package rest

import (
	"errors"
	"fmt"
	"reflect"

	"git.ali33.ru/fcg-xvii/go-tools/json"
)

type IFielder interface {
	Fields(...any) (json.Map, error)
}

type IFieldChecker interface {
	FieldCheck(string) bool
}

/////////////////////////////////////////////////

func NewFielder(source any) *Fielder {
	res := &Fielder{
		source: source,
		fields: make(map[string]reflect.Value),
	}
	res._Prepare()
	return res
}

type Fielder struct {
	source  any
	fields  map[string]reflect.Value
	checker IFieldChecker
}

func (s *Fielder) _Prepare() {
	s.checker, _ = s.source.(IFieldChecker)
	val := reflect.ValueOf(s.source).Elem()
	for i := 0; i < val.NumField(); i++ {
		fName := val.Type().Field(i)
		field := val.Field(i)
		s.fields[CamelToSnake(fName.Name)] = field
	}
}

func (s *Fielder) Fields(names ...any) (json.Map, error) {
	res := make(json.Map)
	for _, rName := range names {
		var name string
		var fields []any
		if sName, check := rName.(string); check {
			name = sName
		} else if sMap, check := rName.(map[string]any); check {
			name = fmt.Sprint(sMap["name"])
			if rFields, check := sMap["fields"]; check {
				if rxFields, check := rFields.([]any); check {
					fields = rxFields
				}
			}
		}
		permission := true
		if s.checker != nil {
			permission = s.checker.FieldCheck(name)
		}
		val, check := s.fields[name]
		if check && permission {
			iface := val.Interface()
			if val.Kind() == reflect.Ptr {
				if val.IsNil() {
					res[name] = nil
				} else {
					if fielder, check := iface.(IFielder); check {
						xVal, err := fielder.Fields(fields...)
						if err != nil {
							return nil, err
						}
						res[name] = xVal
					}
				}
			} else {
				res[name] = val.Interface()
			}
		} else {
			return nil, errors.New(name)
		}
	}
	return res, nil
}