import {z} from 'zod'

export type ISO3 = string;

export type DecisionRequest = {passport: ISO3, itinerary: Array<{country: ISO3, from: string, to: string}>, transit?: Array<ISO3> | undefined, passport_expiry?: (string | null) | undefined, residence?: (string | null) | undefined, purpose?: (string | null) | undefined};

export type CreateApiApiV1VisaDecisionArgs = {body: DecisionRequest};

export type CreateApiApiV1VisaDecisionOptions = {baseUrl?: string | undefined, apiKeyHeader?: string | undefined, fetch?: typeof fetch | undefined};

export const iSO3 = z.string().min(3).max(3);

export const visaRequirement = z.enum(["visa_free", "visa_required", "e_visa", "visa_on_arrival", "eta", "no_admission"]);

export const decisionStep = z.object({country: iSO3.optional(), from: z.string().optional(), to: z.string().optional(), days: z.number().int().optional(), admission: z.enum(["allowed", "conditional", "refused", "unknown"]).optional(), regime: z.object({status: z.enum(["known", "unknown"]).optional(), value: visaRequirement.optional(), granularity: z.literal("pair").optional(), source_url: z.string().nullable().optional(), last_verified: z.string().nullable().optional()}).optional(), max_stay: z.object({status: z.enum(["known", "unknown"]).optional(), days: z.number().int().nullable().optional(), granularity: z.literal("pair").optional(), basis: z.string().optional(), reason: z.string().optional()}).optional(), passport_validity_months: z.object({status: z.enum(["known", "unknown"]).optional(), months: z.number().int().nullable().optional(), granularity: z.literal("destination").optional()}).optional()});

export const decisionResponse = z.object({data: z.object({passport_country: iSO3.optional(), residence: z.string().nullable().optional(), purpose: z.string().nullable().optional(), steps: z.array(decisionStep).optional(), transit: z.array(z.object({country: iSO3.optional(), status: z.enum(["destination_rule", "unknown"]).optional(), granularity: z.literal("destination").optional(), note: z.string().optional(), hubs: z.array(z.object({})).optional()})).optional(), passport: z.object({expiry: z.string().nullable().optional(), status: z.enum(["checked", "unknown"]).optional(), reason: z.string().optional(), latest_arrival: z.string().nullable().optional(), valid_through_itinerary: z.boolean().optional(), per_destination: z.array(z.object({country: iSO3.optional(), arrival: z.string().optional(), required_months: z.number().int().optional(), granularity: z.literal("destination").optional(), satisfied: z.boolean().optional()})).optional()}).optional(), blockers: z.array(z.object({type: z.enum(["no_admission", "admission_refused", "stay_exceeds_allowance", "passport_validity", "passport_expires_before_exit"]).optional(), country: iSO3.optional(), detail: z.string().optional()})).optional(), unknowns: z.array(z.object({field: z.string().optional(), country: iSO3.optional(), reason: z.string().optional()})).optional(), verdict: z.enum(["no_blocker_found", "blocked"]).optional()}).optional(), meta: z.object({api_version: z.string().optional(), pairs_charged: z.number().int().optional(), max_steps: z.number().int().optional(), contract: z.string().optional()}).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
};

/**
 * Itinerary decision — answers a trip, not a pair
 * 
 * POST /api/v1/visa/decision
 * 
 * Also accepts auth: apiKeyQuery
 */
export const createApiApiV1VisaDecision = async (args: CreateApiApiV1VisaDecisionArgs, options?: CreateApiApiV1VisaDecisionOptions) => {
const {baseUrl = "https://visa.orizn.app", fetch: fetchFn = fetch, apiKeyHeader} = options ?? {}

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

if (apiKeyHeader !== undefined) headers.set("x-api-key", apiKeyHeader)

const url = `${baseUrl.replace(/\/+$/, '')}/api/v1/visa/decision${query.size > 0 ? `?${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(decisionResponse, await res.json())
};