package vfs

import (
	_ "embed"
	"strings"

	api "git.zzyxyz.com/zzy/zzyxyz_go_api/gen/vfs_server"
	"git.zzyxyz.com/zzy/zzyxyz_go_api/internal/vfs/models"
	"github.com/gin-gonic/gin"
)

//go:embed vfs_model.conf
var CasbinModel string

// 使用示例：在main.go或路由注册处
func RegisterVFSRoutes(router gin.IRouter, vfsHandler *VfsImpl) {
	// 创建严格模式handler并添加权限中间件
	strictHandler := api.NewStrictHandler(vfsHandler, []api.StrictMiddlewareFunc{
		vfsHandler.PermissionMiddleware,
	})

	// 注册handler
	api.RegisterHandlers(router, strictHandler)
}

// PermissionMiddleware 是一个权限验证中间件
func (v *VfsImpl) PermissionMiddleware(handler api.StrictHandlerFunc, operation string) api.StrictHandlerFunc {
	return func(ctx *gin.Context, request interface{}) (interface{}, error) {
		// 从请求头获取token
		token := ctx.GetHeader("X-VFS-Token")

		// Admin token 拥有所有权限
		if token == v.config.AdminToken && len(token) != 0 {
			return handler(ctx, request)
		}

		// 根据操作类型进行不同的权限检查
		switch operation {
		case "CreateUser":
			// 只有admin或register token可以创建用户
			if token != v.config.RegisterToken {
				return api.CreateUser403JSONResponse{
					ForbiddenErrorJSONResponse: api.ForbiddenErrorJSONResponse{
						Errtype: api.ErrorErrtypeForbidden,
						Message: "Access denied",
					},
				}, nil
			}
			return handler(ctx, request)

		// 如果是删除用户操作，检查是否具有管理员权限
		case "DeleteUser":
			// 获取要删除的用户名
			var username string
			if req, ok := request.(api.DeleteUserRequestObject); ok {
				username = req.Username
			}

			// 验证token对应的用户是否存在
			user, err := v.vfs.GetUserByToken(token)
			if err != nil || (user.Name != username && token != v.config.AdminToken) {
				return api.DeleteUser403JSONResponse{
					ForbiddenErrorJSONResponse: api.ForbiddenErrorJSONResponse{
						Errtype: api.ErrorErrtypeForbidden,
						Message: "Access denied",
					},
				}, nil
			}
			// 如果验证通过，继续执行原处理函数
			return handler(ctx, request)
		case "GetVFSNode", "CreateVFSNode", "UpdateVFSNode", "DeleteVFSNode":
			// VFS节点操作的权限检查
			var path string
			var method string

			// 根据操作类型获取路径和HTTP方法
			switch operation {
			case "GetVFSNode":
				if req, ok := request.(api.GetVFSNodeRequestObject); ok {
					path = req.Params.Path
				}
				method = "GET"
			case "CreateVFSNode":
				if req, ok := request.(api.CreateVFSNodeRequestObject); ok {
					path = req.Params.Path
				}
				method = "POST"
			case "UpdateVFSNode":
				if req, ok := request.(api.UpdateVFSNodeRequestObject); ok {
					path = req.Params.Path
				}
				method = "PATCH"
			case "DeleteVFSNode":
				if req, ok := request.(api.DeleteVFSNodeRequestObject); ok {
					path = req.Params.Path
				}
				method = "DELETE"
			}

			// 检查权限
			allowed, err := v.CheckPermission(token, path, method)
			if err != nil {
				return api.GetVFSNode500JSONResponse{
					ServerInternalErrorJSONResponse: api.ServerInternalErrorJSONResponse{
						Errtype: api.ErrorErrtypeInternalServerError,
						Message: "Failed to check permission: " + err.Error(),
					},
				}, nil
			}

			if !allowed {
				// 根据操作类型返回相应的错误响应
				switch operation {
				case "GetVFSNode":
					return api.GetVFSNode403JSONResponse{
						ForbiddenErrorJSONResponse: api.ForbiddenErrorJSONResponse{
							Errtype: api.ErrorErrtypeForbidden,
							Message: "Access denied",
						},
					}, nil
				case "CreateVFSNode":
					return api.CreateVFSNode403JSONResponse{
						ForbiddenErrorJSONResponse: api.ForbiddenErrorJSONResponse{
							Errtype: api.ErrorErrtypeForbidden,
							Message: "Access denied",
						},
					}, nil
				case "UpdateVFSNode":
					return api.UpdateVFSNode403JSONResponse{
						ForbiddenErrorJSONResponse: api.ForbiddenErrorJSONResponse{
							Errtype: api.ErrorErrtypeForbidden,
							Message: "Access denied",
						},
					}, nil
				case "DeleteVFSNode":
					return api.DeleteVFSNode403JSONResponse{
						ForbiddenErrorJSONResponse: api.ForbiddenErrorJSONResponse{
							Errtype: api.ErrorErrtypeForbidden,
							Message: "Access denied",
						},
					}, nil
				}
			}
			return handler(ctx, request)
		default:
			return api.Error{
				Errtype: api.ErrorErrtypeForbidden,
				Message: "not supported function it's a bug in backend",
			}, nil
		}
	}
}

// CheckPermission 检查用户对指定路径的权限
// FIXME: using casbin to check it
func (v *VfsImpl) CheckPermission(token, path, method string) (bool, error) {
	// Admin token 拥有所有权限
	if token == v.config.AdminToken && len(token) != 0 {
		return true, nil
	}

	// 根据 token 获取用户信息
	user, err := v.vfs.GetUserByToken(token)
	if err != nil {
		// 匿名用户
		user = &models.VfsUser{Name: "", Token: ""}
	}

	// 允许任何人读取 public 目录
	if method == "GET" && strings.HasPrefix(path, "/public") {
		return true, nil
	}

	// 如果是普通用户访问自己的主目录，则允许
	if user.Name != "" && strings.HasPrefix(path, "/home/"+user.Name) {
		return true, nil
	}

	// 使用 Casbin 检查权限
	// sub: 用户名 (匿名用户为空字符串)
	// obj: 路径
	// act: HTTP方法
	allowed, err := v.enfocer.Enforce(user.Name, path, method)
	if err != nil {
		return false, err
	}

	return allowed, nil
}