package service

import (
	"context"
	"errors"
	"fmt"

	commonRepo "gitlab.com/mbugroup/lti-api.git/internal/common/repository"
	common "gitlab.com/mbugroup/lti-api.git/internal/common/service"
	entity "gitlab.com/mbugroup/lti-api.git/internal/entities"
	flockRepository "gitlab.com/mbugroup/lti-api.git/internal/modules/master/flocks/repositories"
	kandangRepository "gitlab.com/mbugroup/lti-api.git/internal/modules/master/kandangs/repositories"
	repository "gitlab.com/mbugroup/lti-api.git/internal/modules/production/project_flocks/repositories"
	validation "gitlab.com/mbugroup/lti-api.git/internal/modules/production/project_flocks/validations"
	"gitlab.com/mbugroup/lti-api.git/internal/utils"

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

type ProjectflockService interface {
	GetAll(ctx *fiber.Ctx, params *validation.Query) ([]entity.ProjectFlock, int64, error)
	GetOne(ctx *fiber.Ctx, id uint) (*entity.ProjectFlock, error)
	CreateOne(ctx *fiber.Ctx, req *validation.Create) (*entity.ProjectFlock, error)
	UpdateOne(ctx *fiber.Ctx, req *validation.Update, id uint) (*entity.ProjectFlock, error)
	DeleteOne(ctx *fiber.Ctx, id uint) error
	GetFlockPeriodSummary(ctx *fiber.Ctx, flockID uint) (*FlockPeriodSummary, error)
}

type projectflockService struct {
	Log         *logrus.Logger
	Validate    *validator.Validate
	Repository  repository.ProjectflockRepository
	FlockRepo   flockRepository.FlockRepository
	KandangRepo kandangRepository.KandangRepository
}

type FlockPeriodSummary struct {
	Flock      entity.Flock
	NextPeriod int
}

func NewProjectflockService(
	repo repository.ProjectflockRepository,
	flockRepo flockRepository.FlockRepository,
	kandangRepo kandangRepository.KandangRepository,
	validate *validator.Validate,
) ProjectflockService {
	return &projectflockService{
		Log:         utils.Log,
		Validate:    validate,
		Repository:  repo,
		FlockRepo:   flockRepo,
		KandangRepo: kandangRepo,
	}
}

func (s projectflockService) withRelations(db *gorm.DB) *gorm.DB {
	return db.
		Preload("CreatedUser").
		Preload("Flock").
		Preload("Area").
		Preload("ProductCategory").
		Preload("Fcr").
		Preload("Location").
		Preload("Kandangs")
}

func (s projectflockService) GetAll(c *fiber.Ctx, params *validation.Query) ([]entity.ProjectFlock, int64, error) {
	if err := s.Validate.Struct(params); err != nil {
		return nil, 0, err
	}

	offset := (params.Page - 1) * params.Limit

	projectflocks, total, err := s.Repository.GetAll(c.Context(), offset, params.Limit, func(db *gorm.DB) *gorm.DB {
		db = s.withRelations(db)
		return db.Order("created_at DESC").Order("updated_at DESC")
	})

	if err != nil {
		s.Log.Errorf("Failed to get projectflocks: %+v", err)
		return nil, 0, err
	}
	return projectflocks, total, nil
}

func (s projectflockService) GetOne(c *fiber.Ctx, id uint) (*entity.ProjectFlock, error) {
	projectflock, err := s.Repository.GetByID(c.Context(), id, s.withRelations)
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return nil, fiber.NewError(fiber.StatusNotFound, "Projectflock not found")
	}
	if err != nil {
		s.Log.Errorf("Failed get projectflock by id: %+v", err)
		return nil, err
	}
	return projectflock, nil
}

func (s *projectflockService) CreateOne(c *fiber.Ctx, req *validation.Create) (*entity.ProjectFlock, error) {
	if err := s.Validate.Struct(req); err != nil {
		return nil, err
	}

	if len(req.KandangIds) == 0 {
		return nil, fiber.NewError(fiber.StatusBadRequest, "kandang_ids is required")
	}

	if err := common.EnsureRelations(c.Context(),
		common.RelationCheck{Name: "Flock", ID: &req.FlockId, Exists: relationExistsChecker[entity.Flock](s.Repository.DB())},
		common.RelationCheck{Name: "Area", ID: &req.AreaId, Exists: relationExistsChecker[entity.Area](s.Repository.DB())},
		common.RelationCheck{Name: "Product category", ID: &req.ProductCategoryId, Exists: relationExistsChecker[entity.ProductCategory](s.Repository.DB())},
		common.RelationCheck{Name: "FCR", ID: &req.FcrId, Exists: relationExistsChecker[entity.Fcr](s.Repository.DB())},
		common.RelationCheck{Name: "Location", ID: &req.LocationId, Exists: relationExistsChecker[entity.Location](s.Repository.DB())},
	); err != nil {
		return nil, err
	}

	kandangIDs := uniqueUintSlice(req.KandangIds)
	kandangs, err := s.KandangRepo.GetByIDs(c.Context(), kandangIDs, nil)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, fiber.NewError(fiber.StatusNotFound, "Some kandangs not found")
		}
		return nil, fiber.NewError(fiber.StatusInternalServerError, "Failed to fetch kandangs")
	}
	if len(kandangs) != len(kandangIDs) {
		return nil, fiber.NewError(fiber.StatusNotFound, "Some kandangs not found")
	}
	for _, kandang := range kandangs {
		if kandang.ProjectFlockId != nil {
			return nil, fiber.NewError(fiber.StatusConflict, fmt.Sprintf("Kandang %s sudah memiliki project flock", kandang.Name))
		}
	}

	tx := s.Repository.DB().Begin()
	if tx.Error != nil {
		return nil, fiber.NewError(fiber.StatusInternalServerError, "Failed to start transaction")
	}

	projectRepo := repository.NewProjectflockRepository(tx)
	nextPeriod, err := projectRepo.GetNextPeriodForFlock(c.Context(), req.FlockId)
	if err != nil {
		tx.Rollback()
		s.Log.Errorf("Failed to determine next period for flock %d: %+v", req.FlockId, err)
		return nil, fiber.NewError(fiber.StatusInternalServerError, "Failed to determine next period")
	}

	createBody := &entity.ProjectFlock{
		FlockId:           req.FlockId,
		AreaId:            req.AreaId,
		ProductCategoryId: req.ProductCategoryId,
		FcrId:             req.FcrId,
		LocationId:        req.LocationId,
		Period:            nextPeriod,
		CreatedBy:         1,
	}

	if err := projectRepo.CreateOne(c.Context(), createBody, nil); err != nil {
		tx.Rollback()
		if errors.Is(err, gorm.ErrDuplicatedKey) {
			return nil, fiber.NewError(fiber.StatusConflict, "Project flock period already exists")
		}
		s.Log.Errorf("Failed to create projectflock: %+v", err)
		return nil, err
	}

	if err := tx.Model(&entity.Kandang{}).
		Where("id IN ?", kandangIDs).
		Updates(map[string]any{"project_flock_id": createBody.Id}).Error; err != nil {
		tx.Rollback()
		s.Log.Errorf("Failed to assign kandangs to projectflock: %+v", err)
		return nil, fiber.NewError(fiber.StatusInternalServerError, "Failed to assign kandangs")
	}

	if err := tx.Commit().Error; err != nil {
		tx.Rollback()
		return nil, fiber.NewError(fiber.StatusInternalServerError, "Failed to commit transaction")
	}

	return s.GetOne(c, createBody.Id)
}

func (s projectflockService) UpdateOne(c *fiber.Ctx, req *validation.Update, id uint) (*entity.ProjectFlock, error) {
	if err := s.Validate.Struct(req); err != nil {
		return nil, err
	}

	existing, err := s.Repository.GetByID(c.Context(), id, s.withRelations)
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return nil, fiber.NewError(fiber.StatusNotFound, "Projectflock not found")
	}
	if err != nil {
		s.Log.Errorf("Failed to fetch projectflock %d before update: %+v", id, err)
		return nil, fiber.NewError(fiber.StatusInternalServerError, "Failed to fetch project flock")
	}

	updateBody := make(map[string]any)
	var relationChecks []common.RelationCheck

	if req.FlockId != nil {
		updateBody["flock_id"] = *req.FlockId
		relationChecks = append(relationChecks, common.RelationCheck{
			Name:   "Flock",
			ID:     req.FlockId,
			Exists: relationExistsChecker[entity.Flock](s.Repository.DB()),
		})
	}
	if req.AreaId != nil {
		updateBody["area_id"] = *req.AreaId
		relationChecks = append(relationChecks, common.RelationCheck{
			Name:   "Area",
			ID:     req.AreaId,
			Exists: relationExistsChecker[entity.Area](s.Repository.DB()),
		})
	}
	if req.ProductCategoryId != nil {
		updateBody["product_category_id"] = *req.ProductCategoryId
		relationChecks = append(relationChecks, common.RelationCheck{
			Name:   "Product category",
			ID:     req.ProductCategoryId,
			Exists: relationExistsChecker[entity.ProductCategory](s.Repository.DB()),
		})
	}
	if req.FcrId != nil {
		updateBody["fcr_id"] = *req.FcrId
		relationChecks = append(relationChecks, common.RelationCheck{
			Name:   "FCR",
			ID:     req.FcrId,
			Exists: relationExistsChecker[entity.Fcr](s.Repository.DB()),
		})
	}
	if req.LocationId != nil {
		updateBody["location_id"] = *req.LocationId
		relationChecks = append(relationChecks, common.RelationCheck{
			Name:   "Location",
			ID:     req.LocationId,
			Exists: relationExistsChecker[entity.Location](s.Repository.DB()),
		})
	}
	if req.Period != nil {
		updateBody["period"] = *req.Period
	}

	if len(relationChecks) > 0 {
		if err := common.EnsureRelations(c.Context(), relationChecks...); err != nil {
			return nil, err
		}
	}

	var newKandangIDs []uint
	if req.KandangIds != nil {
		if len(req.KandangIds) == 0 {
			return nil, fiber.NewError(fiber.StatusBadRequest, "kandang_ids cannot be empty")
		}
		newKandangIDs = uniqueUintSlice(req.KandangIds)
		kandangs, err := s.KandangRepo.GetByIDs(c.Context(), newKandangIDs, nil)
		if err != nil {
			if errors.Is(err, gorm.ErrRecordNotFound) {
				return nil, fiber.NewError(fiber.StatusNotFound, "Some kandangs not found")
			}
			return nil, fiber.NewError(fiber.StatusInternalServerError, "Failed to fetch kandangs")
		}
		if len(kandangs) != len(newKandangIDs) {
			return nil, fiber.NewError(fiber.StatusNotFound, "Some kandangs not found")
		}
		for _, k := range kandangs {
			if k.ProjectFlockId != nil && *k.ProjectFlockId != id {
				return nil, fiber.NewError(fiber.StatusConflict, fmt.Sprintf("Kandang %s sudah terikat dengan project flock lain", k.Name))
			}
		}
	}

	tx := s.Repository.DB().Begin()
	if tx.Error != nil {
		return nil, fiber.NewError(fiber.StatusInternalServerError, "Failed to start transaction")
	}

	projectRepo := repository.NewProjectflockRepository(tx)
	if len(updateBody) > 0 {
		if err := projectRepo.PatchOne(c.Context(), id, updateBody, nil); err != nil {
			tx.Rollback()
			if errors.Is(err, gorm.ErrRecordNotFound) {
				return nil, fiber.NewError(fiber.StatusNotFound, "Projectflock not found")
			}
			s.Log.Errorf("Failed to update projectflock: %+v", err)
			return nil, err
		}
	}

	if req.KandangIds != nil {
		existingIDs := make(map[uint]struct{}, len(existing.Kandangs))
		for _, k := range existing.Kandangs {
			existingIDs[k.Id] = struct{}{}
		}
		newSet := make(map[uint]struct{}, len(newKandangIDs))
		for _, id := range newKandangIDs {
			newSet[id] = struct{}{}
		}

		var toDetach []uint
		for id := range existingIDs {
			if _, ok := newSet[id]; !ok {
				toDetach = append(toDetach, id)
			}
		}

		var toAttach []uint
		for id := range newSet {
			if _, ok := existingIDs[id]; !ok {
				toAttach = append(toAttach, id)
			}
		}

		if len(toDetach) > 0 {
			if err := tx.Model(&entity.Kandang{}).
				Where("id IN ?", toDetach).
				Updates(map[string]any{"project_flock_id": nil}).Error; err != nil {
				tx.Rollback()
				s.Log.Errorf("Failed to detach kandangs: %+v", err)
				return nil, fiber.NewError(fiber.StatusInternalServerError, "Failed to update kandangs")
			}
		}

		if len(toAttach) > 0 {
			if err := tx.Model(&entity.Kandang{}).
				Where("id IN ?", toAttach).
				Updates(map[string]any{"project_flock_id": id}).Error; err != nil {
				tx.Rollback()
				s.Log.Errorf("Failed to attach kandangs: %+v", err)
				return nil, fiber.NewError(fiber.StatusInternalServerError, "Failed to update kandangs")
			}
		}
	}

	if err := tx.Commit().Error; err != nil {
		tx.Rollback()
		return nil, fiber.NewError(fiber.StatusInternalServerError, "Failed to commit transaction")
	}

	return s.GetOne(c, id)
}

func (s projectflockService) DeleteOne(c *fiber.Ctx, id uint) error {
	existing, err := s.Repository.GetByID(c.Context(), id, s.withRelations)
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return fiber.NewError(fiber.StatusNotFound, "Projectflock not found")
	}
	if err != nil {
		s.Log.Errorf("Failed to fetch projectflock %d before delete: %+v", id, err)
		return fiber.NewError(fiber.StatusInternalServerError, "Failed to fetch project flock")
	}

	tx := s.Repository.DB().Begin()
	if tx.Error != nil {
		return fiber.NewError(fiber.StatusInternalServerError, "Failed to start transaction")
	}

	if len(existing.Kandangs) > 0 {
		ids := make([]uint, len(existing.Kandangs))
		for i, k := range existing.Kandangs {
			ids[i] = k.Id
		}
		if err := tx.Model(&entity.Kandang{}).
			Where("id IN ?", ids).
			Updates(map[string]any{"project_flock_id": nil}).Error; err != nil {
			tx.Rollback()
			s.Log.Errorf("Failed to detach kandangs before delete: %+v", err)
			return fiber.NewError(fiber.StatusInternalServerError, "Failed to update kandangs")
		}
	}

	if err := repository.NewProjectflockRepository(tx).DeleteOne(c.Context(), id); err != nil {
		tx.Rollback()
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return fiber.NewError(fiber.StatusNotFound, "Projectflock not found")
		}
		s.Log.Errorf("Failed to delete projectflock: %+v", err)
		return err
	}

	if err := tx.Commit().Error; err != nil {
		tx.Rollback()
		return fiber.NewError(fiber.StatusInternalServerError, "Failed to commit transaction")
	}

	return nil
}

func (s projectflockService) GetFlockPeriodSummary(c *fiber.Ctx, flockID uint) (*FlockPeriodSummary, error) {
	flock, err := s.FlockRepo.GetByID(c.Context(), flockID, func(db *gorm.DB) *gorm.DB {
		return db.Preload("CreatedUser")
	})
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return nil, fiber.NewError(fiber.StatusNotFound, "Flock not found")
	}
	if err != nil {
		s.Log.Errorf("Failed get flock %d for period summary: %+v", flockID, err)
		return nil, fiber.NewError(fiber.StatusInternalServerError, "Failed to fetch flock")
	}

	maxPeriod, err := s.Repository.GetMaxPeriodByFlock(c.Context(), flockID)
	if err != nil {
		s.Log.Errorf("Failed to compute next period for flock %d: %+v", flockID, err)
		return nil, fiber.NewError(fiber.StatusInternalServerError, "Failed to compute next period")
	}

	return &FlockPeriodSummary{
		Flock:      *flock,
		NextPeriod: maxPeriod + 1,
	}, nil
}

func uniqueUintSlice(values []uint) []uint {
	seen := make(map[uint]struct{}, len(values))
	result := make([]uint, 0, len(values))
	for _, v := range values {
		if _, ok := seen[v]; ok {
			continue
		}
		seen[v] = struct{}{}
		result = append(result, v)
	}
	return result
}

func relationExistsChecker[T any](db *gorm.DB) func(context.Context, uint) (bool, error) {
	return func(ctx context.Context, id uint) (bool, error) {
		return commonRepo.Exists[T](ctx, db, id)
	}
}