//
//  UIImage+Scale.m
//  Meet
//
//  Created by yuqingyuan on 2018/9/28.
//  Copyright © 2018年 ko1o. All rights reserved.
//

#import "UIImage+Scale.h"

@implementation UIImage (Scale)

+ (UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)size
{
    if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)]) {
        UIGraphicsBeginImageContextWithOptions(size, NO, [[UIScreen mainScreen] scale]);
    } else {
        UIGraphicsBeginImageContext(size);
    }
    [image drawInRect:CGRectMake(0, 0, size.width, size.height)];
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return newImage;
}

+ (UIImage *)imageWithImage:(UIImage *)image scaledToMaxWidth:(CGFloat)width maxHeight:(CGFloat)height
{
    CGSize newSize = [self sizeWithImageSize:image.size scaledToMaxWidth:width maxHeight:height];
    
    return [self imageWithImage:image scaledToSize:newSize];
}

+ (CGSize)sizeWithImageSize:(CGSize)size scaledToMaxWidth:(CGFloat)width maxHeight:(CGFloat)height
{
    CGFloat oldWidth = size.width;
    CGFloat oldHeight = size.height;
    
    CGFloat scaleFactor = (oldWidth > oldHeight) ? width / oldWidth : height / oldHeight;
    
    CGFloat newHeight = oldHeight * scaleFactor;
    CGFloat newWidth = oldWidth * scaleFactor;
    CGSize newSize = CGSizeMake(newWidth, newHeight);
    
    return newSize;
}

NSData *comprossImageToSize(UIImage *image, int size) {
    int maxLength = size; // 最大500k
    //首先判断原图大小是否在要求内，如果满足要求则不进行压缩，over
    CGFloat compression = 1;
    NSData *data = UIImageJPEGRepresentation(image, compression);
    if (data.length < maxLength) return UIImageJPEGRepresentation(image, 1.0);
    //原图大小超过范围，先进行“压处理”，这里 压缩比 采用二分法进行处理，6次二分后的最小压缩比是0.015625，已经够小了
    CGFloat max = 1;
    CGFloat min = 0;
    for (int i = 0; i < 6; ++i) {
        compression = (max + min) / 2;
        data = UIImageJPEGRepresentation(image, compression);
        if (data.length < maxLength * 0.9) {
            min = compression;
        } else if (data.length > maxLength) {
            max = compression;
        } else {
            break;
        }
    }
    //判断“压处理”的结果是否符合要求，符合要求就over
    UIImage *resultImage = [UIImage imageWithData:data];
    if (data.length < maxLength) return data;
    
    //缩处理，直接用大小的比例作为缩处理的比例进行处理，因为有取整处理，所以一般是需要两次处理
    NSUInteger lastDataLength = 0;
    while (data.length > maxLength && data.length != lastDataLength) {
        lastDataLength = data.length;
        //获取处理后的尺寸
        CGFloat ratio = (CGFloat)maxLength / data.length;
        CGSize size = CGSizeMake((NSUInteger)(resultImage.size.width * sqrtf(ratio)),
                                 (NSUInteger)(resultImage.size.height * sqrtf(ratio)));
        //通过图片上下文进行处理图片
        UIGraphicsBeginImageContext(size);
        [resultImage drawInRect:CGRectMake(0, 0, size.width, size.height)];
        resultImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
        //获取处理后图片的大小
        data = UIImageJPEGRepresentation(resultImage, compression);
    }
    return data;
}

NSData *compressImageToDataIfNeed(UIImage *image)
{
    return comprossImageToSize(image, 500 * 1000);
}

UIImage *compressImageToSizeIfNeed(UIImage *image, int size)
{
    NSData *data = comprossImageToSize(image, size);
    return [[UIImage alloc] initWithData:data];
}

@end