package birdfmt

import (
	"fmt"
	"strings"
)

// ManagedBanner returns a comment block marking EvoBGP-generated files (optional first line in bird.d/*.conf).
func ManagedBanner(revisionHint string) string {
	rev := strings.TrimSpace(revisionHint)
	var b strings.Builder
	b.WriteString("# EvoBGP generated — do not edit by hand.\n")
	if rev != "" {
		b.WriteString("# Revision: ")
		b.WriteString(rev)
		b.WriteByte('\n')
	}
	return b.String()
}

// JoinFragments concatenates non-empty text blocks with a blank line between them.
func JoinFragments(parts ...string) string {
	var out []string
	for _, p := range parts {
		p = strings.TrimSpace(p)
		if p == "" {
			continue
		}
		out = append(out, p)
	}
	if len(out) == 0 {
		return ""
	}
	return strings.Join(out, "\n\n") + "\n"
}

// ValidateIncludePath rejects paths that could break out of the config directory.
func ValidateIncludePath(p string) error {
	p = strings.TrimSpace(p)
	if p == "" {
		return fmt.Errorf("birdfmt: include path is empty")
	}
	if strings.Contains(p, "..") {
		return fmt.Errorf("birdfmt: include path must not contain '..': %q", p)
	}
	return nil
}