package modules

import (
	"encoding/json"
	"fmt"
	"net/http"
	"os"
	"strings"
	"time"

	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/auth"
	"github.com/aws/aws-sdk-go-v2/aws"
	"github.com/aws/aws-sdk-go-v2/config"
	"github.com/spf13/cobra"
	"github.com/spf13/viper"
)

var generatePresignedURLCmd = &cobra.Command{
	Use:   "generate-presigned-url",
	Short: "Generate presigned url using AWS credentials",
	Long: `Generate presigned url using AWS credentials.Credentials must be placed in ~/.aws/credentials.
You 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 generate-presigned-url --method put --bucket my-bucket --object my-object --endpoint http://localhost:8084 --lifetime 12h --region ru --aws-access-key-id ETaA2CadPcA7bAkLsML2PbTudXY8uRt2PDjCCwkvRv9s0FDCxWDXYc1SA1vKv8KbyCNsLY2AmAjJ92Vz5rgvsFCy --aws-secret-access-key c2d65ef2980f03f4f495bdebedeeae760496697880d61d106bb9a4e5cd2e0607 --header 'Content-Type: text/plain'`,
	RunE:    runGeneratePresignedURLCmd,
}

const defaultPresignedLifetime = 12 * time.Hour

const (
	endpointFlag           = "endpoint"
	bucketFlag             = "bucket"
	objectFlag             = "object"
	methodFlag             = "method"
	profileFlag            = "profile"
	regionFlag             = "region"
	awsAccessKeyIDFlag     = "aws-access-key-id"
	awsSecretAccessKeyFlag = "aws-secret-access-key"
	headerFlag             = "header"
	sigV4AFlag             = "sigv4a"
)

func initGeneratePresignedURLCmd() {
	generatePresignedURLCmd.Flags().Duration(lifetimeFlag, defaultPresignedLifetime, "Lifetime of presigned URL. For example 50h30m (note: max time unit is an hour so to set a day you should use 24h).\nIt will be ceil rounded to the nearest amount of epoch.")
	generatePresignedURLCmd.Flags().String(endpointFlag, "", "S3 gateway endpoint")
	generatePresignedURLCmd.Flags().String(bucketFlag, "", "Bucket name to perform action")
	generatePresignedURLCmd.Flags().String(objectFlag, "", "Object name to perform action")
	generatePresignedURLCmd.Flags().String(methodFlag, "", "HTTP method to perform action")
	generatePresignedURLCmd.Flags().String(profileFlag, "", "AWS profile to load")
	generatePresignedURLCmd.Flags().String(regionFlag, "", "AWS region to use in signature (default is taken from ~/.aws/config)")
	generatePresignedURLCmd.Flags().String(awsAccessKeyIDFlag, "", "AWS access key id to sign the URL (default is taken from ~/.aws/credentials)")
	generatePresignedURLCmd.Flags().String(awsSecretAccessKeyFlag, "", "AWS secret access key to sign the URL (default is taken from ~/.aws/credentials)")
	generatePresignedURLCmd.Flags().StringSlice(headerFlag, nil, "Header in form of 'Key: value' to use in presigned URL (use flags repeatedly for multiple headers or separate them by comma)")
	generatePresignedURLCmd.Flags().Bool(sigV4AFlag, false, "Use SigV4A for signing request")

	_ = generatePresignedURLCmd.MarkFlagRequired(endpointFlag)
	_ = generatePresignedURLCmd.MarkFlagRequired(bucketFlag)
	_ = generatePresignedURLCmd.MarkFlagRequired(objectFlag)
}

func runGeneratePresignedURLCmd(cmd *cobra.Command, _ []string) error {
	var (
		region string
		creds  aws.Credentials
	)

	profile := viper.GetString(profileFlag)

	if profile == "" {
		cfg, err := config.LoadDefaultConfig(cmd.Context())
		if err != nil {
			return wrapPreparationError(err)
		}
		region = cfg.Region
		if creds, err = cfg.Credentials.Retrieve(cmd.Context()); err != nil {
			return wrapPreparationError(fmt.Errorf("couldn't get default aws credentials: %w", err))
		}
	} else {
		cfg, err := config.LoadSharedConfigProfile(cmd.Context(), viper.GetString(profileFlag))
		if err != nil {
			return wrapPreparationError(fmt.Errorf("couldn't get '%s' aws credentials: %w", viper.GetString(profileFlag), err))
		}
		region = cfg.Region
		creds = cfg.Credentials
	}

	accessKeyIDArg := viper.GetString(awsAccessKeyIDFlag)
	secretAccessKeyArg := viper.GetString(awsSecretAccessKeyFlag)
	if accessKeyIDArg != "" && secretAccessKeyArg != "" {
		creds.AccessKeyID = accessKeyIDArg
		creds.SecretAccessKey = secretAccessKeyArg
	}

	if regionArg := viper.GetString(regionFlag); regionArg != "" {
		region = regionArg
	}

	reqData := auth.RequestData{
		Method:   viper.GetString(methodFlag),
		Endpoint: viper.GetString(endpointFlag),
		Bucket:   viper.GetString(bucketFlag),
		Object:   viper.GetString(objectFlag),
	}
	presignData := auth.PresignData{
		Service:  "s3",
		Region:   region,
		Lifetime: viper.GetDuration(lifetimeFlag),
		SignTime: time.Now().UTC(),
	}

	headers, err := parseHeaders()
	if err != nil {
		return wrapPreparationError(fmt.Errorf("failed to parse headers: %s", err))
	}
	presignData.Headers = headers

	var req *http.Request
	if viper.GetBool(sigV4AFlag) {
		req, err = auth.PresignRequestV4a(creds, reqData, presignData)
	} else {
		req, err = auth.PresignRequest(cmd.Context(), creds, reqData, presignData)
	}
	if err != nil {
		return wrapBusinessLogicError(err)
	}

	res := &struct{ URL string }{
		URL: req.URL.String(),
	}

	enc := json.NewEncoder(os.Stdout)
	enc.SetIndent("", "  ")
	enc.SetEscapeHTML(false)
	err = enc.Encode(res)
	if err != nil {
		return wrapBusinessLogicError(err)
	}
	return nil
}

func parseHeaders() (map[string]string, error) {
	headers := viper.GetStringSlice(headerFlag)
	if len(headers) == 0 {
		return nil, nil
	}

	result := make(map[string]string, len(headers))
	for _, header := range headers {
		k, v, found := strings.Cut(header, ":")
		if !found {
			return nil, fmt.Errorf("invalid header format: %s", header)
		}
		result[strings.Trim(k, " ")] = strings.Trim(v, " ")
	}

	return result, nil
}