import {z} from 'zod'

export type PreviewLineItemDto = {localId?: string | undefined, unitPrice?: (number | unknown) | undefined, quantity?: (number | unknown) | undefined, discount?: (number | unknown) | undefined, dispenseFee?: (number | unknown) | undefined, groupCodeId?: (string | null) | undefined, serviceCatalogItemId?: (string | null) | undefined, retailItemId?: (string | null) | undefined, inventoryItemId?: (string | null) | undefined};

export type PreviewPriceRulesRequestDto = {items?: Array<PreviewLineItemDto> | undefined, clientId?: (string | null) | undefined, patientId?: (string | null) | undefined};

export type CreateApiInvoicesPreviewRulesArgs = {body: PreviewPriceRulesRequestDto};

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

export const lineRuleDiscountDto = z.object({localId: z.string().optional(), amount: z.union([z.number(), z.string()]).optional()});

export const previewPriceRulesResponseDto = z.object({lineRuleDiscounts: z.array(lineRuleDiscountDto).optional(), ruleOrderDiscountAmount: z.union([z.number(), z.string()]).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
};

/**
 * Runs the price rule engine over a proposed set of line items without
 * persisting. Used by the invoice grid to show rule discounts (BOGO,
 * spend thresholds, etc.) live as the user edits, while keeping the
 * server as the single source of truth for the math — no client-side
 * evaluator to drift.
 * 
 * POST /Invoices/preview-rules
 */
export const createApiInvoicesPreviewRules = async (args: CreateApiInvoicesPreviewRulesArgs, options?: CreateApiInvoicesPreviewRulesOptions) => {
const {baseUrl = "https://api.clinicos.vet/backend/business", fetch: fetchFn = fetch, Bearer} = options ?? {}

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

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

const url = `${baseUrl.replace(/\/+$/, '')}/Invoices/preview-rules${query.size > 0 ? `?${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(previewPriceRulesResponseDto, await res.json())
};