package resources

import (
	"os"
	"path/filepath"
	"strings"
)

// ContextFiles walks from dir toward the filesystem root and concatenates
// AGENTS.md and CLAUDE.md (nearest first). SYSTEM.md and APPEND_SYSTEM.md
// are read from dir only.
func ContextFiles(dir string) (string, error) {
	var parts []string
	cur := dir
	for {
		for _, name := range []string{"AGENTS.md", "CLAUDE.md"} {
			raw, err := os.ReadFile(filepath.Join(cur, name))
			if err != nil {
				continue
			}
			parts = append(parts, "# "+name+" ("+cur+")\n"+string(raw))
		}
		parent := filepath.Dir(cur)
		if parent == cur {
			break
		}
		cur = parent
	}
	for _, name := range []string{"SYSTEM.md", "APPEND_SYSTEM.md"} {
		raw, err := os.ReadFile(filepath.Join(dir, name))
		if err != nil {
			continue
		}
		parts = append(parts, "# "+name+"\n"+string(raw))
	}
	return strings.Join(parts, "\n\n"), nil
}