import { Injectable } from '@nestjs/common';
import { ActivityDossierService } from './activity-dossier.service';
import { AssetsService } from './assets.service';
import { InventoryFunctionService } from './inventory-function.service';
import { InventoryMergeService } from './inventory-merge.service';

type LooseRecord = Record<string, any>;

const MERGEABLE_DOSSIER_TYPES = new Set(['instalacion', 'subinstalacion']);

function dedupeById<T extends LooseRecord>(items: T[]): T[] {
  const seen = new Set<string>();
  const result: T[] = [];
  for (const item of items) {
    const id = String(item.id ?? '');
    if (!id || seen.has(id)) continue;
    seen.add(id);
    result.push(item);
  }
  return result;
}

function sortDesc(items: LooseRecord[], fieldCandidates: string[]): LooseRecord[] {
  return [...items].sort((a, b) => {
    const first = fieldCandidates.map((field) => b[field]).find(Boolean) ?? 0;
    const second = fieldCandidates.map((field) => a[field]).find(Boolean) ?? 0;
    return new Date(String(first)).getTime() - new Date(String(second)).getTime();
  });
}

@Injectable()
export class MergedInventoryDossierService {
  constructor(
    private readonly assets: AssetsService,
    private readonly activity: ActivityDossierService,
    private readonly merges: InventoryMergeService,
    private readonly functions: InventoryFunctionService,
  ) {}

  async dossier(requestedAssetId: string): Promise<Record<string, unknown>> {
    const requestedAsset = await this.assets.getById(requestedAssetId);
    const requestedTypeCode = requestedAsset.type.code.trim().toLowerCase();

    // La conciliación/fusión existe sólo para Instalaciones y Subinstalaciones.
    // Los registros territoriales (Departamento, Área, Yacimiento) deben poder
    // abrir su Actividad sin depender del subsistema de merge.
    if (!MERGEABLE_DOSSIER_TYPES.has(requestedTypeCode)) {
      return await this.activity.dossier(requestedAssetId);
    }

    const mergeStatus = await this.merges.status(requestedAssetId) as LooseRecord;
    const canonical = mergeStatus.canonical as LooseRecord;
    const requested = mergeStatus.requested as LooseRecord;
    const aliases = (mergeStatus.aliases ?? []) as LooseRecord[];
    const inventoryIds = [canonical.id, ...aliases.map((alias) => alias.id)]
      .filter(Boolean)
      .map(String)
      .filter((value, index, all) => all.indexOf(value) === index);

    const dossiers = await Promise.all(inventoryIds.map(async (assetId) => {
      const dossier = await this.activity.dossier(assetId) as LooseRecord;
      const identity = dossier.asset as LooseRecord;
      const functionDossier = await this.functions.getForAsset(assetId).catch(() => null) as LooseRecord | null;
      return { assetId, identity, dossier, functionDossier };
    }));

    const enrich = (entry: LooseRecord, identity: LooseRecord): LooseRecord => ({
      ...entry,
      historicalInventory: {
        id: identity.id,
        code: identity.code,
        name: identity.name,
        commonName: identity.commonName ?? null,
        isCanonical: identity.id === canonical.id,
      },
    });

    const collect = (key: string): LooseRecord[] => dedupeById(
      dossiers.flatMap(({ identity, dossier }) =>
        ((dossier[key] ?? []) as LooseRecord[]).map((entry) => enrich(entry, identity)),
      ),
    );

    const visits = sortDesc(collect('visits'), ['actualStartedAt', 'plannedStartAt', 'createdAt']);
    const acts = sortDesc(collect('acts'), ['occurredAt', 'createdAt']);
    const findings = sortDesc(collect('findings'), ['createdAt', 'updatedAt']);
    const evidence = sortDesc(collect('evidence'), ['capturedAt', 'createdAt']);
    const communications = sortDesc(collect('communications'), ['occurredAt', 'createdAt']);
    const verificationResults = sortDesc(collect('verificationResults'), ['verifiedAt', 'resultRecordedAt']);
    const documents = sortDesc(collect('documents'), ['documentDate', 'linkedAt']);
    const inspectionReports = sortDesc(collect('inspectionReports'), ['generatedAt']);
    const media = sortDesc(collect('media'), ['capturedAt', 'createdAt']);
    const versions = sortDesc(collect('versions'), ['occurredAt']);

    const functionHistory = sortDesc(
      dossiers.flatMap(({ identity, functionDossier }) =>
        (((functionDossier?.history ?? []) as LooseRecord[]).map((entry) => enrich(entry, identity))),
      ),
      ['validFrom', 'createdAt'],
    );
    const canonicalFunctionDossier = dossiers.find((item) => item.assetId === canonical.id)?.functionDossier ?? null;
    const currentFunction = canonicalFunctionDossier?.currentFunction ?? null;

    const timelineSource: LooseRecord[] = dossiers.flatMap(({ identity, dossier }) =>
      ((dossier.timeline ?? []) as LooseRecord[]).map((event): LooseRecord => ({
        ...event,
        meta: {
          ...(event.meta ?? {}),
          historicalInventory: {
            id: identity.id,
            code: identity.code,
            name: identity.name,
            isCanonical: identity.id === canonical.id,
          },
        },
      })),
    );
    const timeline: LooseRecord[] = dedupeById<LooseRecord>(timelineSource);

    for (const assignment of functionHistory) {
      timeline.push({
        id: `function:${String(assignment.id)}`,
        kind: 'FUNCTION_CHANGED',
        occurredAt: assignment.validFrom,
        title: `Cambio de función · ${String(assignment.functionName)}`,
        description: assignment.reason ?? null,
        meta: {
          functionId: assignment.functionId,
          functionCode: assignment.functionCode,
          functionName: assignment.functionName,
          validFrom: assignment.validFrom,
          validUntil: assignment.validUntil,
          changedByUsername: assignment.changedByUsername,
          historicalInventory: assignment.historicalInventory,
        },
      });
    }

    for (const alias of aliases) {
      timeline.push({
        id: `merge:${String(alias.id)}:${String(alias.mergedAt)}`,
        kind: 'MERGE',
        occurredAt: alias.mergedAt,
        title: `Inventario fusionado · ${String(alias.code)}`,
        description: alias.reason,
        meta: {
          sourceAssetId: alias.id,
          sourceCode: alias.code,
          sourceName: alias.name,
          canonicalAssetId: canonical.id,
          canonicalCode: canonical.code,
          canonicalName: canonical.name,
          historyPreserved: true,
        },
      });
    }
    timeline.sort((a, b) => new Date(String(b.occurredAt ?? 0)).getTime() - new Date(String(a.occurredAt ?? 0)).getTime());

    const reports = documents.filter((document) => document.documentType === 'TECHNICAL_REPORT');
    const openFindings = findings.filter((finding) => finding.status === 'OPEN').length;
    const closedFindings = findings.filter((finding) => finding.status === 'CLOSED').length;
    const warnings = dossiers.flatMap(({ assetId, dossier }) =>
      ((dossier.warnings ?? []) as string[]).map((facet) => `${assetId}:${facet}`),
    );

    return {
      asset: {
        id: canonical.id,
        code: canonical.code,
        name: canonical.name,
        commonName: dossiers.find((item) => item.assetId === canonical.id)?.identity?.commonName ?? null,
        currentFunction,
      },
      requestedAsset: {
        id: requested.id,
        code: requested.code,
        name: requested.name,
      },
      merge: {
        requestedWasMerged: requested.id !== canonical.id,
        canonicalAssetId: canonical.id,
        aliases,
        chain: mergeStatus.chain ?? [],
        aggregatedInventoryIds: inventoryIds,
        historyPolicy: 'CHRONOLOGICAL_AGGREGATION_WITH_ORIGINAL_IDENTITY',
      },
      counters: {
        inspections: visits.length,
        acts: acts.length,
        findings: findings.length,
        verifications: verificationResults.length,
        openFindings,
        closedFindings,
        evidence: evidence.length,
        documents: documents.length + media.filter((item) => item.kind === 'DOCUMENT').length,
        photos: evidence.filter((item) => item.kind === 'PHOTO').length + media.filter((item) => item.kind === 'PHOTO').length,
        reports: reports.length + inspectionReports.length,
        functionChanges: functionHistory.length,
      },
      currentFunction,
      functionHistory,
      visits,
      acts,
      findings,
      evidence,
      communications,
      verificationResults,
      documents,
      inspectionReports,
      reports,
      media,
      versions,
      timeline: timeline.slice(0, 1000),
      warnings,
    };
  }
}