package folder

import (
	"context"
	"fmt"

	"queryorchestration/internal/database/repository"
	"queryorchestration/internal/serviceconfig"

	"github.com/google/uuid"
)

// Service provides folder management operations
type Service struct {
	cfg serviceconfig.ConfigProvider
}

// New creates a new folder service instance
func New(cfg serviceconfig.ConfigProvider) *Service {
	return &Service{
		cfg: cfg,
	}
}

// CreateFolder creates a new folder with validation
// Validates that parent folder exists if parentId is provided
func (s *Service) CreateFolder(ctx context.Context, path string, parentID *uuid.UUID, clientID string, createdBy string) (*repository.Folder, error) {
	if path == "" {
		return nil, fmt.Errorf("folder path cannot be empty")
	}

	if clientID == "" {
		return nil, fmt.Errorf("clientID cannot be empty")
	}

	if createdBy == "" {
		return nil, fmt.Errorf("createdBy cannot be empty")
	}

	// Validate parent folder exists if parentID is provided
	if parentID != nil {
		parent, err := s.cfg.GetDBQueries().GetFolderByID(ctx, *parentID)
		if err != nil {
			return nil, fmt.Errorf("parent folder not found: %w", err)
		}

		// Ensure parent belongs to same client
		if parent.Clientid != clientID {
			return nil, fmt.Errorf("parent folder belongs to different client")
		}
	}

	folder, err := s.cfg.GetDBQueries().CreateFolder(ctx, &repository.CreateFolderParams{
		Path:      path,
		Parentid:  parentID,
		Clientid:  clientID,
		Createdby: createdBy,
	})
	if err != nil {
		return nil, fmt.Errorf("failed to create folder: %w", err)
	}

	return folder, nil
}

// GetFolder retrieves a folder by ID
func (s *Service) GetFolder(ctx context.Context, folderID uuid.UUID) (*repository.Folder, error) {
	folder, err := s.cfg.GetDBQueries().GetFolderByID(ctx, folderID)
	if err != nil {
		return nil, fmt.Errorf("folder not found: %w", err)
	}

	return folder, nil
}

// GetFolderByPath retrieves a folder by client and path
func (s *Service) GetFolderByPath(ctx context.Context, clientID string, path string) (*repository.Folder, error) {
	folder, err := s.cfg.GetDBQueries().GetFolderByPath(ctx, &repository.GetFolderByPathParams{
		Clientid: clientID,
		Path:     path,
	})
	if err != nil {
		return nil, fmt.Errorf("folder not found: %w", err)
	}

	return folder, nil
}

// RenameFolder renames a folder
func (s *Service) RenameFolder(ctx context.Context, folderID uuid.UUID, newPath string) error {
	if newPath == "" {
		return fmt.Errorf("new path cannot be empty")
	}

	// Verify folder exists
	_, err := s.cfg.GetDBQueries().GetFolderByID(ctx, folderID)
	if err != nil {
		return fmt.Errorf("folder not found: %w", err)
	}

	err = s.cfg.GetDBQueries().RenameFolder(ctx, &repository.RenameFolderParams{
		ID:   folderID,
		Path: newPath,
	})
	if err != nil {
		return fmt.Errorf("failed to rename folder: %w", err)
	}

	return nil
}

// GetFolderTree retrieves a folder and all its descendants (recursive)
func (s *Service) GetFolderTree(ctx context.Context, folderID uuid.UUID) ([]*repository.GetFolderTreeRow, error) {
	folders, err := s.cfg.GetDBQueries().GetFolderTree(ctx, &folderID)
	if err != nil {
		return nil, fmt.Errorf("failed to get folder tree: %w", err)
	}

	return folders, nil
}

// GetFoldersByClient retrieves all folders for a client
func (s *Service) GetFoldersByClient(ctx context.Context, clientID string) ([]*repository.Folder, error) {
	folders, err := s.cfg.GetDBQueries().GetFoldersByClientID(ctx, clientID)
	if err != nil {
		return nil, fmt.Errorf("failed to get folders: %w", err)
	}

	return folders, nil
}

// GetRootFolders retrieves all root folders (parentId IS NULL) for a client
func (s *Service) GetRootFolders(ctx context.Context, clientID string) ([]*repository.Folder, error) {
	folders, err := s.cfg.GetDBQueries().GetRootFolders(ctx, clientID)
	if err != nil {
		return nil, fmt.Errorf("failed to get root folders: %w", err)
	}

	return folders, nil
}

// GetSubfolders retrieves direct child folders of a parent folder
func (s *Service) GetSubfolders(ctx context.Context, parentID uuid.UUID) ([]*repository.Folder, error) {
	folders, err := s.cfg.GetDBQueries().GetFoldersByParentID(ctx, &parentID)
	if err != nil {
		return nil, fmt.Errorf("failed to get subfolders: %w", err)
	}

	return folders, nil
}

// GetDocumentsByFolder retrieves all documents in a specific folder
func (s *Service) GetDocumentsByFolder(ctx context.Context, folderID uuid.UUID) ([]*repository.Document, error) {
	documents, err := s.cfg.GetDBQueries().GetDocumentsByFolder(ctx, &folderID)
	if err != nil {
		return nil, fmt.Errorf("failed to get documents by folder: %w", err)
	}

	return documents, nil
}

// FolderMetrics contains aggregated metrics for a folder
type FolderMetrics struct {
	TotalDocuments int32
	ByLabel        map[string]int32
}

// GetFolderMetrics retrieves processing metrics for a folder including document counts by label
func (s *Service) GetFolderMetrics(ctx context.Context, folderID uuid.UUID) (*FolderMetrics, error) {
	// Get total document count
	total, err := s.cfg.GetDBQueries().CountDocumentsByFolder(ctx, &folderID)
	if err != nil {
		return nil, fmt.Errorf("failed to count documents: %w", err)
	}

	// Get label counts
	labelCounts, err := s.cfg.GetDBQueries().GetFolderLabelCounts(ctx, &folderID)
	if err != nil {
		return nil, fmt.Errorf("failed to get label counts: %w", err)
	}

	byLabel := make(map[string]int32)
	for _, lc := range labelCounts {
		byLabel[lc.Label] = safeInt64ToInt32(lc.Count)
	}

	return &FolderMetrics{
		TotalDocuments: safeInt64ToInt32(total),
		ByLabel:        byLabel,
	}, nil
}

// safeInt64ToInt32 safely converts int64 to int32, clamping at max int32 if necessary
func safeInt64ToInt32(n int64) int32 {
	const maxInt32 = 2147483647
	if n > maxInt32 {
		return maxInt32
	}
	return int32(n) //nolint:gosec // bounds check performed above
}