package semver

import (
	"errors"
	"fmt"
	"regexp"
	"strconv"
	"strings"
)

//nolint:lll // regex is as it is
var (
	ErrNotASemver = errors.New("the given version does not match the semantic versioning scheme")
	semVerRegex   = regexp.MustCompile(`^(?P<major>0|[1-9]\d*)\.(?P<minor>0|[1-9]\d*)\.(?P<patch>0|[1-9]\d*)(?:-(?P<prerelease>(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\.(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?(?:\+(?P<buildmetadata>[0-9a-zA-Z-]+(?:\.[0-9a-zA-Z-]+)*))?$`)
)

func IsValid(version string) bool {
	return semVerRegex.MatchString(strings.TrimPrefix(version, "v"))
}

func ParseVersion(version string) (v Version, err error) {
	if !IsValid(version) {
		return Version{}, fmt.Errorf("%w: %s", ErrNotASemver, version)
	}

	submatches := semVerRegex.FindStringSubmatch(strings.TrimPrefix(version, "v"))

	for i, name := range semVerRegex.SubexpNames() {
		switch name {
		case "major":
			if v.Major, err = strconv.Atoi(submatches[i]); err != nil {
				return Version{}, err
			}
		case "minor":
			if v.Minor, err = strconv.Atoi(submatches[i]); err != nil {
				return Version{}, err
			}
		case "patch":
			if v.Patch, err = strconv.Atoi(submatches[i]); err != nil {
				return Version{}, err
			}
		case "prerelease":
			v.Prerelease = submatches[i]
		case "buildmetadata":
			v.BuildMetadata = submatches[i]
		}
	}

	return v, nil
}

type Version struct {
	Prerelease    string `cty:"prerelease"`
	BuildMetadata string `cty:"build_metadata"`
	Major         int    `cty:"major"`
	Minor         int    `cty:"minor"`
	Patch         int    `cty:"patch"`
}