import { createRouter, createWebHistory } from "vue-router";
import Appointment from "@/pages/appointment.vue";
import BodyComposition from "@/pages/body-composition.vue";
import Checkin from "@/pages/checkin.vue";
import CheckinDetail from "@/pages/checkinDetail.vue";
import CompleteEmail from "@/pages/complete-email.vue";
import Course from "@/pages/course.vue";
import Index from "@/pages/index.vue";
import Login from "@/pages/login.vue";
import Register from "@/pages/register.vue";
import SelfAssessment from "@/pages/self-assessment.vue";
import {
  APPOINTMENT_ENABLED,
  BODY_COMPOSITION_ENABLED,
  CHECKIN_ENABLED,
  EMAIL_COMPLETION_REQUIRED,
} from "@/config/features";
import { useAppStore } from "@/stores/app";
import { useCourseStore } from "@/stores/course";
import { getApiErrorStatus } from "@/utils/api-error";

const router = createRouter({
  history: createWebHistory(import.meta.env.BASE_URL),
  scrollBehavior(to, _from, savedPosition) {
    if (savedPosition) {
      return savedPosition;
    }

    if (to.hash) {
      return { el: to.hash, top: 68 };
    }

    return { left: 0, top: 0 };
  },
  routes: [
    {
      path: "/",
      name: "home",
      component: Index,
    },
    {
      path: "/login",
      name: "login",
      component: Login,
    },
    {
      path: "/register",
      name: "register",
      component: Register,
      meta: { title: "註冊｜運動玩轉健康力" },
    },
    {
      path: "/self-assessment",
      name: "self-assessment",
      component: SelfAssessment,
      meta: { requiresAuth: true },
    },
    {
      path: "/complete-email",
      name: "complete-email",
      component: CompleteEmail,
      meta: {
        requiresAuth: true,
        title: "補登 E-Mail｜運動玩轉健康力",
      },
    },
    {
      path: "/profile",
      redirect: { name: "home" },
    },
    {
      path: "/body-composition",
      name: "body-composition",
      component: BodyComposition,
      meta: {
        requiresAuth: true,
        requiresUserID: true,
        title: "身體數值分析｜運動玩轉健康力",
      },
    },
    {
      path: "/appointment",
      name: "appointment",
      component: Appointment,
      meta: { requiresAuth: true },
    },
    {
      path: "/course",
      name: "course",
      component: Course,
      meta: {
        requiresAuth: true,
        requiresFitnessGroup: true,
        title: "課程建議｜運動玩轉健康力",
      },
    },
    {
      path: "/checkin",
      name: "checkin",
      component: Checkin,
      meta: { requiresAuth: true },
    },
    {
      path: "/checkin/:code",
      name: "checkin-detail",
      component: CheckinDetail,
      meta: { requiresAuth: true },
    },
  ],
});

const APPOINTMENT_PATH = /^\/appointment(?:\/|$)/;
const BODY_COMPOSITION_PATH = /^\/body-composition(?:\/|$)/;
const CHECKIN_PATH = /^\/checkin(?:\/|$)/;

// 簡單的導航守衛：只有標記需要登入的頁面會導向登入頁
router.beforeEach(async (to) => {
  if (
    (!APPOINTMENT_ENABLED && APPOINTMENT_PATH.test(to.path)) ||
    (!BODY_COMPOSITION_ENABLED && BODY_COMPOSITION_PATH.test(to.path)) ||
    (!CHECKIN_ENABLED && CHECKIN_PATH.test(to.path))
  ) {
    return { name: "home" };
  }

  const store = useAppStore();
  await store.initializeAuthentication();

  if (to.meta.requiresAuth && !store.isLoggedIn) {
    return {
      name: "login",
      query: { redirect: to.fullPath },
    };
  }

  if (to.meta.requiresUserID && !store.userID.trim()) {
    return {
      name: "login",
      query: { redirect: to.fullPath },
    };
  }

  if (
    EMAIL_COMPLETION_REQUIRED &&
    store.isLoggedIn &&
    store.requiresEmailCompletion &&
    to.name !== "complete-email"
  ) {
    return {
      name: "complete-email",
      query: { redirect: to.fullPath },
    };
  }

  if (to.meta.requiresFitnessGroup) {
    const courseStore = useCourseStore();

    try {
      await courseStore.ensureGroup();
    } catch (error) {
      if (getApiErrorStatus(error) === 401 || !store.isLoggedIn) {
        return {
          name: "login",
          query: { redirect: to.fullPath },
        };
      }

      if (courseStore.groupMissing) {
        return {
          name: "appointment",
          query: { reason: "missing-fitness-group" },
        };
      }

      // 技術性錯誤不應被誤導成尚未分組，返回首頁讓使用者重試。
      return { name: "home" };
    }
  }
});

router.afterEach((to) => {
  document.title =
    typeof to.meta.title === "string" ? to.meta.title : "運動玩轉健康力";
});

// 共用 HTTP client 收到登入後 API 的 401 時，清除前端狀態並保留原頁面供登入後返回。
if (typeof window !== "undefined") {
  window.addEventListener("auth-expired", () => {
    const store = useAppStore();
    const courseStore = useCourseStore();
    const currentRoute = router.currentRoute.value;
    const wasLoggedIn = store.isLoggedIn;
    store.clearAuthentication();
    courseStore.resetGroup();

    if (wasLoggedIn && currentRoute.name !== "login") {
      void router.replace({
        name: "login",
        query: { redirect: currentRoute.fullPath },
      });
    }
  });

  // CSRF Token 刷新並重送後仍失敗時，回到登入頁並提示使用者重新整理。
  window.addEventListener("csrf-recovery-required", () => {
    const store = useAppStore();
    const courseStore = useCourseStore();
    const currentRoute = router.currentRoute.value;
    const redirect =
      currentRoute.name === "login"
        ? String(currentRoute.query.redirect ?? "")
        : currentRoute.fullPath;
    store.clearAuthentication();
    courseStore.resetGroup();

    void router.replace({
      name: "login",
      query: {
        ...(redirect ? { redirect } : {}),
        csrf: "refresh",
      },
    });
  });
}

export default router;