package expo.modules.updates

import android.content.Context
import com.facebook.react.ReactApplication
import expo.modules.updates.events.IUpdatesEventManagerObserver
import expo.modules.updates.loader.LoaderTask
import expo.modules.updates.logging.UpdatesErrorCode
import expo.modules.updates.logging.UpdatesLogger
import expo.modules.updatesinterface.UpdatesControllerRegistry
import java.lang.ref.WeakReference

/**
 * Main entry point to expo-updates. Singleton that keeps track of updates state, holds references
 * to instances of other updates classes, and is the central hub for all updates-related tasks.
 *
 * The `start` method in the singleton instance of [IUpdatesController] should be invoked early in
 * the application lifecycle, via [UpdatesPackage]. It delegates to an instance of [LoaderTask] to
 * start the process of loading and launching an update, then responds appropriately depending on
 * the callbacks that are invoked.
 */
object UpdatesController {
  @Volatile
  private var singletonInstance: IUpdatesController? = null

  @Volatile
  private var overrideConfiguration: UpdatesConfiguration? = null

  @JvmStatic
  val instance: IUpdatesController
    get() {
      return checkNotNull(singletonInstance) { "UpdatesController.instance was called before the module was initialized" }
    }

  @JvmStatic
  fun initializeWithoutStarting(context: Context, useDeveloperSupport: Boolean) {
    if (singletonInstance != null) {
      return
    }
    if (useDeveloperSupport && !UpdatesPackage.isUsingNativeDebug) {
      if (BuildConfig.USE_DEV_CLIENT) {
        val devLauncherController = initializeAsDevLauncherWithoutStarting(context)
        singletonInstance = devLauncherController
        UpdatesControllerRegistry.controller = WeakReference(devLauncherController)
      } else {
        singletonInstance = DisabledUpdatesController(context, null)
      }
      return
    }

    val logger = UpdatesLogger(context.filesDir)

    val updatesDirectory = try {
      UpdatesUtils.getOrCreateUpdatesDirectory(context)
    } catch (e: Exception) {
      logger.error(
        "The expo-updates system is disabled due to a storage access error",
        e,
        UpdatesErrorCode.InitializationError
      )
      singletonInstance = DisabledUpdatesController(context, e)
      return
    }

    val updatesConfiguration: UpdatesConfiguration? = overrideConfiguration ?: run {
      when (UpdatesConfiguration.getUpdatesConfigurationValidationResult(context, null)) {
        UpdatesConfigurationValidationResult.VALID -> {
          return@run UpdatesConfiguration(context, null)
        }

        UpdatesConfigurationValidationResult.INVALID_NOT_ENABLED -> logger.warn(
          "The expo-updates system is explicitly disabled. To enable it, set the enabled setting to true.",
          UpdatesErrorCode.InitializationError
        )

        UpdatesConfigurationValidationResult.INVALID_MISSING_URL -> logger.warn(
          "The expo-updates system is disabled due to an invalid configuration. Ensure a valid URL is supplied.",
          UpdatesErrorCode.InitializationError
        )

        UpdatesConfigurationValidationResult.INVALID_MISSING_RUNTIME_VERSION -> logger.warn(
          "The expo-updates system is disabled due to an invalid configuration. Ensure a runtime version is supplied.",
          UpdatesErrorCode.InitializationError
        )
      }
      return@run null
    }

    singletonInstance = if (updatesConfiguration != null) {
      val enabledUpdatesController = EnabledUpdatesController(context, updatesConfiguration, updatesDirectory)
      UpdatesControllerRegistry.controller = WeakReference(enabledUpdatesController)
      enabledUpdatesController
    } else {
      val disabledUpdatesController = DisabledUpdatesController(context, null)
      UpdatesControllerRegistry.controller = WeakReference(disabledUpdatesController)
      disabledUpdatesController
    }
  }

  private fun initializeAsDevLauncherWithoutStarting(context: Context): UpdatesDevLauncherController {
    check(singletonInstance == null) { "UpdatesController must not be initialized prior to calling initializeAsDevLauncherWithoutStarting" }

    var updatesDirectoryException: Exception? = null
    val updatesDirectory = try {
      UpdatesUtils.getOrCreateUpdatesDirectory(context)
    } catch (e: Exception) {
      updatesDirectoryException = e
      null
    }

    val initialUpdatesConfiguration = overrideConfiguration ?: run {
      if (UpdatesConfiguration.getUpdatesConfigurationValidationResult(
          context,
          null
        ) == UpdatesConfigurationValidationResult.VALID
      ) {
        UpdatesConfiguration(context, null)
      } else {
        null
      }
    }

    val instance = UpdatesDevLauncherController(
      context,
      initialUpdatesConfiguration,
      updatesDirectory,
      updatesDirectoryException
    )
    singletonInstance = instance
    return instance
  }

  /**
   * Initializes the UpdatesController singleton. This should be called as early as possible in the
   * application's lifecycle. Can pass additional configuration to this method to set or override
   * configuration values at runtime rather than just AndroidManifest.xml.
   * @param context the base context of the application, ideally a [ReactApplication]
   */
  @JvmStatic
  @Synchronized
  fun initialize(context: Context, useDeveloperSupport: Boolean = false) {
    if (singletonInstance == null) {
      initializeWithoutStarting(context, useDeveloperSupport)
      singletonInstance?.start()
    }
  }

  /**
   * Overrides the [UpdatesConfiguration] that will be used inside [UpdatesController]
   * This should be called as early as possible in the application's lifecycle.
   * Can pass additional configuration to this method to set or override
   * configuration values at runtime rather than just AndroidManifest.xml.
   *
   * @param context the base context of the application, ideally a [ReactApplication]
   * @param configuration map of configuration pairs to override those from AndroidManifest.xml
   */
  @JvmStatic
  fun overrideConfiguration(context: Context, configuration: Map<String, Any>) {
    if (singletonInstance != null) {
      throw AssertionError("The method should be called before UpdatesController.initialize()")
    }
    val updatesConfigurationValidationResult =
      UpdatesConfiguration.getUpdatesConfigurationValidationResult(context, configuration)
    if (updatesConfigurationValidationResult == UpdatesConfigurationValidationResult.VALID) {
      overrideConfiguration = UpdatesConfiguration(context, configuration)
    } else {
      val logger = UpdatesLogger(context.filesDir)
      logger.warn("Failed to overrideConfiguration: invalid configuration: ${updatesConfigurationValidationResult.name}")
    }
  }

  internal fun setUpdatesEventManagerObserver(observer: WeakReference<IUpdatesEventManagerObserver>) {
    singletonInstance?.eventManager?.observer = observer
    singletonInstance?.onEventListenerStartObserving()
  }

  internal fun removeUpdatesEventManagerObserver() {
    singletonInstance?.eventManager?.observer = null
  }
}