// Copyright 2021 The Casdoor Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package object

import (
	"fmt"
	"strings"

	"github.com/casbin/casbin/v2"
	"github.com/casbin/casbin/v2/config"
	"github.com/casbin/casbin/v2/log"
	"github.com/casbin/casbin/v2/model"
	"github.com/casdoor/casdoor/conf"
	xormadapter "github.com/casdoor/xorm-adapter/v3"
)

func getEnforcer(permission *Permission) *casbin.Enforcer {
	tableName := "permission_rule"
	if len(permission.Adapter) != 0 {
		tableName = permission.Adapter
	}
	tableNamePrefix := conf.GetConfigString("tableNamePrefix")
	driverName := conf.GetConfigString("driverName")
	dataSourceName := conf.GetConfigRealDataSourceName(driverName)
	adapter, err := xormadapter.NewAdapterWithTableName(driverName, dataSourceName, tableName, tableNamePrefix, true)
	if err != nil {
		panic(err)
	}

	permissionModel := getModel(permission.Owner, permission.Model)
	m := model.Model{}
	if permissionModel != nil {
		m, err = GetBuiltInModel(permissionModel.ModelText)
	} else {
		m, err = GetBuiltInModel("")
	}

	if err != nil {
		panic(err)
	}

	// Init an enforcer instance without specifying a model or adapter.
	// If you specify an adapter, it will load all policies, which is a
	// heavy process that can slow down the application.
	enforcer, err := casbin.NewEnforcer(&log.DefaultLogger{}, false)
	if err != nil {
		panic(err)
	}

	enforcer.InitWithModelAndAdapter(m, nil)
	enforcer.SetAdapter(adapter)

	policyFilter := xormadapter.Filter{
		V5: []string{permission.GetId()},
	}

	if !HasRoleDefinition(m) {
		policyFilter.Ptype = []string{"p"}
	}

	err = enforcer.LoadFilteredPolicy(policyFilter)
	if err != nil {
		panic(err)
	}

	return enforcer
}

func getPolicies(permission *Permission) [][]string {
	var policies [][]string

	permissionId := permission.GetId()
	domainExist := len(permission.Domains) > 0

	for _, user := range permission.Users {
		for _, resource := range permission.Resources {
			for _, action := range permission.Actions {
				if domainExist {
					for _, domain := range permission.Domains {
						policies = append(policies, []string{user, domain, resource, strings.ToLower(action), "", permissionId})
					}
				} else {
					policies = append(policies, []string{user, resource, strings.ToLower(action), "", "", permissionId})
				}
			}
		}
	}

	for _, role := range permission.Roles {
		for _, resource := range permission.Resources {
			for _, action := range permission.Actions {
				if domainExist {
					for _, domain := range permission.Domains {
						policies = append(policies, []string{role, domain, resource, strings.ToLower(action), "", permissionId})
					}
				} else {
					policies = append(policies, []string{role, resource, strings.ToLower(action), "", "", permissionId})
				}
			}
		}
	}

	return policies
}

func getGroupingPolicies(permission *Permission) [][]string {
	var groupingPolicies [][]string

	domainExist := len(permission.Domains) > 0
	permissionId := permission.GetId()

	for _, role := range permission.Roles {
		roleObj := GetRole(role)
		if roleObj == nil {
			continue
		}

		for _, subUser := range roleObj.Users {
			if domainExist {
				for _, domain := range permission.Domains {
					groupingPolicies = append(groupingPolicies, []string{subUser, domain, role, "", "", permissionId})
				}
			} else {
				groupingPolicies = append(groupingPolicies, []string{subUser, role, "", "", "", permissionId})
			}
		}

		for _, subRole := range roleObj.Roles {
			if domainExist {
				for _, domain := range permission.Domains {
					groupingPolicies = append(groupingPolicies, []string{subRole, domain, role, "", "", permissionId})
				}
			} else {
				groupingPolicies = append(groupingPolicies, []string{subRole, role, "", "", "", permissionId})
			}
		}
	}

	return groupingPolicies
}

func addPolicies(permission *Permission) {
	enforcer := getEnforcer(permission)
	policies := getPolicies(permission)

	_, err := enforcer.AddPolicies(policies)
	if err != nil {
		panic(err)
	}
}

func addGroupingPolicies(permission *Permission) {
	enforcer := getEnforcer(permission)
	groupingPolicies := getGroupingPolicies(permission)

	if len(groupingPolicies) > 0 {
		_, err := enforcer.AddGroupingPolicies(groupingPolicies)
		if err != nil {
			panic(err)
		}
	}
}

func removeGroupingPolicies(permission *Permission) {
	enforcer := getEnforcer(permission)
	groupingPolicies := getGroupingPolicies(permission)

	if len(groupingPolicies) > 0 {
		_, err := enforcer.RemoveGroupingPolicies(groupingPolicies)
		if err != nil {
			panic(err)
		}
	}
}

func removePolicies(permission *Permission) {
	enforcer := getEnforcer(permission)
	policies := getPolicies(permission)

	_, err := enforcer.RemovePolicies(policies)
	if err != nil {
		panic(err)
	}
}

func Enforce(permissionRule *PermissionRule) bool {
	permission := GetPermission(permissionRule.Id)
	enforcer := getEnforcer(permission)

	request, _ := permissionRule.GetRequest(builtInAdapter, permissionRule.Id)

	allow, err := enforcer.Enforce(request...)
	if err != nil {
		panic(err)
	}
	return allow
}

func BatchEnforce(permissionRules []PermissionRule) []bool {
	var requests [][]interface{}
	for _, permissionRule := range permissionRules {
		request, _ := permissionRule.GetRequest(builtInAdapter, permissionRule.Id)
		requests = append(requests, request)
	}
	permission := GetPermission(permissionRules[0].Id)
	enforcer := getEnforcer(permission)
	allow, err := enforcer.BatchEnforce(requests)
	if err != nil {
		panic(err)
	}
	return allow
}

func getAllValues(userId string, fn func(enforcer *casbin.Enforcer) []string) []string {
	permissions := GetPermissionsByUser(userId)
	for _, role := range GetAllRoles(userId) {
		permissions = append(permissions, GetPermissionsByRole(role)...)
	}

	var values []string
	for _, permission := range permissions {
		enforcer := getEnforcer(permission)
		values = append(values, fn(enforcer)...)
	}
	return values
}

func GetAllObjects(userId string) []string {
	return getAllValues(userId, func(enforcer *casbin.Enforcer) []string {
		return enforcer.GetAllObjects()
	})
}

func GetAllActions(userId string) []string {
	return getAllValues(userId, func(enforcer *casbin.Enforcer) []string {
		return enforcer.GetAllActions()
	})
}

func GetAllRoles(userId string) []string {
	roles := GetRolesByUser(userId)
	var res []string
	for _, role := range roles {
		res = append(res, role.Name)
	}
	return res
}

func GetBuiltInModel(modelText string) (model.Model, error) {
	if modelText == "" {
		modelText = `
[request_definition]
r = sub, obj, act

[policy_definition]
p = sub, obj, act, "", "", permissionId

[role_definition]
g = _, _

[policy_effect]
e = some(where (p.eft == allow))

[matchers]
m = g(r.sub, p.sub) && r.obj == p.obj && r.act == p.act`
		return model.NewModelFromString(modelText)
	} else {
		cfg, err := config.NewConfigFromText(modelText)
		if err != nil {
			return nil, err
		}

		// load [policy_definition]
		policyDefinition := strings.Split(cfg.String("policy_definition::p"), ",")
		fieldsNum := len(policyDefinition)
		if fieldsNum > builtInAvailableField {
			panic(fmt.Errorf("the maximum policy_definition field number cannot exceed %d", builtInAvailableField))
		}
		// filled empty field with "" and V5 with "permissionId"
		for i := builtInAvailableField - fieldsNum; i > 0; i-- {
			policyDefinition = append(policyDefinition, "")
		}
		policyDefinition = append(policyDefinition, "permissionId")

		m, _ := model.NewModelFromString(modelText)
		m.AddDef("p", "p", strings.Join(policyDefinition, ","))

		return m, err
	}
}