package jnpf.bizcommon.onlyoffice.service.impl;

import jnpf.dmsEntity.preview.model.DmsFilePreviewTicket;
import jnpf.exception.DataException;
import jnpf.util.TicketUtil;
import org.apache.pdfbox.Loader;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.io.IOException;
import java.util.Locale;
import java.util.UUID;
import java.util.function.Function;

/** Counts the physical pages rendered from the same protected source used by the preview. */
@Service
public class DmsOnlyOfficePageCountService {
    private final OnlyOfficeDmsPrintRenderer renderer;
    private final Function<String, Object> ticketReader;

    @Autowired
    public DmsOnlyOfficePageCountService(OnlyOfficeDmsPrintRenderer renderer) {
        this(renderer, TicketUtil::parseTicket);
    }

    DmsOnlyOfficePageCountService(OnlyOfficeDmsPrintRenderer renderer,
                                 Function<String, Object> ticketReader) {
        this.renderer = renderer;
        this.ticketReader = ticketReader;
    }

    public int getPageCount(UUID fileVersionId, String accessTicket) {
        if (fileVersionId == null || accessTicket == null || accessTicket.isBlank()) {
            throw new DataException("缺少页数查询文件版本或预览票据");
        }
        DmsFilePreviewTicket ticket;
        try {
            ticket = DmsFilePreviewTicket.fromRaw(ticketReader.apply(accessTicket));
        } catch (RuntimeException exception) {
            throw new DataException("DMS 预览票据无效或已过期");
        }
        if (!DmsFilePreviewTicket.SCOPE.equals(ticket.getScope())
                || !fileVersionId.equals(ticket.getFileVersionId())) {
            throw new DataException("页数查询票据与文件版本或预览用途不匹配");
        }
        String name = ticket.getFileName().toLowerCase(Locale.ROOT);
        if (!name.endsWith(".doc") && !name.endsWith(".docx")) {
            throw new DataException("OnlyOffice 页数查询仅支持 doc、docx 文件");
        }
        // Keep preview preparation, approval pages and watermarks identical to the editor.
        // Do not issue a PRINT ticket or use printBase, which changes the preview source.
        byte[] pdf = renderer.render(ticket, accessTicket);
        try (PDDocument document = Loader.loadPDF(pdf)) {
            int pages = document.getNumberOfPages();
            if (pages < 1) {
                throw new DataException("OnlyOffice 排版结果没有有效页面");
            }
            return pages;
        } catch (IOException exception) {
            throw new DataException("无法读取 OnlyOffice 排版结果页数");
        }
    }
}