// The enablement flow: one idempotent procedure pair an organization administrator runs, with the
// platform's checks in front of any configuration change and every denial a typed reason code the
// UI maps to an upgrade or policy state.
//
//   enableDocumentAi: already enabled -> answers the current configuration, writes nothing.
//     Otherwise: eligibility (plan capability + rollout flags) -> quota -> the vector backing
//     (an operator-configured endpoint, validated before it is trusted, or a managed link through
//     the providers API) -> one transaction persists the configuration. A failure at any step
//     writes nothing and is retirable: the same call again resumes from the first failing check.
//
//   disableDocumentAi: preserves everything — collections, documents, vectors and the recorded
//     configuration stay; only `enabled` flips, so re-enabling resumes without duplication.

import { AppError } from "@conusai-kit/core"
import { config, type EnablementReason } from "../contract/index.js"
import type { DocumentAiPlatform, KnowledgeOrgScope } from "./ports.js"

/** A typed enablement denial: the problem's code is the stable reason the UI maps to a state. */
export function enablementDenied(reason: EnablementReason, detail?: string): AppError {
  const status = reason === "quota_exhausted" ? 429 : 403
  const title =
    reason === "plan_required"
      ? "The organization's plan does not include document AI"
      : reason === "feature_disabled"
        ? "Document AI is disabled by policy"
        : "The indexing quota is exhausted"
  return new AppError({
    type: `/problems/${reason}`,
    title,
    status,
    code: reason,
    ...(detail === undefined ? {} : { detail }),
  })
}

export interface SettingsView {
  enabled: boolean
  backend: "vectors" | "platform" | null
  source: "operator" | "managed" | null
  url: string | null
}

async function currentConfig(deps: { data: import("@conusai-kit/data").DataSource }, scope: KnowledgeOrgScope) {
  const row = (await deps.data.forScope(scope).of(config).list({ limit: 1 })).items[0]
  return row ?? null
}

export async function getSettings(
  deps: { data: import("@conusai-kit/data").DataSource },
  scope: KnowledgeOrgScope,
): Promise<SettingsView> {
  const row = await currentConfig(deps, scope)
  return {
    enabled: row?.enabled ?? false,
    backend: row?.backend ?? null,
    source: row?.source ?? null,
    url: row?.url ?? null,
  }
}

export interface SettingsDeps {
  data: import("@conusai-kit/data").DataSource
  platform: DocumentAiPlatform
  now?: () => number
}

export async function enableDocumentAi(deps: SettingsDeps, scope: KnowledgeOrgScope): Promise<SettingsView> {
  const existing = await currentConfig(deps, scope)
  if (existing?.enabled) {
    return { enabled: true, backend: existing.backend, source: existing.source, url: existing.url }
  }

  const eligibility = await deps.platform.checkEligibility(scope)
  if (!eligibility.ok) throw enablementDenied(eligibility.reason, eligibility.detail)

  const remaining = await deps.platform.indexingQuota(scope)
  if (remaining <= 0) throw enablementDenied("quota_exhausted", "the indexing volume for today is spent")

  // The vector backing: an operator-configured endpoint+key when the deployment carries one
  // (validated before it is trusted), otherwise a managed link through the providers API.
  const operator = deps.platform.operatorQdrant()
  let source: "operator" | "managed"
  let serviceId: string | null
  let url: string | null
  if (operator !== null) {
    const probe = await deps.platform.probeQdrant(operator.url, operator.apiKey)
    if (!probe.ok) {
      throw new AppError({
        type: "/problems/validation_failed",
        title: "The configured Qdrant endpoint did not answer",
        status: 422,
        code: "validation_failed",
        detail: probe.detail,
      })
    }
    source = "operator"
    serviceId = null
    url = operator.url
  } else {
    const linked = await deps.platform.linkManagedQdrant(scope)
    source = "managed"
    serviceId = linked.serviceId
    url = linked.url
  }

  await deps.data.unitOfWork.run(scope, async (tx) => {
    const row = (await tx.of(config).list({ limit: 1 })).items[0]
    const patch = {
      enabled: true,
      backend: "vectors" as const,
      source,
      serviceId,
      url,
      updatedBy: scope.actor.userId,
      configuredAt: new Date((deps.now ?? Date.now)()).toISOString(),
    }
    if (row) await tx.of(config).update(row.id, patch, row.version)
    else await tx.of(config).insert(patch)
  })
  return { enabled: true, backend: "vectors", source, url }
}

export async function disableDocumentAi(deps: SettingsDeps, scope: KnowledgeOrgScope): Promise<{ enabled: false }> {
  await deps.data.unitOfWork.run(scope, async (tx) => {
    const row = (await tx.of(config).list({ limit: 1 })).items[0]
    if (!row?.enabled) return
    // Everything else is preserved on purpose: backend, source, the service id, the endpoint, and
    // every collection, document and vector. Disabling fences new work; it deletes nothing.
    await tx.of(config).update(
      row.id,
      {
        enabled: false,
        updatedBy: scope.actor.userId,
        configuredAt: new Date((deps.now ?? Date.now)()).toISOString(),
      },
      row.version,
    )
  })
  return { enabled: false }
}