package com.sercurityControl.proteam.util;

import net.coobird.thumbnailator.Thumbnails;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.*;

public class PicUtils {
    //以下是常量,按照阿里代码开发规范,不允许代码中出现魔法值
    private static final Logger logger = LoggerFactory.getLogger(PicUtils.class);
    private static final Integer ZERO = 0;
    private static final Integer ONE_ZERO_TWO_FOUR = 1024;
    private static final Integer NINE_ZERO_ZERO = 900;
    private static final Integer THREE_TWO_SEVEN_FIVE = 3275;
    private static final Integer TWO_ZERO_FOUR_SEVEN = 2047;
    private static final Double ZERO_EIGHT_FIVE = 0.85;
    private static final Double ZERO_SIX = 0.6;
    private static final Double ZERO_FOUR_FOUR = 0.44;
    private static final Double ZERO_FOUR = 0.4;

    /**
     * 根据指定大小压缩图片
     *
     * @param imageBytes  源图片字节数组
     * @param desFileSize 指定图片大小，单位kb
     * @return 压缩质量后的图片字节数组
     */
    public static byte[] compressPicForScale(byte[] imageBytes, long desFileSize) {
        if (imageBytes == null || imageBytes.length <= ZERO || imageBytes.length < desFileSize * ONE_ZERO_TWO_FOUR) {
            return imageBytes;
        }
        long srcSize = imageBytes.length;
        double accuracy = getAccuracy(srcSize / ONE_ZERO_TWO_FOUR);
        try {
            while (imageBytes.length > desFileSize * ONE_ZERO_TWO_FOUR) {
                ByteArrayInputStream inputStream = new ByteArrayInputStream(imageBytes);
                ByteArrayOutputStream outputStream = new ByteArrayOutputStream(imageBytes.length);
                Thumbnails.of(inputStream)
                        .scale(accuracy)
                        .outputQuality(accuracy)
                        .toOutputStream(outputStream);
                imageBytes = outputStream.toByteArray();
            }
            logger.info("图片原大小={}kb | 压缩后大小={}kb",
                    srcSize / ONE_ZERO_TWO_FOUR, imageBytes.length / ONE_ZERO_TWO_FOUR);
        } catch (Exception e) {
            logger.error("【图片压缩】msg=图片压缩失败!", e);
        }
        return imageBytes;
    }

    /**
     * 自动调节精度(经验数值)
     *
     * @param size 源图片大小
     * @return 图片压缩质量比
     */
    private static double getAccuracy(long size) {
        double accuracy;
        if (size < NINE_ZERO_ZERO) {
            accuracy = ZERO_EIGHT_FIVE;
        } else if (size < TWO_ZERO_FOUR_SEVEN) {
            accuracy = ZERO_SIX;
        } else if (size < THREE_TWO_SEVEN_FIVE) {
            accuracy = ZERO_FOUR_FOUR;
        } else {
            accuracy = ZERO_FOUR;
        }
        return accuracy;
    }

    public static byte[] FileTobyte(File file) {
        FileInputStream fileInputStream = null;
        byte[] imgData = null;

        try {
            imgData = new byte[(int) file.length()];

            //read file into bytes[]
            fileInputStream = new FileInputStream(file);
            fileInputStream.read(imgData);

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (fileInputStream != null) {
                try {
                    fileInputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

        }
        return imgData;
    }

    public static void main(String[] args) throws IOException {
        byte[] bytes = compressPicForScale(FileTobyte(new File("L:\\测试图片\\6.jpg")), 120);
        String newFileName = IDUtils.createID() + ".jpg";
        File fOut = new File("L:\\测试图片\\" + newFileName);
        FileOutputStream fileOutputStream = new FileOutputStream(fOut);
        fileOutputStream.write(bytes);
        fileOutputStream.close();
    }
}