package main

import (
	"errors"
	"fmt"
	"log"
	"os"
	"sort"
	"strconv"
	"strings"

	"github.com/go-git/go-git/v5"
	"github.com/go-git/go-git/v5/plumbing"

	"github.com/spf13/cobra"
	"github.com/spf13/viper"

	"github.com/Masterminds/semver/v3"
)

type FmtPart string

var (
	BumpInt FmtPart = "$BumpInt"
	KeyArg  FmtPart = "$KeyArg"
)

type preReleaseVersion struct {
	Fmt         []string
	KeyArgs     map[string]string
	v           *semver.Version
	versionPart string
}

// incPreRelease bumps a prerelease
// if no existing pre-release render
// if exists find the bump part
func (prf *preReleaseVersion) incPreRelease() (semver.Version, error) {
	currentPreRelease := prf.v.Prerelease()
	newPreRelease := currentPreRelease == ""
	currentPreReleaseParts := strings.Split(currentPreRelease, ".")
	newPreReleaseParts := []string{}
	// Loop over each of the format parts
	// Align the output to match the output
	for idx, fmtPart := range prf.Fmt {
		partArgs := strings.Split(fmtPart, " ")
		switch partArgs[0] {
		case string(BumpInt):
			// Handle a new pre-release
			if newPreRelease {
				newPreReleaseParts = append(newPreReleaseParts, "0")
				continue
			}
			// bump int
			// current int ++
			currentVerStrPart := currentPreReleaseParts[idx]
			currentVerPart, err := strconv.Atoi(currentVerStrPart)
			if err != nil {
				return semver.Version{}, err
			}
			newPreReleaseParts = append(newPreReleaseParts, strconv.Itoa(currentVerPart+1))
		case string(KeyArg):
			// check len
			value, ok := prf.KeyArgs[partArgs[1]]
			if !ok {
				log.Fatalf("%s not found", partArgs[1])
				return semver.Version{}, errors.New("KeyArg not found")
			}
			newPreReleaseParts = append(newPreReleaseParts, value)
		default:
			newPreReleaseParts = append(newPreReleaseParts, partArgs[0])
		}
	}
	nextVersion := semver.Version{}
	preReleaseStr := strings.Join(newPreReleaseParts, ".")
	// When we are _JUST_ bumping the prerelease
	if !newPreRelease {
		newVersion, err := prf.v.SetPrerelease(preReleaseStr)
		if err != nil {
			log.Fatal(err)
			return semver.Version{}, err
		}
		return newVersion, nil
	}
	switch prf.versionPart {
	case "major":
		nextVersion = prf.v.IncMajor()
	case "minor":
		nextVersion = prf.v.IncMinor()
	case "patch":
		nextVersion = prf.v.IncPatch()
	}
	newVersion, err := nextVersion.SetPrerelease(preReleaseStr)
	if err != nil {
		log.Fatal(err)
		return semver.Version{}, err
	}
	return newVersion, nil
}

var (
	errNoRemoteFound  = errors.New("No remotes found")
	clonedRepo        = &git.Repository{}
	localRepo         = &git.Repository{}
	remoteName        string
	preReleaseFmtArgs map[string]string = make(map[string]string)
	preRelease        bool
	rootCmd           = &cobra.Command{
		Use:       "semverbump part [major|minor|patch]",
		Short:     "A tool for bumping semver git tags.",
		ValidArgs: []string{"major", "minor", "patch"},
		Args:      cobra.MatchAll(cobra.ExactArgs(1), cobra.OnlyValidArgs),
		Long:      `Inspired by the python bump2version tool.`,
		RunE: func(cmd *cobra.Command, argz []string) error {
			part := argz[0]
			preRelease := viper.GetBool("prerelease")
			preReleaseFmtString := viper.GetString("prerelease-fmt")
			// remoteName := viper.GetString("remote-name")
			repoDir := viper.GetString("repo-dir")

			localRepo, err := git.PlainOpen(repoDir)
			if err != nil {
				return err
			}
			// finding tags and last version
			tags, err := findTags(localRepo)
			if err != nil {
				return err
			}
			lastVersion := latestTag(tags)
			if (lastVersion == &semver.Version{}) {
				return errors.New("No tags found. Not doing anything")
			}

			versionPart := ""
			if preRelease {
				versionPart = part
				part = "prerelease"
			}
			// actual bump
			nextVersion := semver.Version{}
			switch part {
			case "major":
				nextVersion = lastVersion.IncMajor()
			case "minor":
				nextVersion = lastVersion.IncMinor()
			case "patch":
				nextVersion = lastVersion.IncPatch()
			case "prerelease":
				preRelVersion := preReleaseVersion{
					// []string{"PR", "$KeyArg PR_NUM"},
					parseFmtString(preReleaseFmtString),
					preReleaseFmtArgs,
					lastVersion,
					versionPart,
				}
				nextVersion, err = preRelVersion.incPreRelease()
				if err != nil {
					return err
				}
			}
			fmt.Fprint(cmd.OutOrStdout(), nextVersion)
			return err
		},
	}
)

func latestTag(tags []*semver.Version) *semver.Version {
	numTags := len(tags)
	if numTags == 0 {
		return &semver.Version{}
	}
	return tags[numTags-1]
}

func findTags(repo *git.Repository) ([]*semver.Version, error) {
	repoTagsIter, err := repo.Tags()
	if err != nil {
		return []*semver.Version{}, err
	}
	repoTags := []*semver.Version{}
	if err := repoTagsIter.ForEach(func(ref *plumbing.Reference) error {
		rn := plumbing.ReferenceName(ref.Name())
		version, err := semver.NewVersion(rn.Short())
		if err != nil {
			// not a semver
			return nil
		}
		repoTags = append(repoTags, version)
		return nil
	}); err != nil {
		return []*semver.Version{}, err
	}
	sort.Sort(semver.Collection(repoTags))
	return repoTags, nil
}

func parseFmtString(toSplit string) []string {
	return strings.Split(toSplit, ".")
}

func main() {
	if err := rootCmd.Execute(); err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
}

func init() {
	// global flags
	viper.SetConfigName(".version.toml")
	viper.SetConfigType("toml")
	viper.AddConfigPath(".")
	err := viper.ReadInConfig() // Find and read the config file
	if err != nil {             // Handle errors reading the config file
		fmt.Println(err)
	}
	cwd, err := os.Getwd()
	if err != nil {
		log.Fatal(err)
	}

	rootCmd.PersistentFlags().BoolVarP(&preRelease, "prerelease", "p", false, "create a prerelease tag for the (major|minor|patch)")
	rootCmd.PersistentFlags().String("prerelease-fmt", "PR.$KeyArg PR_NUM.$BumpInt", "The format string for prerelease versions")
	rootCmd.PersistentFlags().StringToStringVarP(&preReleaseFmtArgs, "key-args", "k", nil, "key=arg for the fmt string")
	rootCmd.PersistentFlags().String("repo-dir", cwd, "repo to examine")
	remoteName = *rootCmd.PersistentFlags().String("remote-name", "origin", "remote to search and push to")
	viper.BindPFlags(rootCmd.PersistentFlags())
}