package folder

import (
	"context"
	"fmt"

	"queryorchestration/internal/database/repository"
	"queryorchestration/internal/document"
	"queryorchestration/internal/harddelete"

	"github.com/google/uuid"
)

// HardDelete permanently removes a folder tree and optionally all documents within it.
// The root folder (path '/') cannot be deleted and returns a ConflictError.
//
// If includeDocuments is false and the folder tree contains documents, a ConflictError
// is returned. The caller must either delete the documents first or set includeDocuments
// to true.
//
// When includeDocuments is true, all documents in the folder tree are cascade-deleted
// (using the same document cascade as document.HardDelete), then documentUploads and
// folder rows are removed. The entire operation executes in a single database transaction.
// batch_document_outcomes are handled by database FK actions: document_id is SET NULL
// when a document is deleted, and rows CASCADE-delete when their batch_upload is removed.
//
// S3 source files are intentionally NOT deleted. Their paths are collected, logged at
// INFO level, and returned for optional verbose responses.
//
// Parameters:
//   - ctx: request context
//   - folderID: UUID of the root folder to delete
//   - includeDocuments: if true, cascade-delete all documents in the folder tree
//
// Returns:
//   - []harddelete.S3PathInfo: S3 paths of orphaned source documents (empty if no documents)
//   - error: NotFoundError, ConflictError, or database error
func (s *Service) HardDelete(ctx context.Context, folderID uuid.UUID, includeDocuments bool) ([]harddelete.S3PathInfo, error) {
	queries := s.cfg.GetDBQueries()

	// Verify the folder exists and is not the root folder
	if err := validateFolderForDelete(ctx, queries, folderID); err != nil {
		return nil, err
	}

	// Gather document info and S3 paths before the transaction
	docIDs, allS3Paths, err := collectFolderDocumentInfo(ctx, queries, folderID, includeDocuments)
	if err != nil {
		return nil, err
	}

	err = s.cfg.ExecuteDBTransaction(ctx, func(ctx context.Context, q *repository.Queries) error {
		// Delete all documents in the folder tree if requested
		for _, docID := range docIDs {
			if err := document.DeleteDocumentCascade(ctx, q, docID); err != nil {
				return fmt.Errorf("cascade delete document %s: %w", docID, err)
			}
		}

		// Delete documentUploads referencing folders in the tree
		if err := q.DeleteDocumentUploadsInFolderTree(ctx, &folderID); err != nil {
			return fmt.Errorf("delete document uploads in folder tree: %w", err)
		}

		// Delete the folder tree
		rowsAffected, err := q.HardDeleteFolderTree(ctx, &folderID)
		if err != nil {
			return fmt.Errorf("delete folder tree: %w", err)
		}

		if rowsAffected == 0 {
			return &harddelete.NotFoundError{
				ResourceType: "folder",
				ResourceID:   folderID.String(),
			}
		}

		return nil
	})
	if err != nil {
		return nil, err
	}

	harddelete.LogOrphanedS3Paths(allS3Paths)
	return allS3Paths, nil
}

// validateFolderForDelete checks that a folder exists and is not the root folder.
// Returns NotFoundError or ConflictError as appropriate.
func validateFolderForDelete(ctx context.Context, queries *repository.Queries, folderID uuid.UUID) error {
	fdr, err := queries.GetFolderByID(ctx, folderID)
	if err != nil {
		return &harddelete.NotFoundError{
			ResourceType: "folder",
			ResourceID:   folderID.String(),
		}
	}

	if fdr.Path == "/" {
		return &harddelete.ConflictError{
			Message: "cannot delete root folder",
		}
	}

	return nil
}

// collectFolderDocumentInfo checks for documents in the folder tree and collects their
// S3 paths. Returns ConflictError if documents exist and includeDocuments is false.
func collectFolderDocumentInfo(
	ctx context.Context,
	queries *repository.Queries,
	folderID uuid.UUID,
	includeDocuments bool,
) ([]uuid.UUID, []harddelete.S3PathInfo, error) {
	docCount, err := queries.CountDocumentsInFolderTree(ctx, &folderID)
	if err != nil {
		return nil, nil, fmt.Errorf("failed to count documents in folder tree %s: %w", folderID, err)
	}

	if docCount > 0 && !includeDocuments {
		return nil, nil, &harddelete.ConflictError{
			Message: fmt.Sprintf("folder tree contains %d documents; set include_documents=true to delete them", docCount),
		}
	}

	if docCount == 0 {
		return nil, nil, nil
	}

	docIDs, err := queries.GetDocumentIDsInFolderTree(ctx, &folderID)
	if err != nil {
		return nil, nil, fmt.Errorf("failed to get document IDs in folder tree %s: %w", folderID, err)
	}

	allS3Paths, err := harddelete.CollectS3PathsForDocuments(ctx, docIDs, wrapS3Query(queries))
	if err != nil {
		return nil, nil, err
	}

	return docIDs, allS3Paths, nil
}

// wrapS3Query adapts the repository's CollectDocumentS3Paths to the function signature
// expected by harddelete.CollectS3PathsForDocuments.
func wrapS3Query(queries *repository.Queries) func(ctx context.Context, docID uuid.UUID) ([]harddelete.S3Row, error) {
	return func(ctx context.Context, docID uuid.UUID) ([]harddelete.S3Row, error) {
		rows, err := queries.CollectDocumentS3Paths(ctx, docID)
		if err != nil {
			return nil, err
		}
		result := make([]harddelete.S3Row, len(rows))
		for i, r := range rows {
			result[i] = harddelete.S3Row{Bucket: r.Bucket, Key: r.Key}
		}
		return result, nil
	}
}