package service

import (
	"errors"
	"strings"

	common "gitlab.com/mbugroup/lti-api.git/internal/common/service"

	entity "gitlab.com/mbugroup/lti-api.git/internal/entities"
	validation "gitlab.com/mbugroup/lti-api.git/internal/modules/inventory/adjustments/validations"
	ProductWarehouse "gitlab.com/mbugroup/lti-api.git/internal/modules/inventory/product-warehouses/repositories"
	productRepo "gitlab.com/mbugroup/lti-api.git/internal/modules/master/products/repositories"
	warehouseRepo "gitlab.com/mbugroup/lti-api.git/internal/modules/master/warehouses/repositories"
	stockLogsRepo "gitlab.com/mbugroup/lti-api.git/internal/modules/shared/repositories"
	"gitlab.com/mbugroup/lti-api.git/internal/utils"
	"gorm.io/gorm"

	"github.com/go-playground/validator/v10"
	"github.com/gofiber/fiber/v2"
	"github.com/sirupsen/logrus"
)

type AdjustmentService interface {
	Adjustment(ctx *fiber.Ctx, req *validation.Create) (*entity.StockLog, error)
	GetOne(ctx *fiber.Ctx, id uint) (*entity.StockLog, error)
	AdjustmentHistory(ctx *fiber.Ctx, query *validation.Query) ([]*entity.StockLog, int64, error)
}

type adjustmentService struct {
	Log                  *logrus.Logger
	Validate             *validator.Validate
	StockLogsRepository  stockLogsRepo.StockLogRepository
	WarehouseRepo        warehouseRepo.WarehouseRepository
	ProductWarehouseRepo ProductWarehouse.ProductWarehouseRepository
	ProductRepo          productRepo.ProductRepository
}

func NewAdjustmentService(productRepo productRepo.ProductRepository, stockLogsRepo stockLogsRepo.StockLogRepository, warehouseRepo warehouseRepo.WarehouseRepository, productWarehouseRepo ProductWarehouse.ProductWarehouseRepository, validate *validator.Validate) AdjustmentService {
	return &adjustmentService{
		Log:                  utils.Log,
		Validate:             validate,
		StockLogsRepository:  stockLogsRepo,
		WarehouseRepo:        warehouseRepo,
		ProductWarehouseRepo: productWarehouseRepo,
		ProductRepo:          productRepo,
	}
}

func (s *adjustmentService) withRelations(db *gorm.DB) *gorm.DB {
	return db.
		Preload("ProductWarehouse").
		Preload("ProductWarehouse.Product").
		Preload("ProductWarehouse.Warehouse").
		Preload("CreatedUser")
}

func (s *adjustmentService) GetOne(c *fiber.Ctx, id uint) (*entity.StockLog, error) {
	stockLog, err := s.StockLogsRepository.GetByID(c.Context(), id, func(db *gorm.DB) *gorm.DB {
		return s.withRelations(db).Preload("ProductWarehouse.Product.ProductCategory")
	})
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, fiber.NewError(fiber.StatusNotFound, "Adjustment not found")
		}
		s.Log.Errorf("Failed to get adjustment by id: %+v", err)
		return nil, err
	}

	if stockLog.LogType != entity.LogTypeAdjustment {
		return nil, fiber.NewError(fiber.StatusNotFound, "Adjustment not found")
	}

	return stockLog, nil
}

func (s *adjustmentService) Adjustment(c *fiber.Ctx, req *validation.Create) (*entity.StockLog, error) {
	if err := s.Validate.Struct(req); err != nil {
		return nil, err
	}
	ctx := c.Context()

	if err := common.EnsureRelations(c.Context(),
		common.RelationCheck{Name: "Product", ID: &req.ProductID, Exists: s.ProductRepo.IdExists},
		common.RelationCheck{Name: "Warehouse", ID: &req.WarehouseID, Exists: s.WarehouseRepo.IdExists},
	); err != nil {
		return nil, err
	}

	if req.Quantity <= 0 {
		return nil, fiber.NewError(fiber.StatusBadRequest, "Quantity must be greater than zero")
	}
	transactionType := strings.ToUpper(req.TransactionType)
	if transactionType != entity.TransactionTypeIncrease && transactionType != entity.TransactionTypeDecrease {
		return nil, fiber.NewError(fiber.StatusBadRequest, "Invalid transaction type")
	}

	var createdLogId uint

	isProductWarehouseExist, err := s.ProductWarehouseRepo.ProductWarehouseExistByProductAndWarehouseID(ctx, uint(req.ProductID), uint(req.WarehouseID))
	if err != nil {
		s.Log.Errorf("Failed to check product warehouse existence: %+v", err)
		return nil, fiber.NewError(fiber.StatusInternalServerError, "Failed to validate product warehouse")
	}
	if !isProductWarehouseExist {

		newPW := &entity.ProductWarehouse{
			ProductId:   uint(req.ProductID),
			WarehouseId: uint(req.WarehouseID),
			Quantity:    0,
			CreatedBy:   1, // TODO: should Get from auth middleware
		}

		if err := s.ProductWarehouseRepo.CreateOne(ctx, newPW, nil); err != nil {
			s.Log.Errorf("Failed to create product warehouse: %+v", err)
			return nil, fiber.NewError(fiber.StatusInternalServerError, "Failed to create product warehouse")
		}
		s.Log.Infof("Product warehouse created: %+v", newPW.Id)
	}

	err = s.StockLogsRepository.DB().WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		productWarehouse, err := s.ProductWarehouseRepo.GetProductWarehouseByProductAndWarehouseID(ctx, uint(req.ProductID), uint(req.WarehouseID))
		if err != nil {
			s.Log.Errorf("Failed to get product warehouse: %+v", err)
			return fiber.NewError(fiber.StatusInternalServerError, "Failed to get product warehouse")
		}

		afterQuantity := productWarehouse.Quantity
		if transactionType == entity.TransactionTypeIncrease {
			afterQuantity += req.Quantity
		} else {
			if productWarehouse.Quantity < req.Quantity {
				return fiber.NewError(fiber.StatusBadRequest, "Insufficient stock for adjustment")
			}
			afterQuantity -= req.Quantity
		}

		newLog := &entity.StockLog{
			TransactionType:    transactionType,
			Quantity:           req.Quantity,
			BeforeQuantity:     productWarehouse.Quantity,
			AfterQuantity:      afterQuantity,
			LogType:            entity.LogTypeAdjustment,
			LogId:              0,
			Note:               req.Note,
			ProductWarehouseId: productWarehouse.Id,
			CreatedBy:          1, // TODO: should Get from auth middleware
		}

		if err := s.StockLogsRepository.WithTx(tx).CreateOne(ctx, newLog, nil); err != nil {
			s.Log.Errorf("Failed to create stock log: %+v", err)
			return err
		}

		productWarehouse.Quantity = afterQuantity
		if err := s.ProductWarehouseRepo.WithTx(tx).UpdateOne(ctx, productWarehouse.Id, productWarehouse, nil); err != nil {
			s.Log.Errorf("Failed to update product warehouse quantity: %+v", err)
			return err
		}

		createdLogId = newLog.Id
		return nil
	})

	if err != nil {
		s.Log.Errorf("Transaction failed in CreateOne: %+v", err)
		return nil, fiber.NewError(fiber.StatusInternalServerError, "Failed to process adjustment transaction")
	}

	return s.GetOne(c, createdLogId)
}

func (s *adjustmentService) AdjustmentHistory(c *fiber.Ctx, query *validation.Query) ([]*entity.StockLog, int64, error) {
	if err := s.Validate.Struct(query); err != nil {
		return nil, 0, err
	}
	offset := (query.Page - 1) * query.Limit

	isWarehousesExist, err := s.WarehouseRepo.IdExists(c.Context(), uint(query.WarehouseID))
	if err != nil {
		s.Log.Errorf("Failed to check warehouse existence: %+v", err)
		return nil, 0, fiber.NewError(fiber.StatusInternalServerError, "Failed to validate warehouse")
	}
	if query.WarehouseID > 0 && !isWarehousesExist {
		return nil, 0, fiber.NewError(fiber.StatusNotFound, "Warehouse not found")
	}

	isProductsExist, err := s.ProductRepo.IdExists(c.Context(), uint(query.ProductID))
	if err != nil {
		s.Log.Errorf("Failed to check product existence: %+v", err)
		return nil, 0, fiber.NewError(fiber.StatusInternalServerError, "Failed to validate product")
	}
	if query.ProductID > 0 && !isProductsExist {
		return nil, 0, fiber.NewError(fiber.StatusNotFound, "Product not found")
	}

	stockLogs, total, err := s.StockLogsRepository.GetAll(c.Context(), offset, query.Limit, func(db *gorm.DB) *gorm.DB {

		db = s.withRelations(db)

		db = db.Where("log_type = ?", entity.LogTypeAdjustment)

		if query.TransactionType != "" {
			db = db.Where("transaction_type = ?", strings.ToUpper(query.TransactionType))
		}
		db = s.StockLogsRepository.ApplyProductWarehouseFilters(db, uint(query.ProductID), uint(query.WarehouseID))

		return db.Order("created_at DESC")
	})

	if err != nil {
		s.Log.Errorf("Failed to get adjustments: %+v", err)
		return nil, 0, fiber.NewError(fiber.StatusInternalServerError, "Failed to get adjustment history")
	}

	result := make([]*entity.StockLog, len(stockLogs))
	for i, v := range stockLogs {
		result[i] = &v
	}

	return result, total, nil
}