import {
  BadRequestException,
  ConflictException,
  Injectable,
  NotFoundException,
} from '@nestjs/common';
import { DataSource, EntityManager } from 'typeorm';
import { administrationAuditContext } from '../administration/common/administration-audit';
import { AuditService } from '../audit/audit.service';
import type { AuthPrincipal, RequestWithContext } from '../common/http/request-context';
import { AssetVersionChangeType, AuditAction } from '../database/entities';
import type {
  ChangeInventoryFunctionDto,
  CreateInventoryFunctionDto,
  UpdateInventoryFunctionDto,
} from './dto/inventory-function.dto';
import { AssetHistoryService } from './asset-history.service';

export interface InventoryFunctionRow {
  id: string; code: string; name: string; description: string | null;
  isActive: boolean; sortOrder: number; createdAt: Date; updatedAt: Date;
}

export interface FunctionAssignmentRow {
  id: string; assetId: string; functionId: string; functionCode: string; functionName: string;
  validFrom: Date; validUntil: Date | null; reason: string | null;
  changedBy: string | null; changedByUsername: string | null; createdAt: Date;
}

interface FunctionEligibleAsset {
  id: string; code: string; name: string; typeCode: string; typeName: string;
  familyCode: string | null; familyName: string | null;
}

function normalized(value: string | null): string {
  return (value ?? '').normalize('NFD').replace(/[\u0300-\u036f]/g, '').toLowerCase().replace(/[^a-z0-9]+/g, ' ').trim();
}

@Injectable()
export class InventoryFunctionService {
  constructor(
    private readonly dataSource: DataSource,
    private readonly audit: AuditService,
    private readonly history: AssetHistoryService,
  ) {}

  async list(includeInactive = false): Promise<{ data: InventoryFunctionRow[] }> {
    const data = await this.dataSource.query(`
      SELECT id,code,name,description,is_active AS "isActive",sort_order AS "sortOrder",
        created_at AS "createdAt",updated_at AS "updatedAt"
      FROM inventory_functions
      ${includeInactive ? '' : 'WHERE is_active=true'}
      ORDER BY sort_order,name,code
    `) as InventoryFunctionRow[];
    return { data };
  }

  async create(dto: CreateInventoryFunctionDto, principal: AuthPrincipal, request: RequestWithContext): Promise<InventoryFunctionRow> {
    return this.dataSource.transaction(async (manager) => {
      const [duplicate] = await manager.query('SELECT 1 FROM inventory_functions WHERE lower(code)=lower($1) LIMIT 1', [dto.code]) as unknown[];
      if (duplicate) throw new ConflictException({ code: 'INVENTORY_FUNCTION_CODE_EXISTS', message: 'Ya existe una función con ese código' });
      const [created] = await manager.query(`
        INSERT INTO inventory_functions(code,name,description,is_active,sort_order,created_by,updated_by)
        VALUES($1,$2,$3,true,$4,$5,$5)
        RETURNING id,code,name,description,is_active AS "isActive",sort_order AS "sortOrder",
          created_at AS "createdAt",updated_at AS "updatedAt"
      `, [dto.code, dto.name, dto.description ?? null, dto.sortOrder ?? 0, principal.userId]) as InventoryFunctionRow[];
      await this.audit.record({ ...administrationAuditContext(principal, request), action: AuditAction.INVENTORY_FUNCTION_CREATED,
        entityType: 'inventory_function', entityId: created.id, afterData: created as unknown as Record<string, unknown> }, manager);
      return created;
    });
  }

  async update(id: string, dto: UpdateInventoryFunctionDto, principal: AuthPrincipal, request: RequestWithContext): Promise<InventoryFunctionRow> {
    if (Object.keys(dto).length === 0) throw new BadRequestException({ code: 'NO_CHANGES', message: 'No se recibieron cambios' });
    return this.dataSource.transaction(async (manager) => {
      const before = await this.requireFunction(manager, id, false);
      const [updated] = await manager.query(`
        UPDATE inventory_functions SET
          name=COALESCE($2,name), description=CASE WHEN $3::boolean THEN $4 ELSE description END,
          is_active=COALESCE($5,is_active), sort_order=COALESCE($6,sort_order),
          updated_by=$7,updated_at=CURRENT_TIMESTAMP
        WHERE id=$1
        RETURNING id,code,name,description,is_active AS "isActive",sort_order AS "sortOrder",
          created_at AS "createdAt",updated_at AS "updatedAt"
      `, [id, dto.name ?? null, dto.description !== undefined, dto.description ?? null, dto.isActive ?? null, dto.sortOrder ?? null, principal.userId]) as InventoryFunctionRow[];
      await this.audit.record({ ...administrationAuditContext(principal, request), action: AuditAction.INVENTORY_FUNCTION_UPDATED,
        entityType: 'inventory_function', entityId: id, beforeData: before as unknown as Record<string, unknown>,
        afterData: updated as unknown as Record<string, unknown> }, manager);
      return updated;
    });
  }

  async getForAsset(assetId: string) {
    return this.dataSource.transaction((manager) => this.getForAssetWithManager(manager, assetId));
  }

  async changeForAsset(assetId: string, dto: ChangeInventoryFunctionDto, principal: AuthPrincipal, request: RequestWithContext) {
    return this.dataSource.transaction(async (manager) => {
      const asset = await this.requireEligibleAsset(manager, assetId, true);
      const nextFunction = await this.requireFunction(manager, dto.functionId, true);
      const effectiveAt = dto.effectiveAt ? new Date(dto.effectiveAt) : new Date();
      if (!Number.isFinite(effectiveAt.getTime())) throw new BadRequestException({ code: 'INVENTORY_FUNCTION_EFFECTIVE_DATE_INVALID', message: 'La fecha efectiva del cambio de función no es válida' });
      if (effectiveAt.getTime() > Date.now() + 60_000) throw new BadRequestException({ code: 'INVENTORY_FUNCTION_FUTURE_DATE_NOT_ALLOWED', message: 'El cambio de función no puede registrarse con fecha futura' });

      const current = await this.currentAssignment(manager, assetId, true);
      if (current?.functionId === nextFunction.id) return this.getForAssetWithManager(manager, assetId);
      if (current && effectiveAt.getTime() <= new Date(current.validFrom).getTime()) {
        throw new ConflictException({ code: 'INVENTORY_FUNCTION_EFFECTIVE_DATE_OVERLAP', message: 'La fecha efectiva debe ser posterior al inicio de la función vigente' });
      }
      if (current) await manager.query(`UPDATE inventory_function_assignments SET valid_until=$2 WHERE id=$1 AND valid_until IS NULL`, [current.id, effectiveAt]);
      await manager.query(`INSERT INTO inventory_function_assignments(asset_id,function_id,valid_from,change_reason,changed_by) VALUES($1,$2,$3,$4,$5)`,
        [assetId, nextFunction.id, effectiveAt, dto.reason ?? null, principal.userId]);
      await manager.query(`UPDATE assets SET updated_by=$2,updated_at=CURRENT_TIMESTAMP WHERE id=$1`, [assetId, principal.userId]);

      const versionNumber = await this.history.capture(manager, assetId, AssetVersionChangeType.FUNCTION_CHANGED, principal, request);
      const after = await this.getForAssetWithManager(manager, assetId);
      await this.audit.record({
        ...administrationAuditContext(principal, request), action: AuditAction.ASSET_FUNCTION_CHANGED,
        entityType: 'asset', entityId: assetId,
        beforeData: current ? { functionId: current.functionId, functionCode: current.functionCode, functionName: current.functionName, validFrom: current.validFrom } : { functionId: null },
        afterData: { functionId: nextFunction.id, functionCode: nextFunction.code, functionName: nextFunction.name, effectiveAt, reason: dto.reason ?? null, versionNumber },
        metadata: { inventoryCode: asset.code, inventoryName: asset.name, temporal: true, historySource: 'inventory_function_assignments', assetVersionChangeType: AssetVersionChangeType.FUNCTION_CHANGED },
      }, manager);
      return after;
    });
  }

  private async getForAssetWithManager(manager: EntityManager, assetId: string) {
    const asset = await this.requireEligibleAsset(manager, assetId, false);
    const currentFunction = await this.currentAssignment(manager, assetId, false);
    const history = await manager.query(`
      SELECT assignment.id,assignment.asset_id AS "assetId",assignment.function_id AS "functionId",
        fn.code AS "functionCode",fn.name AS "functionName",
        assignment.valid_from AS "validFrom",assignment.valid_until AS "validUntil",
        assignment.change_reason AS reason,assignment.changed_by AS "changedBy",
        actor.username AS "changedByUsername",assignment.created_at AS "createdAt"
      FROM inventory_function_assignments assignment
      JOIN inventory_functions fn ON fn.id=assignment.function_id
      LEFT JOIN users actor ON actor.id=assignment.changed_by
      WHERE assignment.asset_id=$1
      ORDER BY assignment.valid_from DESC,assignment.created_at DESC
    `, [assetId]) as FunctionAssignmentRow[];
    return { asset: { id: asset.id, code: asset.code, name: asset.name, typeCode: asset.typeCode, typeName: asset.typeName, familyCode: asset.familyCode, familyName: asset.familyName }, currentFunction, history };
  }

  private async currentAssignment(manager: EntityManager, assetId: string, lock: boolean): Promise<FunctionAssignmentRow | null> {
    const [row] = await manager.query(`
      SELECT assignment.id,assignment.asset_id AS "assetId",assignment.function_id AS "functionId",
        fn.code AS "functionCode",fn.name AS "functionName",
        assignment.valid_from AS "validFrom",assignment.valid_until AS "validUntil",
        assignment.change_reason AS reason,assignment.changed_by AS "changedBy",
        actor.username AS "changedByUsername",assignment.created_at AS "createdAt"
      FROM inventory_function_assignments assignment
      JOIN inventory_functions fn ON fn.id=assignment.function_id
      LEFT JOIN users actor ON actor.id=assignment.changed_by
      WHERE assignment.asset_id=$1 AND assignment.valid_until IS NULL
      ${lock ? 'FOR UPDATE OF assignment' : ''}
    `, [assetId]) as FunctionAssignmentRow[];
    return row ?? null;
  }

  private async requireFunction(manager: EntityManager, id: string, active: boolean): Promise<InventoryFunctionRow> {
    const [row] = await manager.query(`
      SELECT id,code,name,description,is_active AS "isActive",sort_order AS "sortOrder",created_at AS "createdAt",updated_at AS "updatedAt"
      FROM inventory_functions WHERE id=$1 ${active ? 'AND is_active=true' : ''}
    `, [id]) as InventoryFunctionRow[];
    if (!row) throw new NotFoundException({ code: 'INVENTORY_FUNCTION_NOT_FOUND', message: active ? 'La función seleccionada no existe o está inactiva' : 'Función no encontrada' });
    return row;
  }

  private async requireEligibleAsset(manager: EntityManager, assetId: string, lock: boolean): Promise<FunctionEligibleAsset> {
    const [asset] = await manager.query(`
      SELECT asset.id,asset.code,asset.name,asset_type.code AS "typeCode",asset_type.name AS "typeName",
        family.code AS "familyCode",family.name AS "familyName"
      FROM assets asset JOIN asset_types asset_type ON asset_type.id=asset.asset_type_id
      LEFT JOIN inventory_families family ON family.id=asset.inventory_family_id
      WHERE asset.id=$1 ${lock ? 'FOR UPDATE OF asset' : ''}
    `, [assetId]) as FunctionEligibleAsset[];
    if (!asset) throw new NotFoundException({ code: 'ASSET_NOT_FOUND', message: 'Inventario no encontrado' });
    const values = [asset.typeCode, asset.typeName, asset.familyCode, asset.familyName].map(normalized);
    const eligible = values.some((value) => value === 'estacion' || value === 'subestacion' || value.includes('estacion ') || value.includes('subestacion ') || value.endsWith(' estacion') || value.endsWith(' subestacion'));
    if (!eligible) throw new ConflictException({ code: 'INVENTORY_FUNCTION_CHANGE_NOT_ALLOWED', message: 'El cambio de función sólo está habilitado para Inventarios de Estación o Subestación' });
    return asset;
  }
}