/**
 * Warehouse Entry Service
 * Mecánicas Diesel - ERP Suite
 *
 * Handles receiving parts into the warehouse/inventory.
 * Manages purchase entries, returns, transfers, and movement history.
 */

import { Repository, DataSource, Between, In, EntityManager } from 'typeorm';
import { Part } from '../entities/part.entity';
import { Supplier } from '../entities/supplier.entity';
import { InventoryMovement, MovementType, MovementReferenceType } from '../entities/inventory-movement.entity';

// ============================================================================
// DTOs
// ============================================================================

export interface CreatePurchaseEntryDto {
  partId: string;
  quantity: number;
  unitCost: number;
  invoiceNumber?: string;
  notes?: string;
}

export interface BulkEntryDto {
  entries: CreatePurchaseEntryDto[];
}

export interface BulkEntryResult {
  successful: Array<{
    partId: string;
    movementId: string;
    quantity: number;
  }>;
  failed: Array<{
    partId: string;
    error: string;
  }>;
  totalProcessed: number;
  totalSuccess: number;
  totalFailed: number;
}

export interface ReceiveFromSupplierItem {
  partId: string;
  quantity: number;
  unitCost: number;
  invoiceNumber?: string;
}

export interface ReceiveFromSupplierResult {
  supplierId: string;
  supplierName: string;
  totalItems: number;
  totalQuantity: number;
  totalValue: number;
  movements: InventoryMovement[];
  receivedAt: Date;
}

export interface ReturnEntryDto {
  orderId: string;
  partId: string;
  quantity: number;
  reason: string;
}

export interface TransferDto {
  partId: string;
  fromLocationId: string;
  toLocationId: string;
  quantity: number;
  notes?: string;
}

export interface TransferResult {
  partId: string;
  fromLocationId: string;
  toLocationId: string;
  quantity: number;
  outMovementId: string;
  inMovementId: string;
}

export interface MovementHistoryFilters {
  startDate?: Date;
  endDate?: Date;
  movementTypes?: MovementType[];
  page?: number;
  limit?: number;
}

export interface MovementHistoryResult {
  data: InventoryMovement[];
  total: number;
  page: number;
  limit: number;
  totalPages: number;
}

export interface DailyMovementsSummary {
  date: Date;
  totalEntries: number;
  totalExits: number;
  netChange: number;
  byType: Record<MovementType, { count: number; quantity: number; value: number }>;
  totalValue: number;
}

// ============================================================================
// Service
// ============================================================================

export class WarehouseEntryService {
  private partRepository: Repository<Part>;
  private supplierRepository: Repository<Supplier>;
  private movementRepository: Repository<InventoryMovement>;
  private dataSource: DataSource;

  constructor(dataSource: DataSource) {
    this.dataSource = dataSource;
    this.partRepository = dataSource.getRepository(Part);
    this.supplierRepository = dataSource.getRepository(Supplier);
    this.movementRepository = dataSource.getRepository(InventoryMovement);
  }

  /**
   * Create a purchase entry - receive parts from purchase
   * Updates part stock and calculates weighted average cost
   */
  async createPurchaseEntry(
    tenantId: string,
    dto: CreatePurchaseEntryDto,
    performedById: string
  ): Promise<InventoryMovement> {
    return this.dataSource.transaction(async (manager) => {
      const partRepo = manager.getRepository(Part);
      const movementRepo = manager.getRepository(InventoryMovement);

      // Validate part exists
      const part = await partRepo.findOne({
        where: { id: dto.partId, tenantId },
      });

      if (!part) {
        throw new Error(`Part with ID ${dto.partId} not found`);
      }

      if (dto.quantity <= 0) {
        throw new Error('Quantity must be greater than zero');
      }

      if (dto.unitCost < 0) {
        throw new Error('Unit cost cannot be negative');
      }

      const previousStock = part.currentStock;
      const newStock = previousStock + dto.quantity;
      const totalCost = dto.quantity * dto.unitCost;

      // Calculate weighted average cost
      const newAverageCost = this.calculateWeightedAverageCost(
        previousStock,
        part.cost || 0,
        dto.quantity,
        dto.unitCost
      );

      // Create movement record
      const movement = movementRepo.create({
        tenantId,
        partId: dto.partId,
        movementType: MovementType.PURCHASE,
        quantity: dto.quantity,
        unitCost: dto.unitCost,
        totalCost,
        previousStock,
        newStock,
        referenceType: MovementReferenceType.PURCHASE_ORDER,
        referenceId: undefined,
        notes: dto.invoiceNumber
          ? `Invoice: ${dto.invoiceNumber}${dto.notes ? ` - ${dto.notes}` : ''}`
          : dto.notes,
        performedById,
        performedAt: new Date(),
      });

      await movementRepo.save(movement);

      // Update part stock and cost
      part.currentStock = newStock;
      part.cost = newAverageCost;
      await partRepo.save(part);

      return movement;
    });
  }

  /**
   * Create bulk entries - receive multiple parts in a single transaction
   */
  async createBulkEntry(
    tenantId: string,
    dto: BulkEntryDto,
    performedById: string
  ): Promise<BulkEntryResult> {
    const result: BulkEntryResult = {
      successful: [],
      failed: [],
      totalProcessed: dto.entries.length,
      totalSuccess: 0,
      totalFailed: 0,
    };

    return this.dataSource.transaction(async (manager) => {
      for (const entry of dto.entries) {
        try {
          const movement = await this.createPurchaseEntryWithManager(
            manager,
            tenantId,
            entry,
            performedById
          );

          result.successful.push({
            partId: entry.partId,
            movementId: movement.id,
            quantity: entry.quantity,
          });
          result.totalSuccess++;
        } catch (error) {
          const errorMessage = error instanceof Error ? error.message : 'Unknown error';
          result.failed.push({
            partId: entry.partId,
            error: errorMessage,
          });
          result.totalFailed++;
        }
      }

      return result;
    });
  }

  /**
   * Receive parts from a specific supplier
   * Full receiving workflow with supplier validation
   */
  async receiveFromSupplier(
    tenantId: string,
    supplierId: string,
    items: ReceiveFromSupplierItem[],
    performedById: string
  ): Promise<ReceiveFromSupplierResult> {
    return this.dataSource.transaction(async (manager) => {
      const supplierRepo = manager.getRepository(Supplier);

      // Validate supplier exists
      const supplier = await supplierRepo.findOne({
        where: { id: supplierId, tenantId },
      });

      if (!supplier) {
        throw new Error(`Supplier with ID ${supplierId} not found`);
      }

      if (!supplier.isActive) {
        throw new Error(`Supplier ${supplier.name} is not active`);
      }

      const movements: InventoryMovement[] = [];
      let totalQuantity = 0;
      let totalValue = 0;

      // Process each item
      for (const item of items) {
        const movement = await this.createPurchaseEntryWithManager(
          manager,
          tenantId,
          {
            partId: item.partId,
            quantity: item.quantity,
            unitCost: item.unitCost,
            invoiceNumber: item.invoiceNumber,
            notes: `Received from supplier: ${supplier.name}`,
          },
          performedById
        );

        movements.push(movement);
        totalQuantity += item.quantity;
        totalValue += item.quantity * item.unitCost;
      }

      const receivedAt = new Date();

      return {
        supplierId,
        supplierName: supplier.name,
        totalItems: items.length,
        totalQuantity,
        totalValue,
        movements,
        receivedAt,
      };
    });
  }

  /**
   * Create return entry - return part to stock from service order
   */
  async createReturnEntry(
    tenantId: string,
    dto: ReturnEntryDto,
    performedById: string
  ): Promise<InventoryMovement> {
    return this.dataSource.transaction(async (manager) => {
      const partRepo = manager.getRepository(Part);
      const movementRepo = manager.getRepository(InventoryMovement);

      // Validate part exists
      const part = await partRepo.findOne({
        where: { id: dto.partId, tenantId },
      });

      if (!part) {
        throw new Error(`Part with ID ${dto.partId} not found`);
      }

      if (dto.quantity <= 0) {
        throw new Error('Return quantity must be greater than zero');
      }

      const previousStock = part.currentStock;
      const newStock = previousStock + dto.quantity;

      // Create movement record
      const movement = movementRepo.create({
        tenantId,
        partId: dto.partId,
        movementType: MovementType.RETURN,
        quantity: dto.quantity,
        unitCost: part.cost,
        totalCost: dto.quantity * (part.cost || 0),
        previousStock,
        newStock,
        referenceType: MovementReferenceType.RETURN,
        referenceId: dto.orderId,
        notes: `Return reason: ${dto.reason}`,
        performedById,
        performedAt: new Date(),
      });

      await movementRepo.save(movement);

      // Update part stock (no cost recalculation for returns)
      part.currentStock = newStock;
      await partRepo.save(part);

      return movement;
    });
  }

  /**
   * Create transfer between warehouse locations
   * Creates two movements: out from source, in to destination
   */
  async createTransfer(
    tenantId: string,
    dto: TransferDto,
    performedById: string
  ): Promise<TransferResult> {
    return this.dataSource.transaction(async (manager) => {
      const partRepo = manager.getRepository(Part);
      const movementRepo = manager.getRepository(InventoryMovement);

      // Validate part exists
      const part = await partRepo.findOne({
        where: { id: dto.partId, tenantId },
      });

      if (!part) {
        throw new Error(`Part with ID ${dto.partId} not found`);
      }

      if (dto.quantity <= 0) {
        throw new Error('Transfer quantity must be greater than zero');
      }

      if (dto.fromLocationId === dto.toLocationId) {
        throw new Error('Source and destination locations cannot be the same');
      }

      // For transfers, stock remains the same (internal movement)
      // We create two movements for traceability
      const currentStock = part.currentStock;
      const performedAt = new Date();

      // Create OUT movement
      const outMovement = movementRepo.create({
        tenantId,
        partId: dto.partId,
        movementType: MovementType.TRANSFER,
        quantity: dto.quantity,
        unitCost: part.cost,
        totalCost: dto.quantity * (part.cost || 0),
        previousStock: currentStock,
        newStock: currentStock, // Stock doesn't change for internal transfers
        referenceType: MovementReferenceType.MANUAL,
        referenceId: dto.fromLocationId,
        notes: `Transfer OUT to location ${dto.toLocationId}${dto.notes ? ` - ${dto.notes}` : ''}`,
        performedById,
        performedAt,
      });

      await movementRepo.save(outMovement);

      // Create IN movement
      const inMovement = movementRepo.create({
        tenantId,
        partId: dto.partId,
        movementType: MovementType.TRANSFER,
        quantity: dto.quantity,
        unitCost: part.cost,
        totalCost: dto.quantity * (part.cost || 0),
        previousStock: currentStock,
        newStock: currentStock,
        referenceType: MovementReferenceType.MANUAL,
        referenceId: dto.toLocationId,
        notes: `Transfer IN from location ${dto.fromLocationId}${dto.notes ? ` - ${dto.notes}` : ''}`,
        performedById,
        performedAt,
      });

      await movementRepo.save(inMovement);

      // Update part location if it has a location assigned
      if (part.locationId === dto.fromLocationId) {
        part.locationId = dto.toLocationId;
        await partRepo.save(part);
      }

      return {
        partId: dto.partId,
        fromLocationId: dto.fromLocationId,
        toLocationId: dto.toLocationId,
        quantity: dto.quantity,
        outMovementId: outMovement.id,
        inMovementId: inMovement.id,
      };
    });
  }

  /**
   * Get movement history for a specific part
   */
  async getMovementHistory(
    tenantId: string,
    partId: string,
    filters: MovementHistoryFilters = {}
  ): Promise<MovementHistoryResult> {
    const page = filters.page || 1;
    const limit = filters.limit || 20;
    const skip = (page - 1) * limit;

    const queryBuilder = this.movementRepository
      .createQueryBuilder('movement')
      .where('movement.tenant_id = :tenantId', { tenantId })
      .andWhere('movement.part_id = :partId', { partId });

    // Apply date range filter
    if (filters.startDate && filters.endDate) {
      queryBuilder.andWhere(
        'movement.performed_at BETWEEN :startDate AND :endDate',
        { startDate: filters.startDate, endDate: filters.endDate }
      );
    } else if (filters.startDate) {
      queryBuilder.andWhere('movement.performed_at >= :startDate', {
        startDate: filters.startDate,
      });
    } else if (filters.endDate) {
      queryBuilder.andWhere('movement.performed_at <= :endDate', {
        endDate: filters.endDate,
      });
    }

    // Apply movement type filter
    if (filters.movementTypes && filters.movementTypes.length > 0) {
      queryBuilder.andWhere('movement.movement_type IN (:...types)', {
        types: filters.movementTypes,
      });
    }

    const [data, total] = await queryBuilder
      .orderBy('movement.performed_at', 'DESC')
      .skip(skip)
      .take(limit)
      .getManyAndCount();

    return {
      data,
      total,
      page,
      limit,
      totalPages: Math.ceil(total / limit),
    };
  }

  /**
   * Get all movements related to a specific service order
   */
  async getMovementsByOrder(
    tenantId: string,
    orderId: string
  ): Promise<InventoryMovement[]> {
    return this.movementRepository.find({
      where: {
        tenantId,
        referenceId: orderId,
        referenceType: In([
          MovementReferenceType.SERVICE_ORDER,
          MovementReferenceType.RETURN,
        ]),
      },
      order: { performedAt: 'DESC' },
      relations: ['part'],
    });
  }

  /**
   * Recalculate weighted average cost for a part
   * Based on all purchase movements
   */
  async calculateAverageCost(tenantId: string, partId: string): Promise<number> {
    return this.dataSource.transaction(async (manager) => {
      const partRepo = manager.getRepository(Part);
      const movementRepo = manager.getRepository(InventoryMovement);

      const part = await partRepo.findOne({
        where: { id: partId, tenantId },
      });

      if (!part) {
        throw new Error(`Part with ID ${partId} not found`);
      }

      // Get all purchase movements
      const purchaseMovements = await movementRepo.find({
        where: {
          tenantId,
          partId,
          movementType: MovementType.PURCHASE,
        },
        order: { performedAt: 'ASC' },
      });

      if (purchaseMovements.length === 0) {
        return part.cost || 0;
      }

      // Calculate weighted average using FIFO-like approach
      let totalQuantity = 0;
      let totalValue = 0;

      for (const movement of purchaseMovements) {
        totalQuantity += Number(movement.quantity);
        totalValue += Number(movement.totalCost || 0);
      }

      const averageCost = totalQuantity > 0 ? totalValue / totalQuantity : 0;

      // Update part cost
      part.cost = averageCost;
      await partRepo.save(part);

      return averageCost;
    });
  }

  /**
   * Get daily movements summary for a specific date
   */
  async getDailyMovementsSummary(
    tenantId: string,
    date: Date
  ): Promise<DailyMovementsSummary> {
    const startOfDay = new Date(date);
    startOfDay.setHours(0, 0, 0, 0);

    const endOfDay = new Date(date);
    endOfDay.setHours(23, 59, 59, 999);

    const movements = await this.movementRepository.find({
      where: {
        tenantId,
        performedAt: Between(startOfDay, endOfDay),
      },
    });

    const inboundTypes = [
      MovementType.PURCHASE,
      MovementType.ADJUSTMENT_IN,
      MovementType.RETURN,
    ];

    const outboundTypes = [
      MovementType.CONSUMPTION,
      MovementType.ADJUSTMENT_OUT,
    ];

    let totalEntries = 0;
    let totalExits = 0;
    let totalValue = 0;

    const byType: Record<MovementType, { count: number; quantity: number; value: number }> = {
      [MovementType.PURCHASE]: { count: 0, quantity: 0, value: 0 },
      [MovementType.CONSUMPTION]: { count: 0, quantity: 0, value: 0 },
      [MovementType.ADJUSTMENT_IN]: { count: 0, quantity: 0, value: 0 },
      [MovementType.ADJUSTMENT_OUT]: { count: 0, quantity: 0, value: 0 },
      [MovementType.RETURN]: { count: 0, quantity: 0, value: 0 },
      [MovementType.TRANSFER]: { count: 0, quantity: 0, value: 0 },
    };

    for (const movement of movements) {
      const quantity = Number(movement.quantity);
      const value = Number(movement.totalCost || 0);

      // Update type statistics
      byType[movement.movementType].count++;
      byType[movement.movementType].quantity += quantity;
      byType[movement.movementType].value += value;

      // Calculate totals
      if (inboundTypes.includes(movement.movementType)) {
        totalEntries += quantity;
        totalValue += value;
      } else if (outboundTypes.includes(movement.movementType)) {
        totalExits += quantity;
        totalValue -= value;
      }
      // Transfers don't affect totals
    }

    return {
      date: startOfDay,
      totalEntries,
      totalExits,
      netChange: totalEntries - totalExits,
      byType,
      totalValue,
    };
  }

  /**
   * Create adjustment entry (manual stock correction)
   */
  async createAdjustmentEntry(
    tenantId: string,
    partId: string,
    quantity: number,
    reason: string,
    performedById: string
  ): Promise<InventoryMovement> {
    return this.dataSource.transaction(async (manager) => {
      const partRepo = manager.getRepository(Part);
      const movementRepo = manager.getRepository(InventoryMovement);

      const part = await partRepo.findOne({
        where: { id: partId, tenantId },
      });

      if (!part) {
        throw new Error(`Part with ID ${partId} not found`);
      }

      const previousStock = part.currentStock;
      const newStock = previousStock + quantity;

      if (newStock < 0) {
        throw new Error('Adjustment would result in negative stock');
      }

      const movementType = quantity >= 0
        ? MovementType.ADJUSTMENT_IN
        : MovementType.ADJUSTMENT_OUT;

      const movement = movementRepo.create({
        tenantId,
        partId,
        movementType,
        quantity: Math.abs(quantity),
        unitCost: part.cost,
        totalCost: Math.abs(quantity) * (part.cost || 0),
        previousStock,
        newStock,
        referenceType: MovementReferenceType.ADJUSTMENT,
        notes: reason,
        performedById,
        performedAt: new Date(),
      });

      await movementRepo.save(movement);

      part.currentStock = newStock;
      await partRepo.save(part);

      return movement;
    });
  }

  /**
   * Create consumption entry (part used in service order)
   */
  async createConsumptionEntry(
    tenantId: string,
    partId: string,
    quantity: number,
    orderId: string,
    performedById: string,
    notes?: string
  ): Promise<InventoryMovement> {
    return this.dataSource.transaction(async (manager) => {
      const partRepo = manager.getRepository(Part);
      const movementRepo = manager.getRepository(InventoryMovement);

      const part = await partRepo.findOne({
        where: { id: partId, tenantId },
      });

      if (!part) {
        throw new Error(`Part with ID ${partId} not found`);
      }

      if (quantity <= 0) {
        throw new Error('Consumption quantity must be greater than zero');
      }

      const previousStock = part.currentStock;
      const newStock = previousStock - quantity;

      if (newStock < 0) {
        throw new Error(`Insufficient stock. Available: ${previousStock}, Requested: ${quantity}`);
      }

      const movement = movementRepo.create({
        tenantId,
        partId,
        movementType: MovementType.CONSUMPTION,
        quantity,
        unitCost: part.cost,
        totalCost: quantity * (part.cost || 0),
        previousStock,
        newStock,
        referenceType: MovementReferenceType.SERVICE_ORDER,
        referenceId: orderId,
        notes,
        performedById,
        performedAt: new Date(),
      });

      await movementRepo.save(movement);

      part.currentStock = newStock;
      await partRepo.save(part);

      return movement;
    });
  }

  /**
   * Get stock value report for all parts
   */
  async getStockValueReport(tenantId: string): Promise<{
    totalParts: number;
    totalQuantity: number;
    totalCostValue: number;
    totalSaleValue: number;
    averageMargin: number;
  }> {
    const result = await this.partRepository
      .createQueryBuilder('part')
      .select('COUNT(part.id)', 'totalParts')
      .addSelect('SUM(part.current_stock)', 'totalQuantity')
      .addSelect('SUM(part.current_stock * COALESCE(part.cost, 0))', 'totalCostValue')
      .addSelect('SUM(part.current_stock * part.price)', 'totalSaleValue')
      .where('part.tenant_id = :tenantId', { tenantId })
      .andWhere('part.is_active = true')
      .getRawOne();

    const totalCostValue = parseFloat(result?.totalCostValue) || 0;
    const totalSaleValue = parseFloat(result?.totalSaleValue) || 0;

    return {
      totalParts: parseInt(result?.totalParts, 10) || 0,
      totalQuantity: parseFloat(result?.totalQuantity) || 0,
      totalCostValue,
      totalSaleValue,
      averageMargin: totalCostValue > 0
        ? ((totalSaleValue - totalCostValue) / totalCostValue) * 100
        : 0,
    };
  }

  // ============================================================================
  // Private Helper Methods
  // ============================================================================

  /**
   * Calculate weighted average cost when receiving new inventory
   */
  private calculateWeightedAverageCost(
    existingQuantity: number,
    existingCost: number,
    newQuantity: number,
    newCost: number
  ): number {
    const totalQuantity = existingQuantity + newQuantity;

    if (totalQuantity === 0) {
      return 0;
    }

    const existingValue = existingQuantity * existingCost;
    const newValue = newQuantity * newCost;
    const totalValue = existingValue + newValue;

    return totalValue / totalQuantity;
  }

  /**
   * Internal method to create purchase entry with a provided EntityManager
   */
  private async createPurchaseEntryWithManager(
    manager: EntityManager,
    tenantId: string,
    dto: CreatePurchaseEntryDto,
    performedById: string
  ): Promise<InventoryMovement> {
    const partRepo = manager.getRepository(Part);
    const movementRepo = manager.getRepository(InventoryMovement);

    // Validate part exists
    const part = await partRepo.findOne({
      where: { id: dto.partId, tenantId },
    });

    if (!part) {
      throw new Error(`Part with ID ${dto.partId} not found`);
    }

    if (dto.quantity <= 0) {
      throw new Error('Quantity must be greater than zero');
    }

    if (dto.unitCost < 0) {
      throw new Error('Unit cost cannot be negative');
    }

    const previousStock = part.currentStock;
    const newStock = previousStock + dto.quantity;
    const totalCost = dto.quantity * dto.unitCost;

    // Calculate weighted average cost
    const newAverageCost = this.calculateWeightedAverageCost(
      previousStock,
      part.cost || 0,
      dto.quantity,
      dto.unitCost
    );

    // Create movement record
    const movement = movementRepo.create({
      tenantId,
      partId: dto.partId,
      movementType: MovementType.PURCHASE,
      quantity: dto.quantity,
      unitCost: dto.unitCost,
      totalCost,
      previousStock,
      newStock,
      referenceType: MovementReferenceType.PURCHASE_ORDER,
      referenceId: undefined,
      notes: dto.invoiceNumber
        ? `Invoice: ${dto.invoiceNumber}${dto.notes ? ` - ${dto.notes}` : ''}`
        : dto.notes,
      performedById,
      performedAt: new Date(),
    });

    await movementRepo.save(movement);

    // Update part stock and cost
    part.currentStock = newStock;
    part.cost = newAverageCost;
    await partRepo.save(part);

    return movement;
  }
}