import type { Computed } from "#Source/reactor/index.ts"
import { computed, signal } from "#Source/reactor/index.ts"

import type { Route, RouteHistoryEntry, Router, RouteRecord } from "../router/index.ts"

/**
 * @description 创建路由驱动器时需要的输入项。
 */
export interface CreateRouteDriverOptions {
  router: Router
}

/**
 * @description 将 Router 暴露为响应式只读视图的驱动器。
 *
 * 该接口把当前历史记录、当前 Route 以及当前 RouteRecord 暴露为可追踪的计算值，
 * 方便响应式系统消费。
 */
export interface RouteDriver {
  router: Router
  routeHistoryEntry: Computed<RouteHistoryEntry>
  route: Computed<Route>
  routeRecord: Computed<RouteRecord>
}

/**
 * @description 基于 Router 创建一组可响应追踪的当前路由派生值。
 *
 * 返回结果中的计算值会随着 Router 的 `history` 事件自动更新。
 */
export const createRouteDriver = (options: CreateRouteDriverOptions): RouteDriver => {
  const { router } = options

  const internalCurrentRouteHistoryEntry = signal(() => {
    return router.getCurrentRouteHistoryEntry()
  })
  router.eventManager.subscribe("history", (routeHistoryEntry) => {
    internalCurrentRouteHistoryEntry.set(routeHistoryEntry)
  })

  const currentRouteHistoryEntry = computed(() => {
    return internalCurrentRouteHistoryEntry.get()
  })
  const currentRoute = computed(() => {
    return currentRouteHistoryEntry.get().to.route
  })
  const currentRouteRecord = computed(() => {
    return currentRoute.get().getRecord()
  })

  return {
    router,
    routeHistoryEntry: currentRouteHistoryEntry,
    route: currentRoute,
    routeRecord: currentRouteRecord,
  }
}