package subscriptions

import (
	"context"
	"encoding/json"
	"fmt"
	"strings"
	"sync"
	"time"

	"github.com/google/uuid"
	"github.com/gorilla/websocket"
	"github.com/llehouerou/go-graphql-client"
	"github.com/pkg/errors"
	"github.com/rs/zerolog/log"
)

const WSURL = "wss://ws.sorare.com/cable"

type wsClient[T any] struct {
	cancel context.CancelFunc
	c      *websocket.Conn

	Done chan struct{}

	rawMessageChan chan []byte
	writeChan      chan []byte

	lastPing  time.Time
	pingMutex *sync.Mutex

	Data               chan T
	subscriptionName   string
	subscriptionParams string

	channelId string

	debug bool
}

func newWsClient[T any](
	ctx context.Context,
	subscriptionName string,
	subscriptionParams string,
	debug bool,
) (*wsClient[T], error) {
	localctx, cancel := context.WithCancel(ctx)
	channelId := uuid.New().String()[0:7]
	w := &wsClient[T]{
		cancel:             cancel,
		rawMessageChan:     make(chan []byte),
		writeChan:          make(chan []byte),
		lastPing:           time.Now(),
		pingMutex:          &sync.Mutex{},
		Data:               make(chan T),
		subscriptionName:   subscriptionName,
		subscriptionParams: subscriptionParams,
		Done:               make(chan struct{}),
		debug:              debug,

		channelId: channelId,
	}
	err := w.connect()
	if err != nil {
		return nil, errors.Wrap(err, "connecting websocket")
	}
	go w.processMessages()
	go w.readMessages(localctx)
	go w.writeMessages(localctx)

	err = w.subscribe()
	if err != nil {
		return nil, errors.Wrap(err, "subscribing")
	}
	return w, nil
}

func (w *wsClient[T]) connect() error {
	dialer := &websocket.Dialer{
		HandshakeTimeout:  30 * time.Second,
		EnableCompression: true,
	}
	connection, _, err := dialer.Dial(WSURL, nil)
	if err != nil {
		return errors.Wrap(err, "dialing websocket")
	}

	w.c = connection
	return nil
}

type WsMessage struct {
	Type    string
	Message json.RawMessage
}

type WsError struct {
	Message   string
	Locations []struct {
		Line   int
		Column int
	}
	Path       []string
	Extensions struct {
		Code         string
		TypeName     string `json:"typeName"`
		ArgumentName string `json:"argumentName"`
	}
}

func (w *wsClient[T]) processMessage(message json.RawMessage) error {
	var m struct {
		More   bool
		Result struct {
			Data   map[string]json.RawMessage
			Errors []WsError
		}
	}
	err := json.Unmarshal(message, &m)
	if err != nil {
		return errors.Wrap(err, "unmarshalling message")
	}

	if len(m.Result.Errors) > 0 {
		return errors.New("graphql errors")
	}

	if len(m.Result.Data) == 0 {
		return nil
	}
	data, ok := m.Result.Data[w.subscriptionName]
	if !ok {
		return nil
	}
	if string(data) == "null" {
		return nil
	}

	var unmarshalledData T
	err = graphql.UnmarshalGraphQL(data, &unmarshalledData)
	if err != nil {
		return errors.Wrap(err, "unmarshalling graphql data")
	}

	w.Data <- unmarshalledData

	if !m.More {
		w.Stop()
	}
	return nil
}

func (w *wsClient[T]) Stop() {
	w.cancel()
	_ = w.c.Close()
}

func (w *wsClient[T]) processMessages() {
	defer close(w.Data)
	for message := range w.rawMessageChan {
		if w.debug {
			fmt.Println("<-- " + string(message))
		}
		var m WsMessage
		err := json.Unmarshal(message, &m)
		if err != nil {
			log.Error().Err(err).Msg("unmarshalling message")
			continue
		}

		switch m.Type {
		case "welcome":
		case "ping":
			err = w.processPing(m.Message)
			if err != nil {
				log.Error().Err(err).Msg("unmarshalling message")
				continue
			}
		case "":
			err = w.processMessage(m.Message)
			if err != nil {
				log.Error().Err(err).Msg("unmarshalling message")
				continue
			}
		}
	}
}

type PingMessage time.Time

func (p *PingMessage) UnmarshalJSON(bytes []byte) error {
	var raw int64
	err := json.Unmarshal(bytes, &raw)
	if err != nil {
		return errors.Wrap(err, "unmarshalling ping message")
	}
	*p = PingMessage(time.Unix(raw, 0))
	return nil
}

func (p *PingMessage) Time() time.Time {
	return time.Time(*p)
}

func (w *wsClient[T]) processPing(message json.RawMessage) error {
	var m PingMessage
	err := json.Unmarshal(message, &m)
	if err != nil {
		return errors.Wrap(err, "unmarshalling ping message")
	}
	w.pingMutex.Lock()
	w.lastPing = m.Time()
	w.pingMutex.Unlock()
	return nil
}

func (w *wsClient[T]) writeMessages(ctx context.Context) {
	for {
		select {
		case <-ctx.Done():
			return
		case d := <-w.writeChan:
			if w.debug {
				fmt.Println("--> " + string(d))
			}
			err := w.c.WriteMessage(websocket.TextMessage, d)
			if err != nil {
				continue
			}
		}
	}
}

func (w *wsClient[T]) readMessages(ctx context.Context) {
	defer close(w.rawMessageChan)
	defer close(w.Done)
	w.c.SetCloseHandler(func(code int, text string) error {
		return nil
	})

	w.c.SetPongHandler(func(pong string) error {
		return nil
	})

	w.c.SetPingHandler(func(ping string) error {
		return nil
	})

	for {
		select {
		case <-ctx.Done():
			return
		default:
			t, msg, err := w.c.ReadMessage()
			if err != nil {
				return
			}

			switch t {
			case websocket.TextMessage:
				w.rawMessageChan <- msg
			case websocket.BinaryMessage:
			default:
			}
		}
	}

}

type identifier struct {
	Channel   string `json:"channel"`
	ChannelId string `json:"channelId"`
}

type message struct {
	Command    string `json:"command"`
	Identifier string `json:"identifier"`
	Data       string `json:"data,omitempty"`
}

type queryData struct {
	Action        string   `json:"action"`
	Query         string   `json:"query"`
	Variables     []string `json:"variables,omitempty"`
	OperationName string   `json:"operationName,omitempty"`
}

func (w *wsClient[T]) sendMessage(message any) error {
	data, err := json.Marshal(message)
	if err != nil {
		return errors.Wrap(err, "marshalling message")
	}
	w.writeChan <- data
	return nil
}

func (w *wsClient[T]) subscribe() error {
	go func() {
		identifier, err := json.Marshal(identifier{
			Channel:   "GraphqlChannel",
			ChannelId: w.channelId,
		})
		if err != nil {
			return
		}
		err = w.sendMessage(message{
			Command:    "subscribe",
			Identifier: string(identifier),
		})
		if err != nil {
			return
		}

		time.Sleep(5 * time.Second)

		var query struct {
			SubscriptionName T
		}
		queryMarshalled, err := graphql.ConstructSubscription(query, nil)
		if err != nil {
			return
		}
		queryMarshalled = strings.Replace(
			queryMarshalled,
			"subscriptionName",
			w.subscriptionName+w.subscriptionParams,
			1,
		)

		querystr, err := json.Marshal(queryData{
			Action: "execute",
			Query:  queryMarshalled,
		})
		if err != nil {
			return
		}

		err = w.sendMessage(message{
			Command:    "message",
			Identifier: string(identifier),
			Data:       string(querystr),
		})
		if err != nil {
			return
		}

	}()
	return nil

}