package jnpf.dmsService;

import jnpf.base.UserInfo;
import jnpf.dmsEntity.download.form.DmsFileDownloadTicketRequest;
import jnpf.dmsEntity.download.model.DmsFileDownloadTicket;
import jnpf.dmsEntity.download.vo.DmsFileDownloadTicketVO;
import jnpf.dmsEntity.permission.entity.DmsFileVersionEntity;
import jnpf.dmsEntity.permission.enums.DmsPermissionAction;
import jnpf.dmsEntity.permission.enums.DmsResourceType;
import jnpf.dmsEntity.storage.entity.DmsFileObjectEntity;
import jnpf.dmsMapper.DmsFileObjectMapper;
import jnpf.dmsMapper.DmsFileVersionMapper;
import jnpf.dmsPermission.DmsCurrentIdentity;
import jnpf.dmsPermission.DmsPermissionError;
import jnpf.dmsPermission.DmsPermissionException;
import jnpf.dmsPermission.DmsPermissionExecutionContext;
import jnpf.dmsPermission.DmsPermissionGuard;
import jnpf.dmsPermission.DmsPermissionOperation;
import jnpf.dmsService.pdf.DmsPersistentPdfSources;
import jnpf.dmsService.pdf.DmsPdfGenerationTaskService;
import lombok.RequiredArgsConstructor;
import org.springframework.stereotype.Service;

import java.util.Date;
import java.util.UUID;

@Service
@RequiredArgsConstructor
public class DmsFileDownloadService {
    static final long TICKET_TTL_SECONDS = 5L * 60L;

    private final DmsCurrentIdentity currentIdentity;
    private final DmsPermissionGuard permissionGuard;
    private final DmsFileVersionMapper fileVersionMapper;
    private final DmsFileObjectMapper fileObjectMapper;
    private final DmsFileDownloadTicketIssuer ticketIssuer;
    private final DmsFileOperationLogService operationLogService;
    private final DmsWatermarkPreviewResolver watermarkResolver;
    private final DmsPdfGenerationTaskService pdfGenerationTaskService;

    public DmsFileDownloadTicketVO createTicket(DmsFileDownloadTicketRequest request) {
        request.normalized();
        UserInfo user = currentIdentity.requireUser();
        String tenantId = currentIdentity.tenantId(user);
        UUID fileVersionId = resolveFileVersionId(request, tenantId);
        long expiresAtMillis = System.currentTimeMillis() + TICKET_TTL_SECONDS * 1000L;

        DmsPermissionExecutionContext context = new DmsPermissionExecutionContext();
        context.setResourceType(DmsResourceType.FILE_VERSION);
        context.setResourceId(fileVersionId);
        context.setActionCode(DmsPermissionAction.DOWNLOAD);
        context.setWorkflowDownloadOnly(request.isWorkflowDownloadOnly());
        context.setOperationId(request.getOperationId());
        context.setSessionExpiresAt(new Date(expiresAtMillis));

        DownloadSource source = permissionGuard.execute(context,
                new DmsPermissionOperation<DownloadSource>() {
                    @Override
                    public DownloadSource execute() {
                        return loadDownloadSource(tenantId, fileVersionId);
                    }

                    @Override
                    public DownloadSource replay() {
                        return loadDownloadSource(tenantId, fileVersionId);
                    }
                });

        if (context.getSessionExpiresAt() != null) {
            expiresAtMillis = Math.min(expiresAtMillis, context.getSessionExpiresAt().getTime());
        }
        DmsFileDownloadTicket payload = payload(user, tenantId, source, expiresAtMillis, request);
        String accessTicket = ticketIssuer.issue(payload, TICKET_TTL_SECONDS);
        DmsFileDownloadTicketVO result = new DmsFileDownloadTicketVO();
        result.setFileVersionId(fileVersionId);
        result.setFileName(source.version.getFileName());
        result.setMimeType(source.version.getMimeType());
        result.setSizeBytes(source.version.getSizeBytes());
        result.setAccessTicket(accessTicket);
        result.setExpiresAt(new Date(expiresAtMillis));
        operationLogService.recordDownload(user, tenantId, source.version.getDocumentId(),
                source.version.getId(), source.version.getFileName(), request.getOperationId());
        return result;
    }

    private UUID resolveFileVersionId(DmsFileDownloadTicketRequest request, String tenantId) {
        if (request.getResourceType() == DmsResourceType.DOCUMENT) {
            DmsFileVersionEntity current = fileVersionMapper.selectCurrentEffective(tenantId,
                    request.getResourceId());
            if (current == null) {
                throw DmsPermissionException.of(DmsPermissionError.RESOURCE_NOT_FOUND,
                        "文件没有现行有效版本");
            }
            return current.getId();
        }
        if (request.getResourceType() == DmsResourceType.FILE_VERSION) {
            DmsFileVersionEntity version = fileVersionMapper.selectReadableByTenantAndId(tenantId,
                    request.getResourceId());
            if (version == null) {
                throw DmsPermissionException.of(DmsPermissionError.RESOURCE_NOT_FOUND,
                        "可下载的文件版本不存在");
            }
            return version.getId();
        }
        throw DmsPermissionException.of(DmsPermissionError.INVALID_REQUEST,
                "仅支持下载 DOCUMENT 或 FILE_VERSION");
    }

    private DownloadSource loadDownloadSource(String tenantId, UUID fileVersionId) {
        DmsFileVersionEntity version = fileVersionMapper.selectReadableByTenantAndId(
                tenantId, fileVersionId);
        DmsFileObjectEntity object = fileObjectMapper.selectByTenantAndFileVersionId(tenantId,
                fileVersionId);
        if (version == null || object == null) {
            throw DmsPermissionException.of(DmsPermissionError.RESOURCE_NOT_FOUND,
                    "文件版本或存储对象不存在");
        }
        return new DownloadSource(version, object);
    }

    private DmsFileDownloadTicket payload(UserInfo user, String tenantId, DownloadSource source,
                                          long expiresAtMillis, DmsFileDownloadTicketRequest request) {
        DmsFileDownloadTicket payload = new DmsFileDownloadTicket();
        payload.setScope(DmsFileDownloadTicket.SCOPE);
        payload.setTenantId(tenantId);
        payload.setUserId(user.getUserId().trim());
        payload.setFileVersionId(source.version.getId());
        payload.setHistoricalAccess(source.version.getLifecycleStatus() != null
                && !"EFFECTIVE".equals(source.version.getLifecycleStatus()));
        payload.setFileName(source.version.getFileName());
        payload.setMimeType(source.version.getMimeType());
        payload.setSizeBytes(source.version.getSizeBytes());
        payload.setStoragePlatform(source.object.getStoragePlatform());
        payload.setBucketName(source.object.getBucketName());
        payload.setBasePath(source.object.getBasePath());
        payload.setObjectPath(source.object.getObjectPath());
        payload.setObjectName(source.object.getObjectName());
        payload.setPdfSource(DmsPersistentPdfSources.valid(source.version, source.object));
        if (payload.getPdfSource() == null) {
            pdfGenerationTaskService.enqueueMissingEligible(tenantId, source.version.getId(),
                    source.version.getFileName(), source.version.getChecksumSha256());
        }
        payload.setWatermarks(watermarkResolver.resolveDownload(user, tenantId, source.version, request));
        payload.setExpiresAt(expiresAtMillis);
        return payload;
    }

    private static final class DownloadSource {
        private final DmsFileVersionEntity version;
        private final DmsFileObjectEntity object;

        private DownloadSource(DmsFileVersionEntity version, DmsFileObjectEntity object) {
            this.version = version;
            this.object = object;
        }
    }
}