/*
 * This file is part of GNU Taler
 * (C) 2020 Taler Systems S.A.
 *
 * GNU Taler is free software; you can redistribute it and/or modify it under the
 * terms of the GNU General Public License as published by the Free Software
 * Foundation; either version 3, or (at your option) any later version.
 *
 * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
 * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
 */

package net.taler.wallet.backend

import android.app.Application
import kotlinx.coroutines.DelicateCoroutinesApi
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.GlobalScope
import kotlinx.coroutines.launch
import kotlinx.coroutines.withContext
import kotlinx.serialization.KSerializer
import kotlinx.serialization.encodeToString
import kotlinx.serialization.json.JsonObject
import kotlinx.serialization.json.decodeFromJsonElement
import net.taler.wallet.backend.TalerErrorCode.NONE
import org.json.JSONObject
import java.io.File

private const val WALLET_DB = "talerwalletdb.sqlite3"

@OptIn(DelicateCoroutinesApi::class)
class WalletBackendApi(
    private val app: Application,
    private val initialConfig: WalletRunConfig,
    private val versionReceiver: VersionReceiver,
    notificationReceiver: NotificationReceiver,
) {

    private val backendManager = BackendManager(notificationReceiver)

    init {
        GlobalScope.launch(Dispatchers.IO) {
            backendManager.run()
            sendInitMessage()
        }
    }

    private suspend fun sendInitMessage() {
        val db = if (File(app.filesDir, "talerwalletdb.sql").isFile) {
            // can be removed after a reasonable migration period (2024-02-02)
            "${app.filesDir}/talerwalletdb.sql"
        } else {
            "${app.filesDir}/${WALLET_DB}"
        }

        request("init", InitResponse.serializer()) {
            put("persistentStoragePath", db)
            put("logLevel", "INFO")
            put("config", JSONObject(BackendManager.json.encodeToString(initialConfig)))
        }.onSuccess { response ->
            versionReceiver.onVersionReceived(response.versionInfo)
        }.onError { error ->
            // TODO expose this to the UI as it can happen when using an older DB version
            error("Error on init message: $error")
        }
    }

    suspend fun setWalletConfig(config: WalletRunConfig): WalletResponse<InitResponse> {
        return request("initWallet", InitResponse.serializer()) {
            put("config", JSONObject(BackendManager.json.encodeToString(config)))
        }
    }

    suspend fun sendRequest(operation: String, args: JSONObject? = null): ApiResponse {
        return backendManager.send(operation, args)
    }

    suspend inline fun <reified T> request(
        operation: String,
        serializer: KSerializer<T>? = null,
        noinline args: (JSONObject.() -> JSONObject)? = null,
    ): WalletResponse<T> = withContext(Dispatchers.Default) {
        val json = BackendManager.json
        try {
            when (val response = sendRequest(operation, args?.invoke(JSONObject()))) {
                is ApiResponse.Response -> {
                    val t: T = serializer?.let {
                        json.decodeFromJsonElement(serializer, response.result)
                    } ?: Unit as T
                    WalletResponse.Success(t)
                }

                is ApiResponse.Error -> {
                    val error: TalerErrorInfo = json.decodeFromJsonElement(response.error)
                    WalletResponse.Error(error)
                }
            }
        } catch (e: Exception) {
            val info = TalerErrorInfo(NONE, "", e.toString())
            WalletResponse.Error(info)
        }
    }

    // Returns raw JSON response instead of serialized object
    suspend inline fun rawRequest(
        operation: String,
        noinline args: (JSONObject.() -> JSONObject)? = null,
    ): WalletResponse<JsonObject> = withContext(Dispatchers.Default) {
        val json = BackendManager.json
        try {
            when (val response = sendRequest(operation, args?.invoke(JSONObject()))) {
                is ApiResponse.Response -> {
                    WalletResponse.Success(response.result)
                }

                is ApiResponse.Error -> {
                    val error: TalerErrorInfo = json.decodeFromJsonElement(response.error)
                    WalletResponse.Error(error)
                }
            }
        } catch (e: Exception) {
            val info = TalerErrorInfo(NONE, "", e.toString())
            WalletResponse.Error(info)
        }
    }
}