package llm

import (
	"strings"
	"unicode"
)

// PrettyModel turns an API model id into the name a person uses for it:
// claude-opus-5 becomes "Opus 5", claude-haiku-4-5-20251001 becomes
// "Haiku 4.5". An id that does not fit the shape is returned unchanged, which
// matters because this also runs against gateways serving models we have
// never heard of.
func PrettyModel(id string) string {
	s := strings.TrimSuffix(strings.TrimPrefix(id, "claude-"), "-latest")
	// Anything bracketed is a variant tag, not part of the name: opus-5[1m].
	tag := ""
	if i := strings.IndexByte(s, '['); i >= 0 {
		tag, s = s[i:], s[:i]
	}
	parts := strings.Split(s, "-")
	if len(parts) < 2 {
		return id
	}
	// A trailing eight-digit date stamp is a build, not a version.
	if last := parts[len(parts)-1]; len(last) == 8 && allDigits(last) {
		parts = parts[:len(parts)-1]
	}
	family, rest := parts[0], parts[1:]
	if family == "" || !isAlpha(family) {
		return id
	}
	name := strings.ToUpper(family[:1]) + family[1:]
	var version []string
	for _, p := range rest {
		if !allDigits(p) {
			return id
		}
		version = append(version, p)
	}
	if len(version) > 0 {
		name += " " + strings.Join(version, ".")
	}
	return name + tag
}

func allDigits(s string) bool {
	if s == "" {
		return false
	}
	for _, r := range s {
		if !unicode.IsDigit(r) {
			return false
		}
	}
	return true
}

func isAlpha(s string) bool {
	for _, r := range s {
		if !unicode.IsLetter(r) {
			return false
		}
	}
	return s != ""
}