EtherscanService.kt

/*
* Code of this class belongs to https://github.com/horizontalsystems/ethereum-kit-android library;
* Modified by Sapien Wallet team on 10.12.2020
* */

import com.google.gson.Gson
import com.google.gson.JsonElement
import com.google.gson.reflect.TypeToken
import com.sapien.wallet.di.modules.ApiKeyModule
import com.sapien.wallet.di.modules.retrofit.GsonModule
import io.horizontalsystems.ethereumkit.api.models.etherscan.EtherscanResponse
import io.horizontalsystems.ethereumkit.core.retryWhenError
import io.horizontalsystems.ethereumkit.models.Address
import io.reactivex.Single
import retrofit2.http.GET
import retrofit2.http.Query
import javax.inject.Inject
import javax.inject.Named
import javax.inject.Singleton

@Singleton
class EtherscanService @Inject constructor(
    @Named(GsonModule.ETHERSCAN_SERVICE) private val gson: Gson,
    private val service: EtherscanServiceAPI,
    @Named(ApiKeyModule.ETHERSCAN) private val apiKey: String
) {
    fun getTransactionList(address: Address, startBlock: Long): Single<EtherscanResponse> {
        return service.getTransactionList("account", "txList", address.hex, startBlock, 99_999_999, "desc", apiKey)
            .map { parseResponse(it) }
            .retryWhenError(RequestError.RateLimitExceed::class)
    }

    fun getInternalTransactionList(address: Address, startBlock: Long): Single<EtherscanResponse> {
        return service.getTransactionList(
            "account",
            "txlistinternal",
            address.hex,
            startBlock,
            99_999_999,
            "desc",
            apiKey
        )
            .map { parseResponse(it) }
            .retryWhenError(RequestError.RateLimitExceed::class)
    }

    fun getTokenTransactions(contractAddress: Address, address: Address, startBlock: Long): Single<EtherscanResponse> {
        return service.getTokenTransactions(
            "account",
            "tokentx",
            contractAddress.hex,
            address.hex,
            startBlock,
            99_999_999,
            "desc",
            apiKey
        )
            .map { parseResponse(it) }
            .retryWhenError(RequestError.RateLimitExceed::class)
    }

    private fun parseResponse(response: JsonElement): EtherscanResponse {
        try {
            val responseObj = response.asJsonObject
            val status = responseObj["status"].asJsonPrimitive.asString
            val message = responseObj["message"].asJsonPrimitive.asString

            if (status == "0" && message != "No transactions found") {
                val result = responseObj["result"].asJsonPrimitive.asString
                if (message == "NOTOK" && result == "Max rate limit reached") {
                    throw RequestError.RateLimitExceed()
                }
            }
            val result: List<Map<String, String>> =
                gson.fromJson(responseObj["result"], object : TypeToken<List<Map<String, String>>>() {}.type)
            return EtherscanResponse(status, message, result)

        } catch (rateLimitExceeded: RequestError.RateLimitExceed) {
            throw rateLimitExceeded
        } catch (err: Throwable) {
            throw RequestError.ResponseError("Unexpected response: $response")
        }
    }

    open class RequestError(message: String? = null) : Exception(message ?: "") {
        class ResponseError(message: String) : RequestError(message)
        class RateLimitExceed : RequestError()
    }

    interface EtherscanServiceAPI {

        @GET("/api")
        fun getTransactionList(
            @Query("module") module: String,
            @Query("action") action: String,
            @Query("address") address: String,
            @Query("startblock") startblock: Long,
            @Query("endblock") endblock: Long,
            @Query("sort") sort: String,
            @Query("apiKey") apiKey: String
        ): Single<JsonElement>

        @GET("/api")
        fun getTokenTransactions(
            @Query("module") module: String,
            @Query("action") action: String,
            @Query("contractaddress") contractAddress: String,
            @Query("address") address: String,
            @Query("startblock") startblock: Long,
            @Query("endblock") endblock: Long,
            @Query("sort") sort: String,
            @Query("apiKey") apiKey: String
        ): Single<JsonElement>
    }

}