package service

import (
	"context"
	"errors"

	"gorm.io/gorm"

	"github.com/gochat/gochat/internal/model"
	"github.com/gochat/gochat/internal/repository"
	applogger "github.com/gochat/gochat/pkg/logger"
	pkgvalidator "github.com/gochat/gochat/pkg/validator"
)

// InboxLimitService implements business logic for inbox limit management.
// Reference: Chatwoot app/controllers/api/v1/accounts/inboxes/inbox_limits_controller.rb
// Inbox limits are create/update/destroy only (no index or show in Chatwoot).
type InboxLimitService struct {
	repo *repository.InboxLimitRepo
}

// NewInboxLimitService creates a new InboxLimit service.
func NewInboxLimitService(repo *repository.InboxLimitRepo) *InboxLimitService {
	return &InboxLimitService{repo: repo}
}

// CreateInboxLimitRequest is the DTO for creating an inbox limit.
// Reference: Chatwoot InboxLimitsController#create — params: {type, value}
type CreateInboxLimitRequest struct {
	Type  string `json:"type" validate:"required,min=1"`
	Value int    `json:"value" validate:"required,min=1"`
}

// UpdateInboxLimitRequest is the DTO for updating an inbox limit.
// Reference: Chatwoot InboxLimitsController#update — params: {type, value}
type UpdateInboxLimitRequest struct {
	Type  string `json:"type,omitempty" validate:"omitempty,min=1"`
	Value int    `json:"value,omitempty" validate:"omitempty,min=1"`
}

// Create creates a new inbox limit for an inbox.
// Reference: Chatwoot InboxLimitsController#create
func (s *InboxLimitService) Create(ctx context.Context, inboxID uint, req CreateInboxLimitRequest) (*model.InboxLimit, error) {
	if err := pkgvalidator.ValidateStruct(req); err != nil {
		return nil, err
	}

	limit := &model.InboxLimit{
		InboxID: inboxID,
		Type:    req.Type,
		Value:   req.Value,
	}
	if err := s.repo.Create(ctx, limit); err != nil {
		return nil, err
	}
	applogger.L().Infof("Inbox limit created for inbox %d, type=%s, value=%d", inboxID, req.Type, req.Value)
	return limit, nil
}

// Update modifies an existing inbox limit.
// Reference: Chatwoot InboxLimitsController#update
func (s *InboxLimitService) Update(ctx context.Context, id uint, req UpdateInboxLimitRequest) (*model.InboxLimit, error) {
	existing, err := s.repo.FindByID(ctx, id)
	if err != nil {
		return nil, err
	}

	if req.Type != "" {
		existing.Type = req.Type
	}
	if req.Value != 0 {
		existing.Value = req.Value
	}

	if err := s.repo.Update(ctx, existing); err != nil {
		return nil, err
	}
	applogger.L().Infof("Inbox limit updated, id=%d", id)
	return existing, nil
}

// Delete removes an inbox limit by ID.
// Reference: Chatwoot InboxLimitsController#destroy
func (s *InboxLimitService) Delete(ctx context.Context, id uint) error {
	// Verify existence before delete
	existing, err := s.repo.FindByID(ctx, id)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return errors.New("inbox limit not found")
		}
		return err
	}
	_ = existing // confirmed exists

	if err := s.repo.Delete(ctx, id); err != nil {
		return err
	}
	applogger.L().Infof("Inbox limit deleted, id=%d", id)
	return nil
}