package selfupdate

import (
	"fmt"
	"strconv"
	"strings"
)

// Version represents a semantic version (Major.Minor.Patch).
type Version struct {
	Major int
	Minor int
	Patch int
	Raw   string
}

// ParseVersion parses "X.Y.Z" or "vX.Y.Z". Returns error for "dev", "latest", or invalid formats.
func ParseVersion(s string) (Version, error) {
	s = strings.TrimPrefix(s, "v")
	if s == "dev" || s == "latest" || s == "" {
		return Version{}, fmt.Errorf("invalid version: %q", s)
	}
	parts := strings.SplitN(s, ".", 3)
	if len(parts) != 3 {
		return Version{}, fmt.Errorf("invalid version format: %q (expected X.Y.Z)", s)
	}
	major, err := strconv.Atoi(parts[0])
	if err != nil {
		return Version{}, fmt.Errorf("invalid major version: %w", err)
	}
	minor, err := strconv.Atoi(parts[1])
	if err != nil {
		return Version{}, fmt.Errorf("invalid minor version: %w", err)
	}
	patch, err := strconv.Atoi(parts[2])
	if err != nil {
		return Version{}, fmt.Errorf("invalid patch version: %w", err)
	}
	return Version{Major: major, Minor: minor, Patch: patch, Raw: s}, nil
}

// Compare returns -1 if a < b, 0 if a == b, 1 if a > b.
func (a Version) Compare(b Version) int {
	if a.Major != b.Major {
		if a.Major < b.Major {
			return -1
		}
		return 1
	}
	if a.Minor != b.Minor {
		if a.Minor < b.Minor {
			return -1
		}
		return 1
	}
	if a.Patch != b.Patch {
		if a.Patch < b.Patch {
			return -1
		}
		return 1
	}
	return 0
}

// String returns the version as "X.Y.Z".
func (v Version) String() string {
	return fmt.Sprintf("%d.%d.%d", v.Major, v.Minor, v.Patch)
}