import { NextResponse } from "next/server"
import type { NextRequest } from "next/server"
import { getToken } from "next-auth/jwt"

import { Permissions } from "@/shared/types/permissions"

// Route prefix → minimum required permission
// Note: /admin/announcements is covered by /admin prefix (requires school:manage)
// Note: /announcements is accessible to all authenticated users (no permission entry needed)
// P0 修复：原先 /teacher 和 /parent 都使用 EXAM_READ，但 student/parent 也有 EXAM_READ，
// 导致跨角色访问漏洞（学生可访问 /teacher/*，教师可访问 /parent/*）。
// 改为使用各角色独有的权限点，确保跨角色访问被拒绝。
const ROUTE_PERMISSIONS: Record<string, string> = {
  "/admin": Permissions.SCHOOL_MANAGE,
  "/teacher": Permissions.EXAM_CREATE,
  "/student": Permissions.HOMEWORK_SUBMIT,
  "/parent": Permissions.DASHBOARD_PARENT_READ,
  "/management": Permissions.GRADE_MANAGE,
}

// 仪表盘路由的细粒度权限（覆盖 ROUTE_PERMISSIONS 的前缀匹配）
// 防止拥有 EXAM_READ 的学生/家长访问 /teacher/dashboard 等
const DASHBOARD_ROUTE_PERMISSIONS: Record<string, string> = {
  "/admin/dashboard": Permissions.DASHBOARD_ADMIN_READ,
  "/teacher/dashboard": Permissions.DASHBOARD_TEACHER_READ,
  "/student/dashboard": Permissions.DASHBOARD_STUDENT_READ,
  "/parent/dashboard": Permissions.DASHBOARD_PARENT_READ,
}

// 精确路由权限（优先级最高，覆盖 ROUTE_PERMISSIONS 的前缀匹配）
// 用于将 /admin/* 下的特定页面开放给非管理员角色
// V3.1：/admin/ai-settings 对所有 AI_CHAT 用户开放（管理自己的 private provider）
const SPECIFIC_ROUTE_PERMISSIONS: Record<string, string> = {
  "/admin/ai-settings": Permissions.AI_CHAT,
}

// API route prefix → required permission
const API_PERMISSIONS: Record<string, string> = {
  "/api/ai/chat": Permissions.AI_CHAT,
}

function resolveDefaultPath(roles: string[]): string {
  if (roles.includes("admin")) return "/admin/dashboard"
  if (roles.includes("grade_head") || roles.includes("teaching_head")) return "/teacher/dashboard"
  if (roles.includes("teacher")) return "/teacher/dashboard"
  if (roles.includes("student")) return "/student/dashboard"
  if (roles.includes("parent")) return "/parent/dashboard"
  return "/dashboard"
}

// Next.js 16 renamed `middleware` to `proxy`.
// See: https://nextjs.org/docs/messages/middleware-to-proxy
export async function proxy(request: NextRequest) {
  const { pathname } = request.nextUrl

  // Skip static assets and auth pages
  if (
    pathname.startsWith("/_next") ||
    pathname.startsWith("/api/auth") ||
    pathname === "/login" ||
    pathname === "/register" ||
    pathname === "/favicon.ico"
  ) {
    return NextResponse.next()
  }

  const token = await getToken({
    req: request,
    secret: process.env.NEXTAUTH_SECRET,
  })

  // Not authenticated → redirect to login
  if (!token) {
    const loginUrl = new URL("/login", request.url)
    loginUrl.searchParams.set("callbackUrl", request.url)
    return NextResponse.redirect(loginUrl)
  }

  // Onboarding gate: 未完成引导的用户只能访问 /onboarding 与白名单路径
  // 修复 P2-1：用 middleware 强制重定向替代客户端 Dialog
  const onboarded = Boolean(token.onboarded)
  const isOnboardingPath = pathname === "/onboarding" || pathname.startsWith("/onboarding/")
  const isWhitelistedApi = pathname.startsWith("/api/auth") || pathname.startsWith("/api/onboarding")
  if (!onboarded && !isOnboardingPath && !isWhitelistedApi) {
    const onboardingUrl = new URL("/onboarding", request.url)
    return NextResponse.redirect(onboardingUrl)
  }
  // 已完成 onboarding 的用户不应停留在 /onboarding
  if (onboarded && isOnboardingPath) {
    const roles: string[] = (token.roles as string[]) ?? []
    const defaultPath = resolveDefaultPath(roles)
    return NextResponse.redirect(new URL(defaultPath, request.url))
  }

  const permissions: string[] = (token.permissions as string[]) ?? []
  const roles: string[] = (token.roles as string[]) ?? []

  // Check API route permissions
  for (const [prefix, requiredPerm] of Object.entries(API_PERMISSIONS)) {
    if (pathname.startsWith(prefix)) {
      if (!permissions.includes(requiredPerm)) {
        return NextResponse.json({ error: "Forbidden" }, { status: 403 })
      }
      break
    }
  }

  // Check page route permissions
  // 优先级 1：精确路由权限（覆盖前缀匹配，用于将 /admin/* 下特定页面开放给非管理员）
  if (Object.prototype.hasOwnProperty.call(SPECIFIC_ROUTE_PERMISSIONS, pathname)) {
    const requiredPerm = SPECIFIC_ROUTE_PERMISSIONS[pathname]
    if (!permissions.includes(requiredPerm)) {
      const defaultPath = resolveDefaultPath(roles)
      const redirectUrl = new URL(defaultPath, request.url)
      redirectUrl.searchParams.set("from", pathname)
      redirectUrl.searchParams.set("reason", "forbidden")
      return NextResponse.redirect(redirectUrl)
    }
    return NextResponse.next()
  }

  // 优先级 2：仪表盘路由的细粒度权限（防止跨角色访问仪表盘）
  if (Object.prototype.hasOwnProperty.call(DASHBOARD_ROUTE_PERMISSIONS, pathname)) {
    const requiredPerm = DASHBOARD_ROUTE_PERMISSIONS[pathname]
    if (!permissions.includes(requiredPerm)) {
      const defaultPath = resolveDefaultPath(roles)
      const redirectUrl = new URL(defaultPath, request.url)
      redirectUrl.searchParams.set("from", pathname)
      redirectUrl.searchParams.set("reason", "forbidden")
      return NextResponse.redirect(redirectUrl)
    }
    return NextResponse.next()
  }

  for (const [prefix, requiredPerm] of Object.entries(ROUTE_PERMISSIONS)) {
    if (pathname.startsWith(prefix)) {
      if (!permissions.includes(requiredPerm)) {
        const defaultPath = resolveDefaultPath(roles)
        // Carry original path + reason in URL so the target page can explain
        // why the user was redirected (Web Interface Guidelines: URL reflects state).
        const redirectUrl = new URL(defaultPath, request.url)
        redirectUrl.searchParams.set("from", pathname)
        redirectUrl.searchParams.set("reason", "forbidden")
        return NextResponse.redirect(redirectUrl)
      }
      break
    }
  }

  return NextResponse.next()
}

export const config = {
  matcher: ["/((?!_next/static|_next/image|favicon.ico).*)"],
}