package versioning

import (
	"fmt"
	"strconv"
	"strings"

	"github.com/pkg/errors"
)

const (
	MaxMajor uint16 = 42948
	MaxMinor uint16 = 999
	MaxPatch uint8  = 99
)

var maxVersion = newVersion(MaxMajor, MaxMinor, MaxPatch)

type Version struct {
	major uint16
	minor uint16
	patch uint8
	code  uint32
}

func (v Version) String() string {
	return fmt.Sprintf("%d.%d.%d", v.major, v.minor, v.patch)
}

func (v Version) Code() uint32 {
	return v.code
}

func (a Version) Less(b Version) bool {
	return a.Code() < b.Code()
}

func ParseVersion(str string) (Version, error) {
	parts := strings.Split(str, ".")
	partsLen := len(parts)
	if partsLen > 3 {
		return Version{}, errors.Errorf("invalid game version: '%s'", str)
	}

	maj, err := parseUint16(parts[0])
	if err != nil {
		return Version{}, err
	}

	var (
		min   uint16
		patch uint8
	)
	if partsLen > 1 {
		min, err = parseUint16(parts[1])
		if err != nil {
			return Version{}, err
		}
	}
	if partsLen > 2 {
		patch, err = parseUint8(parts[2])
		if err != nil {
			return Version{}, err
		}
	}

	if err := validate(maj, min, patch); err != nil {
		return Version{}, err
	}
	return newVersion(maj, min, patch), nil
}

func MustParseVersion(str string) Version {
	v, err := ParseVersion(str)
	if err != nil {
		return Version{}
	}
	return v
}

func ParseVersionFromCode(code uint32) (Version, error) {
	patch := code % 100
	minor := code%100000 - patch
	major := code - minor - patch

	maj, min, p := uint16(major/100000), uint16(minor/100), uint8(patch)

	if err := validate(maj, min, p); err != nil {
		return Version{}, err
	}

	return Version{
		major: maj,
		minor: min,
		patch: p,
		code:  code,
	}, nil
}

func parseUint16(str string) (uint16, error) {
	v, err := strconv.ParseUint(str, 10, 16)
	if err != nil {
		return 0, errors.WithStack(err)
	}
	return uint16(v), nil
}

func parseUint8(str string) (uint8, error) {
	v, err := strconv.ParseUint(str, 10, 8)
	if err != nil {
		return 0, errors.WithStack(err)
	}
	return uint8(v), nil
}

func validate(major, minor uint16, patch uint8) error {
	if major > MaxMajor || minor > MaxMinor || patch > MaxPatch {
		return errors.Errorf("invalid game version. max version: %s", maxVersion)
	}

	return nil
}

func newVersion(major, minor uint16, patch uint8) Version {
	return Version{
		major: major,
		minor: minor,
		patch: patch,
		code:  calcCode(major, minor, patch),
	}
}

func calcCode(major, minor uint16, patch uint8) uint32 {
	return uint32(major)*100000 + uint32(minor)*100 + uint32(patch)
}