package router

import (
	"fmt"
	"reflect"
	"strings"
)

type genericValues map[string][]string

func (gv genericValues) Marshal(data any, tag string) (err error) {
	if gv == nil {
		gv = make(genericValues)
	}
	d := reflect.ValueOf(data)
	if d.Kind() == reflect.Pointer || d.Kind() == reflect.Interface {
		d = d.Elem()
	}
	if d.Kind() != reflect.Struct {
		err = fmt.Errorf("expected struct input for data")
		return
	}
	for i := 0; i < d.NumField(); i++ {
		key, ok := d.Type().Field(i).Tag.Lookup(tag)
		if !ok || key == "" {
			continue
		}
		v := make([]string, 0)
		val := d.Field(i)
		if val.Kind() == reflect.Pointer || val.Kind() == reflect.Interface {
			val = val.Elem()
		}
		if val.Kind() == reflect.Slice || val.Kind() == reflect.Array {
			for j := 0; j < val.Len(); j++ {
				item := val.Index(j)
				if item.Kind() == reflect.Pointer || item.Kind() == reflect.Interface {
					item = item.Elem()
				}
				v = append(v, fmt.Sprintf("%s", item.Interface()))
			}
		} else {
			v = append(v, fmt.Sprintf("%s", val.Interface()))
		}
		gv[key] = v
	}
	return
}

func (gv genericValues) Unmarshal(data any, tag string) (err error) {
	if gv == nil {
		err = fmt.Errorf("expected map to exist")
		return
	}
	d := reflect.ValueOf(data)
	if d.Kind() != reflect.Pointer || d.Kind() != reflect.Interface {
		err = fmt.Errorf("expected pointer for data")
		return
	}
	d = d.Elem()
	if d.Kind() != reflect.Struct {
		err = fmt.Errorf("expected struct input for data")
		return
	}
	for key, value := range gv {
		var v reflect.Value
		if len(value) == 1 {
			v = reflect.ValueOf(value[0])
		} else {
			v = reflect.ValueOf(value)
		}
		for i := 0; i < d.NumField(); i++ {
			k, ok := d.Type().Field(i).Tag.Lookup(tag)
			if !ok || k != key {
				continue
			}
			val := d.Field(i)
			if val.Kind() == reflect.Pointer || val.Kind() == reflect.Interface {
				val = val.Elem()
			}
			if !val.CanSet() {
				err = fmt.Errorf("could not set value for %s", d.Type().Field(i).Name)
			}
			switch val.Kind() {
			case reflect.String:
				val.Set(reflect.ValueOf(strings.Join(value, "; ")))
			default:
				if v.CanConvert(val.Type()) {
					val.Set(v.Convert(val.Type()))
				}
			}
		}
	}
	return
}