import { createHash } from 'node:crypto';
import type { FindingDefinition } from '../../src/domain/canonical-model';
import {
  POLICY_FINDING_FACTORY,
  policyFindingCandidateInvariantCodes,
  storedPolicyFindingRunValidationErrors,
  type CreatePolicyFindingRunRequest,
  type PolicyFindingOccurrence,
  type PolicyFindingRejection,
  type StoredPolicyFindingRun
} from '../../src/domain/policy-finding';
import type { EnvironmentProfile, StoredPolicySnapshotAggregation } from '../../src/domain/gpo-snapshot-aggregation';
import type { StoredPolicyEvaluation } from '../../src/domain/policy-evaluation';
import type { AssessorRepository } from '../../src/persistence/assessor-repository';
import { RepositoryNotFoundError, RepositoryValidationError } from '../../src/persistence/repository-errors';

function stableId(prefix: string, value: string): string {
  return prefix + '-' + createHash('sha256').update(value).digest('hex').slice(0, 32);
}

function sortedUnique(values: string[]): string[] {
  return [...new Set(values)].sort((left, right) => left.localeCompare(right));
}

interface PolicyFindingBuildInput {
  evaluation: StoredPolicyEvaluation;
  aggregation: StoredPolicySnapshotAggregation;
  profile: EnvironmentProfile;
  startedAt: string;
  completedAt: string;
}

function definitionFor(
  result: StoredPolicyEvaluation['results'][number],
  riskRuleId: string,
  createdAt: string
): FindingDefinition {
  const canonicalKey = `policy-risk:${riskRuleId}:${result.identity.id}`;
  return {
    id: stableId('finding-definition', canonicalKey),
    canonicalKey,
    identity: {
      version: 1,
      strategy: 'tool-rule-id',
      durable: true,
      evidence: [riskRuleId, result.identity.id]
    },
    title: `Konfigurierte Policy-Abweichung (${riskRuleId})`,
    description: 'Die eindeutig konfigurierte Policy-Einstellung weicht von der ausdruecklichen Baselineempfehlung ab. Scope unbekannt; Wirksamkeit nicht verifiziert.',
    category: 'group-policy-baseline',
    frameworkReferences: [],
    createdAt,
    updatedAt: createdAt
  };
}

export function buildPolicyFindingRun(input: PolicyFindingBuildInput): StoredPolicyFindingRun {
  if (input.evaluation.run.projectId !== input.aggregation.run.projectId
    || input.evaluation.run.projectId !== input.profile.projectId
    || input.evaluation.run.aggregationRunId !== input.aggregation.run.id
    || input.evaluation.run.environmentProfileId !== input.profile.id) {
    throw new RepositoryValidationError('Policy-Evaluation, Snapshot und Environment Profile gehoeren nicht zusammen.');
  }
  const runId = stableId('policy-finding-run', input.evaluation.run.id + '\0' + POLICY_FINDING_FACTORY.version);
  const eligible = input.evaluation.results
    .filter(result => result.findingEligibility === 'eligible')
    .sort((left, right) => left.id.localeCompare(right.id));
  const definitions = new Map<string, FindingDefinition>();
  const occurrences: PolicyFindingOccurrence[] = [];
  const rejections: PolicyFindingRejection[] = [];
  const states = new Map(input.aggregation.states.map(state => [state.id, state]));

  for (const result of eligible) {
    const codes = new Set(policyFindingCandidateInvariantCodes(input.evaluation, result));
    const state = result.aggregationStateId ? states.get(result.aggregationStateId) : undefined;
    if (!state || state.identity.id !== result.identity.id) codes.add('policy-finding-aggregation-state-missing');
    else {
      if (state.status !== 'configured') codes.add('policy-finding-customer-state-not-configured');
      if (state.completeness !== 'complete') codes.add('policy-finding-customer-state-incomplete');
      if (state.targeting !== 'none') codes.add('policy-finding-targeting-unresolved');
      if (state.effectiveState !== 'unknown') codes.add('policy-finding-effective-state-invalid');
    }
    if (input.aggregation.snapshot.completeness !== 'complete') codes.add('policy-finding-snapshot-incomplete');
    const riskRuleId = result.riskRuleIds[0];
    const riskRules = input.evaluation.run.ruleCatalog.rules
      .filter(rule => rule.riskRule?.id === riskRuleId && result.ruleIds.includes(rule.id))
      .map(rule => rule.riskRule!);
    const severities = new Set(riskRules.map(rule => rule.severity));
    if (!riskRuleId || riskRules.length < 1 || severities.size !== 1) codes.add('policy-finding-risk-rule-unresolved');
    if (codes.size) {
      rejections.push({
        version: 1,
        evaluationResultId: result.id,
        diagnosticCodes: [...codes].sort()
      });
      continue;
    }
    const definition = definitionFor(result, riskRuleId, input.evaluation.run.completedAt);
    definitions.set(definition.id, definition);
    occurrences.push({
      version: 1,
      id: stableId('policy-finding-occurrence', result.id + '\0' + POLICY_FINDING_FACTORY.version),
      factoryRunId: runId,
      projectId: input.evaluation.run.projectId,
      evaluationRunId: input.evaluation.run.id,
      evaluationResultId: result.id,
      aggregationRunId: input.aggregation.run.id,
      aggregationStateId: result.aggregationStateId!,
      snapshotId: input.aggregation.run.snapshotId,
      environmentProfileId: input.profile.id,
      environmentProfileRevision: input.profile.revision,
      definitionId: definition.id,
      identityId: result.identity.id,
      riskRuleId,
      severity: [...severities][0],
      classification: 'confirmed_configured_deviation',
      outcome: 'fail',
      scopeState: 'unknown',
      effectiveState: 'not-verified',
      evidenceIds: sortedUnique(input.evaluation.evidence
        .filter(item => item.evaluationResultId === result.id).map(item => item.id)),
      createdAt: input.completedAt
    });
  }
  const record: StoredPolicyFindingRun = {
    version: 1,
    run: {
      version: 1,
      id: runId,
      projectId: input.evaluation.run.projectId,
      evaluationRunId: input.evaluation.run.id,
      factory: POLICY_FINDING_FACTORY,
      status: rejections.length ? 'partial' : 'complete',
      eligibleResultCount: eligible.length,
      findingCount: occurrences.length,
      rejectedResultCount: rejections.length,
      startedAt: input.startedAt,
      completedAt: input.completedAt
    },
    definitions: [...definitions.values()].sort((left, right) => left.id.localeCompare(right.id)),
    occurrences: occurrences.sort((left, right) => left.id.localeCompare(right.id)),
    rejections: rejections.sort((left, right) => left.evaluationResultId.localeCompare(right.evaluationResultId))
  };
  const errors = storedPolicyFindingRunValidationErrors(record);
  if (errors.length) throw new RepositoryValidationError(errors.join(' '));
  return record;
}

export class GpoPolicyFindingService {
  private readonly now: () => Date;

  constructor(private readonly repository: AssessorRepository, options: { now?: () => Date } = {}) {
    this.now = options.now ?? (() => new Date());
  }

  async create(projectId: string, request: CreatePolicyFindingRunRequest): Promise<StoredPolicyFindingRun> {
    if (!request || typeof request.evaluationRunId !== 'string' || !request.evaluationRunId.trim()) {
      throw new RepositoryValidationError('Die Policy-Finding-Anfrage ist ungueltig.');
    }
    const evaluation = (await this.repository.listPolicyEvaluations(projectId))
      .find(record => record.run.id === request.evaluationRunId);
    if (!evaluation) throw new RepositoryNotFoundError('Die Policy-Evaluation ist im Projekt nicht vorhanden.');
    const expectedId = stableId('policy-finding-run', evaluation.run.id + '\0' + POLICY_FINDING_FACTORY.version);
    const existing = (await this.repository.listPolicyFindingRuns(projectId))
      .find(record => record.run.id === expectedId);
    if (existing) return existing;
    const aggregation = (await this.repository.listPolicySnapshotAggregations(projectId))
      .find(record => record.run.id === evaluation.run.aggregationRunId);
    if (!aggregation) throw new RepositoryNotFoundError('Der Policy-Snapshot der Evaluation ist nicht vorhanden.');
    const profile = (await this.repository.listEnvironmentProfiles(projectId))
      .find(record => record.id === evaluation.run.environmentProfileId);
    if (!profile) throw new RepositoryNotFoundError('Das Environment Profile der Evaluation ist nicht vorhanden.');
    const startedAt = this.now().toISOString();
    const record = buildPolicyFindingRun({
      evaluation,
      aggregation,
      profile,
      startedAt,
      completedAt: this.now().toISOString()
    });
    await this.repository.savePolicyFindingRun(record);
    return record;
  }

  list(projectId: string): Promise<StoredPolicyFindingRun[]> {
    return this.repository.listPolicyFindingRuns(projectId);
  }
}