Result deserialization

result_deserialization.kt

override fun deserialize(json: JsonElement?, typeOfT: Type?, context: JsonDeserializationContext?): Result<*, *>? {
    return when {
        // Is it a JsonObject? Bingo!
        json?.isJsonObject == true -> {
            
            // Let's try to extract the type in order
            // to deserialize this object
            val parameterizedType = typeOfT as ParameterizedType
            
            // Returns an Ok with the value deserialized
            return Result.ok(context?.deserialize<Any>(json, parameterizedType.actualTypeArguments[0])!!)
        }
        // Wow, is it an array of objects? 
        json?.isJsonArray == true -> {
            
            // First, let's try to get the array type
            val parameterizedType = typeOfT as ParameterizedType
            
            // check if the array contains a generic type too,
            // for example, List<Result<T, E>>
            if (parameterizedType.actualTypeArguments[0] is WildcardType) {
                
                // In case of yes, let's try to get the type from the 
                // wildcard type (*)
                val internalListType = (parameterizedType.actualTypeArguments[0] as WildcardType).upperBounds[0] as ParameterizedType
                
                // Deserialize the array with the base type Any
                // It will give us an array full of linkedTreeMaps (the json)
                val arr = context?.deserialize<Any>(json, parameterizedType.actualTypeArguments[0]) as ArrayList<*>
                
                // Iterate the array and 
                // this time, try to deserialize each member with the discovered
                // wildcard type and create new array with these values
                val result = arr.map { linkedTreeMap ->
                    val jsonElement = gson.toJsonTree(linkedTreeMap as LinkedTreeMap<*, *>).asJsonObject
                    return@map context.deserialize<Any>(jsonElement, internalListType.actualTypeArguments[0])
                }
                
                // Return the result inside the Ok state
                return Result.ok(result)
            } else {
                // Fortunately it is a simple list, like Array<String> 
                // Just get the type as with a JsonObject and return an Ok
                return Result.ok(context?.deserialize<Any>(json, parameterizedType.actualTypeArguments[0])!!)
            }
        }
        // It is not a JsonObject or JsonArray
        // Let's returns the default state Loading.
        else -> Result.Loading
    }
}