package handler

import (
	"apskel-pos-be/internal/constants"
	"apskel-pos-be/internal/contract"
	"apskel-pos-be/internal/entities"
	"apskel-pos-be/internal/logger"
	"apskel-pos-be/internal/models"
	"apskel-pos-be/internal/pkg/tabletoken"
	"apskel-pos-be/internal/processor"
	"apskel-pos-be/internal/repository"
	"apskel-pos-be/internal/service"
	"apskel-pos-be/internal/transformer"
	"apskel-pos-be/internal/util"
	"context"
	"fmt"

	"github.com/gin-gonic/gin"
	"github.com/google/uuid"
)

type SelfOrderHandler struct {
	orderService    service.OrderService
	categoryService service.CategoryService
	productService  service.ProductService
	tableRepo       repository.TableRepositoryInterface
	outletRepo      processor.OutletRepository
	userRepo        processor.UserRepository
	sessionRepo     repository.SessionRepository
	orderRepo       repository.OrderRepository
}

func NewSelfOrderHandler(
	orderService service.OrderService,
	categoryService service.CategoryService,
	productService service.ProductService,
	tableRepo repository.TableRepositoryInterface,
	outletRepo processor.OutletRepository,
	userRepo processor.UserRepository,
	sessionRepo repository.SessionRepository,
	orderRepo repository.OrderRepository,
) *SelfOrderHandler {
	return &SelfOrderHandler{
		orderService:    orderService,
		categoryService: categoryService,
		productService:  productService,
		tableRepo:       tableRepo,
		outletRepo:      outletRepo,
		userRepo:        userRepo,
		sessionRepo:     sessionRepo,
		orderRepo:       orderRepo,
	}
}

func (h *SelfOrderHandler) ValidateToken(c *gin.Context) {
	ctx := c.Request.Context()
	token := c.Param("token")

	if token == "" {
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.MissingFieldErrorCode, constants.RequestEntity, "token is required"),
		}), "SelfOrderHandler::ValidateToken")
		return
	}

	tableID, orgID, outletID, err := tabletoken.Decode(token)
	if err != nil {
		logger.FromContext(ctx).WithError(err).Error("SelfOrderHandler::ValidateToken -> invalid token")
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.ValidationErrorCode, constants.RequestEntity, "invalid table token"),
		}), "SelfOrderHandler::ValidateToken")
		return
	}

	table, err := h.tableRepo.GetByID(ctx, tableID)
	if err != nil {
		logger.FromContext(ctx).WithError(err).Error("SelfOrderHandler::ValidateToken -> table not found")
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.NotFoundErrorCode, constants.TableEntity, "table not found"),
		}), "SelfOrderHandler::ValidateToken")
		return
	}

	if !table.IsActive {
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.ValidationErrorCode, constants.TableEntity, "table is not active"),
		}), "SelfOrderHandler::ValidateToken")
		return
	}

	if table.OrganizationID != orgID || table.OutletID != outletID {
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.ValidationErrorCode, constants.TableEntity, "token does not match table"),
		}), "SelfOrderHandler::ValidateToken")
		return
	}

	outlet, err := h.outletRepo.GetByID(ctx, table.OutletID)
	if err != nil {
		logger.FromContext(ctx).WithError(err).Error("SelfOrderHandler::ValidateToken -> outlet not found")
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.NotFoundErrorCode, constants.OrderServiceEntity, "outlet not found"),
		}), "SelfOrderHandler::ValidateToken")
		return
	}

	existingSession, err := h.sessionRepo.GetActiveByTableID(ctx, table.ID)
	if err != nil {
		logger.FromContext(ctx).WithError(err).Error("SelfOrderHandler::ValidateToken -> failed to check session")
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.InternalServerErrorCode, constants.OrderServiceEntity, "failed to check session"),
		}), "SelfOrderHandler::ValidateToken")
		return
	}

	var sessionStatus string
	var sessionID string

	if existingSession != nil {
		sessionStatus = "joined_session"
		sessionID = existingSession.ID
	} else {
		session := &models.SelfOrderSession{
			TableID:        table.ID,
			OrganizationID: table.OrganizationID,
			OutletID:       table.OutletID,
		}
		if err := h.sessionRepo.Create(ctx, session); err != nil {
			logger.FromContext(ctx).WithError(err).Error("SelfOrderHandler::ValidateToken -> failed to create session")
			util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
				contract.NewResponseError(constants.InternalServerErrorCode, constants.OrderServiceEntity, "failed to create session"),
			}), "SelfOrderHandler::ValidateToken")
			return
		}
		sessionStatus = "new_session"
		sessionID = session.ID
	}

	resp := &contract.SelfOrderTableTokenResponse{
		SessionID:      sessionID,
		TableID:        table.ID.String(),
		OrganizationID: table.OrganizationID.String(),
		OutletID:       table.OutletID.String(),
		TableName:      table.TableName,
		OutletName:     outlet.Name,
		Status:         sessionStatus,
	}

	util.HandleResponse(c.Writer, c.Request, contract.BuildSuccessResponse(resp), "SelfOrderHandler::ValidateToken")
}

func (h *SelfOrderHandler) GetMenu(c *gin.Context) {
	ctx := c.Request.Context()

	var req contract.SelfOrderMenuRequest
	if err := c.ShouldBindQuery(&req); err != nil {
		logger.FromContext(ctx).WithError(err).Error("SelfOrderHandler::GetMenu -> query binding failed")
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.MissingFieldErrorCode, constants.RequestEntity, err.Error()),
		}), "SelfOrderHandler::GetMenu")
		return
	}

	session, table, outlet, err := h.resolveSession(ctx, req.SessionID)
	if err != nil {
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.ValidationErrorCode, constants.RequestEntity, err.Error()),
		}), "SelfOrderHandler::GetMenu")
		return
	}
	if session == nil {
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.NotFoundErrorCode, constants.RequestEntity, "session not found or expired"),
		}), "SelfOrderHandler::GetMenu")
		return
	}

	isActive := true
	catResp := h.categoryService.ListCategories(ctx, &contract.ListCategoriesRequest{
		OrganizationID: &table.OrganizationID,
		Page:           1,
		Limit:          100,
	})
	if catResp.HasErrors() {
		logger.FromContext(ctx).WithError(catResp.GetErrors()[0]).Error("SelfOrderHandler::GetMenu -> failed to list categories")
		util.HandleResponse(c.Writer, c.Request, catResp, "SelfOrderHandler::GetMenu")
		return
	}

	prodResp := h.productService.ListProducts(ctx, &contract.ListProductsRequest{
		OrganizationID: &table.OrganizationID,
		IsActive:       &isActive,
		Page:           1,
		Limit:          1000,
	})
	if prodResp.HasErrors() {
		logger.FromContext(ctx).WithError(prodResp.GetErrors()[0]).Error("SelfOrderHandler::GetMenu -> failed to list products")
		util.HandleResponse(c.Writer, c.Request, prodResp, "SelfOrderHandler::GetMenu")
		return
	}

	catList, ok := catResp.Data.(*contract.ListCategoriesResponse)
	if !ok {
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.InternalServerErrorCode, constants.CategoryServiceEntity, "unexpected categories response type"),
		}), "SelfOrderHandler::GetMenu")
		return
	}

	prodList, ok := prodResp.Data.(*contract.ListProductsResponse)
	if !ok {
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.InternalServerErrorCode, constants.ProductServiceEntity, "unexpected products response type"),
		}), "SelfOrderHandler::GetMenu")
		return
	}

	menu := h.buildMenuResponse(outlet, table, catList.Categories, prodList.Products)
	util.HandleResponse(c.Writer, c.Request, contract.BuildSuccessResponse(menu), "SelfOrderHandler::GetMenu")
}

func (h *SelfOrderHandler) buildMenuResponse(
	outlet *entities.Outlet,
	table *entities.Table,
	categories []contract.CategoryResponse,
	products []contract.ProductResponse,
) *contract.SelfOrderMenuResponse {
	productMap := make(map[uuid.UUID][]contract.ProductResponse)
	for _, p := range products {
		productMap[p.CategoryID] = append(productMap[p.CategoryID], p)
	}

	menuCategories := make([]contract.SelfOrderMenuCategory, 0, len(categories))
	for _, cat := range categories {
		menuItems := make([]contract.SelfOrderMenuItem, 0)
		if prods, ok := productMap[cat.ID]; ok {
			for _, p := range prods {
				item := contract.SelfOrderMenuItem{
					ID:          p.ID,
					Name:        p.Name,
					Description: p.Description,
					Price:       p.Price,
					ImageURL:    p.ImageURL,
				}
				for _, v := range p.Variants {
					item.Variants = append(item.Variants, contract.SelfOrderMenuVariant{
						ID:            v.ID,
						Name:          v.Name,
						PriceModifier: v.PriceModifier,
					})
				}
				menuItems = append(menuItems, item)
			}
		}
		menuCategories = append(menuCategories, contract.SelfOrderMenuCategory{
			ID:          cat.ID,
			Name:        cat.Name,
			Description: cat.Description,
			Order:       cat.Order,
			Products:    menuItems,
		})
	}

	return &contract.SelfOrderMenuResponse{
		OutletName: outlet.Name,
		TableName:  table.TableName,
		Categories: menuCategories,
	}
}

func (h *SelfOrderHandler) CreateOrder(c *gin.Context) {
	ctx := c.Request.Context()

	var req contract.SelfOrderCreateOrderRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		logger.FromContext(ctx).WithError(err).Error("SelfOrderHandler::CreateOrder -> request binding failed")
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.MissingFieldErrorCode, constants.RequestEntity, err.Error()),
		}), "SelfOrderHandler::CreateOrder")
		return
	}

	if err := h.validateCreateOrderRequest(&req); err != nil {
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.ValidationErrorCode, constants.RequestEntity, err.Error()),
		}), "SelfOrderHandler::CreateOrder")
		return
	}

	session, table, _, err := h.resolveSession(ctx, req.SessionID)
	if err != nil {
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.ValidationErrorCode, constants.RequestEntity, err.Error()),
		}), "SelfOrderHandler::CreateOrder")
		return
	}
	if session == nil {
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.NotFoundErrorCode, constants.RequestEntity, "session not found or expired"),
		}), "SelfOrderHandler::CreateOrder")
		return
	}

	if !table.IsActive || !table.IsAvailable() {
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.ValidationErrorCode, constants.TableEntity, "table is not available for ordering"),
		}), "SelfOrderHandler::CreateOrder")
		return
	}

	userID, err := h.resolveOrgUser(ctx, table.OrganizationID)
	if err != nil {
		logger.FromContext(ctx).WithError(err).Error("SelfOrderHandler::CreateOrder -> failed to resolve org user")
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.InternalServerErrorCode, constants.OrderServiceEntity, "failed to create self-order"),
		}), "SelfOrderHandler::CreateOrder")
		return
	}

	orderItems := make([]models.CreateOrderItemRequest, 0, len(req.OrderItems))
	for _, item := range req.OrderItems {
		orderItems = append(orderItems, models.CreateOrderItemRequest{
			ProductID:        item.ProductID,
			ProductVariantID: item.ProductVariantID,
			Quantity:         item.Quantity,
			Notes:            item.Notes,
		})
	}

	metadata := make(map[string]interface{})
	metadata["self_order"] = true
	metadata["session_id"] = session.ID
	metadata["customer_name"] = req.CustomerName

	tableID := table.ID
	modelReq := &models.CreateOrderRequest{
		OutletID:    table.OutletID,
		UserID:      userID,
		TableID:     &tableID,
		TableNumber: &table.TableName,
		OrderType:   constants.OrderType(req.OrderType),
		OrderItems:  orderItems,
		Metadata:    metadata,
	}

	response, err := h.orderService.CreateOrder(ctx, modelReq, table.OrganizationID)
	if err != nil {
		logger.FromContext(ctx).WithError(err).Error("SelfOrderHandler::CreateOrder -> failed to create order")
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.InternalServerErrorCode, constants.OrderServiceEntity, err.Error()),
		}), "SelfOrderHandler::CreateOrder")
		return
	}

	contractResp := transformer.OrderModelToContract(response)
	util.HandleResponse(c.Writer, c.Request, contract.BuildSuccessResponse(contractResp), "SelfOrderHandler::CreateOrder")
}

func (h *SelfOrderHandler) GetOrdersBySession(c *gin.Context) {
	ctx := c.Request.Context()
	sessionID := c.Param("session_id")

	if sessionID == "" {
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.MissingFieldErrorCode, constants.RequestEntity, "session_id is required"),
		}), "SelfOrderHandler::GetOrdersBySession")
		return
	}

	session, err := h.sessionRepo.GetByID(ctx, sessionID)
	if err != nil {
		logger.FromContext(ctx).WithError(err).Error("SelfOrderHandler::GetOrdersBySession -> failed to get session")
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.NotFoundErrorCode, constants.RequestEntity, "session not found"),
		}), "SelfOrderHandler::GetOrdersBySession")
		return
	}
	if session == nil {
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.NotFoundErrorCode, constants.RequestEntity, "session not found"),
		}), "SelfOrderHandler::GetOrdersBySession")
		return
	}

	orders, err := h.orderRepo.ListBySessionID(ctx, sessionID)
	if err != nil {
		logger.FromContext(ctx).WithError(err).Error("SelfOrderHandler::GetOrdersBySession -> failed to list orders")
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.InternalServerErrorCode, constants.OrderServiceEntity, "failed to list orders"),
		}), "SelfOrderHandler::GetOrdersBySession")
		return
	}

	resp := &contract.SelfOrderListOrdersResponse{
		Orders: make([]contract.SelfOrderOrderItem, 0, len(orders)),
	}
	for _, o := range orders {
		item := contract.SelfOrderOrderItem{
			ID:              o.ID,
			OrderNumber:     o.OrderNumber,
			TableNumber:     o.TableNumber,
			OrderType:       string(o.OrderType),
			Status:          string(o.Status),
			Subtotal:        o.Subtotal,
			TaxAmount:       o.TaxAmount,
			DiscountAmount:  o.DiscountAmount,
			TotalAmount:     o.TotalAmount,
			RemainingAmount: o.RemainingAmount,
			PaymentStatus:   string(o.PaymentStatus),
			IsVoid:          o.IsVoid,
			Metadata:        o.Metadata,
			IsRefund:        o.IsRefund,
			CreatedAt:       o.CreatedAt,
		}
		for _, oi := range o.OrderItems {
			lineItem := contract.SelfOrderOrderLineItem{
				ProductID:        oi.ProductID,
				Quantity:         oi.Quantity,
				UnitPrice:        oi.UnitPrice,
				TotalPrice:       oi.TotalPrice,
				Notes:            oi.Notes,
				Status:           string(oi.Status),
				ProductVariantID: oi.ProductVariantID,
			}
			if oi.Product.ID != uuid.Nil {
				lineItem.ProductName = oi.Product.Name
			}
			if oi.ProductVariant != nil {
				lineItem.ProductVariantNam = &oi.ProductVariant.Name
			}
			item.Items = append(item.Items, lineItem)
		}
		resp.Orders = append(resp.Orders, item)
	}

	util.HandleResponse(c.Writer, c.Request, contract.BuildSuccessResponse(resp), "SelfOrderHandler::GetOrdersBySession")
}

func (h *SelfOrderHandler) validateCreateOrderRequest(req *contract.SelfOrderCreateOrderRequest) error {
	if req.SessionID == "" {
		return fmt.Errorf("session_id is required")
	}
	if len(req.OrderItems) == 0 {
		return fmt.Errorf("at least one order item is required")
	}
	for i, item := range req.OrderItems {
		if item.ProductID == uuid.Nil {
			return fmt.Errorf("product_id is required for item %d", i+1)
		}
		if item.Quantity <= 0 {
			return fmt.Errorf("quantity must be greater than zero for item %d", i+1)
		}
	}
	return nil
}

func (h *SelfOrderHandler) ListCategories(c *gin.Context) {
	ctx := c.Request.Context()

	var req contract.SelfOrderListCategoriesRequest
	if err := c.ShouldBindQuery(&req); err != nil {
		logger.FromContext(ctx).WithError(err).Error("SelfOrderHandler::ListCategories -> query binding failed")
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.MissingFieldErrorCode, constants.RequestEntity, err.Error()),
		}), "SelfOrderHandler::ListCategories")
		return
	}

	if req.OrganizationID == "" {
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.MissingFieldErrorCode, constants.RequestEntity, "organization_id is required"),
		}), "SelfOrderHandler::ListCategories")
		return
	}

	if req.OutletID == "" {
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.MissingFieldErrorCode, constants.RequestEntity, "outlet_id is required"),
		}), "SelfOrderHandler::ListCategories")
		return
	}

	orgID, err := uuid.Parse(req.OrganizationID)
	if err != nil {
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.ValidationErrorCode, constants.RequestEntity, "invalid organization_id format"),
		}), "SelfOrderHandler::ListCategories")
		return
	}

	outletID, err := uuid.Parse(req.OutletID)
	if err != nil {
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.ValidationErrorCode, constants.RequestEntity, "invalid outlet_id format"),
		}), "SelfOrderHandler::ListCategories")
		return
	}

	outlet, err := h.outletRepo.GetByID(ctx, outletID)
	if err != nil || outlet == nil {
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.NotFoundErrorCode, constants.RequestEntity, "outlet not found"),
		}), "SelfOrderHandler::ListCategories")
		return
	}

	if outlet.OrganizationID != orgID {
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.ValidationErrorCode, constants.RequestEntity, "outlet does not belong to the specified organization"),
		}), "SelfOrderHandler::ListCategories")
		return
	}

	catResp := h.categoryService.ListCategories(ctx, &contract.ListCategoriesRequest{
		OrganizationID: &orgID,
		Page:           1,
		Limit:          100,
	})
	if catResp.HasErrors() {
		logger.FromContext(ctx).WithError(catResp.GetErrors()[0]).Error("SelfOrderHandler::ListCategories -> failed to list categories")
		util.HandleResponse(c.Writer, c.Request, catResp, "SelfOrderHandler::ListCategories")
		return
	}

	catList, ok := catResp.Data.(*contract.ListCategoriesResponse)
	if !ok {
		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
			contract.NewResponseError(constants.InternalServerErrorCode, constants.CategoryServiceEntity, "unexpected categories response type"),
		}), "SelfOrderHandler::ListCategories")
		return
	}

	items := make([]contract.SelfOrderCategoryItem, 0, len(catList.Categories))
	for _, cat := range catList.Categories {
		items = append(items, contract.SelfOrderCategoryItem{
			ID:          cat.ID,
			Name:        cat.Name,
			Description: cat.Description,
			Order:       cat.Order,
		})
	}

	util.HandleResponse(c.Writer, c.Request, contract.BuildSuccessResponse(&contract.SelfOrderListCategoriesResponse{
		Categories: items,
	}), "SelfOrderHandler::ListCategories")
}

func (h *SelfOrderHandler) resolveSession(ctx context.Context, sessionID string) (*models.SelfOrderSession, *entities.Table, *entities.Outlet, error) {
	session, err := h.sessionRepo.GetByID(ctx, sessionID)
	if err != nil {
		return nil, nil, nil, fmt.Errorf("failed to get session: %w", err)
	}
	if session == nil {
		return nil, nil, nil, nil
	}
	if session.Status != "active" {
		return nil, nil, nil, fmt.Errorf("session is no longer active")
	}

	table, err := h.tableRepo.GetByID(ctx, session.TableID)
	if err != nil {
		return nil, nil, nil, fmt.Errorf("table not found for session")
	}

	outlet, err := h.outletRepo.GetByID(ctx, table.OutletID)
	if err != nil {
		return nil, nil, nil, fmt.Errorf("outlet not found for session")
	}

	return session, table, outlet, nil
}

func (h *SelfOrderHandler) resolveOrgUser(ctx context.Context, organizationID uuid.UUID) (uuid.UUID, error) {
	users, err := h.userRepo.GetByOrganizationID(ctx, organizationID)
	if err != nil {
		return uuid.Nil, fmt.Errorf("failed to get users for organization: %w", err)
	}
	if len(users) == 0 {
		return uuid.Nil, fmt.Errorf("no users found for organization")
	}
	return users[0].ID, nil
}