package rpc

import (
	"errors"
	"fmt"
	"net/http"

	"github.com/waku-org/go-waku/cmd/waku/server"
	"github.com/waku-org/go-waku/logging"
	"github.com/waku-org/go-waku/waku/v2/node"
	"github.com/waku-org/go-waku/waku/v2/protocol"
	"github.com/waku-org/go-waku/waku/v2/protocol/relay"
	"go.uber.org/zap"
)

var errChannelClosed = errors.New("consume channel is closed for subscription")

// RelayService represents the JSON RPC service for WakuRelay
type RelayService struct {
	node *node.WakuNode

	log *zap.Logger

	cacheCapacity int
}

// RelayMessageArgs represents the requests used for posting messages
type RelayMessageArgs struct {
	Topic   string          `json:"topic,omitempty"`
	Message *RPCWakuMessage `json:"message,omitempty"`
}

// RelayAutoMessageArgs represents the requests used for posting messages
type RelayAutoMessageArgs struct {
	Message *RPCWakuMessage `json:"message,omitempty"`
}

// TopicsArgs represents the lists of topics to use when subscribing / unsubscribing
type TopicsArgs struct {
	Topics []string `json:"topics,omitempty"`
}

// TopicArgs represents a request that contains a single topic
type TopicArgs struct {
	Topic string `json:"topic,omitempty"`
}

// NewRelayService returns an instance of RelayService
func NewRelayService(node *node.WakuNode, cacheCapacity int, log *zap.Logger) *RelayService {
	s := &RelayService{
		node:          node,
		cacheCapacity: cacheCapacity,
		log:           log.Named("relay"),
	}

	return s
}

// Start starts the RelayService
func (r *RelayService) Start() {
}

// Stop stops the RelayService
func (r *RelayService) Stop() {
}

// PostV1Message is invoked when the json rpc request uses the post_waku_v2_relay_v1_message method
func (r *RelayService) PostV1Message(req *http.Request, args *RelayMessageArgs, reply *SuccessReply) error {
	var err error

	topic := relay.DefaultWakuTopic
	if args.Topic != "" {
		topic = args.Topic
	}

	msg, err := args.Message.toProto()
	if err != nil {
		return err
	}

	if err = server.AppendRLNProof(r.node, msg); err != nil {
		return err
	}

	_, err = r.node.Relay().Publish(req.Context(), msg, relay.WithPubSubTopic(topic))
	if err != nil {
		r.log.Error("publishing message", zap.Error(err))
		return err
	}

	*reply = true
	return nil
}

// PostV1AutoSubscription is invoked when the json rpc request uses the post_waku_v2_relay_v1_auto_subscription
// Note that this method takes contentTopics as an argument instead of pubsubtopics and uses autosharding to derive pubsubTopics.
func (r *RelayService) PostV1AutoSubscription(req *http.Request, args *TopicsArgs, reply *SuccessReply) error {

	_, err := r.node.Relay().Subscribe(r.node.Relay().Context(), protocol.NewContentFilter("", args.Topics...), relay.WithCacheSize(uint(r.cacheCapacity)))
	if err != nil {
		r.log.Error("subscribing to topics", zap.Strings("topics", args.Topics), zap.Error(err))
		return err
	}
	//TODO: Handle partial errors.

	*reply = true
	return nil
}

// DeleteV1AutoSubscription is invoked when the json rpc request uses the delete_waku_v2_relay_v1_auto_subscription
// Note that this method takes contentTopics as an argument instead of pubsubtopics and uses autosharding to derive pubsubTopics.
func (r *RelayService) DeleteV1AutoSubscription(req *http.Request, args *TopicsArgs, reply *SuccessReply) error {
	ctx := req.Context()

	err := r.node.Relay().Unsubscribe(ctx, protocol.NewContentFilter("", args.Topics...))
	if err != nil {
		r.log.Error("unsubscribing from topics", zap.Strings("topic", args.Topics), zap.Error(err))
		return err
	}
	//TODO: Handle partial errors.
	*reply = true
	return nil
}

// PostV1AutoMessage is invoked when the json rpc request uses the post_waku_v2_relay_v1_auto_message
func (r *RelayService) PostV1AutoMessage(req *http.Request, args *RelayAutoMessageArgs, reply *SuccessReply) error {
	msg, err := args.Message.toProto()
	if err != nil {
		err = fmt.Errorf("invalid message format received: %w", err)
		r.log.Error("publishing message", zap.Error(err))
		return err
	}

	if err = server.AppendRLNProof(r.node, msg); err != nil {
		return err
	}

	_, err = r.node.Relay().Publish(req.Context(), msg)
	if err != nil {
		r.log.Error("publishing message", zap.Error(err))
		return err
	}

	*reply = true
	return nil
}

// GetV1AutoMessages is invoked when the json rpc request uses the get_waku_v2_relay_v1_auto_messages method
// Note that this method takes contentTopic as an argument instead of pubSubtopic and uses autosharding.
func (r *RelayService) GetV1AutoMessages(req *http.Request, args *TopicArgs, reply *MessagesReply) error {
	sub, err := r.node.Relay().GetSubscription(args.Topic)
	if err != nil {
		return err
	}
	select {
	case msg, open := <-sub.Ch:
		if !open {
			r.log.Error("consume channel is closed for subscription", zap.String("pubsubTopic", args.Topic))
			return errChannelClosed
		}
		rpcMsg, err := ProtoToRPC(msg.Message())
		if err != nil {
			r.log.Warn("could not include message in response", logging.HexBytes("hash", msg.Hash()), zap.Error(err))
		} else {
			*reply = append(*reply, rpcMsg)
		}
	default:
		break
	}
	return nil
}

// PostV1Subscription is invoked when the json rpc request uses the post_waku_v2_relay_v1_subscription method
func (r *RelayService) PostV1Subscription(req *http.Request, args *TopicsArgs, reply *SuccessReply) error {

	for _, topic := range args.Topics {
		var err error
		if topic == "" {
			topic = relay.DefaultWakuTopic
		}
		_, err = r.node.Relay().Subscribe(r.node.Relay().Context(), protocol.NewContentFilter(topic), relay.WithCacheSize(uint(r.cacheCapacity)))
		if err != nil {
			r.log.Error("subscribing to topic", zap.String("topic", topic), zap.Error(err))
			return err
		}

	}

	*reply = true
	return nil
}

// DeleteV1Subscription is invoked when the json rpc request uses the delete_waku_v2_relay_v1_subscription method
func (r *RelayService) DeleteV1Subscription(req *http.Request, args *TopicsArgs, reply *SuccessReply) error {
	ctx := req.Context()
	for _, topic := range args.Topics {
		err := r.node.Relay().Unsubscribe(ctx, protocol.NewContentFilter(topic))
		if err != nil {
			r.log.Error("unsubscribing from topic", zap.String("topic", topic), zap.Error(err))
			return err
		}
	}

	*reply = true
	return nil
}

// GetV1Messages is invoked when the json rpc request uses the get_waku_v2_relay_v1_messages method
func (r *RelayService) GetV1Messages(req *http.Request, args *TopicArgs, reply *MessagesReply) error {

	sub, err := r.node.Relay().GetSubscriptionWithPubsubTopic(args.Topic, "")
	if err != nil {
		return err
	}
	select {
	case msg, open := <-sub.Ch:
		if !open {
			r.log.Error("consume channel is closed for subscription", zap.String("pubsubTopic", args.Topic))
			return errChannelClosed
		}
		m, err := ProtoToRPC(msg.Message())
		if err == nil {
			*reply = append(*reply, m)
		}
	default:
		break
	}
	return nil
}