package special

import (
	"encoding/json"
	"errors"
	"io"
	"os"
	"slices"
	"strings"

	"github.com/Loyalsoldier/geoip/lib"
)

const (
	TypeStdout = "stdout"
	DescStdout = "Convert data to plaintext CIDR format and output to standard output"
)

func init() {
	lib.RegisterOutputConfigCreator(TypeStdout, func(action lib.Action, data json.RawMessage) (lib.OutputConverter, error) {
		return newStdout(action, data)
	})
	lib.RegisterOutputConverter(TypeStdout, &Stdout{
		Description: DescStdout,
	})
}

func newStdout(action lib.Action, data json.RawMessage) (lib.OutputConverter, error) {
	var tmp struct {
		Want       []string   `json:"wantedList"`
		Exclude    []string   `json:"excludedList"`
		OnlyIPType lib.IPType `json:"onlyIPType"`
	}

	if len(data) > 0 {
		if err := json.Unmarshal(data, &tmp); err != nil {
			return nil, err
		}
	}

	return &Stdout{
		Type:        TypeStdout,
		Action:      action,
		Description: DescStdout,
		Want:        tmp.Want,
		Exclude:     tmp.Exclude,
		OnlyIPType:  tmp.OnlyIPType,
	}, nil
}

type Stdout struct {
	Type        string
	Action      lib.Action
	Description string
	Want        []string
	Exclude     []string
	OnlyIPType  lib.IPType
}

func (s *Stdout) GetType() string {
	return s.Type
}

func (s *Stdout) GetAction() lib.Action {
	return s.Action
}

func (s *Stdout) GetDescription() string {
	return s.Description
}

func (s *Stdout) Output(container lib.Container) error {
	for _, name := range s.filterAndSortList(container) {
		entry, found := container.GetEntry(name)
		if !found {
			continue
		}

		cidrList, err := s.generateCIDRList(entry)
		if err != nil {
			continue
		}

		for _, cidr := range cidrList {
			io.WriteString(os.Stdout, cidr+"\n")
		}
	}

	return nil
}

func (s *Stdout) filterAndSortList(container lib.Container) []string {
	excludeMap := make(map[string]bool)
	for _, exclude := range s.Exclude {
		if exclude = strings.ToUpper(strings.TrimSpace(exclude)); exclude != "" {
			excludeMap[exclude] = true
		}
	}

	wantList := make([]string, 0, len(s.Want))
	for _, want := range s.Want {
		if want = strings.ToUpper(strings.TrimSpace(want)); want != "" && !excludeMap[want] {
			wantList = append(wantList, want)
		}
	}

	if len(wantList) > 0 {
		// Sort the list
		slices.Sort(wantList)
		return wantList
	}

	list := make([]string, 0, 300)
	for entry := range container.Loop() {
		name := entry.GetName()
		if excludeMap[name] {
			continue
		}
		list = append(list, name)
	}

	// Sort the list
	slices.Sort(list)

	return list
}

func (s *Stdout) generateCIDRList(entry *lib.Entry) ([]string, error) {
	var entryList []string
	var err error
	switch s.OnlyIPType {
	case lib.IPv4:
		entryList, err = entry.MarshalText(lib.IgnoreIPv6)
	case lib.IPv6:
		entryList, err = entry.MarshalText(lib.IgnoreIPv4)
	default:
		entryList, err = entry.MarshalText()
	}
	if err != nil {
		return nil, err
	}

	if len(entryList) == 0 {
		return nil, errors.New("empty CIDR list")
	}

	return entryList, nil
}