/*
Copyright 2016 The Kubernetes 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.
*/

package validation

import (
	"fmt"
	"net"
	"net/url"
	"os"
	"path/filepath"
	"strings"

	"github.com/spf13/pflag"

	"k8s.io/apimachinery/pkg/util/validation"
	"k8s.io/apimachinery/pkg/util/validation/field"
	"k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
	"k8s.io/kubernetes/cmd/kubeadm/app/features"
	kubeadmutil "k8s.io/kubernetes/cmd/kubeadm/app/util"
	tokenutil "k8s.io/kubernetes/cmd/kubeadm/app/util/token"
	apivalidation "k8s.io/kubernetes/pkg/api/validation"
	authzmodes "k8s.io/kubernetes/pkg/kubeapiserver/authorizer/modes"
	"k8s.io/kubernetes/pkg/registry/core/service/ipallocator"
	"k8s.io/kubernetes/pkg/util/node"
)

// TODO: Break out the cloudprovider functionality out of core and only support the new flow
// described in https://github.com/kubernetes/community/pull/128
var cloudproviders = []string{
	"aws",
	"azure",
	"cloudstack",
	"gce",
	"openstack",
	"ovirt",
	"photon",
	"rackspace",
	"vsphere",
}

// Describes the authorization modes that are enforced by kubeadm
var requiredAuthzModes = []string{
	authzmodes.ModeRBAC,
	authzmodes.ModeNode,
}

func ValidateMasterConfiguration(c *kubeadm.MasterConfiguration) field.ErrorList {
	allErrs := field.ErrorList{}
	allErrs = append(allErrs, ValidateCloudProvider(c.CloudProvider, field.NewPath("cloudprovider"))...)
	allErrs = append(allErrs, ValidateAuthorizationModes(c.AuthorizationModes, field.NewPath("authorization-modes"))...)
	allErrs = append(allErrs, ValidateNetworking(&c.Networking, field.NewPath("networking"))...)
	allErrs = append(allErrs, ValidateAPIServerCertSANs(c.APIServerCertSANs, field.NewPath("cert-altnames"))...)
	allErrs = append(allErrs, ValidateAbsolutePath(c.CertificatesDir, field.NewPath("certificates-dir"))...)
	allErrs = append(allErrs, ValidateNodeName(c.NodeName, field.NewPath("node-name"))...)
	allErrs = append(allErrs, ValidateToken(c.Token, field.NewPath("token"))...)
	allErrs = append(allErrs, ValidateFeatureGates(c.FeatureGates, field.NewPath("feature-gates"))...)
	allErrs = append(allErrs, ValidateAPIEndpoint(c, field.NewPath("api-endpoint"))...)
	return allErrs
}

func ValidateNodeConfiguration(c *kubeadm.NodeConfiguration) field.ErrorList {
	allErrs := field.ErrorList{}
	allErrs = append(allErrs, ValidateDiscovery(c, field.NewPath("discovery"))...)

	if !filepath.IsAbs(c.CACertPath) || !strings.HasSuffix(c.CACertPath, ".crt") {
		allErrs = append(allErrs, field.Invalid(field.NewPath("ca-cert-path"), c.CACertPath, "the ca certificate path must be an absolute path"))
	}
	return allErrs
}

func ValidateAuthorizationModes(authzModes []string, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}
	found := map[string]bool{}

	for _, authzMode := range authzModes {
		if !authzmodes.IsValidAuthorizationMode(authzMode) {
			allErrs = append(allErrs, field.Invalid(fldPath, authzMode, "invalid authorization mode"))
		}

		if found[authzMode] {
			allErrs = append(allErrs, field.Invalid(fldPath, authzMode, "duplicate authorization mode"))
			continue
		}
		found[authzMode] = true
	}
	for _, requiredMode := range requiredAuthzModes {
		if !found[requiredMode] {
			allErrs = append(allErrs, field.Required(fldPath, fmt.Sprintf("authorization mode %s must be enabled", requiredMode)))
		}
	}
	return allErrs
}

func ValidateDiscovery(c *kubeadm.NodeConfiguration, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}
	if len(c.DiscoveryToken) != 0 {
		allErrs = append(allErrs, ValidateToken(c.DiscoveryToken, fldPath)...)
	}
	if len(c.DiscoveryFile) != 0 {
		allErrs = append(allErrs, ValidateDiscoveryFile(c.DiscoveryFile, fldPath)...)
	}
	allErrs = append(allErrs, ValidateArgSelection(c, fldPath)...)
	allErrs = append(allErrs, ValidateToken(c.TLSBootstrapToken, fldPath)...)
	allErrs = append(allErrs, ValidateJoinDiscoveryTokenAPIServer(c, fldPath)...)

	if len(c.DiscoveryToken) != 0 {
		allErrs = append(allErrs, ValidateToken(c.DiscoveryToken, fldPath)...)
	}
	if len(c.DiscoveryFile) != 0 {
		allErrs = append(allErrs, ValidateDiscoveryFile(c.DiscoveryFile, fldPath)...)
	}

	return allErrs
}

func ValidateArgSelection(cfg *kubeadm.NodeConfiguration, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}
	if len(cfg.DiscoveryToken) != 0 && len(cfg.DiscoveryFile) != 0 {
		allErrs = append(allErrs, field.Invalid(fldPath, "", "DiscoveryToken and DiscoveryFile cannot both be set"))
	}
	if len(cfg.DiscoveryToken) == 0 && len(cfg.DiscoveryFile) == 0 {
		allErrs = append(allErrs, field.Invalid(fldPath, "", "DiscoveryToken or DiscoveryFile must be set"))
	}
	if len(cfg.DiscoveryTokenAPIServers) < 1 && len(cfg.DiscoveryToken) != 0 {
		allErrs = append(allErrs, field.Required(fldPath, "DiscoveryTokenAPIServers not set"))
	}

	if len(cfg.DiscoveryFile) != 0 && len(cfg.DiscoveryTokenCACertHashes) != 0 {
		allErrs = append(allErrs, field.Invalid(fldPath, "", "DiscoveryTokenCACertHashes cannot be used with DiscoveryFile"))
	}

	// TODO: convert this warning to an error after v1.8
	if len(cfg.DiscoveryFile) == 0 && len(cfg.DiscoveryTokenCACertHashes) == 0 && !cfg.DiscoveryTokenUnsafeSkipCAVerification {
		fmt.Println("[validation] WARNING: using token-based discovery without DiscoveryTokenCACertHashes can be unsafe (see https://kubernetes.io/docs/admin/kubeadm/#kubeadm-join).")
		fmt.Println("[validation] WARNING: Pass --discovery-token-unsafe-skip-ca-verification to disable this warning. This warning will become an error in Kubernetes 1.9.")
	}

	// TODO remove once we support multiple api servers
	if len(cfg.DiscoveryTokenAPIServers) > 1 {
		fmt.Println("[validation] WARNING: kubeadm doesn't fully support multiple API Servers yet")
	}
	return allErrs
}

func ValidateJoinDiscoveryTokenAPIServer(c *kubeadm.NodeConfiguration, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}
	for _, m := range c.DiscoveryTokenAPIServers {
		_, _, err := net.SplitHostPort(m)
		if err != nil {
			allErrs = append(allErrs, field.Invalid(fldPath, m, err.Error()))
		}
	}
	return allErrs
}

func ValidateDiscoveryFile(discoveryFile string, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}
	u, err := url.Parse(discoveryFile)
	if err != nil {
		allErrs = append(allErrs, field.Invalid(fldPath, discoveryFile, "not a valid HTTPS URL or a file on disk"))
		return allErrs
	}

	if u.Scheme == "" {
		// URIs with no scheme should be treated as files
		if _, err := os.Stat(discoveryFile); os.IsNotExist(err) {
			allErrs = append(allErrs, field.Invalid(fldPath, discoveryFile, "not a valid HTTPS URL or a file on disk"))
		}
		return allErrs
	}

	if u.Scheme != "https" {
		allErrs = append(allErrs, field.Invalid(fldPath, discoveryFile, "if an URL is used, the scheme must be https"))
	}
	return allErrs
}

func ValidateToken(t string, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}

	id, secret, err := tokenutil.ParseToken(t)
	if err != nil {
		allErrs = append(allErrs, field.Invalid(fldPath, t, err.Error()))
	}

	if len(id) == 0 || len(secret) == 0 {
		allErrs = append(allErrs, field.Invalid(fldPath, t, "token must be of form '[a-z0-9]{6}.[a-z0-9]{16}'"))
	}
	return allErrs
}

func ValidateAPIServerCertSANs(altnames []string, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}
	for _, altname := range altnames {
		if len(validation.IsDNS1123Subdomain(altname)) != 0 && net.ParseIP(altname) == nil {
			allErrs = append(allErrs, field.Invalid(fldPath, altname, "altname is not a valid dns label or ip address"))
		}
	}
	return allErrs
}

func ValidateIPFromString(ipaddr string, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}
	if net.ParseIP(ipaddr) == nil {
		allErrs = append(allErrs, field.Invalid(fldPath, ipaddr, "ip address is not valid"))
	}
	return allErrs
}

func ValidateIPNetFromString(subnet string, minAddrs int64, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}
	_, svcSubnet, err := net.ParseCIDR(subnet)
	if err != nil {
		allErrs = append(allErrs, field.Invalid(fldPath, subnet, "couldn't parse subnet"))
		return allErrs
	}
	numAddresses := ipallocator.RangeSize(svcSubnet)
	if numAddresses < minAddrs {
		allErrs = append(allErrs, field.Invalid(fldPath, subnet, "subnet is too small"))
	}
	return allErrs
}

func ValidateNetworking(c *kubeadm.Networking, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}
	allErrs = append(allErrs, apivalidation.ValidateDNS1123Subdomain(c.DNSDomain, field.NewPath("dns-domain"))...)
	allErrs = append(allErrs, ValidateIPNetFromString(c.ServiceSubnet, constants.MinimumAddressesInServiceSubnet, field.NewPath("service-subnet"))...)
	if len(c.PodSubnet) != 0 {
		allErrs = append(allErrs, ValidateIPNetFromString(c.PodSubnet, constants.MinimumAddressesInServiceSubnet, field.NewPath("pod-subnet"))...)
	}
	return allErrs
}

func ValidateAbsolutePath(path string, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}
	if !filepath.IsAbs(path) {
		allErrs = append(allErrs, field.Invalid(fldPath, path, "path is not absolute"))
	}
	return allErrs
}

func ValidateNodeName(nodename string, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}
	if node.GetHostname(nodename) != nodename {
		allErrs = append(allErrs, field.Invalid(fldPath, nodename, "nodename is not valid, must be lower case"))
	}
	return allErrs
}

func ValidateCloudProvider(provider string, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}
	if len(provider) == 0 {
		return allErrs
	}
	for _, supported := range cloudproviders {
		if provider == supported {
			return allErrs
		}
	}
	allErrs = append(allErrs, field.Invalid(fldPath, provider, "cloudprovider not supported"))
	return allErrs
}

func ValidateMixedArguments(flag *pflag.FlagSet) error {
	// If --config isn't set, we have nothing to validate
	if !flag.Changed("config") {
		return nil
	}

	mixedInvalidFlags := []string{}
	flag.Visit(func(f *pflag.Flag) {
		if f.Name == "config" || strings.HasPrefix(f.Name, "skip-") || f.Name == "dry-run" || f.Name == "kubeconfig" {
			// "--skip-*" flags or other whitelisted flags can be set with --config
			return
		}
		mixedInvalidFlags = append(mixedInvalidFlags, f.Name)
	})

	if len(mixedInvalidFlags) != 0 {
		return fmt.Errorf("can not mix '--config' with arguments %v", mixedInvalidFlags)
	}
	return nil
}

func ValidateFeatureGates(featureGates map[string]bool, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}
	validFeatures := features.Keys(features.InitFeatureGates)

	// check valid feature names are provided
	for k := range featureGates {
		if !features.Supports(features.InitFeatureGates, k) {
			allErrs = append(allErrs, field.Invalid(fldPath, featureGates,
				fmt.Sprintf("%s is not a valid feature name. Valid features are: %s", k, validFeatures)))
		}
	}

	return allErrs
}

func ValidateAPIEndpoint(c *kubeadm.MasterConfiguration, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}

	endpoint, err := kubeadmutil.GetMasterEndpoint(c)
	if err != nil {
		allErrs = append(allErrs, field.Invalid(fldPath, endpoint, "Invalid API Endpoint"))
	}
	return allErrs
}