import { useCallback, useEffect, useRef, useState } from 'react';
import { AssessorApiClient } from '../../api/assessor-api-client';
import { useEnginePreferences } from '../../app/engine-preferences';
import { useBackendWorkActivity } from './use-backend-work-activity';
import { statusPollApi } from './status-poll-client';
import { Dialog } from '../../components/Dialog/Dialog';
import type { RegulatoryFramework, RegulatoryMappingBatchResponse, RegulatoryMappingBatchScope } from '../regulatory-mapping';

const assessorApi = new AssessorApiClient();

export interface RegulatoryMappingBatchController {
  /** False while the Compliance Engine is switched off. */
  available: boolean;
  response?: RegulatoryMappingBatchResponse;
  loading: boolean;
  starting: boolean;
  error?: string;
  start(): Promise<void>;
}

/** The ISO batch, with the direct BSI batch of the same filters beside it (Phase 13F, BSI stage 2). */
export function useRegulatoryMappingBatch(requestedProjectId: string | undefined, scope: RegulatoryMappingBatchScope | undefined): RegulatoryMappingBatchController & { bsi: RegulatoryMappingBatchController } {
  const iso = useFrameworkBatch(requestedProjectId, scope, 'iso27001');
  const bsi = useFrameworkBatch(requestedProjectId, scope, 'bsi-kernel');
  return { ...iso, bsi };
}

function useFrameworkBatch(requestedProjectId: string | undefined, scope: RegulatoryMappingBatchScope | undefined, framework: RegulatoryFramework): RegulatoryMappingBatchController {
  // A switched-off Compliance Engine requests no batch status and offers no batch action.
  const available = useEnginePreferences().compliance;
  const projectId = available ? requestedProjectId : undefined;
  const [response, setResponse] = useState<RegulatoryMappingBatchResponse>();
  const [loading, setLoading] = useState(false);
  const [starting, setStarting] = useState(false);
  const [error, setError] = useState<string>();
  const scopeKey = JSON.stringify(scope ?? null);
  const requestKey = `${projectId ?? ''}\u0000${scopeKey}\u0000${framework}`;
  const activeRequestKey = useRef(requestKey);
  activeRequestKey.current = requestKey;

  const refresh = useCallback(async (poll = false) => {
    if (!projectId || !scope || (!scope.assessmentIds.length && !scope.scanRunIds.length)) {
      setResponse(undefined);
      return;
    }
    try {
      const next = await (poll ? statusPollApi : assessorApi).getRegulatoryMappingBatch(projectId, scope, framework);
      if (activeRequestKey.current !== requestKey) return;
      setResponse(next);
      setError(undefined);
    } catch (reason) {
      if (activeRequestKey.current !== requestKey) return;
      setError(reason instanceof Error ? reason.message : 'Compliance mapping batch status could not be loaded.');
    }
  }, [projectId, requestKey, scopeKey]); // eslint-disable-line react-hooks/exhaustive-deps

  useEffect(() => {
    let active = true;
    setLoading(true);
    setStarting(false);
    setError(undefined);
    setResponse(undefined);
    void refresh().finally(() => { if (active) setLoading(false); });
    return () => { active = false; };
  }, [refresh, scopeKey]);

  useEffect(() => {
    if (!response || !['queued', 'running'].includes(response.state)) return;
    const timer = window.setTimeout(() => void refresh(true), response.pollAfterMs ?? 1_500);
    return () => window.clearTimeout(timer);
  }, [refresh, response]);

  const start = useCallback(async () => {
    if (!projectId || !scope) return;
    setStarting(true);
    setError(undefined);
    try {
      const next = await assessorApi.startRegulatoryMappingBatch(projectId, {
        ...scope,
        idempotencyKey: `regulatory-batch-${crypto.randomUUID()}`,
        ...(framework === 'iso27001' ? {} : { framework })
      });
      if (activeRequestKey.current !== requestKey) return;
      setResponse(next);
    } catch (reason) {
      if (activeRequestKey.current !== requestKey) return;
      setError(reason instanceof Error ? reason.message : `${framework === 'bsi-kernel' ? 'BSI' : 'ISO'} mapping batch could not be started.`);
    } finally {
      if (activeRequestKey.current === requestKey) setStarting(false);
    }
  }, [projectId, requestKey, scopeKey]); // eslint-disable-line react-hooks/exhaustive-deps

  useBackendWorkActivity(framework === 'bsi-kernel' ? 'Mapping all BSI requirements' : 'Mapping all ISO controls', !response || response.state === 'empty' ? 'idle'
    : response.state === 'completed' ? 'finished' : response.state);

  return { available, response, loading, starting, error, start };
}

export function RegulatoryMappingBatchDialog({ controller, filteredResultCount, onClose }: {
  controller: RegulatoryMappingBatchController & { bsi?: RegulatoryMappingBatchController };
  filteredResultCount: number;
  onClose(): void;
}) {
  return <Dialog title="Compliance mapping" onClose={onClose}>
    <div className="regulatory-batch-dialog">
      <p>Generate ISO control proposals for all <strong>{filteredResultCount.toLocaleString('en-US')}</strong> results matching the current Result DB filters.</p>
      <p>Pagination, “Load more,” and loaded-row limits do not restrict this batch. Proposals remain subject to manual Accept/Reject review.</p>
      <BatchSection controller={controller} filteredResultCount={filteredResultCount}/>
      {/* User decision 2026-10-09: the direct BSI mapping of the same filters, compared with ISO in the Client Info Compliance tab. */}
      {controller.bsi && <>
        <h3 className="regulatory-batch-heading">BSI Grundschutz++ requirements</h3>
        <p>Map the same results directly to BSI Kernel requirements. The Compliance tab compares them with the BSI requirements derived from the accepted ISO controls.</p>
        <BatchSection controller={controller.bsi} filteredResultCount={filteredResultCount} startLabel="Start BSI mapping batch"/>
      </>}
      <div className="dialog-actions">
        <button className="btn" type="button" onClick={onClose}>Close</button>
      </div>
    </div>
  </Dialog>;
}

function BatchSection({ controller, filteredResultCount, startLabel = 'Start mapping batch' }: {
  controller: RegulatoryMappingBatchController;
  filteredResultCount: number;
  startLabel?: string;
}) {
  const { response, loading, starting, error, start } = controller;
  const run = response?.run;
  const active = response && ['queued', 'running'].includes(response.state);
  const counts = run?.counts;
  const actionLabel = run ? 'Run again for current filters' : startLabel;
  return <>
      {loading && !response && <p role="status">Loading batch status…</p>}
      {error && <p className="regulatory-mapping-error" role="alert">{error}</p>}
      {response && !response.generationEnabled && <p role="status">{response.disabledReason ?? 'Regulatory mapping is unavailable.'}</p>}
      {run && <>
        <p className="regulatory-batch-state" role="status">Status: <strong>{run.status === 'completed' && run.counts.failedRuleCount ? 'completed with failures' : run.status}</strong></p>
        <dl className="regulatory-batch-counts">
          <BatchCount label="Filtered results" value={counts!.filteredResultCount}/>
          <BatchCount label="Excluded context rows" value={counts!.excludedNonScannerCount}/>
          <BatchCount label="Eligible findings" value={counts!.eligibleFindingCount}/>
          <BatchCount label="Unsupported findings" value={counts!.unsupportedFindingCount}/>
          <BatchCount label="Distinct rules" value={counts!.distinctRuleCount}/>
          <BatchCount label="Reused mappings" value={counts!.reusedSucceededRuleCount + counts!.reusedActiveRuleCount}/>
          <BatchCount label="Completed" value={counts!.succeededRuleCount}/>
          <BatchCount label="Failed" value={counts!.failedRuleCount}/>
        </dl>
        {run.errorDetail && <p className="regulatory-mapping-error-detail">{run.errorDetail}</p>}
      </>}
      {active && <p role="status">Mapping is running on the server. You can close this dialog and return later.</p>}
      {response?.generationEnabled && <div className="dialog-actions">
        <button className="btn primary" type="button"
          disabled={Boolean(active) || starting || filteredResultCount === 0}
          onClick={() => void start()}>{starting ? 'Starting…' : actionLabel}</button>
      </div>}
  </>;
}

function BatchCount({ label, value }: { label: string; value: number }) {
  return <div><dt>{label}</dt><dd>{value.toLocaleString('en-US')}</dd></div>;
}