import { TurnContext } from '../turnContext'
import { AgentApplication } from './agentApplication'
import { RouteHandler } from './routeHandler'
import { RouteRank } from './routeRank'
import { RouteSelector } from './routeSelector'
import { TurnState } from './turnState'

/**
 * Represents an extension that adds channel-specific routing functionality to an agent application.
 * This class allows you to register routes that are only active for a specific channel.
 *
 * @typeParam TState - The type of turn state that extends TurnState
 */
export class AgentExtension<TState extends TurnState> {
  /** The channel ID that this extension is associated with */
  channelId: string

  /**
   * Creates a new AgentExtension instance for the specified channel.
   *
   * @param channelId - The channel ID that this extension will be associated with
   */
  constructor (channelId: string) {
    this.channelId = channelId
  }

  /**
   * Adds a route to the agent application that is only active for the channel specified in this extension.
   * This method creates a channel-specific route by wrapping the provided route selector with an additional
   * check to ensure the incoming activity matches the extension's channel ID.
   *
   * @param app - The agent application instance to add the route to
   * @param routeSelector - A function that determines if the route should handle the incoming activity
   * @param routeHandler - The handler function that will process the activity when the route is matched
   * @param isInvokeRoute - Optional. Whether this route handles invoke activities. Defaults to false
   * @param rank - Optional. The priority rank of this route for routing precedence. Defaults to RouteRank.Unspecified
   *
   * @example
   * ```typescript
   * const teamsExtension = new AgentExtension<MyState>('msteams');
   * teamsExtension.addRoute(
   *   app,
   *   (context) => context.activity.type === 'message',
   *   async (context, state) => {
   *     // Handle Teams-specific message
   *     await context.sendActivity('Hello from Teams!');
   *   }
   * );
   * ```
   */
  addRoute (
    app: AgentApplication<TState>,
    routeSelector: RouteSelector,
    routeHandler: RouteHandler<TurnState>,
    isInvokeRoute: boolean = false,
    rank: number = RouteRank.Unspecified) {
    const ensureChannelMatches = async (context: TurnContext) => {
      return context.activity.channelId === this.channelId && routeSelector(context)
    }
    app.addRoute(ensureChannelMatches, routeHandler, isInvokeRoute, rank)
  }
}