package generate

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"strconv"
	"strings"
	"time"

	"github.com/pkg/errors"

	"github.com/spf13/cobra"
	"tildegit.org/PigeonProtocolConsortium/pigeongo/internal/codec"
)

const (
	outStdout           = "stdout"
	outFile             = "file"
	outGoGen            = "go-generate"
	errMsgParsingSeq    = "there was ana error parsing the sequence"
	errMsgEmptyFilePath = "required file path is empty"
	errMsgWritingFile   = "there was an error writing the file"
	errMsgMissingGoPkg  = "required go package name is empty"
)

var (
	goGenTmp = `// Auto generated
// By: tildegit.org/PigeonProtocolConsortium/pigeongo/internal/cmd/lipsenq
// On: %s

package %s

var GeneratedLipmaaLayerSequences = []uint{%v}
`
	seqConf = struct {
		Layer, Depth     uint
		Sequences        []uint
		FilePath         string
		GoGenPackageName string
		Format           string
	}{}
	seqCmd = cobra.Command{
		Use:   "sequences",
		Short: "Generate Lipmaa Layer Sequences",
		Run: func(cmd *cobra.Command, args []string) {
			seq := codec.CalculateLipmaaLayerSequence(
				seqConf.Layer, seqConf.Depth, seqConf.Sequences,
			)
			seqBuff, err := json.Marshal(seq)
			if err != nil {
				exitWithErrMsg(cmd, fmt.Sprintf("%v: %v", errMsgParsingSeq, err.Error()))
			}
			switch seqConf.Format {
			case outGoGen:
				if seqConf.GoGenPackageName == "" {
					exitWithErrMsg(cmd, errMsgMissingGoPkg)
					break
				}
				var seqStr []string
				for _, s := range seq {
					seqStr = append(seqStr, strconv.Itoa(int(s)))
				}
				goGenTmp := fmt.Sprintf(
					goGenTmp,
					time.Now().UTC(),
					seqConf.GoGenPackageName, strings.Join(seqStr, ","),
				)
				if seqConf.FilePath == "" {
					fmt.Println(goGenTmp)
					break
				}
				if err := writeToFile(seqConf.FilePath, []byte(goGenTmp)); err != nil {
					exitWithErrMsg(cmd, err.Error())
					break
				}
			case outFile:
				if err := writeToFile(seqConf.FilePath, seqBuff); err != nil {
					exitWithErrMsg(cmd, err.Error())
				}
			default:
				fmt.Println(seq)
			}
		},
	}
)

func exitWithErrMsg(cmd *cobra.Command, msg string) {
	fmt.Printf("\nError: %s\n\n", msg)
	cmd.Help()
}

func writeToFile(p string, d []byte) error {
	if p == "" {
		return errors.New(errMsgEmptyFilePath)
	}
	if err := ioutil.WriteFile(p, d, 0644); err != nil {
		return errors.Wrap(err, errMsgWritingFile)
	}
	return nil
}

func init() {
	seqCmd.Flags().UintVarP(&seqConf.Layer, "layer", "l", uint(1),
		"The layer that you would like to start the sequence generation from")
	seqCmd.Flags().UintVarP(&seqConf.Depth, "depth", "d", uint(1),
		"The Layer that you would like to stop the sequence generation at")
	seqCmd.Flags().UintSliceVarP(&seqConf.Sequences, "sequences", "s", []uint{0},
		"A list of sequences that you'de like to start with")
	seqCmd.Flags().StringVarP(&seqConf.Format, "format", "f", outStdout,
		"The kind of format you want")
	seqCmd.Flags().StringVarP(&seqConf.FilePath, "output", "o", "",
		"Where you want to output written to")
	seqCmd.Flags().StringVarP(&seqConf.GoGenPackageName, "go-package", "g", "",
		"A package name for the go-generate format")
}