// A refusal of the platform's knowledge service as this module's one closed set of codes
// (`KNOWLEDGE_REFUSALS`), which the pages and forms show in the reader's language. A refusal that is the
// deployment's or the platform's says so; the service's own words stay in `detail`, for the log and the API.

import { AppError, notFound } from "@conusai-kit/core"
import { KnowledgeError, type KnowledgeReasonCode } from "@conusai-kit/platform"
import type { KnowledgeRefusal, ServiceState } from "../contract/index.js"

const REFUSAL: Readonly<Record<Exclude<KnowledgeReasonCode, "unavailable_resource">, KnowledgeRefusal>> = {
  plan_required: "plan_required",
  feature_disabled: "feature_disabled",
  quota_exhausted: "quota_exhausted",
  budget_exhausted: "budget_exhausted",
  // The service refused the token itself: `knowledge.collections:use` is missing, `*` never carries it.
  forbidden: "scope_missing",
  indexing: "indexing",
  approval_required: "approval_required",
  runtime_unavailable: "runtime_unavailable",
  configuration_missing: "configuration_missing",
  // The platform refused the token's identity: nothing the person can act on, the app is not served.
  unauthenticated: "runtime_unavailable",
}

const STATUS: Readonly<Record<KnowledgeRefusal, number>> = {
  plan_required: 403,
  feature_disabled: 403,
  approval_required: 403,
  quota_exhausted: 429,
  budget_exhausted: 429,
  scope_missing: 503,
  indexing: 503,
  runtime_unavailable: 503,
  configuration_missing: 503,
}

const TITLE: Readonly<Record<KnowledgeRefusal, string>> = {
  plan_required: "The organization's plan does not include document search",
  feature_disabled: "Document search is disabled by policy",
  approval_required: "The platform asks for an approval first",
  quota_exhausted: "The indexing quota is exhausted",
  budget_exhausted: "The AI budget is exhausted",
  scope_missing: "This deployment's token does not hold knowledge.collections:use",
  indexing: "The knowledge service is building its index",
  runtime_unavailable: "The knowledge service is unavailable",
  configuration_missing: "The knowledge deployment configuration is incomplete",
}

/** The typed refusal of a service error; a resource it does not hold has none, it is simply not there. */
export function refusalOfReason(reason: KnowledgeReasonCode): KnowledgeRefusal | undefined {
  return reason === "unavailable_resource" ? undefined : REFUSAL[reason]
}

/** The readiness state a refusal puts the service in: a plan or a policy is "disabled", not "down". */
export function stateOfRefusal(refusal: KnowledgeRefusal | undefined): ServiceState {
  if (refusal === "plan_required" || refusal === "feature_disabled") return "disabled"
  return refusal === "indexing" ? "indexing" : "unavailable"
}

/** The app error for anything the service threw; a programming error passes through as it is. */
export function knowledgeRefusal(error: unknown): unknown {
  if (!(error instanceof KnowledgeError)) return error
  const refusal = refusalOfReason(error.reason)
  if (refusal === undefined) return notFound(error.message)
  return new AppError({
    type: `/problems/${refusal}`,
    title: TITLE[refusal],
    status: STATUS[refusal],
    code: refusal,
    detail: error.message,
  })
}

/** A refusal waiting cannot fix: the index job records it on the document instead of retrying it. */
export function permanentRefusal(error: KnowledgeError): KnowledgeRefusal | undefined {
  const refusal = refusalOfReason(error.reason)
  return refusal === "indexing" || refusal === "runtime_unavailable" ? undefined : refusal
}