mixpanel-swift/Sources/JSONHandler.swift

//
//  JSONHandler.swift
//  Mixpanel
//
//  Created by Yarden Eitan on 6/3/16.
//  Copyright © 2016 Mixpanel. All rights reserved.
//

import Foundation

class JSONHandler {

    typealias MPObjectToParse = Any

    class func encodeAPIData(_ obj: MPObjectToParse) -> String? {
        let data: Data? = serializeJSONObject(obj)

        guard let d = data else {
            Logger.warn(message: "couldn't serialize object")
            return nil
        }

        let base64Encoded = d.base64EncodedString(options: .lineLength64Characters)

        guard let b64 = base64Encoded
            .addingPercentEncoding(withAllowedCharacters: CharacterSet.urlQueryAllowed) else {
            Logger.warn(message: "couldn't replace characters to allowed URL character set")
            return nil
        }

        return b64
    }
    
    class func deserializeData(_ data: Data) -> MPObjectToParse? {
        var object: MPObjectToParse?
        do {
            object = try JSONSerialization.jsonObject(with: data, options: [])
        } catch {
            Logger.warn(message: "exception decoding object data")
        }
        return object
    }

    class func serializeJSONObject(_ obj: MPObjectToParse) -> Data? {
        let serializableJSONObject: MPObjectToParse
        if let jsonObject = makeObjectSerializable(obj) as? [Any] {
            serializableJSONObject = jsonObject.filter {
                JSONSerialization.isValidJSONObject($0)
            }
        } else {
            serializableJSONObject = makeObjectSerializable(obj)
        }
        
        guard JSONSerialization.isValidJSONObject(serializableJSONObject) else {
            Logger.warn(message: "object isn't valid and can't be serialzed to JSON")
            return nil
        }
        
        var serializedObject: Data?
        do {
            serializedObject = try JSONSerialization
                .data(withJSONObject: serializableJSONObject, options: [])
        } catch {
            Logger.warn(message: "exception encoding api data")
        }
        return serializedObject
    }

    private class func makeObjectSerializable(_ obj: MPObjectToParse) -> MPObjectToParse {
        switch obj {
        case let obj as NSNumber:
            if isBoolNumber(obj) {
                return obj.boolValue
            } else if isInvalidNumber(obj) {
                return String(describing: obj)
            } else {
                return obj
            }

        case let obj as Double where obj.isFinite && !obj.isNaN:
            return obj
            
        case let obj as Float where obj.isFinite && !obj.isNaN:
            return obj

        case is String, is Int, is UInt, is UInt64, is Bool:
            return obj
            
        case let obj as [Any?]:
            // nil values in Array properties are dropped
            let nonNilEls: [Any] = obj.compactMap({ $0 })
            return nonNilEls.map { makeObjectSerializable($0) }

        case let obj as [Any]:
            return obj.map { makeObjectSerializable($0) }

        case let obj as InternalProperties:
            var serializedDict = InternalProperties()
            _ = obj.map { e in
                serializedDict[e.key] =
                    makeObjectSerializable(e.value)
            }
            return serializedDict

        case let obj as Date:
            let dateFormatter = DateFormatter()
            dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"
            dateFormatter.timeZone = TimeZone(abbreviation: "UTC")
            dateFormatter.locale = Locale(identifier: "en_US_POSIX")
            return dateFormatter.string(from: obj)

        case let obj as URL:
            return obj.absoluteString

        default:
            let objString = String(describing: obj)
            if objString == "nil" {
                // all nil properties outside of Arrays are converted to NSNull()
                return NSNull()
            } else {
                Logger.info(message: "enforcing string on object")
                return objString
            }
        }
    }

    private class func isBoolNumber(_ num: NSNumber) -> Bool {
        let boolID = CFBooleanGetTypeID()
        let numID = CFGetTypeID(num)
        return numID == boolID
    }

    private class func isInvalidNumber(_ num: NSNumber) -> Bool {
        return  num.doubleValue.isInfinite ||  num.doubleValue.isNaN
    }
}