ImgixURL.h

//
//  ImgixURL.h
//  Cluster
//
//  Created by Taylor Hughes on 12/18/12.
//  Copyright (c) 2012 Taylor Hughes. All rights reserved.
//


#import "NSDictionary+FormEncoded.h"


typedef enum {
    ImgixFitClip,
    ImgixFitCrop,
    ImgixFitScale,
    ImgixFitFill,
    ImgixFitMax,
} ImgixFit;


@interface ImgixURL : NSObject


- initWithS3URL:(NSURL*)URL s3Bucket:(NSString*)bucketName imgixDomain:(NSString*)domain;

- (NSURL*) urlWithWidth:(NSUInteger)width height:(NSUInteger)height;
- (NSURL*) urlWithWidth:(NSUInteger)width height:(NSUInteger)height fit:(ImgixFit)fit;


@end

ImgixURL.m

//
//  ImgixURL.m
//  Cluster
//
//  Created by Taylor Hughes on 12/18/12.
//  Copyright (c) 2012 Taylor Hughes. All rights reserved.
//

#import "ImgixURL.h"


NSString *ImgixFitToUrlParam(ImgixFit fit) {
    switch (fit) {
        case ImgixFitClip:
            return @"clip";
        case ImgixFitCrop:
            return @"crop";
        case ImgixFitFill:
            return @"fill";
        case ImgixFitMax:
            return @"max";
        case ImgixFitScale:
            return @"scale";
    }
    return nil;
}



@interface ImgixURL ()

@property (strong, nonatomic) NSString *baseURL;
@property (assign, nonatomic) NSString *joinChar;

@end


@implementation ImgixURL


- initWithS3URL:(NSURL*)URL s3Bucket:(NSString*)bucketName imgixDomain:(NSString*)domain
{
    self = [super init];
    if (self) {
        NSString *bucketHost = [NSString stringWithFormat:@"%@.s3.amazonaws.com", bucketName];
        NSString *baseURL = [[URL absoluteString] stringByReplacingOccurrencesOfString:bucketHost withString:domain];

        NSString *bucketPath = [NSString stringWithFormat:@"//s3.amazonaws.com/%@/", bucketName];
        NSString *imgixPath = [NSString stringWithFormat:@"//%@/", domain];

        self.baseURL = [baseURL stringByReplacingOccurrencesOfString:bucketPath withString:imgixPath];
        
        // TODO(taylor): Actually parse the URL.
        if ([self.baseURL rangeOfString:@"?"].location != NSNotFound) {
            self.joinChar = @"&";
        } else {
            self.joinChar = @"?";
        }
    }
    return self;
}


- (NSURL*) urlWithWidth:(NSUInteger)width height:(NSUInteger)height
{
    return [self urlWithWidth:width height:height fit:ImgixFitCrop];
}


- (NSURL*) urlWithWidth:(NSUInteger)width height:(NSUInteger)height fit:(ImgixFit)fit
{
    // Figure out the device-pixel ratio.
    CGFloat devicePixelRatio = [[UIScreen mainScreen] scale];

    NSDictionary *params = @{
        @"w": [NSString stringWithFormat:@"%d", width],
        @"h": [NSString stringWithFormat:@"%d", height],
        @"fit": ImgixFitToUrlParam(fit),
        @"dpr": [NSString stringWithFormat:@"%0.2f", devicePixelRatio],
    };
    
    NSURL *url = [NSURL URLWithString:[self.baseURL stringByAppendingFormat:@"%@%@", self.joinChar, [params toFormEncodedString]]];
    return url;
}