Account.kt

/**
 * @property accountNumber Text(40) 
 * @property accountSource Picklist 
 * @property active__c Picklist 
 * @property annualRevenue Currency(18, 0) 
 * @property billingAddress Address 
 * @property cleanStatus Picklist 
 * @property createdById Lookup(User) 
 * @property createdDate Date/Time 
 * @property customerPriority__c Picklist 
 * @property dandbCompanyId Lookup(D&B Company) 
 * @property description Long Text Area(32000) 
 * @property dunsNumber Text(9) 
 * @property fax Fax 
 * @property id Lookup() 
 * @property industry Picklist 
 * @property isDeleted Checkbox 
 * @property jigsaw Text(20) 
 * @property jigsawCompanyId External Lookup 
 * @property lastActivityDate Date 
 * @property lastModifiedById Lookup(User) 
 * @property lastModifiedDate Date/Time 
 * @property lastReferencedDate Date/Time 
 * @property lastViewedDate Date/Time 
 * @property masterRecordId Lookup(Account) 
 * @property naicsCode Text(8) 
 * @property naicsDesc Text(120) 
 * @property name Name 
 * @property numberOfEmployees Number(8, 0) 
 * @property numberofLocations__c Number(3, 0) 
 * @property operatingHoursId Lookup(Operating Hours) 
 * @property ownerId Lookup(User) 
 * @property ownership Picklist 
 * @property parentId Hierarchy 
 * @property phone Phone 
 * @property photoUrl URL(255) 
 * @property rating Picklist 
 * @property sLAExpirationDate__c Date 
 * @property sLASerialNumber__c Text(10) 
 * @property sLA__c Picklist 
 * @property shippingAddress Address 
 * @property sic Text(20) 
 * @property sicDesc Text(80) 
 * @property site Text(80) 
 * @property systemModstamp Date/Time 
 * @property tickerSymbol Content(20) 
 * @property tradestyle Text(255) 
 * @property type Picklist 
 * @property upsellOpportunity__c Picklist 
 * @property userRecordAccessId Lookup(User Record Access) 
 * @property website URL(255) 
 * @property yearStarted Text(4) 
 */
class Account (
    @JsonProperty("AccountNumber") val accountNumber: String? = null,
    @JsonProperty("AccountSource") val accountSource: String? = null,
    @JsonProperty("Active__c") val active__c: String? = null,
    @JsonProperty("AnnualRevenue") val annualRevenue: Double? = null,
    @JsonProperty("BillingAddress") val billingAddress: Map<String, Any?>? = null,
    @JsonProperty("CleanStatus") val cleanStatus: String? = null,
    @JsonProperty("CreatedById") val createdById: String,
    @JsonProperty("CreatedDate") val createdDate: String,
    @JsonProperty("CustomerPriority__c") val customerPriority__c: String? = null,
    @JsonProperty("DandbCompanyId") val dandbCompanyId: String? = null,
    @JsonProperty("Description") val description: String? = null,
    @JsonProperty("DunsNumber") val dunsNumber: String? = null,
    @JsonProperty("Fax") val fax: String? = null,
    @JsonProperty("Industry") val industry: String? = null,
    @JsonProperty("IsDeleted") val isDeleted: Boolean,
    @JsonProperty("Jigsaw") val jigsaw: String? = null,
    @JsonProperty("JigsawCompanyId") val jigsawCompanyId: String? = null,
    @JsonProperty("LastActivityDate") val lastActivityDate: String? = null,
    @JsonProperty("LastModifiedById") val lastModifiedById: String,
    @JsonProperty("LastModifiedDate") val lastModifiedDate: String,
    @JsonProperty("LastReferencedDate") val lastReferencedDate: String? = null,
    @JsonProperty("LastViewedDate") val lastViewedDate: String? = null,
    @JsonProperty("MasterRecordId") val masterRecordId: String? = null,
    @JsonProperty("NaicsCode") val naicsCode: String? = null,
    @JsonProperty("NaicsDesc") val naicsDesc: String? = null,
    @JsonProperty("Name") val name: String,
    @JsonProperty("NumberOfEmployees") val numberOfEmployees: Double? = null,
    @JsonProperty("NumberofLocations__c") val numberofLocations__c: Double? = null,
    @JsonProperty("OperatingHoursId") val operatingHoursId: String? = null,
    @JsonProperty("OwnerId") val ownerId: String,
    @JsonProperty("Ownership") val ownership: String? = null,
    @JsonProperty("ParentId") val parentId: Map<String, Any?>? = null,
    @JsonProperty("Phone") val phone: String? = null,
    @JsonProperty("PhotoUrl") val photoUrl: String? = null,
    @JsonProperty("Rating") val rating: String? = null,
    @JsonProperty("SLAExpirationDate__c") val sLAExpirationDate__c: String? = null,
    @JsonProperty("SLASerialNumber__c") val sLASerialNumber__c: String? = null,
    @JsonProperty("SLA__c") val sLA__c: String? = null,
    @JsonProperty("ShippingAddress") val shippingAddress: Map<String, Any?>? = null,
    @JsonProperty("Sic") val sic: String? = null,
    @JsonProperty("SicDesc") val sicDesc: String? = null,
    @JsonProperty("Site") val site: String? = null,
    @JsonProperty("SystemModstamp") val systemModstamp: String,
    @JsonProperty("TickerSymbol") val tickerSymbol: String? = null,
    @JsonProperty("Tradestyle") val tradestyle: String? = null,
    @JsonProperty("Type") val type: String? = null,
    @JsonProperty("UpsellOpportunity__c") val upsellOpportunity__c: String? = null,
    @JsonProperty("UserRecordAccessId") val userRecordAccessId: String? = null,
    @JsonProperty("Website") val website: String? = null,
    @JsonProperty("YearStarted") val yearStarted: String? = null,
) : AbstractSObject<SObjectType>(type = SObjectType.ACCOUNT)

SalesforceClient.kt

import com.fasterxml.jackson.annotation.JsonProperty
import com.fasterxml.jackson.core.type.TypeReference
import com.fasterxml.jackson.databind.DeserializationFeature
import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
import com.fasterxml.jackson.module.kotlin.registerKotlinModule
import java.net.HttpURLConnection
import java.net.IDN
import java.net.URI
import java.net.URL
import kotlin.reflect.KVisibility
import kotlin.reflect.full.findAnnotations
import kotlin.reflect.full.memberProperties
import kotlin.reflect.full.primaryConstructor
import kotlin.reflect.jvm.javaField

/**
 * @param accessToken has to have [web, chatter_api, api] permissions for querying
 * @param instanceUrl acquired in the same response as accessToken
 *
 * @credits to mjg123 https://github.com/mjg123/java-http-clients/blob/master/src/main/java/com/twilio/JavaHttpURLConnectionDemo.java
 * @credits to madmax1028, broot https://discuss.kotlinlang.org/t/how-to-specify-generic-output-type-to-be-subclass-of-generic-type/24637/12
 */
class SalesforceClient(
    @PublishedApi internal inline val accessToken: String,
    @PublishedApi internal inline val instanceUrl: String,
) {
    @PublishedApi
    internal val apiVersion = "v53.0"

    @PublishedApi
    internal val mapper = jacksonObjectMapper().registerKotlinModule()
        .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)

    inline fun <reified T: SObjectInterface> getAll(): SfResponse<T> =
        getResponse<T>("SELECT ${getFields<T>().joinToString()} FROM ${T::class.simpleName}")

    inline fun <reified T: SObjectInterface> count(): Int =
        getResponse<T>("SELECT COUNT() FROM+${T::class.simpleName}")
        .totalSize

    @PublishedApi
    internal inline fun <reified T: SObjectInterface> getResponse(query: String): SfResponse<T> {

        val url = URL("$instanceUrl/services/data/$apiVersion/query?q=$query").toUri().toURL()
        val connection: HttpURLConnection = url.openConnection() as HttpURLConnection

        connection.setRequestProperty("accept", "application/json")
        connection.setRequestProperty("Authorization", "Bearer $accessToken")

        return mapper.readValue(connection.inputStream, object : TypeReference<SfResponse<T>>() {})
    }

    @OptIn(ExperimentalStdlibApi::class)
    inline fun <reified T: SObjectInterface> getFields(): List<String> {
        val propertiesWeWant = T::class.java.kotlin.memberProperties
            .filter { prop ->
                prop.visibility == KVisibility.PUBLIC
                        && listOf("java.util", "java.lang").contains(prop.javaField?.type?.packageName)
                        && prop.name != "attributes"
            }

        val bodyProps = propertiesWeWant.mapNotNull { it.javaField?.getAnnotation(JsonProperty::class.java)?.value }
        val constructorProps = T::class.java.kotlin.primaryConstructor?.parameters
            ?.filter { it.name in (propertiesWeWant.map { it.name }) }
            ?.map { it.findAnnotations(JsonProperty::class).first().value }
            ?: emptyList()

        return bodyProps + constructorProps
    }

    /**
     * URI is used for URL encoding.
     */
    @PublishedApi
    internal fun URL.toUri() = URI(
        this.protocol,
        this.userInfo,
        IDN.toASCII(this.host),
        this.port,
        this.path,
        this.query, this.ref,
    )
}

class SfResponse<T: SObjectInterface>(
    val totalSize: Int,
    val done: Boolean,
    val records: List<T>,
)

SObjectInterface.kt

interface SObjectInterface

data class SObjectAttributes<T: SObjectType>(
    val type: T,
    val url: String? = null,
)

abstract class AbstractSObject<T: SObjectType>(
    type: T,
) : SObjectInterface {
    val attributes: SObjectAttributes<T> = SObjectAttributes(type = type)
    @JsonProperty("Id") val id: String? = null
}

SObjectType.kt

enum class SObjectType(val jsonName: String) {
    @JsonProperty("Account") ACCOUNT("Account"),
}