// Package gpuconfig implements routines for manipulating proto based
// GPU build configuration files.
//
// It also implements the construction of these configs for
// the COS Image and the COS Kernel CI.
package gpuconfig

import (
	"errors"
	"fmt"
	"regexp"
	"strings"

	"cos.googlesource.com/cos/tools.git/src/pkg/gpuconfig/pb"
	log "github.com/golang/glog"
	"google.golang.org/protobuf/proto"
)

const (
	defaultLabel string = "DEFAULT"
	latestLabel  string = "LATEST"
)

type gpuDriverVersion struct {
	gpuType               string
	labelToDriverVersion  map[string]string
	driverVersionToLabels map[string][]string
}

// parseGPUDriverVersionInfoLists will parse the GPU driver version proto content to pb.GPUDriverVersionInfoList.
func parseGPUDriverVersionInfoList(gpuDriverVersionContent []byte) (*pb.GPUDriverVersionInfoList, error) {
	var gpuDriverVersionInfoList = &pb.GPUDriverVersionInfoList{}
	if gpuDriverVersionContent == nil {
		return nil, errors.New("the gpu proto content must not be empty")
	}
	err := (proto.UnmarshalOptions{DiscardUnknown: true, AllowPartial: true}).Unmarshal(gpuDriverVersionContent, gpuDriverVersionInfoList)
	if err != nil {
		return nil, fmt.Errorf("failed when parsing the GPU driver version: %v", err)
	}
	return gpuDriverVersionInfoList, nil
}

// parseGPUDriverVersion will parse the GPU driver version content to gpuDriverVersion struct.
func parseGPUDriverVersion(gpuDriverVersionContent []byte, gpuType string) (*gpuDriverVersion, error) {
	gpuDriverVersionInfoList, err := parseGPUDriverVersionInfoList(gpuDriverVersionContent)
	if err != nil {
		return nil, err
	}
	var labelToDriverVersion = map[string]string{}
	var driverVersionToLabels = map[string][]string{}
	for _, gpuDriverVersionInfo := range gpuDriverVersionInfoList.GetGpuDriverVersionInfo() {
		if strings.EqualFold(strings.TrimSpace(gpuType), strings.TrimSpace(gpuDriverVersionInfo.GetGpuDevice().GetGpuType())) {
			for _, driverVersionInfo := range gpuDriverVersionInfo.GetSupportedDriverVersions() {
				driverVersion := driverVersionInfo.GetVersion()
				driverVersionLabel := driverVersionInfo.GetLabel()
				if _, ok := driverVersionToLabels[driverVersion]; !ok {
					driverVersionToLabels[driverVersion] = []string{}
				}
				if driverVersionLabel != "" {
					labelToDriverVersion[driverVersionLabel] = driverVersion
					driverVersionToLabels[driverVersion] = append(driverVersionToLabels[driverVersion], driverVersionLabel)
				}
			}
		}
	}
	// If the driverVersionToLabels is empty means the input GPU type is not found in the GPU driver version proto content
	if len(driverVersionToLabels) == 0 {
		return nil, fmt.Errorf("no supported driver versions found for gpu: %s", gpuType)
	}
	return &gpuDriverVersion{gpuType, labelToDriverVersion, driverVersionToLabels}, nil

}

// GetGPUDriverVersion fetch the GPU driver version from the input given the specific gpuType, fallback flag and proto bytes.
// The input here can be:
//  1. Precise GPU driver versions, e.g. 535.125.67, 560.38
//     In this case, we will check whether this version is compatible with gpuType.
//  2. Major GPU version label, e.g. R535, or default or latest or empty label.
//     In this case, we will find out the driver version which is associated to this label for gpuType.
func GetGPUDriverVersion(gpuProtoContent []byte, gpuType string, input string, fallback bool) (string, error) {
	preciseVersionPattern := regexp.MustCompile(`^\d+(\.\d+){1,2}$`)
	majorVersionPattern := regexp.MustCompile(`^R\d+$`)
	processedInput := strings.ToUpper(strings.TrimSpace(input))
	if processedInput != "" && processedInput != defaultLabel && processedInput != latestLabel &&
		!preciseVersionPattern.MatchString(processedInput) && !majorVersionPattern.MatchString(processedInput) {
		return "", fmt.Errorf("the input is invalid: %s", input)
	}
	if gpuType == "" {
		return "", errors.New("the GPU type must not be empty")
	}
	if gpuProtoContent == nil {
		return "", errors.New("the gpu proto content must not be empty")
	}
	gpuDriverVersions, err := parseGPUDriverVersion(gpuProtoContent, gpuType)
	if err != nil {
		return "", fmt.Errorf("cannot parse the GPU driver versions info given the proto content and gpuType with error: %v", err)
	}
	// If the input label is empty, we will just use default GPU driver versions for this gpu type.
	if processedInput == "" {
		processedInput = defaultLabel
	}
	// The input label is the precise GPU driver version.
	if preciseVersionPattern.MatchString(processedInput) {
		// If the input driver version is compatible with the current GPUType, we just return as it is.
		log.Infof("The input label: %s is a precise GPU driver version, checking whether it's compatible with GPU: %s", processedInput, gpuType)
		_, found := gpuDriverVersions.driverVersionToLabels[processedInput]
		if found {
			log.Infof("%s is compatible with GPU: %s", processedInput, gpuType)
			return processedInput, nil
		}
	}

	driverVersion, ok := gpuDriverVersions.labelToDriverVersion[processedInput]
	if !ok {
		// The input label is not supported in current GPU Type.
		if fallback {
			//If fallback flag is true, we will try to fetch the default GPU driver version for this gpu type.
			defaultDriverVersion, ok := gpuDriverVersions.labelToDriverVersion[defaultLabel]
			if !ok {
				return "", fmt.Errorf("default label is not supported in current gpu type: %s", gpuType)
			}
			return defaultDriverVersion, nil
		} else {
			// If fallback flag is false, an error will be thrown.
			return "", fmt.Errorf("failed to check driver compatibility, the input: %s is not supported for GPU type: %s, please use a compatible driver, or use the default/latest flag or consider forcing a fallback using `--force-fallback=true` for the installer to select a compatible driver for the device", processedInput, gpuType)
		}
	}
	return driverVersion, nil
}

// GetGPUDriverVersions will fetch a list of GPU driver versions that support the gpuType.
func GetGPUDriverVersions(gpuProtoContent []byte, gpuType string) ([]*pb.DriverVersion, error) {
	if gpuType == "" {
		return nil, errors.New("the GPU type must not be empty")
	}
	if gpuProtoContent == nil {
		return nil, errors.New("the gpu proto content must not be empty")
	}
	gpuDriverVersionInfoList, err := parseGPUDriverVersionInfoList(gpuProtoContent)
	if err != nil {
		return nil, err
	}
	for _, gpuDriverVersionInfo := range gpuDriverVersionInfoList.GetGpuDriverVersionInfo() {
		if gpuType == gpuDriverVersionInfo.GetGpuDevice().GetGpuType() {
			return gpuDriverVersionInfo.GetSupportedDriverVersions(), nil
		}
	}
	return nil, fmt.Errorf("no supported driver versions found for gpu: %s", gpuType)
}