/*
Copyright (c) Edgeless Systems GmbH

SPDX-License-Identifier: AGPL-3.0-only
*/

package config

import (
	"bytes"
	"errors"
	"fmt"
	"os"
	"regexp"
	"sort"
	"strconv"
	"strings"

	ut "github.com/go-playground/universal-translator"
	"github.com/go-playground/validator/v10"
	"golang.org/x/mod/semver"

	"github.com/edgelesssys/constellation/v2/internal/api/versionsapi"
	"github.com/edgelesssys/constellation/v2/internal/attestation/measurements"
	"github.com/edgelesssys/constellation/v2/internal/attestation/variant"
	"github.com/edgelesssys/constellation/v2/internal/cloud/cloudprovider"
	"github.com/edgelesssys/constellation/v2/internal/compatibility"
	"github.com/edgelesssys/constellation/v2/internal/config/instancetypes"
	"github.com/edgelesssys/constellation/v2/internal/constants"
	"github.com/edgelesssys/constellation/v2/internal/versions"
)

// ValidationError occurs when the validation of a config fails.
// It contains a list of errors that occurred during validation.
type ValidationError struct {
	validationErrMsgs []string
}

func (e *ValidationError) Error() string {
	return "invalid configuration"
}

// LongMessage prints the errors that occurred during validation in a verbose and user friendly way.
func (e *ValidationError) LongMessage() string {
	msg := "Problems validating config file:\n"
	for _, ve := range e.validationErrMsgs {
		msg += fmt.Sprintf("\t%s\n", ve)
	}
	msg += "Fix the invalid entries or generate a new configuration using `constellation config generate`"
	return msg
}

func (e *ValidationError) messagesCount() int {
	return len(e.validationErrMsgs)
}

func registerInvalidK8sVersionError(ut ut.Translator) error {
	return ut.Add("supported_k8s_version", "{0} specifies an unsupported Kubernetes version. {1}", true)
}

func translateInvalidK8sVersionError(ut ut.Translator, fe validator.FieldError) string {
	validVersions := make([]string, len(versions.VersionConfigs))
	i := 0
	for k := range versions.VersionConfigs {
		validVersions[i] = string(k)
		i++
	}
	validVersionsSorted := semver.ByVersion(validVersions)
	sort.Sort(validVersionsSorted)

	if len(validVersionsSorted) == 0 {
		t, _ := ut.T("supported_k8s_version", fe.Field(), "No valid versions available. This should never happen")
		return t
	}
	maxVersion := validVersionsSorted[len(validVersionsSorted)-1]
	minVersion := validVersionsSorted[0]

	var errorMsg string
	configured, ok := fe.Value().(string)
	if !ok {
		errorMsg = fmt.Sprintf("The configured version is not a valid string. Supported versions: %s", strings.Join(validVersionsSorted, " "))
		t, _ := ut.T("supported_k8s_version", fe.Field(), errorMsg)
		return t
	}

	configured = compatibility.EnsurePrefixV(configured)
	switch {
	case !semver.IsValid(configured):
		errorMsg = "The configured version is not a valid semantic version"
	case semver.Compare(configured, minVersion) == -1:
		errorMsg = fmt.Sprintf("The configured version %s is older than the oldest version supported by this CLI: %s", configured, minVersion)
	case semver.Compare(configured, maxVersion) == 1:
		errorMsg = fmt.Sprintf("The configured version %s is newer than the newest version supported by this CLI: %s", configured, maxVersion)
	}

	errorMsg = errorMsg + fmt.Sprintf("Supported versions: %s", strings.Join(validVersionsSorted, " "))

	t, _ := ut.T("supported_k8s_version", fe.Field(), errorMsg)

	return t
}

func (c *Config) validateAWSInstanceType(fl validator.FieldLevel) bool {
	acceptNonCVM := c.GetAttestationConfig().GetVariant().Equal(variant.AWSNitroTPM{})
	return validInstanceTypeForProvider(fl.Field().String(), acceptNonCVM, cloudprovider.AWS)
}

func (c *Config) validateAzureInstanceType(fl validator.FieldLevel) bool {
	acceptNonCVM := c.GetAttestationConfig().GetVariant().Equal(variant.AzureTrustedLaunch{})
	return validInstanceTypeForProvider(fl.Field().String(), acceptNonCVM, cloudprovider.Azure)
}

func validateGCPInstanceType(fl validator.FieldLevel) bool {
	return validInstanceTypeForProvider(fl.Field().String(), false, cloudprovider.GCP)
}

func validateAWSRegionField(fl validator.FieldLevel) bool {
	return ValidateAWSRegion(fl.Field().String())
}

func validateAWSZoneField(fl validator.FieldLevel) bool {
	return ValidateAWSZone(fl.Field().String())
}

// ValidateAWSZone validates that the zone is in the correct format.
func ValidateAWSZone(zone string) bool {
	awsZoneRegex := regexp.MustCompile(`^\w+-\w+-[1-9][abc]$`)
	return awsZoneRegex.MatchString(zone)
}

// ValidateAWSRegion validates that the region is in the correct format.
func ValidateAWSRegion(region string) bool {
	awsRegionRegex := regexp.MustCompile(`^\w+-\w+-[1-9]$`)
	return awsRegionRegex.MatchString(region)
}

// validateProvider checks if zero or more than one providers are defined in the config.
func validateProvider(sl validator.StructLevel) {
	provider := sl.Current().Interface().(ProviderConfig)
	providerCount := 0

	if provider.AWS != nil {
		providerCount++
	}
	if provider.Azure != nil {
		providerCount++
	}
	if provider.GCP != nil {
		providerCount++
	}
	if provider.OpenStack != nil {
		providerCount++
	}
	if provider.QEMU != nil {
		providerCount++
	}

	if providerCount < 1 {
		sl.ReportError(provider, "Provider", "Provider", "no_provider", "")
	} else if providerCount > 1 {
		sl.ReportError(provider, "Provider", "Provider", "more_than_one_provider", "")
	}
}

func validateAttestation(sl validator.StructLevel) {
	attestation := sl.Current().Interface().(AttestationConfig)
	attestationCount := 0

	if attestation.AWSSEVSNP != nil {
		attestationCount++
	}
	if attestation.AWSNitroTPM != nil {
		attestationCount++
	}
	if attestation.AzureSEVSNP != nil {
		attestationCount++
	}
	if attestation.AzureTrustedLaunch != nil {
		attestationCount++
	}
	if attestation.GCPSEVES != nil {
		attestationCount++
	}
	if attestation.QEMUVTPM != nil {
		attestationCount++
	}

	if attestationCount < 1 {
		sl.ReportError(attestation, "Attestation", "Attestation", "no_attestation", "")
	} else if attestationCount > 1 {
		sl.ReportError(attestation, "Attestation", "Attestation", "more_than_one_attestation", "")
	}
}

func translateNoAttestationError(ut ut.Translator, fe validator.FieldError) string {
	t, _ := ut.T("no_attestation", fe.Field())

	return t
}

func registerNoAttestationError(ut ut.Translator) error {
	return ut.Add("no_attestation", "{0}: No attestation has been defined (requires either awsSEVSNP, awsNitroTPM, azureSEVSNP, azureTrustedLaunch, gcpSEVES, or qemuVTPM)", true)
}

func registerAWSRegionError(ut ut.Translator) error {
	return ut.Add("aws_region", "{0}: has invalid format: {1}", true)
}

func translateAWSRegionError(ut ut.Translator, fe validator.FieldError) string {
	t, _ := ut.T("aws_region", fe.Field(), "field must be of format eu-central-1")

	return t
}

func translateAWSZoneError(ut ut.Translator, fe validator.FieldError) string {
	t, _ := ut.T("aws_zone", fe.Field(), "field must be of format eu-central-1a")

	return t
}

func registerAWSZoneError(ut ut.Translator) error {
	return ut.Add("aws_zone", "{0}: has invalid format: {1}", true)
}

func registerMoreThanOneAttestationError(ut ut.Translator) error {
	return ut.Add("more_than_one_attestation", "{0}: Only one attestation can be defined ({1} are defined)", true)
}

func (c *Config) translateMoreThanOneAttestationError(ut ut.Translator, fe validator.FieldError) string {
	definedAttestations := make([]string, 0)

	if c.Attestation.AWSNitroTPM != nil {
		definedAttestations = append(definedAttestations, "AWSNitroTPM")
	}
	if c.Attestation.AWSSEVSNP != nil {
		definedAttestations = append(definedAttestations, "AWSSEVSNP")
	}
	if c.Attestation.AzureSEVSNP != nil {
		definedAttestations = append(definedAttestations, "AzureSEVSNP")
	}
	if c.Attestation.AzureTrustedLaunch != nil {
		definedAttestations = append(definedAttestations, "AzureTrustedLaunch")
	}
	if c.Attestation.GCPSEVES != nil {
		definedAttestations = append(definedAttestations, "GCPSEVES")
	}
	if c.Attestation.QEMUVTPM != nil {
		definedAttestations = append(definedAttestations, "QEMUVTPM")
	}

	t, _ := ut.T("more_than_one_attestation", fe.Field(), strings.Join(definedAttestations, ", "))

	return t
}

func registerTranslateAWSInstanceTypeError(ut ut.Translator) error {
	return ut.Add("aws_instance_type", "{0} must be an instance from one of the following families types with size xlarge or higher: {1}", true)
}

func (c *Config) translateAWSInstanceTypeError(ut ut.Translator, fe validator.FieldError) string {
	var t string

	attestVariant := c.GetAttestationConfig().GetVariant()

	instances := instancetypes.AWSSNPSupportedInstanceFamilies
	if attestVariant.Equal(variant.AWSNitroTPM{}) {
		instances = instancetypes.AWSSupportedInstanceFamilies
	}

	t, _ = ut.T("aws_instance_type", fe.Field(), fmt.Sprintf("%v", instances))

	return t
}

func registerTranslateGCPInstanceTypeError(ut ut.Translator) error {
	return ut.Add("gcp_instance_type", fmt.Sprintf("{0} must be one of %v", instancetypes.GCPInstanceTypes), true)
}

func translateGCPInstanceTypeError(ut ut.Translator, fe validator.FieldError) string {
	t, _ := ut.T("gcp_instance_type", fe.Field())

	return t
}

// Validation translation functions for Azure & GCP instance type errors.
func registerTranslateAzureInstanceTypeError(ut ut.Translator) error {
	return ut.Add("azure_instance_type", "{0} must be one of {1}", true)
}

func (c *Config) translateAzureInstanceTypeError(ut ut.Translator, fe validator.FieldError) string {
	// Suggest trusted launch VMs if confidential VMs have been specifically disabled
	var t string

	attestVariant := c.GetAttestationConfig().GetVariant()

	instances := instancetypes.AzureCVMInstanceTypes
	if attestVariant.Equal(variant.AzureTrustedLaunch{}) {
		instances = instancetypes.AzureTrustedLaunchInstanceTypes
	}

	t, _ = ut.T("azure_instance_type", fe.Field(), fmt.Sprintf("%v", instances))

	return t
}

// Validation translation functions for Provider errors.
func registerNoProviderError(ut ut.Translator) error {
	return ut.Add("no_provider", "{0}: No provider has been defined (requires either Azure, GCP, OpenStack or QEMU)", true)
}

func translateNoProviderError(ut ut.Translator, fe validator.FieldError) string {
	t, _ := ut.T("no_provider", fe.Field())

	return t
}

func registerMoreThanOneProviderError(ut ut.Translator) error {
	return ut.Add("more_than_one_provider", "{0}: Only one provider can be defined ({1} are defined)", true)
}

func (c *Config) translateMoreThanOneProviderError(ut ut.Translator, fe validator.FieldError) string {
	definedProviders := make([]string, 0)

	// c.Provider should not be nil as Provider would need to be defined for the validation to fail in this place.
	if c.Provider.AWS != nil {
		definedProviders = append(definedProviders, "AWS")
	}
	if c.Provider.Azure != nil {
		definedProviders = append(definedProviders, "Azure")
	}
	if c.Provider.GCP != nil {
		definedProviders = append(definedProviders, "GCP")
	}
	if c.Provider.OpenStack != nil {
		definedProviders = append(definedProviders, "OpenStack")
	}
	if c.Provider.QEMU != nil {
		definedProviders = append(definedProviders, "QEMU")
	}

	// Show single string if only one other provider is defined, show list with brackets if multiple are defined.
	t, _ := ut.T("more_than_one_provider", fe.Field(), strings.Join(definedProviders, ", "))

	return t
}

func validInstanceTypeForProvider(insType string, acceptNonCVM bool, provider cloudprovider.Provider) bool {
	switch provider {
	case cloudprovider.AWS:
		return isSupportedAWSInstanceType(insType, acceptNonCVM)
	case cloudprovider.Azure:
		if acceptNonCVM {
			for _, instanceType := range instancetypes.AzureTrustedLaunchInstanceTypes {
				if insType == instanceType {
					return true
				}
			}
		} else {
			for _, instanceType := range instancetypes.AzureCVMInstanceTypes {
				if insType == instanceType {
					return true
				}
			}
		}
		return false
	case cloudprovider.GCP:
		for _, instanceType := range instancetypes.GCPInstanceTypes {
			if insType == instanceType {
				return true
			}
		}
		return false
	default:
		return false
	}
}

// isSupportedAWSInstanceType checks if an AWS instance type passed as user input is in one of the supported instance types.
func isSupportedAWSInstanceType(userInput string, acceptNonCVM bool) bool {
	// Check if user or code does anything weird and tries to pass multiple strings as one
	if strings.Contains(userInput, " ") {
		return false
	}
	if strings.Contains(userInput, ",") {
		return false
	}
	if strings.Contains(userInput, ";") {
		return false
	}

	splitInstanceType := strings.Split(userInput, ".")

	if len(splitInstanceType) != 2 {
		return false
	}

	userDefinedFamily := splitInstanceType[0]
	userDefinedSize := splitInstanceType[1]

	// Check if instace type has at least 4 vCPUs (= contains "xlarge" in its name)
	hasEnoughVCPUs := strings.Contains(userDefinedSize, "xlarge")
	if !hasEnoughVCPUs {
		return false
	}

	instances := instancetypes.AWSSNPSupportedInstanceFamilies
	if acceptNonCVM {
		instances = instancetypes.AWSSupportedInstanceFamilies
	}

	// Now check if the user input is a supported family
	// Note that we cannot directly use the family split from the Graviton check above, as some instances are directly specified by their full name and not just the family in general
	for _, supportedFamily := range instances {
		supportedFamilyLowercase := strings.ToLower(supportedFamily)
		if userDefinedFamily == supportedFamilyLowercase {
			return true
		}
	}

	return false
}

func validateNoPlaceholder(fl validator.FieldLevel) bool {
	return len(getPlaceholderEntries(fl.Field().Interface().(measurements.M))) == 0
}

// validateMeasurement acts like validateNoPlaceholder, but is used for the measurements.Measurement type.
func validateMeasurement(sl validator.StructLevel) {
	measurement := sl.Current().Interface().(measurements.Measurement)
	actual := measurement.Expected
	placeHolder := measurements.PlaceHolderMeasurement(measurements.PCRMeasurementLength).Expected
	if bytes.Equal(actual, placeHolder) {
		sl.ReportError(measurement, "launchMeasurement", "launchMeasurement", "no_placeholders", "")
	}
}

func registerContainsPlaceholderError(ut ut.Translator) error {
	return ut.Add("no_placeholders", "{0} placeholder values (repeated 1234...)", true)
}

func translateContainsPlaceholderError(ut ut.Translator, fe validator.FieldError) string {
	var msg string
	switch fe.Field() {
	case "launchMeasurement":
		msg = "launchMeasurement contains"
	case "measurements":
		placeholders := getPlaceholderEntries(fe.Value().(measurements.M))
		msg = fmt.Sprintf("measurements %v contain", placeholders)
		if len(placeholders) == 1 {
			msg = fmt.Sprintf("measurement %v contains", placeholders)
		}
	}

	t, _ := ut.T("no_placeholders", msg)
	return t
}

func getPlaceholderEntries(m measurements.M) []uint32 {
	var placeholders []uint32
	placeholderTDX := measurements.PlaceHolderMeasurement(measurements.TDXMeasurementLength)
	placeholderTPM := measurements.PlaceHolderMeasurement(measurements.PCRMeasurementLength)

	for idx, measurement := range m {
		if bytes.Equal(measurement.Expected, placeholderTDX.Expected) ||
			bytes.Equal(measurement.Expected, placeholderTPM.Expected) {
			placeholders = append(placeholders, idx)
		}
	}

	return placeholders
}

// validateK8sVersion does not check the patch version.
func (c *Config) validateK8sVersion(fl validator.FieldLevel) bool {
	_, err := versions.NewValidK8sVersion(compatibility.EnsurePrefixV(fl.Field().String()), false)
	return err == nil
}

// K8sVersionFromMajorMinor takes a semver in format MAJOR.MINOR
// and returns the version in format MAJOR.MINOR.PATCH with the
// supported patch version as PATCH.
func K8sVersionFromMajorMinor(version string) string {
	switch version {
	case semver.MajorMinor(string(versions.V1_25)):
		return string(versions.V1_25)
	case semver.MajorMinor(string(versions.V1_26)):
		return string(versions.V1_26)
	case semver.MajorMinor(string(versions.V1_27)):
		return string(versions.V1_27)
	default:
		return ""
	}
}

func registerVersionCompatibilityError(ut ut.Translator) error {
	return ut.Add("version_compatibility", "{0} specifies an invalid version: {1}", true)
}

func translateVersionCompatibilityError(ut ut.Translator, fe validator.FieldError) string {
	binaryVersion := constants.VersionInfo()
	err := validateVersionCompatibilityHelper(binaryVersion, fe.Field(), fe.Value().(string))
	var msg string

	switch {
	case errors.Is(err, compatibility.ErrSemVer):
		msg = fmt.Sprintf("configured version (%s) does not adhere to SemVer syntax", fe.Value().(string))
	case errors.Is(err, compatibility.ErrMajorMismatch):
		msg = fmt.Sprintf("the CLI's major version (%s) has to match your configured major version (%s). Use --force to ignore the version mismatch.", constants.VersionInfo(), fe.Value().(string))
	case errors.Is(err, compatibility.ErrMinorDrift):
		msg = fmt.Sprintf("the CLI's minor version (%s) and the configured version (%s) are more than one minor version apart. Use --force to ignore the version mismatch.", constants.VersionInfo(), fe.Value().(string))
	case errors.Is(err, compatibility.ErrOutdatedCLI):
		msg = fmt.Sprintf("the CLI's version (%s) is older than the configured version (%s). Use --force to ignore the version mismatch.", constants.VersionInfo(), fe.Value().(string))
	default:
		msg = err.Error()
	}

	t, _ := ut.T("version_compatibility", fe.Field(), msg)

	return t
}

// Check that the validated field and the CLI version are not more than one minor version apart.
func validateVersionCompatibility(fl validator.FieldLevel) bool {
	binaryVersion := constants.VersionInfo()
	if err := validateVersionCompatibilityHelper(binaryVersion, fl.FieldName(), fl.Field().String()); err != nil {
		return false
	}

	return true
}

func validateVersionCompatibilityHelper(binaryVersion, fieldName, configuredVersion string) error {
	if fieldName == "image" {
		imageVersion, err := versionsapi.NewVersionFromShortPath(configuredVersion, versionsapi.VersionKindImage)
		if err != nil {
			return err
		}
		configuredVersion = imageVersion.Version
	}

	if fieldName == "microserviceVersion" {
		cliVersion := compatibility.EnsurePrefixV(binaryVersion)
		serviceVersion := compatibility.EnsurePrefixV(configuredVersion)
		if semver.Compare(cliVersion, serviceVersion) == -1 {
			return fmt.Errorf("the CLI's version (%s) is older than the configured version (%s)", cliVersion, serviceVersion)
		}
	}

	return compatibility.BinaryWith(binaryVersion, configuredVersion)
}

func returnsTrue(_ validator.FieldLevel) bool {
	return true
}

func registerValidateNameError(ut ut.Translator) error {
	return ut.Add("validate_name", "{0} must be no more than {1} characters long", true)
}

func (c *Config) translateValidateNameError(ut ut.Translator, fe validator.FieldError) string {
	var t string
	if c.Provider.AWS != nil {
		t, _ = ut.T("validate_name", fe.Field(), strconv.Itoa(constants.AWSConstellationNameLength))
	} else {
		t, _ = ut.T("validate_name", fe.Field(), strconv.Itoa(constants.ConstellationNameLength))
	}

	return t
}

// validateName makes sure the name of the constellation is not too long.
// Since this value may differ between providers, we can't simply use built-in validation.
// This also allows us to eventually add more validation rules for constellation names if necessary.
func (c *Config) validateName(fl validator.FieldLevel) bool {
	if c.Provider.AWS != nil {
		return len(fl.Field().String()) <= constants.AWSConstellationNameLength
	}
	return len(fl.Field().String()) <= constants.ConstellationNameLength
}

func warnDeprecated(fl validator.FieldLevel) bool {
	fmt.Fprintf(
		os.Stderr,
		"WARNING: The config key %q is deprecated and will be removed in an upcoming version.\n",
		fl.FieldName(),
	)
	return true
}