package app.pulse.updates

import android.content.Context
import com.facebook.react.ReactHost
import com.facebook.react.ReactNativeHost
import com.facebook.react.ReactPackage
import com.facebook.react.ReactPackageTurboModuleManagerDelegate
import com.facebook.react.bridge.JSBundleLoader
import com.facebook.react.common.annotations.UnstableReactNativeAPI
import com.facebook.react.defaults.DefaultComponentsRegistry
import com.facebook.react.defaults.DefaultTurboModuleManagerDelegate
import com.facebook.react.fabric.ComponentFactory
import com.facebook.react.runtime.BindingsInstaller
import com.facebook.react.runtime.JSRuntimeFactory
import com.facebook.react.runtime.ReactHostDelegate
import com.facebook.react.runtime.ReactHostImpl
import com.facebook.react.runtime.hermes.HermesInstance
import java.lang.ref.WeakReference

/**
 * Custom ReactHostDelegate that supports dynamic bundle reloading.
 *
 * Unlike DefaultReactHostDelegate which caches the bundle loader at construction time,
 * this delegate re-queries PulseController every time jsBundleLoader is accessed.
 * This allows reload() to pick up the new bundle path after an OTA update.
 */
@OptIn(UnstableReactNativeAPI::class)
private class PulseReactHostDelegate(
    private val weakContext: WeakReference<Context>,
    override val jsMainModulePath: String,
    override val reactPackages: List<ReactPackage>,
    override val jsRuntimeFactory: JSRuntimeFactory = HermesInstance(),
    override val bindingsInstaller: BindingsInstaller? = null,
    override val turboModuleManagerDelegateBuilder: ReactPackageTurboModuleManagerDelegate.Builder = DefaultTurboModuleManagerDelegate.Builder(),
    private val exceptionHandler: (Exception) -> Unit = { throw it }
) : ReactHostDelegate {

    /**
     * Override jsBundleLoader to dynamically query PulseController.
     * This is called every time React Native needs the bundle, including on reload.
     */
    override val jsBundleLoader: JSBundleLoader
        get() {
            val context = weakContext.get()
                ?: throw IllegalStateException("Context is no longer available")

            val bundleFile = PulseUpdatesModule.getBundleFile(context)

            return if (bundleFile != null) {
                pulseLog("PulseReactHostDelegate", "jsBundleLoader: ${bundleFile.absolutePath}")
                JSBundleLoader.createFileLoader(bundleFile.absolutePath)
            } else {
                pulseLog("PulseReactHostDelegate", "jsBundleLoader: using default asset bundle")
                JSBundleLoader.createAssetLoader(context, "assets://index.android.bundle", true)
            }
        }

    override fun handleInstanceException(error: Exception) = exceptionHandler(error)
}

/**
 * Factory for creating a ReactHost that supports dynamic bundle reloading.
 *
 * Usage in MainApplication:
 * ```kotlin
 * override val reactHost: ReactHost
 *     get() = PulseReactHostFactory.createReactHost(
 *         applicationContext,
 *         packages = reactNativeHost.packages, // or getPackages()
 *         jsMainModuleName = "index",
 *         useDevSupport = BuildConfig.DEBUG
 *     )
 * ```
 */
object PulseReactHostFactory {

    @Volatile
    private var reactHost: ReactHost? = null

    @OptIn(UnstableReactNativeAPI::class)
    @JvmStatic
    fun createReactHost(
        context: Context,
        packages: List<ReactPackage>,
        jsMainModuleName: String = "index",
        useDevSupport: Boolean = false
    ): ReactHost {
        if (reactHost == null) {
            synchronized(this) {
                if (reactHost == null) {
                    val weakContext = WeakReference(context.applicationContext)

                    pulseLog("PulseReactHostFactory", "Creating ReactHost with ${packages.size} packages, jsMainModuleName=$jsMainModuleName")

                    val delegate = PulseReactHostDelegate(
                        weakContext = weakContext,
                        jsMainModulePath = jsMainModuleName,
                        reactPackages = packages
                    )

                    val componentFactory = ComponentFactory()
                    DefaultComponentsRegistry.register(componentFactory)

                    reactHost = ReactHostImpl(
                        context.applicationContext,
                        delegate,
                        componentFactory,
                        true, // allowPackagerServerAccess
                        useDevSupport
                    )
                }
            }
        }
        return reactHost!!
    }
}