package ru.soune.nocopy.handler;

import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;
import ru.soune.nocopy.dto.*;
import ru.soune.nocopy.dto.file.*;
import ru.soune.nocopy.entity.file.FileEntity;
import ru.soune.nocopy.entity.file.FileStatus;
import ru.soune.nocopy.entity.file.ProtectionStatus;
import ru.soune.nocopy.exception.FileEntityNotFoundException;
import ru.soune.nocopy.exception.NotFoundAuthToken;
import ru.soune.nocopy.repository.FileEntityRepository;
import ru.soune.nocopy.service.register.AuthService;
import ru.soune.nocopy.service.file.FileEntityService;
import ru.soune.nocopy.service.file.FileStatsService;

import java.time.LocalDate;
import java.util.*;
import java.util.stream.Collectors;

@Slf4j
@Component
@RequiredArgsConstructor
public class FileEntityHandler implements RequestHandler {

    private final FileEntityService fileEntityService;

    private final AuthService authService;

    private final FileStatsService fileStatsService;

    private final ObjectMapper objectMapper;

    private final FileEntityRepository fileEntityRepository;

    @Override
    public BaseResponse handle(BaseRequest request) {
        try {
            FileEntityRequest fileRequest = objectMapper.convertValue(
                    request.getMessageBody(), FileEntityRequest.class);

            String action = fileRequest.getAction();

            switch (action) {
                case "file_info":
                    return handleGetFileInfo(request, fileRequest);
                case "user_files_info":
                    return handleGetFilesUserInfo(request, fileRequest);
                case "file_by_session":
                    return handleGetFileBySession(request, fileRequest);
                case "user_files":
                    return handleGetUserFiles(request, fileRequest);
                case "search_files":
                    return handleSearchFiles(request, fileRequest);
                case "storage_usage":
                    return handleGetStorageUsage(request, fileRequest);
                case "check_protected":
                    return handleProtectFile(request, fileRequest);
                case "delete_file":
                    return handleDeleteFile(request, fileRequest);
                default:
                    ActionResponse response = ActionResponse.builder()
                            .action(action)
                            .availableActions(Arrays.asList(
                                    "file_info", "file_by_session", "user_files",
                                    "search_files", "storage_usage", "delete_file",
                                    "user_files_info"))
                            .build();

                    return new BaseResponse(request.getMsgId(),
                            MessageCode.INVALID_ACTION.getCode(),
                            "Invalid action: " + action,
                            response);
            }
        } catch (Exception e) {
            log.error("Error in FileEntityHandler", e);
            return new BaseResponse(request.getMsgId(),
                    MessageCode.FILE_UPLOAD_ERROR.getCode(),
                    "Handler error: " + e.getMessage(),
                    null);
        }
    }

    private BaseResponse handleGetFilesUserInfo(BaseRequest request, FileEntityRequest fileRequest) {
        Long userId = authService.useUserAuthToken(fileRequest.getToken());
        FileInfoUserResponse userFileStats = fileStatsService.getUserFileStats(userId);

        return new BaseResponse(request.getMsgId(),
                MessageCode.SUCCESS.getCode(),
                MessageCode.SUCCESS.getDescription(),
                userFileStats);
    }

    private BaseResponse handleGetFileInfo(BaseRequest request, FileEntityRequest fileRequest) {
        try {
            Long userId =  authService.useUserAuthToken(fileRequest.getToken());
            FileEntityResponse fileInfo = fileEntityService.getById(fileRequest.getFileId(), request.getVersion());

            if (!fileInfo.getUserId().equals(userId)) {
                return new BaseResponse(request.getMsgId(),
                        MessageCode.ACCESS_DENIED.getCode(),
                        "Access denied",
                        null);
            }

            return new BaseResponse(request.getMsgId(),
                    MessageCode.SUCCESS.getCode(),
                    MessageCode.SUCCESS.getDescription(),
                    fileInfo);

        } catch (NotFoundAuthToken e) {
            return new BaseResponse(request.getMsgId(),
                    MessageCode.INVALID_TOKEN.getCode(),
                    "Authentication required",
                    null);
        } catch (Exception e) {
            log.error("Error getting file info", e);
            return new BaseResponse(request.getMsgId(),
                    MessageCode.FILE_UPLOAD_ERROR.getCode(),
                    "Failed to get file info: " + e.getMessage(),
                    null);
        }
    }

    private BaseResponse handleGetFileBySession(BaseRequest request, FileEntityRequest fileRequest) {
        try {
            Long userId = authService.useUserAuthToken(fileRequest.getToken());
            FileEntityResponse fileInfo = fileEntityService.getByUploadSessionId(fileRequest.getUploadSessionId(),
                    request.getVersion());

            if (!fileInfo.getUserId().equals(userId)) {
                return new BaseResponse(request.getMsgId(),
                        MessageCode.ACCESS_DENIED.getCode(),
                        "Access denied",
                        null);
            }

            return new BaseResponse(request.getMsgId(),
                    MessageCode.SUCCESS.getCode(),
                    MessageCode.SUCCESS.getDescription(),
                    fileInfo);

        } catch (NotFoundAuthToken e) {
            return new BaseResponse(request.getMsgId(),
                    MessageCode.INVALID_TOKEN.getCode(),
                    "Authentication required",
                    null);
        } catch (Exception e) {
            log.error("Error getting file by session", e);
            return new BaseResponse(request.getMsgId(),
                    MessageCode.FILE_UPLOAD_ERROR.getCode(),
                    "Failed to get file: " + e.getMessage(),
                    null);
        }
    }

    private BaseResponse handleGetUserFiles(BaseRequest request, FileEntityRequest fileRequest) {
        try {
            Long userId = authService.useUserAuthToken(fileRequest.getToken());
            int page = fileRequest.getPage() != null ? fileRequest.getPage() : 1;
            int pageSize = fileRequest.getPageSize() != null ? fileRequest.getPageSize() : 20;

            FileResponse files = fileEntityService.getUserFiles(userId, page, pageSize, request.getVersion());

            return new BaseResponse(request.getMsgId(),
                    MessageCode.SUCCESS.getCode(),
                    MessageCode.SUCCESS.getDescription(),
                    files);

        } catch (NotFoundAuthToken e) {
            return new BaseResponse(request.getMsgId(),
                    MessageCode.INVALID_TOKEN.getCode(),
                    "Authentication required",
                    null);
        } catch (Exception e) {
            log.error("Error getting user files", e);
            return new BaseResponse(request.getMsgId(),
                    MessageCode.FILE_UPLOAD_ERROR.getCode(),
                    "Failed to get files: " + e.getMessage(),
                    null);
        }
    }

    private BaseResponse handleSearchFiles(BaseRequest request, FileEntityRequest fileRequest) {
        try {
            Long userId = authService.useUserAuthToken(fileRequest.getToken());
            int page = fileRequest.getPage() != null ? fileRequest.getPage() : 1;
            int pageSize = fileRequest.getPageSize() != null ? fileRequest.getPageSize() : 20;

            String sortBy = fileRequest.getSortBy() != null ? fileRequest.getSortBy() : "fileName";
            SortOrder sortOrder = SortOrder.fromString(fileRequest.getSortOrder());

            FileResponse allFiles = fileEntityService.getUserFiles(userId, 1, 1000, request.getVersion());

            String searchQuery = fileRequest.getQuery() != null ? fileRequest.getQuery().toLowerCase().trim() : "";
            String[] searchTerms = searchQuery.split("\\s+");
            String filterType = fileRequest.getType();
            String dateFilter = fileRequest.getDateFilter();

            List<FileEntityResponse> filteredFiles = allFiles.getFiles().stream()
                    .filter(f -> matchesSearch(f, searchTerms, searchQuery, filterType))
                    .filter(f -> matchesDateFilter(f, dateFilter))
                    .collect(Collectors.toList());

            Comparator<FileEntityResponse> comparator = getComparator(sortBy, sortOrder);
            filteredFiles.sort(comparator);

            int start = (page - 1) * pageSize;
            int end = Math.min(start + pageSize, filteredFiles.size());

            if (start >= filteredFiles.size()) {
                return createEmptyResponse(request, page, pageSize, sortBy, sortOrder.getValue());
            }

            List<FileEntityResponse> paginatedFiles = filteredFiles.subList(start, end);
            long totalSize = paginatedFiles.stream()
                    .mapToLong(FileEntityResponse::getFileSize)
                    .sum();

            FileListResponse response = FileListResponse.builder()
                    .files(paginatedFiles)
                    .totalCount(filteredFiles.size())
                    .totalSize(totalSize)
                    .formattedTotalSize(fileEntityService.formatFileSize(totalSize))
                    .page(page)
                    .pageSize(pageSize)
                    .sortBy(sortBy)
                    .sortOrder(sortOrder.getValue())
                    .build();

            return new BaseResponse(request.getMsgId(),
                    MessageCode.SUCCESS.getCode(),
                    MessageCode.SUCCESS.getDescription(),
                    response);

        } catch (NotFoundAuthToken e) {
            return new BaseResponse(request.getMsgId(),
                    MessageCode.INVALID_TOKEN.getCode(),
                    "Authentication required", null);
        } catch (Exception e) {
            log.error("Error searching files", e);
            return new BaseResponse(request.getMsgId(),
                    MessageCode.FILE_UPLOAD_ERROR.getCode(),
                    "Failed to search files: " + e.getMessage(), null);
        }
    }

    private boolean matchesDateFilter(FileEntityResponse file, String dateFilter) {
        if (dateFilter == null || dateFilter.isEmpty()) {
            return true;
        }

        LocalDate fileDate = file.getCreatedAt().toLocalDate();
        LocalDate now = LocalDate.now();

        switch (dateFilter.toLowerCase()) {
            case "today":
                return fileDate.equals(now);
            case "week":
                return fileDate.isAfter(now.minusWeeks(1)) && !fileDate.isAfter(now);
            case "month":
                return fileDate.isAfter(now.minusMonths(1)) && !fileDate.isAfter(now);
            default:
                return true;
        }
    }

    private boolean matchesSearch(FileEntityResponse file, String[] searchTerms, String fullQuery, String type) {
        String fileName = getSafeString(file.getFileName());
        String originalFileName = getSafeString(file.getOriginalFileName());
        String mimeType = getSafeString(file.getMimeType());
        String fileFormat = getSafeString(file.getFileFormat());
        String fullFileName = fileName + " " + originalFileName;

        boolean matchesType = true;
        if (type != null && !type.isEmpty()) {
            matchesType = matchesMimeType(mimeType, type);
        }

        if (!matchesType) {
            return false;
        }

        if (fullQuery != null && !fullQuery.isEmpty()) {
            if (fullFileName.toLowerCase().contains(fullQuery)) {
                return true;
            }

            for (String term : searchTerms) {
                if (term.length() < 2) continue;
                if (fullFileName.toLowerCase().contains(term)) {
                    return true;
                }
            }

            if (fileFormat.toLowerCase().contains(fullQuery)) {
                return true;
            }

            if (mimeType.toLowerCase().contains(fullQuery)) {
                return true;
            }

            if (!fileFormat.isEmpty() && !fileName.toLowerCase().endsWith("." + fileFormat.toLowerCase())) {
                String fileNameWithExtension = fileName + "." + fileFormat;
                if (fileNameWithExtension.toLowerCase().contains(fullQuery)) {
                    return true;
                }
            }

            return false;
        }

        return true;
    }

    private boolean matchesMimeType(String mimeType, String filterType) {
        if (filterType == null || filterType.isEmpty()) return true;

        String mimeTypeLower = mimeType.toLowerCase();
        String filterTypeLower = filterType.toLowerCase().trim();

        return mimeTypeLower.equals(filterTypeLower);
    }

    private String getSafeString(String value) {
        return value != null ? value : "";
    }

    private Comparator<FileEntityResponse> getComparator(String sortBy, SortOrder sortOrder) {
        Comparator<FileEntityResponse> comparator;

        switch (sortBy) {
            case "fileSize":
                comparator = Comparator.comparingLong(
                        FileEntityResponse::getFileSize
                );
                break;

            case "fileType":
                comparator = Comparator.comparing(
                        FileEntityResponse::getMimeType);
                break;

            case "createdAt":
                comparator = Comparator.comparing(
                        FileEntityResponse::getCreatedAt,
                        Comparator.nullsLast(Comparator.naturalOrder())
                );
                break;

            case "updatedAt":
                comparator = Comparator.comparing(
                        FileEntityResponse::getUpdatedAt,
                        Comparator.nullsLast(Comparator.naturalOrder())
                );
                break;

            case "fileName":
                comparator = Comparator.comparing(
                        f -> getSafeString(f.getFileName()).toLowerCase(),
                        Comparator.nullsLast(Comparator.naturalOrder())
                );
                break;

            case "protectStatus":
                comparator = Comparator.comparing(
                        f -> getSafeString(f.getProtectStatus()).toLowerCase(),
                        Comparator.nullsLast(Comparator.naturalOrder())
                );
                break;

            case "supportId":
                comparator = Comparator.comparing(
                        FileEntityResponse::getSupportId,
                        Comparator.nullsLast(Comparator.naturalOrder())
                );
                break;

            default:
                comparator = Comparator.comparing(
                        f -> getSafeString(f.getFileName()).toLowerCase(),
                        Comparator.nullsLast(Comparator.naturalOrder())
                );
                break;
        }

        return sortOrder == SortOrder.DESC ? comparator.reversed() : comparator;
    }

    private BaseResponse createEmptyResponse(BaseRequest request, int page, int pageSize,
                                             String sortBy, String sortOrder) {
        FileListResponse emptyResponse = FileListResponse.builder()
                .files(Collections.emptyList())
                .totalCount(0)
                .totalSize(0L)
                .formattedTotalSize("0 B")
                .page(page)
                .pageSize(pageSize)
                .sortBy(sortBy)
                .sortOrder(sortOrder)
                .build();

        return new BaseResponse(request.getMsgId(),
                MessageCode.SUCCESS.getCode(),
                MessageCode.SUCCESS.getDescription(),
                emptyResponse);
    }

    private BaseResponse handleGetUserFilesWithSort(BaseRequest request, FileEntityRequest fileRequest,
                                                    String sortBy, SortOrder sortOrder) {
        try {
            Long userId = authService.useUserAuthToken(fileRequest.getToken());
            int page = fileRequest.getPage() != null ? fileRequest.getPage() : 1;
            int pageSize = fileRequest.getPageSize() != null ? fileRequest.getPageSize() : 20;

            FileResponse allFiles = fileEntityService.getUserFiles(userId, 1, 1000, request.getVersion());

            List<FileEntityResponse> files = new ArrayList<>(allFiles.getFiles());

            Comparator<FileEntityResponse> comparator = getComparator(sortBy, sortOrder);
            files.sort(comparator);

            int start = (page - 1) * pageSize;
            int end = Math.min(start + pageSize, files.size());

            if (start >= files.size()) {
                return createEmptyResponse(request, page, pageSize, sortBy, sortOrder.getValue());
            }

            List<FileEntityResponse> paginatedFiles = files.subList(start, end);
            long totalSize = paginatedFiles.stream()
                    .mapToLong(FileEntityResponse::getFileSize)
                    .sum();

            FileListResponse response = FileListResponse.builder()
                    .files(paginatedFiles)
                    .totalCount(files.size())
                    .totalSize(totalSize)
                    .formattedTotalSize(fileEntityService.formatFileSize(totalSize))
                    .page(page)
                    .pageSize(pageSize)
                    .sortBy(sortBy)
                    .sortOrder(sortOrder.getValue())
                    .build();

            return new BaseResponse(request.getMsgId(),
                    MessageCode.SUCCESS.getCode(),
                    MessageCode.SUCCESS.getDescription(),
                    response);

        } catch (NotFoundAuthToken e) {
            return new BaseResponse(request.getMsgId(),
                    MessageCode.INVALID_TOKEN.getCode(),
                    "Authentication required", null);
        } catch (Exception e) {
            log.error("Error getting user files with sort", e);
            return new BaseResponse(request.getMsgId(),
                    MessageCode.FILE_UPLOAD_ERROR.getCode(),
                    "Failed to get files: " + e.getMessage(),
                    null);
        }
    }

    private BaseResponse handleGetStorageUsage(BaseRequest request, FileEntityRequest fileRequest) {
        try {
            Long userId = authService.useUserAuthToken(fileRequest.getToken());
            long usage = fileEntityService.getUserStorageUsed(userId);

            StorageUsageResponse response = StorageUsageResponse.builder()
                    .userId(userId)
                    .storageUsed(usage)
                    .formattedStorageUsed(formatFileSize(usage))
                    .build();

            return new BaseResponse(request.getMsgId(),
                    MessageCode.SUCCESS.getCode(),
                    MessageCode.SUCCESS.getDescription(),
                    response);

        } catch (NotFoundAuthToken e) {
            return new BaseResponse(request.getMsgId(),
                    MessageCode.INVALID_TOKEN.getCode(),
                    "Authentication required",
                    null);
        } catch (Exception e) {
            log.error("Error getting storage usage", e);
            return new BaseResponse(request.getMsgId(),
                    MessageCode.FILE_UPLOAD_ERROR.getCode(),
                    "Failed to get storage usage: " + e.getMessage(),
                    null);
        }
    }

    private BaseResponse handleProtectFile(BaseRequest request, FileEntityRequest fileRequest) {
        String fileId = fileRequest.getFileId();
        Optional<FileEntity> optionalFileEntity = fileEntityRepository.findById(fileId);

        if (optionalFileEntity.isEmpty()) {
            return new BaseResponse(request.getMsgId(),
                    MessageCode.FILE_NOT_FOUND.getCode(),
                    "File not found exception: " + fileRequest.getFileId(),
                    null);
        }

        FileEntity fileEntity = optionalFileEntity.get();
        ProtectionStatus protectionStatus = fileEntity.getProtectionStatus();

        Integer code = protectionStatus == ProtectionStatus.PROTECTED ? MessageCode.FILE_IS_PROTECTED.getCode():
                MessageCode.FILE_IS_NOT_PROTECTED.getCode();
        String message = protectionStatus == ProtectionStatus.PROTECTED ? MessageCode.FILE_IS_PROTECTED.getDescription():
                MessageCode.FILE_IS_NOT_PROTECTED.getDescription();

        return new BaseResponse(request.getMsgId(), code, message, fileEntityService.getById(fileId,
                request.getVersion()));
    }

    private BaseResponse handleDeleteFile(BaseRequest request, FileEntityRequest fileRequest) {
        try {
            Long userId = authService.useUserAuthToken(fileRequest.getToken());
            String fileId = fileRequest.getFileId();
            FileEntityResponse fileInfo = fileEntityService.getById(fileId, request.getVersion());
            DeleteFileResponse response;

            if (!fileInfo.getUserId().equals(userId)) {
                return new BaseResponse(request.getMsgId(),
                        MessageCode.ACCESS_DENIED.getCode(),
                        "Access denied",
                        null);
            }

            FileEntity fileEntity = fileEntityRepository.findById(fileId)
                    .orElseThrow(() -> new FileEntityNotFoundException(fileId));
            int fullDelete = fileRequest.getFullDelete() == null ? 0 : fileRequest.getFullDelete();

            if (fileEntity.getStatus().equals(FileStatus.DELETED) || fullDelete == 1) {
                fileEntityService.deleteFromDisk(fileEntity);
                response = DeleteFileResponse.builder()
                        .fileId(fileRequest.getFileId())
                        .message("File deleted from disk")
                        .build();
            } else {
                fileEntityService.softDeleteFileWithHash(fileEntity);

                response = DeleteFileResponse.builder()
                        .fileId(fileRequest.getFileId())
                        .message("File marked as deleted")
                        .build();
            }

            return new BaseResponse(request.getMsgId(),
                    MessageCode.SUCCESS.getCode(),
                    "File marked as deleted",
                    response);
        } catch (NotFoundAuthToken e) {
            return new BaseResponse(request.getMsgId(),
                    MessageCode.INVALID_TOKEN.getCode(),
                    "Authentication required",
                    null);
        } catch (Exception e) {
            log.error("Error deleting file", e);
            return new BaseResponse(request.getMsgId(),
                    MessageCode.FILE_UPLOAD_ERROR.getCode(),
                    "Failed to delete file: " + e.getMessage(),
                    null);
        }
    }

    private String formatFileSize(long size) {
        if (size < 1024) return size + " B";
        int exp = (int) (Math.log(size) / Math.log(1024));
        String pre = "KMGTPE".charAt(exp-1) + "";
        return String.format("%.1f %sB", size / Math.pow(1024, exp), pre);
    }
}