//
//  RQEXTRuntimeExtensions.m
//  RQCommon
//
//  Created by 张嵘 on 2018/11/16.
//  Copyright © 2018 张嵘. All rights reserved.
//

#import "RQEXTRuntimeExtensions.h"
#import <Foundation/Foundation.h>

rq_propertyAttributes *rq_copyPropertyAttributes (objc_property_t property) {
	const char * const attrString = property_getAttributes(property);
	if (!attrString) {
		fprintf(stderr, "ERROR: Could not get attribute string from property %s\n", property_getName(property));
		return NULL;
	}
	
	if (attrString[0] != 'T') {
		fprintf(stderr, "ERROR: Expected attribute string \"%s\" for property %s to start with 'T'\n", attrString, property_getName(property));
		return NULL;
	}
	
	const char *typeString = attrString + 1;
	const char *next = NSGetSizeAndAlignment(typeString, NULL, NULL);
	if (!next) {
		fprintf(stderr, "ERROR: Could not read past type in attribute string \"%s\" for property %s\n", attrString, property_getName(property));
		return NULL;
	}
	
	size_t typeLength = next - typeString;
	if (!typeLength) {
		fprintf(stderr, "ERROR: Invalid type in attribute string \"%s\" for property %s\n", attrString, property_getName(property));
		return NULL;
	}
	
	// allocate enough space for the structure and the type string (plus a NUL)
	rq_propertyAttributes *attributes = calloc(1, sizeof(rq_propertyAttributes) + typeLength + 1);
	if (!attributes) {
		fprintf(stderr, "ERROR: Could not allocate rq_propertyAttributes structure for attribute string \"%s\" for property %s\n", attrString, property_getName(property));
		return NULL;
	}
	
	// copy the type string
	strncpy(attributes->type, typeString, typeLength);
	attributes->type[typeLength] = '\0';
	
	// if this is an object type, and immediately followed by a quoted string...
	if (typeString[0] == *(@encode(id)) && typeString[1] == '"') {
		// we should be able to extract a class name
		const char *className = typeString + 2;
		next = strchr(className, '"');
		
		if (!next) {
			fprintf(stderr, "ERROR: Could not read class name in attribute string \"%s\" for property %s\n", attrString, property_getName(property));
			return NULL;
		}
		
		if (className != next) {
			size_t classNameLength = next - className;
			char trimmedName[classNameLength + 1];
			
			strncpy(trimmedName, className, classNameLength);
			trimmedName[classNameLength] = '\0';
			
			// attempt to look up the class in the runtime
			attributes->objectClass = objc_getClass(trimmedName);
		}
	}
	
	if (*next != '\0') {
		// skip past any junk before the first flag
		next = strchr(next, ',');
	}
	
	while (next && *next == ',') {
		char flag = next[1];
		next += 2;
		
		switch (flag) {
			case '\0':
				break;
				
			case 'R':
				attributes->readonly = YES;
				break;
				
			case 'C':
				attributes->memoryManagementPolicy = rq_propertyMemoryManagementPolicyCopy;
				break;
				
			case '&':
				attributes->memoryManagementPolicy = rq_propertyMemoryManagementPolicyRetain;
				break;
				
			case 'N':
				attributes->nonatomic = YES;
				break;
				
			case 'G':
			case 'S':
			{
				const char *nextFlag = strchr(next, ',');
				SEL name = NULL;
				
				if (!nextFlag) {
					// assume that the rest of the string is the selector
					const char *selectorString = next;
					next = "";
					
					name = sel_registerName(selectorString);
				} else {
					size_t selectorLength = nextFlag - next;
					if (!selectorLength) {
						fprintf(stderr, "ERROR: Found zero length selector name in attribute string \"%s\" for property %s\n", attrString, property_getName(property));
						goto errorOut;
					}
					
					char selectorString[selectorLength + 1];
					
					strncpy(selectorString, next, selectorLength);
					selectorString[selectorLength] = '\0';
					
					name = sel_registerName(selectorString);
					next = nextFlag;
				}
				
				if (flag == 'G')
					attributes->getter = name;
				else
					attributes->setter = name;
			}
				
				break;
				
			case 'D':
				attributes->dynamic = YES;
				attributes->ivar = NULL;
				break;
				
			case 'V':
				// assume that the rest of the string (if present) is the ivar name
				if (*next == '\0') {
					// if there's nothing there, let's assume this is dynamic
					attributes->ivar = NULL;
				} else {
					attributes->ivar = next;
					next = "";
				}
				
				break;
				
			case 'W':
				attributes->weak = YES;
				break;
				
			case 'P':
				attributes->canBeCollected = YES;
				break;
				
			case 't':
				fprintf(stderr, "ERROR: Old-style type encoding is unsupported in attribute string \"%s\" for property %s\n", attrString, property_getName(property));
				
				// skip over this type encoding
				while (*next != ',' && *next != '\0')
					++next;
				
				break;
				
			default:
				fprintf(stderr, "ERROR: Unrecognized attribute string flag '%c' in attribute string \"%s\" for property %s\n", flag, attrString, property_getName(property));
		}
	}
	
	if (next && *next != '\0') {
		fprintf(stderr, "Warning: Unparsed data \"%s\" in attribute string \"%s\" for property %s\n", next, attrString, property_getName(property));
	}
	
	if (!attributes->getter) {
		// use the property name as the getter by default
		attributes->getter = sel_registerName(property_getName(property));
	}
	
	if (!attributes->setter) {
		const char *propertyName = property_getName(property);
		size_t propertyNameLength = strlen(propertyName);
		
		// we want to transform the name to setProperty: style
		size_t setterLength = propertyNameLength + 4;
		
		char setterName[setterLength + 1];
		strncpy(setterName, "set", 3);
		strncpy(setterName + 3, propertyName, propertyNameLength);
		
		// capitalize property name for the setter
		setterName[3] = (char)toupper(setterName[3]);
		
		setterName[setterLength - 1] = ':';
		setterName[setterLength] = '\0';
		
		attributes->setter = sel_registerName(setterName);
	}
	
	return attributes;
	
errorOut:
	free(attributes);
	return NULL;
}