stardb/reflect.go

package stardb

import (
	"errors"
	"reflect"
	"time"
)

// setStructFieldsFromRow sets struct fields from a row result using reflection
func (r *StarRows) setStructFieldsFromRow(target interface{}, tagKey string, rowIndex int) error {
	targetType := reflect.TypeOf(target)
	targetValue := reflect.ValueOf(target)

	if targetType.Kind() == reflect.Ptr {
		targetValue = targetValue.Elem()
	}

	if targetType.Kind() != reflect.Ptr && !targetValue.CanSet() {
		return errors.New("target is not writable")
	}

	if targetType.Kind() == reflect.Ptr {
		targetType = targetType.Elem()
	}

	if targetValue.Kind() != reflect.Struct {
		return errors.New("target is not a struct")
	}

	for i := 0; i < targetType.NumField(); i++ {
		field := targetType.Field(i)
		fieldValue := targetValue.Field(i)
		tagValue := field.Tag.Get(tagKey)

		// Handle nested structs
		if fieldValue.Kind() == reflect.Ptr && reflect.TypeOf(fieldValue.Interface()).Elem().Kind() == reflect.Struct {
			if tagValue == "" {
				continue
			}
			if tagValue == "---" {
				nestedPtr := reflect.New(reflect.TypeOf(fieldValue.Interface()).Elem()).Interface()
				r.setStructFieldsFromRow(nestedPtr, tagKey, rowIndex)
				targetValue.Field(i).Set(reflect.ValueOf(nestedPtr))
				continue
			}
		}

		if fieldValue.Kind() == reflect.Struct {
			if tagValue == "" {
				continue
			}
			if tagValue == "---" {
				nestedPtr := reflect.New(reflect.TypeOf(targetValue.Field(i).Interface())).Interface()
				r.setStructFieldsFromRow(nestedPtr, tagKey, rowIndex)
				targetValue.Field(i).Set(reflect.ValueOf(nestedPtr).Elem())
				continue
			}
		}

		if tagValue == "" {
			continue
		}

		// Check if column exists
		if _, ok := r.Row(rowIndex).columnIndex[tagValue]; !ok {
			continue
		}

		// Set field value based on type
		r.setFieldValue(fieldValue, tagValue, rowIndex)
	}
	return nil
}

// setFieldValue sets a single field value
func (r *StarRows) setFieldValue(fieldValue reflect.Value, columnName string, rowIndex int) {
	row := r.Row(rowIndex)

	switch fieldValue.Kind() {
	case reflect.String:
		fieldValue.SetString(row.MustString(columnName))
	case reflect.Int:
		fieldValue.SetInt(int64(row.MustInt(columnName)))
	case reflect.Int8:
		fieldValue.SetInt(int64(int8(row.MustInt64(columnName))))
	case reflect.Int16:
		fieldValue.SetInt(int64(int16(row.MustInt64(columnName))))
	case reflect.Int32:
		fieldValue.SetInt(int64(row.MustInt32(columnName)))
	case reflect.Int64:
		fieldValue.SetInt(row.MustInt64(columnName))
	case reflect.Uint:
		fieldValue.SetUint(uint64(row.MustUint64(columnName)))
	case reflect.Uint8:
		fieldValue.SetUint(uint64(uint8(row.MustUint64(columnName))))
	case reflect.Uint16:
		fieldValue.SetUint(uint64(uint16(row.MustUint64(columnName))))
	case reflect.Uint32:
		fieldValue.SetUint(uint64(uint32(row.MustUint64(columnName))))
	case reflect.Uint64:
		fieldValue.SetUint(row.MustUint64(columnName))
	case reflect.Bool:
		fieldValue.SetBool(row.MustBool(columnName))
	case reflect.Float32:
		fieldValue.SetFloat(float64(row.MustFloat32(columnName)))
	case reflect.Float64:
		fieldValue.SetFloat(row.MustFloat64(columnName))
	case reflect.Interface, reflect.Struct, reflect.Ptr:
		// Handle special types like time.Time
		colIndex := r.columnIndex[columnName]
		val := row.Result()[colIndex]
		if t, ok := val.(time.Time); ok {
			fieldValue.Set(reflect.ValueOf(t))
		}
	}
}

// getStructFieldValues extracts all field values from a struct
func getStructFieldValues(target interface{}, tagKey string) (map[string]interface{}, error) {
	result := make(map[string]interface{})
	targetType := reflect.TypeOf(target)
	targetValue := reflect.ValueOf(target)

	if targetType.Kind() == reflect.Ptr {
		if targetValue.IsNil() {
			return nil, errors.New("pointer target is nil")
		}
		targetType = targetType.Elem()
		targetValue = targetValue.Elem()
	}

	if targetValue.Kind() != reflect.Struct {
		return nil, errors.New("target is not a struct")
	}

	for i := 0; i < targetType.NumField(); i++ {
		field := targetType.Field(i)
		fieldValue := targetValue.Field(i)
		tagValue := field.Tag.Get(tagKey)

		// Handle nested pointer structs
		if fieldValue.Kind() == reflect.Ptr && reflect.TypeOf(fieldValue.Interface()).Elem().Kind() == reflect.Struct {
			if fieldValue.IsNil() {
				continue
			}
			if tagValue == "---" {
				nestedValues, err := getStructFieldValues(reflect.ValueOf(fieldValue.Elem().Interface()).Interface(), tagKey)
				if err != nil {
					return result, err
				}
				for k, v := range nestedValues {
					result[k] = v
				}
				continue
			}
		}

		// Handle nested structs
		if targetValue.Field(i).Kind() == reflect.Struct {
			if tagValue == "---" {
				nestedValues, err := getStructFieldValues(targetValue.Field(i).Interface(), tagKey)
				if err != nil {
					return result, err
				}
				for k, v := range nestedValues {
					result[k] = v
				}
				continue
			}
		}

		if tagValue == "" {
			continue
		}

		if !fieldValue.CanInterface() {
			continue
		}

		result[tagValue] = fieldValue.Interface()
	}

	return result, nil
}

// getStructFieldNames extracts all field names (tag values) from a struct
func getStructFieldNames(target interface{}, tagKey string) ([]string, error) {
	var result []string

	if !isStruct(target) {
		return []string{}, errors.New("target is not a struct")
	}

	targetType := reflect.TypeOf(target)
	targetValue := reflect.ValueOf(target)

	if targetType.Kind() == reflect.Ptr {
		if targetValue.IsNil() {
			return []string{}, errors.New("pointer target is nil")
		}
		targetType = targetType.Elem()
		targetValue = targetValue.Elem()
	}

	for i := 0; i < targetType.NumField(); i++ {
		fieldValue := targetValue.Field(i)
		field := targetType.Field(i)
		tagValue := field.Tag.Get(tagKey)

		// Handle nested pointer structs
		if fieldValue.Kind() == reflect.Ptr && reflect.TypeOf(fieldValue.Interface()).Elem().Kind() == reflect.Struct {
			if fieldValue.IsNil() {
				continue
			}
			if tagValue == "---" {
				nestedNames, err := getStructFieldNames(reflect.ValueOf(fieldValue.Elem().Interface()).Interface(), tagKey)
				if err != nil {
					return result, err
				}
				result = append(result, nestedNames...)
				continue
			}
		}

		// Handle nested structs
		if targetValue.Field(i).Kind() == reflect.Struct && tagValue == "---" {
			nestedNames, err := getStructFieldNames(targetValue.Field(i).Interface(), tagKey)
			if err != nil {
				return result, err
			}
			result = append(result, nestedNames...)
			continue
		}

		if tagValue != "" {
			result = append(result, tagValue)
		}
	}

	return result, nil
}

// isWritable checks if a value is writable
func isWritable(target interface{}) bool {
	targetType := reflect.TypeOf(target)
	targetValue := reflect.ValueOf(target)
	return targetType.Kind() == reflect.Ptr || targetValue.CanSet()
}

// isStruct checks if a value is a struct
func isStruct(target interface{}) bool {
	targetValue := reflect.ValueOf(target)
	if targetValue.Kind() == reflect.Ptr {
		targetValue = targetValue.Elem()
	}
	return targetValue.Kind() == reflect.Struct
}