package sqlite

import (
	"fmt"
	"strings"
	"unicode"
)

// DeriveProjectCode builds a 3-letter uppercase code from a project name.
// Non-letters are skipped; short results are padded with X.
func DeriveProjectCode(name string) string {
	var b strings.Builder
	for _, r := range strings.ToUpper(name) {
		if unicode.IsLetter(r) && r < unicode.MaxASCII {
			b.WriteRune(r)
			if b.Len() == 3 {
				break
			}
		}
	}
	code := b.String()
	for len(code) < 3 {
		code += "X"
	}
	return code
}

// nextUniqueCode returns base or a nearby 3-char variant until unused.
// used maps existing codes (uppercase) → true.
func nextUniqueCode(base string, used map[string]bool) string {
	base = DeriveProjectCode(base)
	if !used[base] {
		return base
	}
	prefix := base[:2]
	for _, c := range "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789" {
		cand := prefix + string(c)
		if !used[cand] {
			return cand
		}
	}
	for i := 0; i < 1000; i++ {
		cand := fmt.Sprintf("%c%02d", base[0], i)
		if !used[cand] {
			return cand
		}
	}
	return fmt.Sprintf("X%02d", len(used)%100)
}