package registry

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

// IndexResult holds stats from an indexing run.
type IndexResult struct {
	Functions int
	Types     int
	Errors    []string
}

// Index walks the registry root, parses all .md files, and populates the database.
// It purges existing data first to ensure a clean rebuild.
func Index(db *DB, root string) (*IndexResult, error) {
	if err := db.Purge(); err != nil {
		return nil, fmt.Errorf("purging database: %w", err)
	}

	result := &IndexResult{}

	// Index functions
	functionsDir := filepath.Join(root, "functions")
	if _, err := os.Stat(functionsDir); err == nil {
		err := filepath.Walk(functionsDir, func(path string, info os.FileInfo, err error) error {
			if err != nil {
				return nil
			}
			if info.IsDir() || !strings.HasSuffix(path, ".md") {
				return nil
			}

			f, err := ParseFunctionMD(path)
			if err != nil {
				result.Errors = append(result.Errors, fmt.Sprintf("%s: %v", path, err))
				return nil
			}

			if err := db.InsertFunction(f); err != nil {
				result.Errors = append(result.Errors, fmt.Sprintf("insert %s: %v", f.ID, err))
				return nil
			}

			result.Functions++
			return nil
		})
		if err != nil {
			return nil, fmt.Errorf("walking functions: %w", err)
		}
	}

	// Index types
	typesDir := filepath.Join(root, "types")
	if _, err := os.Stat(typesDir); err == nil {
		err := filepath.Walk(typesDir, func(path string, info os.FileInfo, err error) error {
			if err != nil {
				return nil
			}
			if info.IsDir() || !strings.HasSuffix(path, ".md") {
				return nil
			}

			t, err := ParseTypeMD(path)
			if err != nil {
				result.Errors = append(result.Errors, fmt.Sprintf("%s: %v", path, err))
				return nil
			}

			if err := db.InsertType(t); err != nil {
				result.Errors = append(result.Errors, fmt.Sprintf("insert %s: %v", t.ID, err))
				return nil
			}

			result.Types++
			return nil
		})
		if err != nil {
			return nil, fmt.Errorf("walking types: %w", err)
		}
	}

	return result, nil
}