// Copyright 2015 flannel authors
//
// 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.
// +build !windows

package network

import (
	"fmt"
	"net"
	"reflect"
	"strings"
	"testing"

	"github.com/flannel-io/flannel/pkg/ip"
	"github.com/flannel-io/flannel/subnet"
)

func lease() *subnet.Lease {
	_, net, _ := net.ParseCIDR("192.168.0.0/16")
	return &subnet.Lease{
		Subnet: ip.FromIPNet(net),
	}
}

type MockIPTables struct {
	rules    []IPTablesRule
	t        *testing.T
	failures map[string]*MockIPTablesError
}

type MockIPTablesError struct {
	notExist bool
}

func (mock *MockIPTablesError) IsNotExist() bool {
	return mock.notExist
}

func (mock *MockIPTablesError) Error() string {
	return fmt.Sprintf("IsNotExist: %v", !mock.notExist)
}

func (mock *MockIPTables) failDelete(table string, chain string, rulespec []string, notExist bool) {

	if mock.failures == nil {
		mock.failures = make(map[string]*MockIPTablesError)
	}
	key := table + chain + strings.Join(rulespec, "")
	mock.failures[key] = &MockIPTablesError{
		notExist: notExist,
	}
}

func (mock *MockIPTables) ruleIndex(table string, chain string, rulespec []string) int {
	for i, rule := range mock.rules {
		if rule.table == table && rule.chain == chain && reflect.DeepEqual(rule.rulespec, rulespec) {
			return i
		}
	}
	return -1
}

func (mock *MockIPTables) Delete(table string, chain string, rulespec ...string) error {
	var ruleIndex = mock.ruleIndex(table, chain, rulespec)
	key := table + chain + strings.Join(rulespec, "")
	reason := mock.failures[key]
	if reason != nil {
		return reason
	}

	if ruleIndex != -1 {
		mock.rules = append(mock.rules[:ruleIndex], mock.rules[ruleIndex+1:]...)
	}
	return nil
}

func (mock *MockIPTables) Exists(table string, chain string, rulespec ...string) (bool, error) {
	var ruleIndex = mock.ruleIndex(table, chain, rulespec)
	if ruleIndex != -1 {
		return true, nil
	}
	return false, nil
}

func (mock *MockIPTables) AppendUnique(table string, chain string, rulespec ...string) error {
	var ruleIndex = mock.ruleIndex(table, chain, rulespec)
	if ruleIndex == -1 {
		mock.rules = append(mock.rules, IPTablesRule{table: table, chain: chain, rulespec: rulespec})
	}
	return nil
}

func TestDeleteRules(t *testing.T) {
	ipt := &MockIPTables{t: t}
	setupIPTables(ipt, MasqRules(ip.IP4Net{}, lease()))
	if len(ipt.rules) != 4 {
		t.Errorf("Should be 4 masqRules, there are actually %d: %#v", len(ipt.rules), ipt.rules)
	}
	teardownIPTables(ipt, MasqRules(ip.IP4Net{}, lease()))
	if len(ipt.rules) != 0 {
		t.Errorf("Should be 0 masqRules, there are actually %d: %#v", len(ipt.rules), ipt.rules)
	}
}

func TestEnsureRulesError(t *testing.T) {
	// If an error prevents a rule from being deleted, ensureIPTables should leave the rules as is
	// rather than potentially re-appending rules in an incorrect order
	ipt_correct := &MockIPTables{t: t}
	setupIPTables(ipt_correct, MasqRules(ip.IP4Net{}, lease()))
	// setup a mock instance where we delete some masqRules and run `ensureIPTables`
	ipt_recreate := &MockIPTables{t: t}
	setupIPTables(ipt_recreate, MasqRules(ip.IP4Net{}, lease()))
	ipt_recreate.rules = ipt_recreate.rules[0:2]

	rule := ipt_recreate.rules[1]
	ipt_recreate.failDelete(rule.table, rule.chain, rule.rulespec, false)
	err := ensureIPTables(ipt_recreate, MasqRules(ip.IP4Net{}, lease()))
	if err == nil {
		t.Errorf("ensureIPTables should have failed but did not.")
	}

	if len(ipt_recreate.rules) == len(ipt_correct.rules) {
		t.Errorf("ensureIPTables should not have completed.")
	}
}

func TestEnsureRules(t *testing.T) {
	// If any masqRules are missing, they should be all deleted and recreated in the correct order
	ipt_correct := &MockIPTables{t: t}
	setupIPTables(ipt_correct, MasqRules(ip.IP4Net{}, lease()))
	// setup a mock instance where we delete some masqRules and run `ensureIPTables`
	ipt_recreate := &MockIPTables{t: t}
	setupIPTables(ipt_recreate, MasqRules(ip.IP4Net{}, lease()))
	ipt_recreate.rules = ipt_recreate.rules[0:2]
	// set up a normal error that iptables returns when deleting a rule that is already gone
	deletedRule := ipt_correct.rules[3]
	ipt_recreate.failDelete(deletedRule.table, deletedRule.chain, deletedRule.rulespec, true)
	err := ensureIPTables(ipt_recreate, MasqRules(ip.IP4Net{}, lease()))
	if err != nil {
		t.Errorf("ensureIPTables should have completed without errors")
	}
	if !reflect.DeepEqual(ipt_recreate.rules, ipt_correct.rules) {
		t.Errorf("iptables masqRules after ensureIPTables are incorrect. Expected: %#v, Actual: %#v", ipt_recreate.rules, ipt_correct.rules)
	}
}