package form

// @license GNU AGPL version 3 or any later version
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

import (
	"encoding/json"
	"reflect"

	"github.com/spf13/cast"
	"gitnet.fr/deblan/go-form/validation"
)

type Choice struct {
	Value string
	Label string
	Data  any
}

func (c Choice) Match(value string) bool {
	return c.Value == value
}

type Choices struct {
	Data         any                            `json:"data"`
	ValueBuilder func(key int, item any) string `json:"-"`
	LabelBuilder func(key int, item any) string `json:"-"`
}

func (c *Choices) Match(f *Field, value string) bool {
	if f.Data == nil {
		return false
	}

	if f.IsSlice {
		v := reflect.ValueOf(f.Data)

		for key, _ := range c.GetChoices() {
			for i := 0; i < v.Len(); i++ {
				item := v.Index(i).Interface()

				switch item.(type) {
				case string:
					if item == value {
						return true
					}
				default:
					if c.ValueBuilder(key, item) == value {
						return true
					}
				}
			}
		}

		return false
	}

	return f.Data == value
}

func (c *Choices) WithValueBuilder(builder func(key int, item any) string) *Choices {
	c.ValueBuilder = builder

	return c
}

func (c *Choices) WithLabelBuilder(builder func(key int, item any) string) *Choices {
	c.LabelBuilder = builder

	return c
}

func (c *Choices) GetChoices() []Choice {
	choices := []Choice{}

	v := reflect.ValueOf(c.Data)

	switch v.Kind() {
	case reflect.Slice, reflect.Array, reflect.String, reflect.Map:
		for i := 0; i < v.Len(); i++ {
			choices = append(choices, Choice{
				Value: c.ValueBuilder(i, v.Index(i).Interface()),
				Label: c.LabelBuilder(i, v.Index(i).Interface()),
				Data:  v.Index(i).Interface(),
			})
		}
	}

	return choices
}

func (c Choices) MarshalJSON() ([]byte, error) {
	var choices []map[string]string

	v := reflect.ValueOf(c.Data)

	switch v.Kind() {
	case reflect.Slice, reflect.Array, reflect.String, reflect.Map:
		for i := 0; i < v.Len(); i++ {
			choices = append(choices, map[string]string{
				"value": c.ValueBuilder(i, v.Index(i).Interface()),
				"label": c.LabelBuilder(i, v.Index(i).Interface()),
			})
		}
	}

	return json.Marshal(choices)
}

// Generates an instance of Choices
func NewChoices(items any) *Choices {
	builder := func(key int, item any) string {
		return cast.ToString(key)
	}

	choices := Choices{
		ValueBuilder: builder,
		LabelBuilder: builder,
		Data:         items,
	}

	return &choices
}

// Generates inputs (checkbox or radio) or selects
func NewFieldChoice(name string) *Field {
	f := NewField(name, "choice").
		WithOptions(
			NewOption("choices", &Choices{}),
			NewOption("expanded", false),
			NewOption("multiple", false),
			NewOption("empty_choice_label", "None"),
		)

	f.Validate = func(field *Field) bool {
		isValid := field.Validate(field)

		if len(validation.NewNotBlank().Validate(field.Data)) == 0 {
			choices := field.GetOption("choices").Value.(*Choices)
			isValidChoice := false

			for _, choice := range choices.GetChoices() {
				if choices.Match(field, choice.Value) {
					isValidChoice = true
				}
			}

			if !isValidChoice {
				field.Errors = append(field.Errors, validation.Error("This value is not valid."))
				isValid = false
			}
		}

		return isValid
	}

	f.WithBeforeBind(func(data any) (any, error) {
		choices := f.GetOption("choices").Value.(*Choices)

		switch data.(type) {
		case string:
			v := data.(string)
			for _, c := range choices.GetChoices() {
				if c.Match(v) {
					return c.Data, nil
				}
			}
		case []string:
			v := reflect.ValueOf(data)
			var res []interface{}

			for _, choice := range choices.GetChoices() {
				for i := 0; i < v.Len(); i++ {
					item := v.Index(i).Interface().(string)
					if choice.Match(item) {
						res = append(res, choice.Data)
					}
				}
			}

			return res, nil
		}

		return data, nil
	})

	return f
}