package com.ard.work.utils.file;

import java.io.*;
import java.util.Base64;

import org.springframework.web.multipart.MultipartFile;

public class MultipartFileUtil {

    /**
     * 通过InputStream获取MultipartFile
     */
    public static MultipartFile inputStreamToMultipartFile(InputStream inputStream, String fileName, String contentType) {
        try {
            byte[] content = inputStream.readAllBytes();  // Java 9+ 可用
            return new ByteArrayMultipartFile(content, "file", fileName, contentType);
        } catch (IOException e) {
            throw new RuntimeException("输入流转换失败: " + e.getMessage(), e);
        } finally {
            try {
                if (inputStream != null) {
                    inputStream.close();
                }
            } catch (IOException e) {
                // 忽略关闭异常
            }
        }
    }

    /**
     * 通过文件路径获取MultipartFile
     */
    public static MultipartFile filePathToMultipartFile(String filePath, String fileName, String contentType) {
        File file = new File(filePath);

        if (!fileName.contains(".") && filePath.contains(".")) {
            String extension = filePath.substring(filePath.lastIndexOf('.'));
            fileName = fileName + extension;
        }

        try {
            byte[] content = java.nio.file.Files.readAllBytes(file.toPath());
            return new ByteArrayMultipartFile(content, "file", fileName, contentType);
        } catch (IOException e) {
            throw new RuntimeException("文件转换失败: " + e.getMessage(), e);
        }
    }

    /**
     * Base64字符串转MultipartFile
     */
    public static MultipartFile base64ToMultipartFile(String base64Str, String fileName, String contentType) {
        if (base64Str == null || base64Str.isEmpty()) {
            throw new IllegalArgumentException("Base64字符串不能为空");
        }

        String pureBase64Str = base64Str.contains(",") ? base64Str.split(",")[1] : base64Str;

        try {
            byte[] fileBytes = Base64.getDecoder().decode(pureBase64Str);
            return new ByteArrayMultipartFile(fileBytes, "file", fileName, contentType);
        } catch (IllegalArgumentException e) {
            throw new RuntimeException("Base64字符串格式非法，解码失败", e);
        }
    }

    /**
     * 自定义 MultipartFile 实现（不依赖 MockMultipartFile）
     */
    private static class ByteArrayMultipartFile implements MultipartFile {
        private final byte[] content;
        private final String name;
        private final String originalFilename;
        private final String contentType;

        public ByteArrayMultipartFile(byte[] content, String name, String originalFilename, String contentType) {
            this.content = content;
            this.name = name;
            this.originalFilename = originalFilename;
            this.contentType = contentType;
        }

        @Override
        public String getName() {
            return name;
        }

        @Override
        public String getOriginalFilename() {
            return originalFilename;
        }

        @Override
        public String getContentType() {
            return contentType;
        }

        @Override
        public boolean isEmpty() {
            return content == null || content.length == 0;
        }

        @Override
        public long getSize() {
            return content.length;
        }

        @Override
        public byte[] getBytes() throws IOException {
            return content;
        }

        @Override
        public InputStream getInputStream() throws IOException {
            return new ByteArrayInputStream(content);
        }

        @Override
        public void transferTo(File dest) throws IOException, IllegalStateException {
            try (FileOutputStream fos = new FileOutputStream(dest)) {
                fos.write(content);
            }
        }
    }
}