import {z} from 'zod'

export type GetApiV1PoliciesCapabilitiesOptions = {baseUrl: string, APIKeyHeader?: string | undefined, fetch?: typeof fetch | undefined};

export const policyEnforcementPoint = z.enum(["input", "pre_tool", "post_tool", "agent_response"]);

export const policyCheckType = z.enum(["expression", "llm_judge"]);

export const policyPointCheckCapability = z.object({check_type: policyCheckType, strictness_options: z.array(z.string()), cost_note: z.string().nullable().optional()});

export const policyAction = z.enum(["block", "redact", "append", "require_approval", "handoff"]);

export const policyActionCapability = z.object({action: policyAction, label: z.string(), degradation_note: z.string().nullable().optional(), config_requirements: z.array(z.string()).optional(), warning: z.string().nullable().optional(), warning_applies_to_checks: z.array(z.string()).nullable().optional(), supports_judge_message: z.boolean().optional()});

export const policyPointCapability = z.object({enforcement_point: policyEnforcementPoint, description: z.string(), checks: z.array(policyPointCheckCapability), actions: z.array(policyActionCapability), supports_tool_target: z.boolean().optional()});

export const resolutionEntry = z.object({enforcement_point: policyEnforcementPoint, transport_class: z.string(), strictness: z.string(), check_type: policyCheckType, strategy: z.string(), consequence: z.string()});

export const policyCheckCapability = z.object({check_type: policyCheckType, label: z.string(), hint: z.string()});

export const policyCrossCuttingFact = z.object({key: z.string(), note: z.string()});

export const policyCapabilitiesResponse = z.object({points: z.array(policyPointCapability), resolutions: z.array(resolutionEntry), check_types: z.array(policyCheckCapability), cross_cutting: z.array(policyCrossCuttingFact)});

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
};

/**
 * Describe the policy authoring cascade + per-transport runtime resolution
 * 
 * GET /v1/policies/capabilities
 */
export const getApiV1PoliciesCapabilities = async (options: GetApiV1PoliciesCapabilitiesOptions) => {
const {baseUrl, fetch: fetchFn = fetch, APIKeyHeader} = options ?? {}

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

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

const url = `${baseUrl.replace(/\/+$/, '')}/v1/policies/capabilities${query.size > 0 ? `?${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(policyCapabilitiesResponse, await res.json())
};