package jnpf.service;

import jnpf.exception.DataException;
import org.docx4j.TraversalUtil;
import org.docx4j.XmlUtils;
import org.docx4j.openpackaging.packages.WordprocessingMLPackage;
import org.docx4j.wml.ObjectFactory;
import org.docx4j.wml.SdtBlock;
import org.docx4j.wml.SdtContentBlock;
import org.docx4j.wml.SdtElement;
import org.docx4j.wml.SdtPr;
import org.docx4j.wml.Tag;
import org.springframework.http.MediaType;
import org.springframework.stereotype.Service;
import org.springframework.web.multipart.MultipartFile;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Files;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Deque;
import java.util.IdentityHashMap;
import java.util.List;
import java.util.Locale;
import java.util.Set;

/** Embeds and detects the non-printing content-control marker carried by a DMS approval page. */
@Service
public class DmsApprovalPageTagService {
    public static final String TAG_VALUE = "DMS_APPROVAL_PAGE";
    private static final ObjectFactory WML = new ObjectFactory();

    public MultipartFile tagApprovalPage(MultipartFile file) {
        String name = filename(file);
        String extension = extension(name);
        if ("pdf".equals(extension)) {
            return file;
        }
        if (!"docx".equals(extension)) {
            throw new DataException("审批页仅支持 PDF 或 DOCX 格式");
        }
        try {
            WordprocessingMLPackage word = WordprocessingMLPackage.load(file.getInputStream());
            if (hasApprovalPage(word)) {
                return file;
            }
            List<Object> original = new ArrayList<>(word.getMainDocumentPart().getContent());
            word.getMainDocumentPart().getContent().clear();
            word.getMainDocumentPart().getContent().add(taggedBlock(original));
            return generated(file, save(word));
        } catch (DataException exception) {
            throw exception;
        } catch (Exception exception) {
            throw new DataException("写入审批页标签失败：" + message(exception));
        }
    }

    public boolean hasApprovalPage(MultipartFile file) {
        if (file == null || file.isEmpty() || !"docx".equals(extension(file.getOriginalFilename()))) {
            return false;
        }
        try {
            return hasApprovalPage(WordprocessingMLPackage.load(file.getInputStream()));
        } catch (Exception exception) {
            throw new DataException("检查审批页标签失败：" + message(exception));
        }
    }

    public boolean hasApprovalPage(WordprocessingMLPackage word) {
        if (word == null || word.getMainDocumentPart() == null) {
            return false;
        }
        Deque<Object> pending = new ArrayDeque<>();
        pending.push(word.getMainDocumentPart().getJaxbElement());
        Set<Object> visited = Collections.newSetFromMap(new IdentityHashMap<>());
        while (!pending.isEmpty()) {
            Object value = XmlUtils.unwrap(pending.pop());
            if (value == null || !visited.add(value)) {
                continue;
            }
            if (value instanceof SdtElement && isApprovalPage((SdtElement) value)) {
                return true;
            }
            List<Object> children = TraversalUtil.getChildrenImpl(value);
            if (children != null) {
                for (Object child : children) {
                    if (child != null) pending.push(child);
                }
            }
        }
        return false;
    }

    public SdtBlock taggedBlock(List<Object> content) {
        Tag tag = WML.createTag();
        tag.setVal(TAG_VALUE);
        SdtPr properties = WML.createSdtPr();
        properties.setTag(tag);
        SdtContentBlock taggedContent = WML.createSdtContentBlock();
        if (content != null) taggedContent.getContent().addAll(content);
        SdtBlock block = WML.createSdtBlock();
        block.setSdtPr(properties);
        block.setSdtContent(taggedContent);
        return block;
    }

    /** Removes approval pages created by this service; they are direct blocks in the main document. */
    public int removeApprovalPages(WordprocessingMLPackage word) {
        if (word == null || word.getMainDocumentPart() == null) return 0;
        List<Object> content = word.getMainDocumentPart().getContent();
        int before = content.size();
        content.removeIf(value -> {
            Object unwrapped = XmlUtils.unwrap(value);
            return unwrapped instanceof SdtElement && isApprovalPage((SdtElement) unwrapped);
        });
        return before - content.size();
    }

    private boolean isApprovalPage(SdtElement element) {
        SdtPr properties = element.getSdtPr();
        Tag tag = properties == null ? null : properties.getTag();
        return tag != null && TAG_VALUE.equals(tag.getVal());
    }

    private byte[] save(WordprocessingMLPackage word) throws Exception {
        ByteArrayOutputStream output = new ByteArrayOutputStream();
        word.save(output);
        return output.toByteArray();
    }

    private MultipartFile generated(MultipartFile source, byte[] content) {
        return new GeneratedMultipartFile(source.getName(), source.getOriginalFilename(), content);
    }

    private String filename(MultipartFile file) {
        String name = file == null ? null : file.getOriginalFilename();
        if (file == null || file.isEmpty() || name == null || name.isBlank()) {
            throw new DataException("审批页为空或缺少文件名");
        }
        return name.trim();
    }

    private String extension(String filename) {
        if (filename == null) return "";
        int separator = filename.lastIndexOf('.');
        return separator < 0 ? "" : filename.substring(separator + 1).toLowerCase(Locale.ROOT);
    }

    private String message(Exception exception) {
        String value = exception.getMessage();
        return value == null || value.isBlank() ? exception.getClass().getSimpleName() : value;
    }

    private static final class GeneratedMultipartFile implements MultipartFile {
        private final String name;
        private final String originalFilename;
        private final byte[] content;

        private GeneratedMultipartFile(String name, String originalFilename, byte[] content) {
            this.name = name;
            this.originalFilename = originalFilename;
            this.content = content;
        }

        @Override public String getName() { return name; }
        @Override public String getOriginalFilename() { return originalFilename; }
        @Override public String getContentType() { return MediaType.parseMediaType(
                "application/vnd.openxmlformats-officedocument.wordprocessingml.document").toString(); }
        @Override public boolean isEmpty() { return content.length == 0; }
        @Override public long getSize() { return content.length; }
        @Override public byte[] getBytes() { return content.clone(); }
        @Override public InputStream getInputStream() { return new ByteArrayInputStream(content); }
        @Override public void transferTo(File destination) throws IOException { Files.write(destination.toPath(), content); }
    }
}