package uk.silverlabs.silverdroid.config

import android.content.Context
import android.util.Log
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.withContext
import kotlinx.serialization.json.Json
import java.net.HttpURLConnection
import java.net.URL

private const val TAG = "RemoteConfigLoader"

/**
 * Loads configuration from remote AppStore server
 */
object RemoteConfigLoader {

    private val json = Json {
        ignoreUnknownKeys = true
        isLenient = true
    }

    /**
     * Fetch configuration from remote URL with optional authentication
     */
    suspend fun fetchConfig(
        remoteSettings: RemoteConfigSettings,
        userId: String? = null
    ): kotlin.Result<AppConfig> = withContext(Dispatchers.IO) {
        try {
            val url = buildConfigUrl(remoteSettings, userId)
            Log.i(TAG, "Fetching config from: $url")

            val connection = URL(url).openConnection() as HttpURLConnection
            connection.requestMethod = "GET"
            connection.connectTimeout = 10000
            connection.readTimeout = 10000

            // Add authentication if provided
            remoteSettings.authToken?.let {
                connection.setRequestProperty("Authorization", "Bearer $it")
            }

            // Add user ID if user-specific config
            userId?.let {
                connection.setRequestProperty("X-User-ID", it)
            }

            val responseCode = connection.responseCode
            if (responseCode == HttpURLConnection.HTTP_OK) {
                val response = connection.inputStream.bufferedReader().use { it.readText() }
                val config = json.decodeFromString<AppConfig>(response)

                Log.i(TAG, "Successfully loaded remote config for: ${config.appName}")
                kotlin.Result.success(config)
            } else {
                val error = "HTTP $responseCode: ${connection.responseMessage}"
                Log.e(TAG, "Failed to fetch config: $error")
                kotlin.Result.failure(Exception(error))
            }
        } catch (e: Exception) {
            Log.e(TAG, "Error fetching remote config", e)
            kotlin.Result.failure(e)
        }
    }

    private fun buildConfigUrl(settings: RemoteConfigSettings, userId: String?): String {
        var url = settings.url

        // Add user parameter if user-specific
        if (settings.userSpecific && userId != null) {
            url = if (url.contains("?")) {
                "$url&userId=$userId"
            } else {
                "$url?userId=$userId"
            }
        }

        return url
    }

    /**
     * Load config with remote fallback
     * 1. Try to load local config
     * 2. If remote is configured, fetch from server
     * 3. Merge remote with local (remote takes precedence)
     */
    suspend fun loadConfigWithRemote(
        context: Context,
        userId: String? = null
    ): AppConfig {
        // Load local config first
        val localConfig = ConfigLoader.loadConfig(context)

        // Check if remote config is enabled
        val remoteSettings = localConfig.remoteConfig
        if (remoteSettings == null || !remoteSettings.enabled) {
            Log.i(TAG, "Remote config disabled, using local config")
            return localConfig
        }

        // Fetch remote config
        return fetchConfig(remoteSettings, userId).getOrElse { error ->
            Log.w(TAG, "Remote config failed, falling back to local", error)
            localConfig
        }.also {
            if (it != localConfig) {
                Log.i(TAG, "Using remote configuration")
            }
        }
    }
}