JSObjectionUtils.m

#import <objc/runtime.h>
#import "JSObjectionUtils.h"
#import "JSObjectionInjector.h"
#import "JSObjection.h"
#import "NSObject+Objection.h"

static NSString *const JSObjectionException = @"JSObjectionException";

NSString *const JSObjectionInitializerKey = @"initializer";
NSString *const JSObjectionDefaultArgumentsKey = @"arguments";

static JSObjectionPropertyInfo FindClassOrProtocolForProperty(objc_property_t property) {
    NSString *attributes = [NSString stringWithCString: property_getAttributes(property) encoding: NSASCIIStringEncoding];  
    NSString *propertyName = [NSString stringWithCString:property_getName(property) encoding:NSASCIIStringEncoding];

    NSRange startRange = [attributes rangeOfString:@"T@\""];
    if (startRange.location == NSNotFound) {
        @throw [NSException exceptionWithName:JSObjectionException reason:[NSString stringWithFormat:@"Unable to determine class type for property declaration: '%@'", propertyName] userInfo:nil];
    }

    NSString *startOfClassName = [attributes substringFromIndex:startRange.length];
    NSRange endRange = [startOfClassName rangeOfString:@"\""];

    if (endRange.location == NSNotFound) {
        @throw [NSException exceptionWithName:JSObjectionException reason:[NSString stringWithFormat:@"Unable to determine class type for property declaration: '%@'", propertyName] userInfo:nil];        
    }

    NSString *classOrProtocolName = [startOfClassName substringToIndex:endRange.location];
    id classOrProtocol = nil;
    JSObjectionPropertyInfo propertyInfo;

    if ([classOrProtocolName hasPrefix:@"<"] && [classOrProtocolName hasSuffix:@">"]) {
        classOrProtocolName = [classOrProtocolName stringByReplacingOccurrencesOfString:@"<" withString:@""];
        classOrProtocolName = [classOrProtocolName stringByReplacingOccurrencesOfString:@">" withString:@""];
        classOrProtocol = objc_getProtocol([classOrProtocolName UTF8String]);
        propertyInfo.type = JSObjectionTypeProtocol;
    } else {
        if ([classOrProtocolName hasSuffix:@">"]) {
            classOrProtocolName = [classOrProtocolName substringToIndex:[classOrProtocolName rangeOfString:@"<"].location];
        }
        
        classOrProtocol = NSClassFromString(classOrProtocolName);
        propertyInfo.type = JSObjectionTypeClass;
    }

    if(!classOrProtocol) {
        @throw [NSException exceptionWithName:JSObjectionException reason:[NSString stringWithFormat:@"Unable get class for name '%@' for property '%@'", classOrProtocolName, propertyName] userInfo:nil];            
    }
    propertyInfo.value = classOrProtocol;

    return propertyInfo;      
}

static NSSet* BuildDependenciesForClass(Class klass, NSSet *requirements) {
    Class superClass = class_getSuperclass([klass class]);
    if([superClass respondsToSelector:@selector(objectionRequires)]) {
        NSSet *parentsRequirements = [superClass objectionRequires];
        NSMutableSet *dependencies = [NSMutableSet setWithSet:parentsRequirements];
        [dependencies unionSet:requirements];
        requirements = dependencies;
    }
    return requirements;  
}

static NSDictionary* BuildNamedDependenciesForClass(Class klass, NSDictionary *namedRequirements) {
    Class superClass = class_getSuperclass([klass class]);
    if([superClass respondsToSelector:@selector(objectionRequiresNames)]) {
       NSDictionary *parentsNamedRequirements = [superClass objectionRequiresNames];
       NSMutableDictionary *namedDependencies = [NSMutableDictionary dictionaryWithDictionary:parentsNamedRequirements];
       [namedDependencies addEntriesFromDictionary:namedRequirements];
       namedRequirements = namedDependencies;
    }
    return namedRequirements;
}

static NSDictionary* BuildInitializer(SEL selector, NSArray *defaultArguments) {
    return [NSDictionary dictionaryWithObjectsAndKeys:
                NSStringFromSelector(selector), JSObjectionInitializerKey,
                defaultArguments, JSObjectionDefaultArgumentsKey
            , nil];
}

static NSArray* TransformVariadicArgsToArray(va_list va_arguments) {
    NSMutableArray *arguments = [NSMutableArray array];    
    
    id object;
    while ((object = va_arg( va_arguments, id ))) {
        [arguments addObject:object];
    }
    
    return [arguments copy];
}

static objc_property_t GetProperty(Class klass, NSString *propertyName) {
    objc_property_t property = class_getProperty(klass, (const char *)[propertyName UTF8String]);
    if (property == NULL) {
        @throw [NSException exceptionWithName:JSObjectionException reason:[NSString stringWithFormat:@"Unable to find property declaration: '%@' for class '%@'", propertyName, NSStringFromClass(klass)] userInfo:nil];
    }
    return property;
}


static id BuildObjectWithInitializer(Class klass, SEL initializer, NSArray *arguments) {
	NSMethodSignature *signature = [klass methodSignatureForSelector:initializer];
	__autoreleasing id instance = nil;
    BOOL isClassMethod = signature != nil && initializer != @selector(init);
    
	if (!isClassMethod) {
		instance = [klass alloc];
		signature = [klass instanceMethodSignatureForSelector:initializer];
	}
    
    if (signature) {
        NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:signature];
        [invocation setTarget:isClassMethod ? klass : instance];
        [invocation setSelector:initializer];
        for (int i = 0; i < arguments.count; i++) {
            __unsafe_unretained id argument = [arguments objectAtIndex:i];
            [invocation setArgument:&argument atIndex:i + 2];
        }
        [invocation invoke];
		[invocation getReturnValue:&instance];
        return instance;
    } else {
        @throw [NSException exceptionWithName:JSObjectionException reason:[NSString stringWithFormat:@"Could not find initializer '%@' on %@", NSStringFromSelector(initializer), NSStringFromClass(klass)] userInfo:nil]; 
    }
    return nil;
}

static void _getPropertyInfo(Class klass, NSString *propertyName, JSObjectionPropertyInfo *propertyInfo, id *desiredClassOrProtocol) {
    (*propertyInfo) = [JSObjection propertyForClass:klass andProperty:propertyName];
    (*desiredClassOrProtocol) = propertyInfo->value;
    // Ensure that the class is initialized before attempting to retrieve it.
    // Using +load would force all registered classes to be initialized so we are
    // lazily initializing them.
    if ((*propertyInfo).type == JSObjectionTypeClass) {
        [*desiredClassOrProtocol class];
    }
}

static void _validateObjectReturnedFromInjector(id *theObject, JSObjectionPropertyInfo propertyInfo, id desiredClassOrProtocol, NSString *propertyName) {
    if(*theObject == nil && propertyInfo.type == JSObjectionTypeProtocol) {
        @throw [NSException exceptionWithName:@"JSObjectionException"
                                       reason:[NSString stringWithFormat:@"Cannot find an instance that is bound to the protocol '%@' to assign to the property '%@'", NSStringFromProtocol(desiredClassOrProtocol), propertyName]
                                     userInfo:nil];
    } else if (*theObject == nil) {
        *theObject = [NSNull null];
    }
}

static void InjectDependenciesIntoProperties(JSObjectionInjector *injector, Class klass, id object) {
    if ([klass respondsToSelector:@selector(objectionRequires)]) {
        NSSet *properties = [klass objectionRequires];
        NSMutableDictionary *propertiesDictionary = [NSMutableDictionary dictionaryWithCapacity:properties.count];
        for (NSString *propertyName in properties) {
            JSObjectionPropertyInfo propertyInfo;
            id desiredClassOrProtocol;
            _getPropertyInfo(klass, propertyName, &propertyInfo, &desiredClassOrProtocol);
            id theObject = [injector getObject:desiredClassOrProtocol];
            _validateObjectReturnedFromInjector(&theObject, propertyInfo, desiredClassOrProtocol, propertyName);
            [propertiesDictionary setObject:theObject forKey:propertyName];
        }
        
        [object setValuesForKeysWithDictionary:propertiesDictionary];
    }

    if ([klass respondsToSelector:@selector(objectionRequiresNames)]) {
        NSDictionary *namedProperties = [klass objectionRequiresNames];
        NSMutableDictionary *propertiesDictionary = [NSMutableDictionary dictionaryWithCapacity:namedProperties.count];
        for (NSString *namedPropertyKey in [namedProperties allKeys]) {
            NSString* propertyName = [namedProperties valueForKey:namedPropertyKey];
            JSObjectionPropertyInfo propertyInfo;
            id desiredClassOrProtocol;
            _getPropertyInfo(klass, propertyName, &propertyInfo, &desiredClassOrProtocol);
            id theObject = [injector getObject:desiredClassOrProtocol named:namedPropertyKey];
            _validateObjectReturnedFromInjector(&theObject, propertyInfo, desiredClassOrProtocol, propertyName);
            [propertiesDictionary setObject:theObject forKey:propertyName];
        }

        [object setValuesForKeysWithDictionary:propertiesDictionary];
    }

    if ([object respondsToSelector:@selector(awakeFromObjection)]) {
        [object awakeFromObjection];
    }
}

const struct JSObjectionUtils JSObjectionUtils = {
    .findClassOrProtocolForProperty = FindClassOrProtocolForProperty,
    .propertyForClass = GetProperty,
    .buildDependenciesForClass = BuildDependenciesForClass,
    .buildNamedDependenciesForClass = BuildNamedDependenciesForClass,
    .buildInitializer = BuildInitializer,
    .transformVariadicArgsToArray = TransformVariadicArgsToArray,
    .buildObjectWithInitializer = BuildObjectWithInitializer,
    .injectDependenciesIntoProperties = InjectDependenciesIntoProperties
};