package modules

import (
	"errors"
	"fmt"
	"os"
	"strings"
	"time"

	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/auth"
	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/aws/credentials"
	"github.com/aws/aws-sdk-go/aws/session"
	"github.com/spf13/cobra"
	"github.com/spf13/viper"
)

var signCmd = &cobra.Command{
	Use:   "sign",
	Short: "Sign arbitrary data using AWS Signature Version 4",
	Long: `Generate signature for provided data using AWS credentials. Credentials must be placed in ~/.aws/credentials.
You can provide profile to load using --profile flag or explicitly provide credentials and region using
--aws-access-key-id, --aws-secret-access-key, --region.
Note to override credentials you must provide both access key and secret key.`,
	Example: `frostfs-s3-authmate sign --data some-data
frostfs-s3-authmate sign --data file://data.txt
frostfs-s3-authmate sign --data file://data.txt --profile my-profile --time 2024-09-27
frostfs-s3-authmate sign --data some-data --region ru --service s3 --time 2024-09-27 --aws-access-key-id ETaA2CadPcA7bAkLsML2PbTudXY8uRt2PDjCCwkvRv9s0FDCxWDXYc1SA1vKv8KbyCNsLY2AmAjJ92Vz5rgvsFCy --aws-secret-access-key c2d65ef2980f03f4f495bdebedeeae760496697880d61d106bb9a4e5cd2e0607`,
	RunE: runSignCmd,
}

const (
	serviceFlag = "s3"
	timeFlag    = "time"
	dataFlag    = "data"
)

func initSignCmd() {
	signCmd.Flags().StringP(dataFlag, "d", "", "Data to sign. Can be provided as string or as a file ('file://path-to-file')")
	signCmd.Flags().String(profileFlag, "", "AWS profile to load")
	signCmd.Flags().String(serviceFlag, "s3", "AWS service name to form signature")
	signCmd.Flags().String(timeFlag, "", "Signing time in '2006-01-02' format (default is current UTC time)")
	signCmd.Flags().String(regionFlag, "", "AWS region to use in signature (default is taken from ~/.aws/config)")
	signCmd.Flags().String(awsAccessKeyIDFlag, "", "AWS access key id to sign data (default is taken from ~/.aws/credentials)")
	signCmd.Flags().String(awsSecretAccessKeyFlag, "", "AWS secret access key to sign data (default is taken from ~/.aws/credentials)")

	_ = signCmd.MarkFlagRequired(dataFlag)
}

func runSignCmd(cmd *cobra.Command, _ []string) error {
	var cfg aws.Config

	if region := viper.GetString(regionFlag); region != "" {
		cfg.Region = &region
	}
	accessKeyID := viper.GetString(awsAccessKeyIDFlag)
	secretAccessKey := viper.GetString(awsSecretAccessKeyFlag)

	if accessKeyID != "" && secretAccessKey != "" {
		cfg.Credentials = credentials.NewStaticCredentialsFromCreds(credentials.Value{
			AccessKeyID:     accessKeyID,
			SecretAccessKey: secretAccessKey,
		})
	} else if accessKeyID != "" || secretAccessKey != "" {
		return wrapPreparationError(fmt.Errorf("both flags '%s' and '%s' must be provided", accessKeyIDFlag, awsSecretAccessKeyFlag))
	}

	sess, err := session.NewSessionWithOptions(session.Options{
		Config:            cfg,
		Profile:           viper.GetString(profileFlag),
		SharedConfigState: session.SharedConfigEnable,
	})
	if err != nil {
		return wrapPreparationError(fmt.Errorf("couldn't get aws credentials: %w", err))
	}

	data := viper.GetString(dataFlag)
	if strings.HasPrefix(data, "file://") {
		dataToSign, err := os.ReadFile(data[7:])
		if err != nil {
			return wrapPreparationError(fmt.Errorf("read data file: %w", err))
		}
		data = string(dataToSign)
	}

	creds, err := sess.Config.Credentials.Get()
	if err != nil {
		return wrapPreparationError(fmt.Errorf("get creds: %w", err))
	}

	if sess.Config.Region == nil || *sess.Config.Region == "" {
		return wrapPreparationError(errors.New("missing region"))
	}

	service := viper.GetString(serviceFlag)
	if service == "" {
		return wrapPreparationError(errors.New("missing service"))
	}

	signTime := viper.GetTime(timeFlag)
	if signTime.IsZero() {
		signTime = time.Now()
	}

	signature := auth.SignStr(creds.SecretAccessKey, service, *sess.Config.Region, signTime, data)

	cmd.Println("service:", service)
	cmd.Println("region:", *sess.Config.Region)
	cmd.Println("time:", signTime.UTC().Format("20060102"))
	cmd.Println("accessKeyId:", creds.AccessKeyID)
	cmd.Printf("secretAccessKey: [****************%s]\n", creds.SecretAccessKey[max(0, len(creds.SecretAccessKey)-4):])
	cmd.Println("signature:", signature)

	return nil
}