package debtik

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

//go:embed VERSION
var files embed.FS
var pattern = regexp.MustCompile(`^(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)$`)

func Version() string { b, _ := files.ReadFile("VERSION"); return strings.TrimSpace(string(b)) }
func ParseVersion(s string) ([3]uint64, error) {
	var out [3]uint64
	if !pattern.MatchString(s) {
		return out, fmt.Errorf("invalid release version: %s", s)
	}
	for i, p := range strings.Split(s, ".") {
		n, err := strconv.ParseUint(p, 10, 64)
		if err != nil {
			return out, err
		}
		out[i] = n
	}
	return out, nil
}
func Newer(candidate, current string) (bool, error) {
	a, err := ParseVersion(candidate)
	if err != nil {
		return false, err
	}
	b, err := ParseVersion(current)
	if err != nil {
		return false, err
	}
	for i := range a {
		if a[i] != b[i] {
			return a[i] > b[i], nil
		}
	}
	return false, nil
}
func LatestTag(output string) (string, string, error) {
	best := ""
	commit := ""
	for _, line := range strings.Split(output, "\n") {
		fields := strings.Fields(line)
		if len(fields) != 2 {
			continue
		}
		tag := strings.TrimSuffix(fields[1], "^{}")
		if !strings.HasPrefix(tag, "refs/tags/v") {
			continue
		}
		version := strings.TrimPrefix(tag, "refs/tags/v")
		if _, err := ParseVersion(version); err != nil {
			continue
		}
		greater := best == ""
		if best != "" {
			greater, _ = Newer(version, best)
		}
		if greater {
			best = version
			commit = fields[0]
		} else if version == best && strings.HasSuffix(fields[1], "^{}") {
			commit = fields[0]
		}
	}
	if best == "" {
		return "", "", fmt.Errorf("repository has no stable vMAJOR.MINOR.PATCH release tags")
	}
	return best, commit, nil
}