undefined, role?: (string | null) | undefined, value?: Record<string, never> | undefined, display_text?: string | undefined, confidence?: number | undefined, is_system_entity?: boolean | undefined};

export type Params = {target_dialogue_state?: (string | null) | undefined, dynamic_resource?: (Record<string, never> | null) | undefined, allowed_intents?: (Array<string> | null) | undefined, time_zone?: (string | null) | undefined, language?: (string | null) | undefined, locale?: (string | null) | undefined, timestamp?: (number | null) | undefined};

export type Request = {text?: string | undefined, domain?: string | undefined, intent?: string | undefined, entities?: Array<Entity> | undefined, context?: Record<string, never> | undefined, params?: Params | undefined};

export type Directive = {name?: string | undefined, type?: ('view' | 'action') | undefined, payload?: Record<string, never> | undefined};

export type Responder = {directives?: Array<Directive> | undefined, frame?: Record<string, never> | undefined, params?: Params | undefined, slots?: Record<string, never> | undefined};

export type Data = {request?: Request | undefined, responder?: Responder | undefined, action?: string | undefined};

export type CreateApiActionArgs = {body: Data};

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

export const directive = z.object({name: z.string().optional(), type: z.enum(["view", "action"]).optional(), payload: z.object({}).optional()});

export const params = z.object({target_dialogue_state: z.string().nullable().optional(), dynamic_resource: z.object({}).nullable().optional(), allowed_intents: z.array(z.string()).nullable().optional(), time_zone: z.string().nullable().optional(), language: z.string().nullable().optional(), locale: z.string().nullable().optional(), timestamp: z.number().int().nullable().optional()});

export const responder = z.object({directives: z.array(directive).optional(), frame: z.object({}).optional(), params: params.optional(), slots: z.object({}).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
};

/**
 * Invoke an action 
 * 
 * POST /action
 */
export const createApiAction = async (args: CreateApiActionArgs, options: CreateApiActionOptions) => {
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 = `${baseUrl.replace(/\/+$/, '')}/action${query.size > 0 ? `?${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(responder, await res.json())
};